Lowland

Forest

Loss

in

Protected

Areas

of

Indonesian

Borneo

L.

M.

Curran

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We

thank

J.

Zipfel

for

loaning

thin

sections

of

Dar

al

Gani

and

Dar

al

Gani

C.

M.

Allen

for

her

help

and

fruitful

discussions

concerning

LA-ICPMS

data

reduction

and

H.

St.

O'Neill

and

D.

Kelly

for

their

support

during

the

stay

of

A.P.

at

Australian

National

University

Supported

by

Deutsche

Forschungsgemeinschaft

grants

PA

-LRB-

H.P.

-RRB-

and

-LRB-

A.P.

DFG

Emmy

Noether-Programm

-RRB-

Supporting

Online

Material

Materials

and

Methods

References

October

accepted

January

Lowland

Forest

Loss

in

Protected

Areas

of

Indonesian

Borneo

L.

M.

Curran

S.

N.

Trigg

A.

K.

McDonald

D.

Astiani

Y.

M.

Hardiono

P.

Siregar

I.

Caniago

E.

The

ecology

of

Bornean

rainforests

is

driven

by

El

Nino

induced

droughts

that

trigger

synchronous

fruiting

among

trees

and

bursts

of

faunal

reproduction

that

sustain

vertebrate

populations

However

many

of

these

species

and

carbonrich

ecosystems

have

been

destroyed

by

logging

and

conversion

which

increasingly

threaten

protected

areas

Our

satellite

Geographic

Information

System

and

field-based

analyses

show

that

from

to

Kalimantan

's

protected

lowland

forests

declined

by

more

than

-LRB-

square

kilometers

-RRB-

Even

uninhabited

frontier

parks

are

logged

to

supply

international

markets

Protected

forests

have

become

increasingly

isolated

and

deforested

and

their

buffer

zones

degraded

Preserving

the

ecological

integrity

of

Kalimantan

's

rainforests

requires

immediate

transnational

management

Conversion

degradation

and

fragmentation

threaten

the

integrity

of

forested

ecosystems

worldwide

-LRB-

-RRB-

In

Indonesian

Borneo

-LRB-

Kalimantan

-RRB-

concession-based

timber

extraction

plantation

establishment

and

weak

institutions

have

resulted

in

highly

fragmented

and

degraded

forests

-LRB-

-RRB-

In

such

dynamic

tropical

rainforest

frontiers

with

high

biodiversity

-LRB-

-RRB-

investigations

are

required

at

local

to

regional

scales

to

understand

how

changes

in

land

use

and

land

cover

alter

ecological

interactions

-LRB-

-RRB-

Kalimantan

's

rainforests

are

driven

by

El

Nino

Southern

Oscillation

events

which

trig

ger

synchronous

fruiting

among

the

regionally

dominant

timber

trees

the

Dipterocarpaceae

and

bursts

of

faunal

reproduction

-LRB-

-RRB-

Dipterocarp

reproductive

cycles

are

linked

to

rural

livelihoods

communities

both

trade

dipterocarp

seeds

and

hunt

wild

game

-LRB-

primarily

bearded

pigs

-RRB-

that

eat

dipterocarp

Yale

School

of

Forestry

and

Environmental

Studies

Prospect

Street

New

Haven

CT

USA

Department

of

Geography

University

of

Maryland

College

Park

MD

USA

of

Forestry

University

of

Tanjungpura

Pontianak

West

Kalimantan

Indonesia

Abdurrachman

Saleh

Pontianak

West

Kalimantan

Indonesia

To

whom

correspondence

should

be

addressed

Email

lisa.curran@yale.edu

fruit

-LRB-

-RRB-

However

forest

fragmentation

and

land

cover

change

have

transformed

El

Nino

from

a

regenerative

to

a

highly

destruc

tive

phenomenon

one

that

triggers

droughts

and

wildfires

with

increasing

frequency

and

intensity

disrupts

dipterocarp

fruiting

interrupts

wildlife

reproductive

cycles

and

erodes

the

basis

for

rural

livelihoods

-LRB-

-RRB-

Protected

areas

-LSB-

PAs

including

IUCN

-LRB-

World

Conservation

Union

-RRB-

Categories

I

to

VI

-RSB-

of

sufficient

extent

and

connectivity

are

required

to

sustain

ecological

integrity

Although

of

Kalimantan

's

land

area

-LRB-

-RRB-

was

allocated

to

industrial

federal

forest

uses

from

to

PAs

were

delineated

or

redrawn

in

and

to

maintain

representative

ecosystems

and

to

be

managed

by

the

government

-LRB-

-RRB-

Since

then

however

PAs

have

experienced

concomitant

threats

from

logging

wildfires

and

conversion

Conserving

Kalimantan

's

PAs

requires

current

information

on

their

condition

and

the

nature

of

the

threats

they

face

Within

PAs

we

mapped

lowland

deforestation

and

measured

deforestation

rates

within

a

nested

design

We

assessed

Gunung

Palung

National

Park

-LRB-

GPNP

-RRB-

in

West

Kalimantan

and

its

buffer

zone

-LRB-

spatial

extent

-RRB-

from

to

the

West

Kalimantan

province

-LRB-

-RRB-

in

and

Kalimantan

as

a

whole

-LRB-

-RRB-

in

-LRB-

Fig.

-RRB-

-LRB-

-RRB-

We

determined

the

distribution

and

condition

of

remaining

lowlands

-LSB-

m

above

sea

level

-LRB-

a.s.l.

-RRB-

rather

than

m

-RSB-

because

such

forests

contain

distinctive

dipterocarp

habitats

the

majority

of

vertebrates

the

greatest

canopy

tree

diversity

and

the

majority

of

land

used

by

humans

Major

drivers

of

deforestation

were

identified

from

West

Kalimantan

field

studies

-LRB-

-RRB-

and

contrasted

with

those

reported

for

PAs

elsewhere

GPNP

was

selected

for

our

detailed

case

study

because

of

its

biological

importance

-LRB-

-RRB-

and

our

field-based

research

within

GPNP

and

surrounds

from

to

Because

West

Kalimantan

contains

the

largest

PA

network

of

lowland

dipterocarp

forest

in

Kalimantan

this

province

served

as

our

focal

region

For

the

GPNP

time-series

and

West

Kalimantan

analyses

we

mapped

forest

and

nonforest

using

spatial

resolution

satellite

images

The

Kalimantan-wide

analysis

used

satellite

images

at

a

coarser

spatial

resolution

-LRB-

m

-RRB-

Images

were

classified

into

forest

or

nonforest

classes

with

supervised

classification

and

visual

interpretation

results

were

validated

with

field

and

aerial

surveys

-LRB-

from

to

-RRB-

and

with

reference

satellite

images

with

fine

spatial

resolution

-LRB-

m

and

m

-RRB-

-LRB-

-RRB-

Our

GPNP

time-series

analysis

-LRB-

Fig.

-RRB-

documents

expansive

and

accelerating

deforestation

Within

the

park

's

Fig.

Our

case

study

area

GPNP

and

its

surrounding

buffer

-LRB-

black

-RRB-

is

located

on

the

southwest

coast

of

the

island

of

Borneo

in

the

province

of

West

Kalimantan

-LRB-

light

gray

-RRB-

Other

areas

of

Borneo

surrounding

Indonesian

islands

and

East

Timor

are

depicted

in

dark

gray

FEBRUARY

VOL

SCIENCE

Downloaded

from

on

May

REPORTS

wide

buffer

strip

surrounding

the

outer

perimeter

of

the

reserve

of

lowlands

were

deforested

-LRB-

year

-RRB-

from

to

leaving

of

the

buffer

in

lowland

forest

From

to

of

GPNP

's

lowlands

were

deforested

-LRB-

year

-RRB-

Because

of

the

high

density

and

volume

-LRB-

to

ha

-RRB-

of

commercial

timber

-LRB-

of

which

is

dipterocarps

-RRB-

in

Kalimantan

intensively

logged

forests

typically

have

of

the

canopy

basal

area

removed

or

destroyed

-LRB-

-RRB-

Deforestation

within

GPNP

's

buffer

resulted

primarily

from

intensive

logging

by

timber

concessions

followed

by

the

clear

cutting

of

residual

stands

by

oil

palm

plantations

-LSB-

concessions

and

plantations

comprise

of

the

buffer

zone

-LRB-

Fig.

-RRB-

-RSB-

After

when

of

the

buffer

remained

forested

a

rapid

acceleration

of

deforestation

-LRB-

year

-RRB-

occurred

within

GPNP

-LRB-

Fig.

-RRB-

Lowland

PAs

such

as

GPNP

are

critical

to

maintaining

Borneo

's

biodiversity

More

than

resident

bird

and

mammal

species

occur

on

Borneo

of

these

birds

and

to

of

the

mammals

are

confined

to

lowland

forests

including

of

the

endemic

avian

and

of

the

endemic

mammalian

species

-LRB-

-RRB-

GPNP

harbors

or

of

Bornean

bird

species

-LRB-

-RRB-

and

mammal

species

that

depend

on

lowlands

-LRB-

-RRB-

Logging

within

GPNP

's

lowlands

will

adversely

affect

biodiversity

in

addition

to

felling

dipterocarp

trees

logging

removes

the

associated

asynchronously

fruiting

hemiepiphytic

figs

-LRB-

Ficus

spp.

-RRB-

that

serve

as

keystone

resources

for

local

vertebrates

-LRB-

-RRB-

In

this

region

at

least

to

avian

species

-LRB-

to

of

the

avifauna

-RRB-

respond

negatively

to

lowland

forest

fragmentation

and

or

logging

-LRB-

-RRB-

Although

mammalian

response

to

such

conditions

varies

by

species

and

guilds

lowland-dependent

species

occur

at

much

reduced

densities

in

logged

forests

For

example

GPNP

with

of

Borneo

's

population

of

endangered

orangutans

experienced

a

to

reduction

in

orangutan

densities

in

logged

areas

compared

with

unlogged

areas

-LRB-

-RRB-

Given

the

deforestation

observed

at

our

case

study

site

analyses

were

extended

to

evaluate

all

lowland

PAs

across

West

Kalimantan

In

-LRB-

-RRB-

of

West

Kalimantan

PAs

-LRB-

spatial

extent

-RRB-

contained

well-drained

lowland

dipterocarp

forest

-LRB-

fig

-RRB-

Nonlowland

PAs

were

remote

montane

or

swamp

forests

with

relatively

low

economic

value

for

timber

Our

combined

Geographic

Information

System

and

remote

sensing

analyses

indicate

that

from

to

West

Kalimantan

's

lowland

PAs

were

reduced

by

-LRB-

-RRB-

primarily

by

intensive

logging

By

only

remained

of

protected

lowland

forest

fragments

larger

than

-LRB-

fig

-RRB-

Of

the

remaining

fragments

were

-LRB-

mean

SE

-RRB-

Only

fragments

-LRB-

total

-RRB-

are

considered

large

enough

-LRB-

-RRB-

to

support

intact

vertebrate

fauna

-LRB-

-RRB-

The

remote

Betung

Kerihun

National

Park

-LRB-

BKNP

-RRB-

-LRB-

gazetted

-RRB-

contains

of

the

remaining

protected

lowlands

in

the

province

Moreover

several

potentially

viable

fragments

are

isolated

-LRB-

km

apart

-RRB-

-LRB-

fig

-RRB-

Our

Landsat

Enhanced

Thematic

Mapper

Plus

-LRB-

ETM

-RRB-

analysis

of

buffers

around

West

Kalimantan

's

World

Conservation

Monitoring

Centre

-LRB-

WCMC

-RRB-

PAs

-LRB-

total

extent

-RRB-

reveals

substantial

deforestation

seven

of

eight

buffers

contained

to

lowland

forest

-LRB-

mean

SE

-RRB-

Although

of

BKNP

's

buffer

contains

lowland

forest

both

this

park

and

its

buffer

are

currently

being

logged

-LRB-

-RRB-

Across

Kalimantan

's

other

provinces

-LRB-

-RRB-

we

evaluated

the

condition

of

WCMC

lowland

PAs

Within

of

lowland

PAs

outside

West

Kalimantan

-LRB-

of

the

total

protected

area

-RRB-

only

fragments

-LRB-

-RRB-

remain

forested

-LRB-

a

loss

of

or

of

the

lowland

forest

cover

-RRB-

-LRB-

fig

-RRB-

Although

fragments

contain

sufficient

area

to

support

most

vertebrates

of

these

are

isolates

Moreover

of

these

protected

forests

-LRB-

-RRB-

overlap

industrial

timber

concessions

or

plantations

-LRB-

fig

-RRB-

Given

this

extensive

reduction

in

Kalimantan

's

protected

lowland

forest

widespread

effects

are

expected

to

cascade

throughout

their

ecosystems

Because

mastfruiting

dipterocarp

communities

satiate

seed

predators

by

employing

a

strategy

of

regional

reproductive

synchrony

the

observed

fragmentation

is

likely

to

trigger

direct

and

indirect

effects

including

those

demonstrated

in

frugivore-food

web

dynamics

-LRB-

-RRB-

Except

for

BKNP

large

intact

protected

lowlands

no

longer

exist

in

Kalimantan

-LRB-

fig

-RRB-

Therefore

threatened

nomadic

and

large

vertebrates

with

extensive

lowland

ranges

are

predicted

to

decline

precipitously

especially

carnivores

ungulates

and

primates

-LRB-

e.g.

the

Malayan

sun

bear

Helarctos

malayanus

the

bearded

pig

Sus

barbatus

and

the

orangutan

Fig.

Cumulative

forest

loss

within

the

GPNP

boundary

-LRB-

yellow

-RRB-

and

its

surrounding

buffer

Forest

and

nonforest

classifications

-LRB-

-RRB-

are

based

on

a

Landsat

Thematic

Mapper

time

series

-LRB-

and

-RRB-

Classifications

are

shown

for

-LRB-

A

-RRB-

-LRB-

B

-RRB-

and

-LRB-

C

-RRB-

-LRB-

The

full

time

series

is

given

in

fig

-RRB-

Lowland

-LRB-

green

-RRB-

and

peat

-LRB-

olive

-RRB-

forests

were

converted

to

nonforest

-LRB-

red

-RRB-

first

predominantly

in

the

buffer

and

later

within

the

park

Gray

areas

are

montane

forest

-LRB-

more

than

m

a.s.l.

-RRB-

and

were

excluded

from

analyses

The

well-defined

nonforest

area

that

appears

northeast

of

GPNP

in

-LRB-

B

-RRB-

has

been

clear-felled

for

an

oil

palm

plantation

-LRB-

D

-RRB-

Industrial

land

uses

areas

formerly

allocated

to

timber

concessions

-LRB-

green

-RRB-

and

current

plantation

allocations

-LRB-

dotted

red

-RRB-

account

for

most

of

the

deforestation

within

the

buffer

The

coastal

road

paved

in

is

shown

in

black

-LRB-

km

-RRB-

unpaved

primary

logging

transport

roads

are

shown

in

purple

-LRB-

km

-RRB-

The

GPNP

area

is

shown

in

tan

SCIENCE

VOL

FEBRUARY

Downloaded

from

on

May

REPORTS

Pongo

pygmaeus

-RRB-

Preliminary

evidence

for

such

declines

includes

emaciated

dead

sun

bears

and

bearded

pigs

radiotracked

and

observed

in

northeast

Borneo

and

West

and

Central

Kalimantan

in

and

-LRB-

-RRB-

Given

local

vertebrate

extinctions

after

deforestation

in

Singapore

-LRB-

-RRB-

these

Kalimantan

results

appear

foreboding

Kalimantan

's

PA

forest

loss

provides

a

marked

contrast

to

findings

from

Costa

Rica

-LRB-

-RRB-

where

negligible

deforestation

occurred

within

PAs

from

to

and

from

the

Brazilian

Amazon

where

PAs

and

especially

extractive

and

indigenous

reserves

substantially

inhibited

forest

cover

loss

-LRB-

-RRB-

Moreover

interview-based

assessments

of

PAs

worldwide

-LRB-

-RRB-

suggest

that

of

sites

surveyed

are

maintaining

or

increasing

their

forest

cover

Our

contrasting

figures

of

PA

forest

loss

appear

to

be

explained

by

distinctive

drivers

of

deforestation

occurring

in

Kalimantan

Deforestation

in

Kalimantan

's

PAs

is

not

primarily

due

to

local

human

population

density

smallholder

agricultural

clearing

or

paved

roads

Kalimantan

has

relatively

low

human

population

density

and

growth

rates

-LRB-

annually

for

West

Kalimantan

between

and

-RRB-

with

of

the

total

population

in

coastal

cities

-LRB-

-RRB-

Moreover

inland

rural

populations

live

primarily

in

small

villages

-LRB-

adults

per

-RRB-

outside

of

PAs

where

they

historically

engaged

in

smallholder

agroforestry

to

parcels

cleared

per

household

mostly

from

secondary

forest

with

to

agricultural

fallows

-RRB-

and

temporary

off-farm

labor

-LRB-

-RRB-

Neither

can

Kalimantan

's

deforestation

be

explained

as

a

direct

consequence

of

paved

road

construction

or

spontaneous

interior

migration

as

documented

in

the

Amazon

basin

-LRB-

-RRB-

In

West

Kalimantan

in

the

extent

of

paved

roads

remained

small

-LRB-

-RRB-

and

primarily

connected

coastal

ports

only

has

been

added

since

Borneo

is

distinctive

because

of

the

dominance

of

the

federal

timber

industry

and

the

commercial

value

and

stock

of

dipterocarp

forests

Over

the

past

two

decades

the

volume

of

dipterocarp

timber

exports

-LRB-

in

cubic

meters

-RRB-

from

Borneo

-LRB-

Kalimantan

Sarawak

and

Sabah

-RRB-

exceeded

all

tropical

wood

exports

from

tropical

Africa

and

Latin

America

combined

-LRB-

-RRB-

Logging

within

PAs

results

from

to

years

of

forest

overexploitation

evidenced

by

the

recent

and

rapid

decline

in

federal

timber

concessions

-LRB-

-RRB-

In

West

Kalimantan

only

of

the

original

concessions

-LRB-

formerly

-RRB-

allocated

in

the

have

an

active

harvest

in

and

This

represents

a

reduction

in

logging

operations

land

area

-LRB-

now

-RRB-

Within

these

active

holdings

primary

forest

remains

on

-LRB-

-RRB-

distributed

within

a

logged

mosaic

Most

concessions

having

been

depleted

of

their

harvestable

timber

are

abandoned

In

the

Indonesian

Ministry

of

Forestry

reported

that

abandoned

or

expired

timber

concessions

across

Kalimantan

contained

to

primary

forest

Because

timber

was

depleted

within

concessions

loggers

illegally

expanded

their

operations

into

PAs

to

maintain

supplies

for

wood-based

industries

More

than

of

the

concession

operations

we

surveyed

from

to

either

directly

harvested

or

received

timber

from

PAs

At

least

to

of

these

operations

were

processing

this

wood

for

international

markets

-LRB-

-RRB-

Logging

within

PAs

is

further

confirmed

by

our

Landsat

ETM

analysis

which

revealed

concession-style

logging

active

in

all

WCMC

PAs

examined

-LRB-

-RRB-

-LRB-

table

-RRB-

Within

these

PAs

the

length

of

industrial

logging

roads

ranges

from

km

-LRB-

BKNP

-RRB-

to

km

-LRB-

Bukit

Raya

-RRB-

-LRB-

x

SE

-RRB-

Logging

within

PAs

is

expected

to

increase

for

two

main

reasons

First

decentralization

regulations

implemented

in

now

allow

local

districts

to

issue

small

logging

parcel

leases

-LRB-

-RRB-

this

has

resulted

in

the

virtually

uncontrolled

harvest

of

remaining

accessible

lowland

For

example

based

on

months

of

field

surveys

in

West

Kalimantan

's

six

timber

producing

districts

we

determined

that

small

parcels

were

granted

locally

to

permit

logging

of

of

predominately

protected

lowlands

or

expired

concessions

during

January

to

June

Timber

volume

extracted

from

district-issued

parcels

increased

by

from

Second

widespread

oil

palm

plantation

establishment

is

converting

logged

lowland

forest

outside

PAs

thus

increasing

pressure

on

PAs

From

to

the

central

government

reclaimed

several

former

West

Kalimantan

timber

concessions

-LRB-

-RRB-

and

funded

the

clearance

of

residual

wood

purportedly

to

establish

oil

palm

plantations

Plantation

establishment

is

promoted

by

state

policies

-LRB-

e.g.

interest-free

loans

from

the

national

reforestation

fund

-RRB-

often

with

encouragement

-LRB-

such

as

loans

loan

guarantees

and

export

finance

schemes

-RRB-

from

international

institutions

These

incentives

fueled

a

rapid

expansion

and

conversion

of

lowlands

to

oil

palm

In

the

area

allotted

to

industrial

plantations

in

West

Kalimantan

totaled

with

slated

for

oil

palm

production

a

increase

in

the

plantation

area

designated

since

-LRB-

-RRB-

These

areas

are

cleared

of

residual

wood

and

burned

to

establish

plantations

Despite

the

declining

resource

base

Indonesia

's

wood-based

industries

have

maintained

excessive

production

capacity

-LRB-

-RRB-

For

example

in

West

Kalimantan

such

industries

had

a

total

capacity

of

year

in

-LRB-

-RRB-

Fourteen

plywood

industries

alone

-LRB-

year

-RRB-

exceeded

provincial

wood

volume

production

capacity

from

federal

timber

concessions

by

in

and

in

and

and

in

and

Wood

shortages

are

now

met

primarily

through

clearing

for

plantations

and

logging

PAs

More

than

of

West

Kalimantan

's

oil

palm

plantations

were

formerly

timber

concessions

and

clearing

of

their

residual

forest

stands

is

either

planned

or

completed

-LRB-

in

the

GPNP

buffer

for

instance

-RRB-

Most

high-quality

timber

is

now

found

in

PAs

however

it

is

not

protected

in

practice

Rates

and

extent

of

lowland

PA

forest

loss

in

Kalimantan

far

exceed

previous

projections

-LRB-

-RRB-

Stemming

the

flow

of

illegal

wood

from

Borneo

requires

international

efforts

to

document

a

legitimate

chain-of-custody

from

the

forest

stand

to

consumers

through

independent

monitoring

Indonesia

's

wood-based

industries

must

demonstrate

sufficient

timber

concession

stock

or

reduce

capacity

Timber

and

plantation

operations

must

be

closely

monitored

-LRB-

with

annual

satellite-based

assessments

-RRB-

with

strictly

enforced

penalties

to

prevent

further

incursions

into

the

PAs

Failure

to

institute

transparent

and

equitable

land

use

solutions

will

lead

to

the

irreversible

ecological

degradation

of

Borneo

's

terrestrial

ecosystems

Effective

frontier

governance

-LRB-

-RRB-

and

sound

regional

land-use

planning

are

critical

to

protecting

even

uninhabited

and

remote

PAs

from

regional

and

increasingly

international

market

forces

F.

Achard

et

al.

Science

-LRB-

-RRB-

D.

C.

Nepstad

et

al.

Nature

-LRB-

-RRB-

C.

Gascon

G.

B.

Williamson

G.

A.

B.

da

Fonseca

Science

-LRB-

-RRB-

C.

Barr

in

Which

Way

Forward

People

Forests

and

Policymaking

in

Indonesia

C.

J.

P.

Colfer

I.

A.

P.

Resosudarmo

Eds

-LRB-

Resources

for

the

Future

Washington

DC

-RRB-

pp.

Fig.

Annual

rates

of

forest

cover

change

in

the

buffer

zone

and

within

GPNP

from

to

from

a

baseline

During

this

period

a

total

of

of

lowland

dipterocarp

forest

within

the

park

buffer

and

within

the

park

were

lost

primarily

through

logging

and

conversion

to

plantations

After

when

of

the

buffer

had

been

deforested

the

rate

of

deforestation

within

the

park

increased

to

year

References

and

Notes

FEBRUARY

VOL

SCIENCE

Downloaded

from

on

May

REPORTS

M.

L.

Ross

Timber

Booms

and

Institutional

Breakdown

in

Southeast

Asia

-LRB-

Cambridge

Univ.

Press

Cambridge

-RRB-

D.

C.

Nepstad

et

al.

Science

-LRB-

-RRB-

J.

Terborgh

et

al.

Science

-LRB-

-RRB-

L.

M.

Curran

et

al.

Science

-LRB-

-RRB-

L.

M.

Curran

M.

Leighton

Ecol

Monogr

-LRB-

-RRB-

L.

M.

Curran

C.

O.

Webb

Ecol

Monogr

-LRB-

-RRB-

F.

G.

Siegert

G.

Ruecker

A.

Hinrichs

A.

A.

Hoffmann

Nature

-LRB-

-RRB-

K.

S.

MacKinnon

G.

Hatta

H.

Halim

A.

Mangalik

The

Ecology

of

Kalimantan

-LRB-

Periplus

Editions

Singapore

-RRB-

Materials

and

methods

are

available

as

supporting

material

on

Science

Online

F.

R.

Lambert

N.

J.

Collar

Forktail

-LRB-

-RRB-

T.

G.

Laman

J.

C.

Gaither

D.

E.

Lukas

Trop

Biodivers

-LRB-

-RRB-

A.

Blundell

Trop

Biodivers

-LRB-

-RRB-

M.

Leighton

D.

R.

Leighton

in

Tropical

Rain

Forest

Ecology

and

Management

S.

L.

Sutton

T.

C.

Whitmore

A.

C.

Chadwick

Eds

-LRB-

Blackwell

Oxford

-RRB-

pp.

A.

E.

Johnson

C.

D.

Knott

B.

Pamungkas

A.

J.

Marshall

in

preparation

Laidlaw

reports

that

is

required

to

maintain

the

majority

of

avian

and

mammalian

species

-LRB-

-RRB-

-LRB-

and

preferably

-RRB-

is

required

to

maintain

intact

vertebrate

faunas

in

the

Sunda

region

-LRB-

-RRB-

T.

Budiarto

Investigasi

Aktivitas

Illegal

Logging

Di

Propinsi

Kalbar

oleh

Tim

WWF-Indonesia

Kalimantan

Barat

-LRB-

World

Wide

Fund

for

Nature

Pontianak

Indonesia

-RRB-

S.

T.

Wong

thesis

University

of

Montana

Missoula

-LRB-

-RRB-

B.

W.

Brook

N.

S.

Sodhi

P.

K.

L.

Ng

Nature

-LRB-

-RRB-

G.

A.

Sanchez-Azofeifa

G.

C.

Daily

A.

S.

P.

Pfaff

C.

Busch

Biol

Conserv

-LRB-

-RRB-

S.

Schwartzman

A.

Moreira

D.

C.

Nepstad

Conserv

Biol

-LRB-

-RRB-

D.

C.

Nepstad

et

al.

in

preparation

A.

G.

Bruner

R.

E.

Gullison

R.

E.

Rice

G.

A.

B.

da

Fonseca

Science

-LRB-

-RRB-

D.

M.

Lawrence

M.

Leighton

D.

R.

Peart

Conserv

Biol

-LRB-

-RRB-

D.

C.

Nepstad

et

al.

For

Ecol

Manag

-LRB-

-RRB-

International

Tropical

Timber

Organization

-LRB-

IT

TO

-RRB-

Annual

Review

and

Assessment

of

the

World

Tropical

Timber

Situation

-LRB-

Japan

IT

TO

Yokohama

-RRB-

D.

Holmes

Deforestation

in

Indonesia

A

Review

of

the

Situation

in

Sumatra

Kalimantan

and

Sulawesi

-LRB-

World

Bank

Jakarta

June

-RRB-

R.

K.

Laidlaw

Conserv

Biol

-LRB-

-RRB-

We

thank

the

Indonesian

Institute

of

Sciences

Directorate

General

for

Nature

Conservation

and

Forest

Protection

Ministry

of

Forestry

University

of

Tanjungpura

National

-LRB-

BAPPENAS

-RRB-

and

Regional

Development

Planning

Agency

-LRB-

BAPPEDA-KALBAR

-RRB-

timber

and

plantation

company

management

and

the

U.S.

Agency

for

International

Development

-LRB-

USAID

-RRB-

Indonesia

for

sponsorship

The

World

Wide

Fund

for

Nature-Indonesia-Kalbar-BKNP

Biodamar

YPPN

and

Titian

provided

local

nongovernmental

support

A.

Tjiu

Syrahirsyah

Darmawan

J.

Belsky

S.

Siebert

R.

DeFries

D.

McCauley

J.

Fox

S.

J.

Lansing

M.

Dove

C.

O'Connor

D.

Nepstad

W.

Sandler

A.

Doolittle

G.

Paoli

J.

Dempewolf

K.

Wessels

J.

Hewson

K.

Pittman

A.

Johnson

A.

Gorog

E.

DeMattia

K.

Peay

F.

Miller

J.

Balch

D.

Skelly

O.

Schmitz

N.

Sizer

A.

Marshall

S.

Unser

A.

Purwono

J.

Harting

T.

Alexander

I.

Zulkarnain

F.

Soenoen

Ignatius

K.

Atok

D.

Rasel

Umar

and

five

anonymous

reviewers

provided

invaluable

contributions

Supported

by

the

NASA

Earth

Sciences

Program

-LRB-

grant

nos

NAG

and

NAG

-RRB-

a

NASA

Earth

System

Sciences

Fellowship

NSF

BE-CNH

-LRB-

grant

no.

-RRB-

Space

Imaging

Inc.

the

Yale

School

of

Forestry

and

Environmental

Studies

the

Tropical

Resources

Institute

the

Conservation

Food

and

Health

Foundation

the

Indonesia

program

the

East-West

Center

Hawaii

and

the

University

of

Michigan

September

accepted

January

Photoreceptor

Regulation

of

CONSTANS

Protein

in

Photoperiodic

Flowering

Federico

Valverde

Aidyn

Mouradov

Wim

Soppe

Dean

Ravenscroft

Alon

Samach

George

Many

plants

flower

in

response

to

seasonal

fluctuations

in

day

length

The

CONSTANS

-LRB-

CO

-RRB-

gene

of

Arabidopsis

promotes

flowering

in

long

days

Flowering

is

induced

when

CO

messenger

RNA

expression

coincides

with

the

exposure

of

plants

to

light

However

how

this

promotes

CO

activity

is

unknown

We

show

that

light

stabilizes

nuclear

CO

protein

in

the

evening

whereas

in

the

morning

or

in

darkness

the

protein

is

degraded

by

the

proteasome

Photoreceptors

regulate

CO

stability

and

act

antagonistically

to

generate

daily

rhythms

in

CO

abundance

This

layer

of

regulation

refines

the

circadian

rhythm

in

CO

messenger

RNA

and

is

central

to

the

mechanism

by

which

day

length

controls

flowering

Day

length

provides

an

environmental

cue

that

allows

plants

to

flower

in

response

to

the

changing

seasons

-LRB-

-RRB-

Long

days

-LRB-

LDs

-RRB-

trigger

flowering

of

Arabidopsis

and

a

genetic

pathway

controlling

this

response

-LRB-

-RRB-

is

conserved

in

distantly

related

Angiosperms

-LRB-

-RRB-

In

Arabidopsis

CONSTANS

-LRB-

CO

-RRB-

plays

a

central

role

in

the

induction

of

flowering

by

LDs

and

encodes

a

nuclear

Max

Planck

Institute

for

Plant

Breeding

Carl-vonLinne

Weg

Cologne

Germany

H.

Smith

Institute

of

Plant

Sciences

and

Genetics

in

Agriculture

The

Hebrew

University

of

Jerusalem

Rehovot

Israel

These

authors

contributed

equally

to

this

work

To

whom

correspondence

should

be

addressed

E-mail

coupland@mpiz-koeln.mpg.de

protein

containing

zinc

fingers

-LRB-

-RRB-

CO

mRNA

abundance

is

regulated

by

the

circadian

clock

and

accumulates

late

in

the

day

when

plants

growing

under

LDs

are

exposed

to

light

-LRB-

-RRB-

Under

these

conditions

CO

activates

transcription

of

the

FT

gene

which

encodes

a

RAF-kinaseinhibitor-like

protein

that

promotes

flowering

-LRB-

-RRB-

Activation

of

FT

transcription

is

proposed

to

depend

on

posttranscriptional

regulation

of

CO

that

is

triggered

by

light

and

therefore

flowering

under

LDs

occurs

because

of

the

coincidence

of

circadianclock-controlled

transcription

of

CO

and

light-mediated

posttranscriptional

regulation

-LRB-

-RRB-

How

CO

is

regulated

by

light

has

not

been

described

We

demonstrate

that

CO

protein

abundance

and

activity

respond

to

light

and

define

roles

for

photoreceptors

in

controlling

these

responses

CO

activity

can

be

followed

indirectly

by

measuring

FT

mRNA

levels

The

CO

plants

which

overexpress

CO

mRNA

at

constant

levels

independently

of

the

circadian

clock

or

exposure

to

light

contain

FT

mRNA

at

higher

abundance

during

the

photoperiod

than

in

the

dark

-LRB-

-RRB-

A

fusion

of

FT

regulatory

sequences

to

luciferase

-LRB-

LUC

-RRB-

was

introduced

into

wild-type

and

CO

plants

and

accurately

reported

the

up-regulation

of

FT

caused

by

CO

overexpression

-LRB-

fig

-RRB-

The

CO

FT

LUC

plants

were

shifted

from

darkness

to

light

of

different

wavelengths

Luminescence

increased

rapidly

after

exposure

to

white

-LRB-

W

-RRB-

or

blue

-LRB-

B

-RRB-

light

and

more

slowly

when

plants

were

exposed

to

far-red

light

-LRB-

FR

-RRB-

but

did

not

markedly

increase

in

red

light

-LRB-

R

-RRB-

-LRB-

Fig.

-RRB-

In

CO

plants

FT

mRNA

abundance

showed

similar

regulation

to

FT

LUC

whereas

CO

mRNA

levels

were

not

significantly

altered

by

light

-LRB-

Fig.

B

and

C

-RRB-

Therefore

posttranscriptional

regulation

of

CO

activity

by

B

and

FR

rapidly

activates

FT

transcription

after

transfer

from

darkness

as

described

for

the

maintenance

of

CO

activity

after

transfer

from

W

-LRB-

-RRB-

We

tested

whether

exposure

to

light

regulates

FT

by

influencing

the

abundance

of

CO

protein

Fluorescence

of

GFP

CO

-LRB-

green

fluorescent

protein

CO

-RRB-

was

detected

in

the

nucleus

of

stomatal

guard

cells

of

GFP

CO

plants

under

W

B

or

FR

but

not

in

plants

exposed

to

darkness

or

R

-LRB-

Fig.

-RRB-

To

follow

native

CO

protein

antibodies

SCIENCE

VOL

FEBRUARY

Downloaded

from

on

May

Supporting

Online

Material

Materials

and

Methods

References

and

Notes

Figs

to

Table

O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O B O O O O O O O O O O B O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O B O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O B O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O B O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O O O O O O O O O O O O O B O O O O O O O B O O O O B O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O B O B O B O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O B O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O B O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

borneo deforestation indonesia satellite kalimantan


Stabilization

Wedges

Solving

the

Climate

Problem

for

the

Next

Years

with

Current

Technologies

S.

Pacala

et

al.

Science

-LRB-

-RRB-

DOI

science

The

following

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article

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is

current

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of

May

-RRB-

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and

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including

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be

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in

the

online

version

of

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article

at

Supporting

Online

Material

can

be

found

at

A

list

of

selected

additional

articles

on

the

Science

Web

sites

related

to

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article

can

be

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at

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The

title

Science

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AAAS

Downloaded

from

on

May

TOWARD

A

HYDROGEN

ECONOMY

SPECIAL

SECTION

REVIEW

Stabilization

Wedges

Solving

the

Climate

Problem

for

the

Next

Years

with

Current

Technologies

S.

and

R.

Humanity

already

possesses

the

fundamental

scientific

technical

and

industrial

know-how

to

solve

the

carbon

and

climate

problem

for

the

next

half-century

A

portfolio

of

technologies

now

exists

to

meet

the

world

's

energy

needs

over

the

next

years

and

limit

atmospheric

to

a

trajectory

that

avoids

a

doubling

of

the

preindustrial

concentration

Every

element

in

this

portfolio

has

passed

beyond

the

laboratory

bench

and

demonstration

project

many

are

already

implemented

somewhere

at

full

industrial

scale

Although

no

element

is

a

credible

candidate

for

doing

the

entire

job

-LRB-

or

even

half

the

job

-RRB-

by

itself

the

portfolio

as

a

whole

is

large

enough

that

not

every

element

has

to

be

used

The

debate

in

the

current

literature

about

stabilizing

atmospheric

at

less

than

a

doubling

of

the

preindustrial

concentration

has

led

to

needless

confusion

about

current

options

for

mitigation

On

one

side

the

Intergovernmental

Panel

on

Climate

Change

-LRB-

IPCC

-RRB-

has

claimed

that

technologies

that

exist

in

operation

or

pilot

stage

today

are

sufficient

to

follow

a

less-thandoubling

trajectory

over

the

next

hundred

years

or

more

-LSB-

-LRB-

-RRB-

p.

-RSB-

On

the

other

side

a

recent

review

in

Science

asserts

that

the

IPCC

claim

demonstrates

misperceptions

of

technological

readiness

and

calls

for

revolutionary

changes

in

mitigation

technology

such

as

fusion

space-based

solar

electricity

and

artificial

photosynthesis

-LRB-

-RRB-

We

agree

that

fundamental

research

is

vital

to

develop

the

revolutionary

mitigation

strategies

needed

in

the

second

half

of

this

century

and

beyond

But

it

is

important

not

to

become

beguiled

by

the

possibility

of

revolutionary

technology

Humanity

can

solve

the

carbon

and

climate

problem

in

the

first

half

of

this

century

simply

by

scaling

up

what

we

already

know

how

to

do

-LRB-

BAU

-RRB-

trajectory

-RSB-

the

quantitative

details

of

the

stabilization

target

and

the

future

behavior

of

natural

sinks

for

atmospheric

-LRB-

i.e.

the

oceans

and

terrestrial

biosphere

-RRB-

We

focus

exclusively

on

because

it

is

the

dominant

anthropogenic

greenhouse

gas

industrial-scale

mitigation

options

also

exist

for

subordinate

gases

such

as

methane

and

Very

roughly

stabilization

at

ppm

requires

that

emissions

be

held

near

the

present

level

of

billion

tons

of

carbon

per

year

-LRB-

GtC/year

-RRB-

for

the

next

years

even

though

they

are

currently

on

course

to

more

than

double

-LRB-

Fig.

-RRB-

The

next

years

is

a

sensible

horizon

from

several

perspectives

It

is

the

length

of

a

career

the

lifetime

of

a

power

plant

and

an

interval

for

which

the

technology

is

close

enough

to

envision

The

calculations

behind

Fig.

are

explained

in

Section

of

the

supporting

online

material

-LRB-

SOM

-RRB-

text

The

BAU

and

stabilization

emissions

in

Fig.

are

near

the

center

of

the

cloud

of

variation

in

the

large

published

literature

-LRB-

-RRB-

and

climate

problem

over

the

next

half-century

means

to

deploy

the

technologies

and/or

lifestyle

changes

necessary

to

fill

all

seven

wedges

of

the

stabilization

triangle

Stabilization

at

any

level

requires

that

net

emissions

do

not

simply

remain

constant

but

eventually

drop

to

zero

For

example

in

one

simple

model

-LRB-

-RRB-

that

begins

with

the

stabilization

triangle

but

looks

beyond

stabilization

is

achieved

by

years

of

flat

emissions

followed

by

a

linear

decline

of

about

two-thirds

in

the

following

years

and

a

very

slow

decline

thereafter

that

matches

the

declining

ocean

sink

To

develop

the

revolutionary

technologies

required

for

such

large

emissions

reductions

in

the

second

half

of

the

century

enhanced

research

and

development

would

have

to

begin

immediately

Policies

designed

to

stabilize

at

ppm

would

inevitably

be

renegotiated

periodically

to

take

into

account

the

results

of

research

and

development

experience

with

specific

wedges

and

revised

estimates

of

the

size

of

the

stabilization

triangle

But

not

filling

the

stabilization

triangle

will

put

stabilization

out

of

reach

In

that

same

simple

model

-LRB-

-RRB-

years

of

BAU

emissions

followed

by

years

of

a

flat

trajectory

at

GtC/year

leads

to

more

than

a

tripling

of

the

preindustrial

concentration

It

is

important

to

understand

that

each

of

the

seven

wedges

represents

an

effort

beyond

what

would

occur

under

BAU

Our

BAU

simply

continues

the

annual

carbon

emissions

growth

of

the

past

years

This

historic

trend

in

emissions

has

been

accompanied

by

growth

in

primary

energy

consumption

and

growth

in

gross

world

product

-LRB-

GWP

-RRB-

-LRB-

Section

of

SOM

text

-RRB-

If

carbon

emissions

were

to

grow

per

year

then

wedges

would

be

needed

instead

of

and

if

carbon

emissions

were

to

grow

at

per

year

then

wedges

would

be

required

-LRB-

Section

of

SOM

text

-RRB-

Thus

a

continuation

of

the

historical

rate

of

decarbonization

of

the

fuel

mix

prevents

the

need

for

three

additional

wedges

and

ongoing

improvements

in

energy

efficiency

prevent

the

need

for

eight

additional

wedges

Most

readers

will

reject

at

least

one

of

the

wedges

listed

here

believing

that

the

corresponding

deployment

is

certain

to

occur

in

BAU

but

readers

will

disagree

about

which

to

reject

on

such

grounds

On

the

other

hand

our

list

of

mitigation

options

is

not

exhaustive

What

Do

We

Mean

by

Solving

the

Carbon

and

Climate

Problem

for

the

Next

Half-Century

Proposals

to

limit

atmospheric

to

a

concentration

that

would

prevent

most

damaging

climate

change

have

focused

on

a

goal

of

parts

per

million

-LRB-

ppm

-RRB-

or

less

than

double

the

preindustrial

concentration

of

ppm

-LRB-

-RRB-

The

current

concentration

is

ppm

The

emissions

reductions

necessary

to

achieve

any

such

target

depend

on

the

emissions

judged

likely

to

occur

in

the

absence

of

a

focus

on

carbon

-LSB-

called

a

business-as-usual

The

Stabilization

Triangle

We

idealize

the

emissions

reductions

as

a

perfect

triangle

in

Fig.

Stabilization

is

represented

by

a

flat

trajectory

of

fossil

fuel

emissions

at

GtC/year

and

BAU

is

represented

by

a

straight-line

ramp

trajectory

rising

to

GtC/year

in

The

stabilization

triangle

located

between

the

flat

trajectory

and

BAU

removes

exactly

onethird

of

BAU

emissions

To

keep

the

focus

on

technologies

that

have

the

potential

to

produce

a

material

difference

by

we

divide

the

stabilization

triangle

into

seven

equal

wedges

A

wedge

represents

an

activity

that

reduces

emissions

to

the

atmosphere

that

starts

at

zero

today

and

increases

linearly

until

it

accounts

for

GtC/year

of

reduced

carbon

emissions

in

years

It

thus

represents

a

cumulative

total

of

GtC

of

reduced

emissions

over

years

In

this

paper

to

solve

the

carbon

Department

of

Ecology

and

Evolutionary

Biology

Department

of

Mechanical

and

Aerospace

Engineering

Princeton

University

Princeton

NJ

USA

To

whom

correspondence

should

be

addressed

Email

pacala@princeton.edu

-LRB-

S.P.

-RRB-

socolow@princeton

edu

-LRB-

R.S.

-RRB-

AUGUST

VOL

SCIENCE

Downloaded

from

on

May

TOWARD

A

HYDROGEN

ECONOMY

SPECIAL

SECTION

What

Current

Options

Could

Be

Scaled

Up

to

Produce

at

Least

One

Wedge

Wedges

can

be

achieved

from

energy

efficiency

from

the

decarbonization

of

the

supply

of

electricity

and

fuels

-LRB-

by

means

of

fuel

shifting

carbon

capture

and

storage

nuclear

energy

and

renewable

energy

-RRB-

and

from

biological

storage

in

forests

and

agricultural

soils

Below

we

discuss

different

examples

of

options

that

are

already

deployed

at

an

industrial

scale

and

that

could

be

scaled

up

further

to

produce

at

least

one

wedge

-LRB-

summarized

in

Table

-RRB-

Although

several

options

could

be

scaled

up

to

two

or

more

wedges

we

doubt

that

any

could

fill

the

stabilization

triangle

or

even

half

of

it

alone

Because

the

same

BAU

carbon

emissions

can

not

be

displaced

twice

achieving

one

wedge

often

interacts

with

achieving

another

The

more

the

electricity

system

becomes

decarbonized

for

example

the

less

the

available

savings

from

greater

efficiency

of

electricity

use

and

vice

versa

Interactions

among

wedges

are

discussed

in

the

SOM

text

Also

our

focus

is

not

on

costs

In

general

the

achievement

of

a

wedge

will

require

some

price

trajectory

for

carbon

the

details

of

which

depend

on

many

assumptions

including

future

fuels

prices

public

acceptance

and

cost

reductions

by

means

of

learning

Instead

our

analysis

is

intended

to

complement

the

comprehensive

but

complex

integrated

assessments

-LRB-

-RRB-

of

carbon

mitigation

by

letting

the

full-scale

examples

that

are

already

in

the

marketplace

make

a

simple

case

for

technological

readiness

Category

I

Efficiency

and

Conservation

Improvements

in

efficiency

and

conservation

probably

offer

the

greatest

potential

to

provide

wedges

For

example

in

the

United

States

announced

the

goal

of

decreasing

its

carbon

intensity

-LRB-

carbon

emissions

per

unit

GDP

-RRB-

by

over

the

next

decade

a

decrease

of

per

year

An

entire

wedge

would

be

created

if

the

United

States

were

to

reset

its

carbon

intensity

goal

to

a

decrease

of

per

year

and

extend

it

to

years

and

if

every

country

were

to

follow

suit

by

adding

the

same

per

year

increment

to

its

own

carbon

intensity

goal

However

efficiency

and

conservation

options

are

less

tangible

than

those

from

the

other

categories

Improvements

in

energy

efficiency

will

come

from

literally

hundreds

of

innovations

that

range

from

new

catalysts

and

chemical

processes

to

more

efficient

lighting

and

insulation

for

buildings

to

the

growth

of

the

service

economy

and

telecommuting

Here

we

provide

four

of

many

possible

comparisons

of

greater

and

less

efficiency

in

-LRB-

See

references

and

details

in

Section

of

the

SOM

text

-RRB-

Option

Improved

fuel

economy

Suppose

that

in

billion

cars

-LRB-

roughly

four

times

as

many

as

today

-RRB-

average

miles

per

year

-LRB-

as

they

do

today

-RRB-

One

wedge

would

be

achieved

if

instead

of

averaging

miles

per

gallon

-LRB-

mpg

-RRB-

on

conventional

fuel

cars

in

bon

at

a

rate

of

GtC/year

a

wedge

would

be

averaged

mpg

with

fuel

type

and

achieved

by

displacing

GW

of

baseload

coal

distance

traveled

unchanged

with

baseload

gas

by

The

power

shifted

to

Option

Reduced

reliance

on

cars

A

gas

for

this

wedge

is

four

times

as

large

as

the

total

wedge

would

also

be

achieved

if

the

average

current

gas-based

power

fuel

economy

of

the

billion

cars

were

Option

Storage

of

carbon

captured

in

mpg

but

the

annual

distance

traveled

were

power

plants

Carbon

capture

and

storage

miles

instead

of

miles

-LRB-

CCS

-RRB-

technology

prevents

about

of

the

Option

More

efficient

buildings

According

fossil

carbon

from

reaching

the

atmosphere

to

a

study

by

the

IPCC

a

wedge

is

the

so

a

wedge

would

be

provided

by

the

instaldifference

between

pursuing

and

not

pursuing

lation

of

CCS

at

GW

of

baseload

coal

known

and

established

approaches

to

energyplants

by

or

GW

of

baseload

efficient

space

heating

and

cooling

water

heating

natural

gas

plants

The

most

likely

approach

lighting

and

refrigeration

in

residential

and

commercial

buildings

These

approaches

reduce

midcentury

emissions

from

buildings

by

about

one-fourth

About

half

of

potential

savings

are

in

the

buildings

in

developing

countries

-LRB-

-RRB-

Option

Improved

power

plant

efficiency

In

coal

power

plants

operating

on

average

at

efficiency

produced

about

onefourth

of

all

carbon

emissions

GtC

year

out

of

GtC

year

A

wedge

would

be

created

if

twice

today

's

quantity

of

coal-based

electricity

in

were

produced

at

instead

of

efficiency

Category

II

Decarbonization

of

Electricity

and

Fuels

-LRB-

See

references

and

details

in

Section

of

the

SOM

text

-RRB-

Option

SubstiFig

-LRB-

A

-RRB-

The

top

curve

is

a

representative

BAU

emissions

path

for

global

tuting

natural

gas

for

carbon

emissions

as

CO

from

fossil

fuel

combustion

and

cement

coal

Carbon

emis

ture

per

year

growth

starting

from

GtC/year

in

The

bottom

sions

per

unit

of

elec

curve

is

a

emissions

path

consistent

with

atmospheric

stabilization

tricity

are

about

half

at

ppm

by

akin

to

the

Wigley

Richels

and

Edmonds

-LRB-

WRE

-RRB-

family

as

large

from

natural

of

stabilization

curves

described

in

-LRB-

-RRB-

modified

as

described

in

Section

of

gas

power

plants

as

the

SOM

text

The

bottom

curve

assumes

an

ocean

uptake

calculated

with

the

High-Latitude

Exchange

Interior

Diffusion

Advection

-LRB-

HILDA

-RRB-

ocean

model

from

coal

plants

As

-LRB-

-RRB-

and

a

constant

net

land

uptake

of

GtC/year

-LRB-

Section

of

the

SOM

sume

that

the

capaci

text

-RRB-

The

area

between

the

two

curves

represents

the

avoided

carbon

ty

factor

of

the

aver

emissions

required

for

stabilization

-LRB-

B

-RRB-

Idealization

of

-LRB-

A

-RRB-

A

stabilization

age

baseload

coal

triangle

of

avoided

emissions

-LRB-

green

-RRB-

and

allowed

emissions

-LRB-

blue

-RRB-

The

plant

in

has

in

allowed

emissions

are

fixed

at

GtC/year

beginning

in

The

stabilicreased

to

and

zation

triangle

is

divided

into

seven

wedges

each

of

which

reaches

GtC/year

in

With

linear

growth

the

total

avoided

emissions

per

that

its

efficiency

has

wedge

is

GtC

and

the

total

area

of

the

stabilization

triangle

is

GtC

improved

to

The

arrow

at

the

bottom

right

of

the

stabilization

triangle

points

downBecause

GW

of

ward

to

emphasize

that

fossil

fuel

emissions

must

decline

substantially

such

plants

emit

car

below

GtC/year

after

to

achieve

stabilization

at

ppm

SCIENCE

VOL

AUGUST

Downloaded

from

on

May

TOWARD

A

HYDROGEN

ECONOMY

SPECIAL

SECTION

has

two

steps

-LRB-

i

-RRB-

precombustion

capture

of

in

which

hydrogen

and

are

produced

and

the

hydrogen

is

then

burned

to

produce

electricity

followed

by

-LRB-

ii

-RRB-

geologic

storage

in

which

the

waste

is

injected

into

subsurface

geologic

reservoirs

Hydrogen

production

from

fossil

fuels

is

already

a

very

large

business

Globally

hydrogen

plants

consume

about

of

primary

energy

and

emit

GtC/year

of

The

capture

part

of

a

wedge

of

CCS

electricity

would

thus

require

only

a

tenfold

expansion

of

plants

resembling

today

's

large

hydrogen

plants

over

the

next

years

The

scale

of

the

storage

part

of

this

wedge

can

be

expressed

as

a

multiple

of

the

scale

of

current

enhanced

oil

recovery

or

current

seasonal

storage

of

natural

gas

or

the

first

geological

storage

demonstration

project

Today

about

GtC/year

of

carbon

as

is

injected

into

geologic

reservoirs

to

spur

enhanced

oil

recovery

so

a

wedge

of

geologic

storage

requires

that

injection

be

scaled

up

by

a

factor

of

over

the

next

years

To

smooth

out

seasonal

demand

in

the

United

States

the

natural

gas

industry

annually

draws

roughly

billion

standard

cubic

feet

-LRB-

Bscf

-RRB-

into

and

out

of

geologic

storage

and

a

carbon

flow

of

GtC/year

-LRB-

whether

as

methane

or

-RRB-

is

a

flow

of

Bscf/year

-LRB-

Bscf

per

day

-RRB-

so

a

wedge

would

be

a

flow

to

storage

and

times

as

large

as

the

current

flow

Norway

's

Sleipner

project

in

the

North

Sea

strips

from

natural

gas

offshore

and

reinjects

million

tons

of

carbon

a

year

-LRB-

MtC/year

-RRB-

into

a

non

fossil-fuel

bearing

formation

so

a

wedge

would

be

Sleipner-sized

projects

-LRB-

or

fewer

larger

projects

-RRB-

over

the

next

years

A

worldwide

effort

is

under

way

to

assess

the

capacity

available

for

multicentury

storage

and

to

assess

risks

of

leaks

large

enough

to

endanger

human

or

environmental

health

Option

Storage

of

carbon

captured

in

hydrogen

plants

The

hydrogen

resulting

from

precombustion

capture

of

can

be

sent

offsite

to

displace

the

consumption

of

conventional

fuels

rather

than

being

consumed

onsite

to

produce

electricity

The

capture

part

of

a

wedge

Option

Economy-wide

carbon-intensity

reduction

-LRB-

emissions

GDP

-RRB-

Efficient

vehicles

Reduced

use

of

vehicles

Efficient

buildings

Efficient

baseload

coal

plants

Effort

by

for

one

wedge

relative

to

GtC/year

BAU

Energy

efficiency

and

conservation

Increase

reduction

by

additional

per

year

-LRB-

e.g.

increase

U.S.

goal

of

reduction

per

year

to

per

year

-RRB-

Increase

fuel

economy

for

billion

cars

from

to

mpg

Decrease

car

travel

for

billion

cars

from

to

miles

per

year

Cut

carbon

emissions

by

one-fourth

in

buildings

and

appliances

projected

for

Produce

twice

today

's

coal

power

output

at

instead

of

efficiency

-LRB-

compared

with

today

-RRB-

Fuel

shift

Replace

GW

efficient

coal

plants

with

gas

plants

-LRB-

four

times

the

current

production

of

gas-based

power

-RRB-

Capture

and

Storage

-LRB-

CCS

-RRB-

Introduce

CCS

at

GW

coal

or

GW

natural

gas

-LRB-

compared

with

GW

coal

in

-RRB-

Introduce

CCS

at

plants

producing

from

coal

or

from

natural

gas

-LRB-

compared

with

today

from

all

sources

-RRB-

Introduce

CCS

at

synfuels

plants

producing

million

barrels

a

day

from

coal

-LRB-

times

Sasol

-RRB-

if

half

of

feedstock

carbon

is

available

for

capture

Create

Sleipners

Nuclear

fission

Add

GW

-LRB-

twice

the

current

capacity

-RRB-

Renewable

electricity

and

fuels

Add

million

windmills

-LRB-

times

the

current

capacity

-RRB-

occupying

ha

on

land

or

offshore

Add

GW-peak

PV

-LRB-

times

the

current

capacity

-RRB-

on

ha

Add

million

windmills

-LRB-

times

the

current

capacity

-RRB-

Add

times

the

current

Brazil

or

U.S.

ethanol

production

with

the

use

of

ha

-LRB-

one-sixth

of

world

cropland

-RRB-

Forests

and

agricultural

soils

Decrease

tropical

deforestation

to

zero

instead

of

GtC/year

and

establish

Mha

of

new

tree

plantations

-LRB-

twice

the

current

rate

-RRB-

Apply

to

all

cropland

-LRB-

times

the

current

usage

-RRB-

Comments

issues

Can

be

tuned

by

carbon

policy

Car

size

power

Urban

design

mass

transit

telecommuting

Weak

incentives

Advanced

high-temperature

materials

Gas

baseload

power

for

coal

baseload

power

Capture

at

baseload

power

plant

Capture

at

plant

Competing

demands

for

natural

gas

Technology

already

in

use

for

production

safety

infrastructure

Capture

at

coal-to-synfuels

plant

Geological

storage

Nuclear

power

for

coal

power

Wind

power

for

coal

power

PV

power

for

coal

power

Wind

in

fuel-cell

car

for

gasoline

in

hybrid

car

Biomass

fuel

for

fossil

fuel

Increased

emissions

if

synfuels

are

produced

without

CCS

Durable

storage

successful

permitting

Nuclear

proliferation

terrorism

waste

Multiple

uses

of

land

because

windmills

are

widely

spaced

PV

production

cost

safety

infrastructure

Biodiversity

competing

land

use

Reduced

deforestation

plus

reforestation

afforestation

and

new

plantations

Conservation

tillage

Land

demands

of

agriculture

benefits

to

biodiversity

from

reduced

deforestation

Reversibility

verification

AUGUST

VOL

SCIENCE

Downloaded

from

on

May

Table

Potential

wedges

Strategies

available

to

reduce

the

carbon

emission

rate

in

by

GtC/year

or

to

reduce

carbon

emissions

from

to

by

GtC

TOWARD

A

HYDROGEN

ECONOMY

SPECIAL

SECTION

would

require

the

installation

of

CCS

by

at

coal

plants

producing

or

at

natural

gas

plants

producing

The

former

is

six

times

the

current

rate

of

hydrogen

production

The

storage

part

of

this

option

is

the

same

as

in

Option

Option

Storage

of

carbon

captured

in

synfuels

plants

Looming

over

carbon

management

in

is

the

possibility

of

large-scale

production

of

synthetic

fuel

-LRB-

synfuel

-RRB-

from

coal

Carbon

emissions

however

need

not

exceed

those

associated

with

fuel

refined

from

crude

oil

if

synfuels

production

is

accompanied

by

CCS

Assuming

that

half

of

the

carbon

entering

a

synfuels

plant

leaves

as

fuel

but

the

other

half

can

be

captured

as

the

capture

part

of

a

wedge

in

would

be

the

difference

between

capturing

and

venting

the

from

coal

synfuels

plants

producing

million

barrels

of

synfuels

per

day

-LRB-

The

flow

of

carbon

in

million

barrels

per

day

of

crude

oil

is

GtC/year

we

assume

the

same

value

for

the

flow

in

synfuels

and

allow

for

imperfect

capture

-RRB-

Currently

the

Sasol

plants

in

South

Africa

the

world

's

largest

synfuels

facility

produce

barrels

per

day

from

coal

Thus

a

wedge

requires

Sasol-scale

coal-to-synfuels

facilities

with

CCS

in

The

storage

part

of

this

option

is

again

the

same

as

in

Option

Option

Nuclear

fission

On

the

basis

of

the

Option

estimates

a

wedge

of

nuclear

electricity

would

displace

GW

of

efficient

baseload

coal

capacity

in

This

would

require

GW

of

nuclear

power

with

the

same

capacity

factor

assumed

for

the

coal

plants

or

about

twice

the

nuclear

capacity

currently

deployed

The

global

pace

of

nuclear

power

plant

construction

from

to

would

yield

a

wedge

if

it

continued

for

years

-LRB-

-RRB-

Substantial

expansion

in

nuclear

power

requires

restoration

of

public

confidence

in

safety

and

waste

disposal

and

international

security

agreements

governing

uranium

enrichment

and

plutonium

recycling

Option

Wind

electricity

We

account

for

the

intermittent

output

of

windmills

by

equating

GW

of

nominal

peak

capacity

-LRB-

GWp

-RRB-

with

GW

of

baseload

capacity

Thus

a

wedge

of

wind

electricity

would

require

the

deployment

of

GWp

that

displaces

coal

electricity

in

-LRB-

or

million

wind

turbines

-RRB-

Installed

wind

capacity

has

been

growing

at

about

per

year

for

more

than

years

and

is

currently

about

GWp

A

wedge

of

wind

electricity

would

thus

require

times

today

's

deployment

The

wind

turbines

would

occupy

about

million

hectares

-LRB-

about

of

the

area

of

the

United

States

-RRB-

some

on

land

and

some

offshore

Because

windmills

are

widely

spaced

land

with

windmills

can

have

multiple

uses

Option

Photovoltaic

electricity

Similar

to

a

wedge

of

wind

electricity

a

wedge

from

photovoltaic

-LRB-

PV

-RRB-

electricity

would

require

GWp

of

installed

capacity

that

displaces

coal

electricity

in

Although

only

GWp

of

PV

are

currently

installed

PV

electricity

has

been

growing

at

a

rate

of

per

year

A

wedge

of

PV

electricity

would

require

times

today

's

deployment

and

about

million

hectares

of

land

in

or

to

per

person

Option

Renewable

hydrogen

Renewable

electricity

can

produce

carbonfree

hydrogen

for

vehicle

fuel

by

the

electrolysis

of

water

The

hydrogen

produced

by

million

windmills

in

if

used

in

high-efficiency

fuel-cell

cars

would

achieve

a

wedge

of

displaced

gasoline

or

diesel

fuel

Compared

with

Option

this

is

twice

as

many

windmills

as

would

be

required

to

produce

the

electricity

that

achieves

a

wedge

by

displacing

high-efficiency

baseload

coal

This

interesting

factor-of-two

carbon-saving

advantage

of

wind-electricity

over

wind-hydrogen

is

still

larger

if

the

coal

plant

is

less

efficient

or

the

fuel-cell

vehicle

is

less

spectacular

Option

Biofuels

Fossil-carbon

fuels

can

also

be

replaced

by

biofuels

such

as

ethanol

A

wedge

of

biofuel

would

be

achieved

by

the

production

of

about

million

barrels

per

day

of

ethanol

in

that

could

displace

gasoline

provided

the

ethanol

itself

were

fossil-carbon

free

This

ethanol

production

rate

would

be

about

times

larger

than

today

's

global

production

rate

almost

all

of

which

can

be

attributed

to

Brazilian

sugarcane

and

United

States

corn

An

ethanol

wedge

would

require

million

hectares

committed

to

high-yield

-LRB-

dry

tons/hectare

-RRB-

plantations

by

an

area

equal

to

about

one-sixth

of

the

world

's

cropland

An

even

larger

area

would

be

required

to

the

extent

that

the

biofuels

require

fossil-carbon

inputs

Because

land

suitable

for

annually

harvested

biofuels

crops

is

also

often

suitable

for

conventional

agriculture

biofuels

production

could

compromise

agricultural

productivity

Category

III

Natural

Sinks

Although

the

literature

on

biological

sequestration

includes

a

diverse

array

of

options

and

some

very

large

estimates

of

the

global

potential

here

we

restrict

our

attention

to

the

pair

of

options

that

are

already

implemented

at

large

scale

and

that

could

be

scaled

up

to

a

wedge

or

more

without

a

lot

of

new

research

-LRB-

See

Section

of

the

SOM

text

for

references

and

details

-RRB-

Option

Forest

management

Conservative

assumptions

lead

to

the

conclusion

that

at

least

one

wedge

would

be

available

from

reduced

tropical

deforestation

and

the

management

of

temperate

and

tropical

forests

At

least

one

half-wedge

would

be

created

if

the

current

rate

of

clear-cutting

of

primary

tropical

forest

were

reduced

to

zero

over

years

instead

of

being

halved

A

second

half-wedge

would

Conclusions

In

confronting

the

problem

of

greenhouse

warming

the

choice

today

is

between

action

and

delay

Here

we

presented

a

part

of

the

case

for

action

by

identifying

a

set

of

options

that

have

the

capacity

to

provide

the

seven

stabilization

wedges

and

solve

the

climate

problem

for

the

next

half-century

of

the

options

is

a

pipe

dream

or

an

unproven

idea

Today

one

can

buy

electricity

from

a

wind

turbine

PV

array

gas

turbine

or

nuclear

power

plant

One

can

buy

hydrogen

produced

with

the

chemistry

of

carbon

capture

biofuel

to

power

one

's

car

and

hundreds

of

devices

that

improve

energy

efficiency

One

can

visit

tropical

forests

where

clear-cutting

has

ceased

farms

practicing

conservation

tillage

and

facilities

that

inject

carbon

into

geologic

reservoirs

Every

one

of

these

options

is

already

implemented

at

an

industrial

scale

and

could

be

scaled

up

further

over

years

to

provide

at

least

one

wedge

References

and

Notes

IPCC

Climate

Change

Mitigation

B.

Metz

et

al.

Eds

-LRB-

IPCC

Secretariat

Geneva

Switzerland

-RRB-

available

at

index.htm

M.

I.

Hoffert

et

al.

Science

-LRB-

-RRB-

R.

T.

Watson

et

al.

Climate

Change

Synthesis

Report

Contribution

to

the

Third

Assessment

Report

of

the

Intergovernmental

Panel

on

Climate

Change

-LRB-

Cambridge

Univ.

Press

Cambridge

UK

-RRB-

B.

C.

O'Neill

M.

Oppenheimer

Science

-LRB-

-RRB-

Royal

Commission

on

Environmental

Pollution

En

SCIENCE

VOL

AUGUST

Downloaded

from

on

May

be

created

by

reforesting

or

afforesting

approximately

million

hectares

in

the

tropics

or

million

hectares

in

the

temperate

zone

-LRB-

current

areas

of

tropical

and

temperate

forests

are

and

million

hectares

respectively

-RRB-

A

third

half-wedge

would

be

created

by

establishing

approximately

million

hectares

of

plantations

on

nonforested

land

Option

Agricultural

soils

management

When

forest

or

natural

grassland

is

converted

to

cropland

up

to

one-half

of

the

soil

carbon

is

lost

primarily

because

annual

tilling

increases

the

rate

of

decomposition

by

aerating

undecomposed

organic

matter

About

GtC

or

two

wedges

worth

has

been

lost

historically

in

this

way

Practices

such

as

conservation

tillage

-LRB-

e.g.

seeds

are

drilled

into

the

soil

without

plowing

-RRB-

the

use

of

cover

crops

and

erosion

control

can

reverse

the

losses

By

conservation

tillage

practices

had

been

adopted

on

million

hectares

of

the

world

's

million

hectares

of

cropland

If

conservation

tillage

could

be

extended

to

all

cropland

accompanied

by

a

verification

program

that

enforces

the

adoption

of

soil

conservation

practices

that

actually

work

as

advertised

a

good

case

could

be

made

for

the

IPCC

's

estimate

that

an

additional

half

to

one

wedge

could

be

stored

in

this

way

TOWARD

A

HYDROGEN

ECONOMY

SPECIAL

SECTION

ergy

The

Changing

Climate

-LRB-

-RRB-

available

at

Environmental

Defense

Adequacy

of

Commitments

Avoiding

Dangerous

Climate

Change

A

Narrow

Time

Window

for

Reductions

and

a

Steep

Price

for

Delay

-LRB-

-RRB-

available

at

Climate

OptiOns

for

the

Long

Term

-LRB-

COOL

-RRB-

synthesis

report

NRP

Rep.

-LRB-

-RRB-

available

at

IPCC

Special

Report

on

Emissions

Scenarios

-LRB-

-RRB-

available

at

index.htm

R.

Socolow

S.

Pacala

J.

Greenblatt

Proceedings

of

the

Seventh

International

Conference

on

Greenhouse

Gas

Control

Technology

Vancouver

Canada

to

September

in

press

BP

Statistical

Review

of

World

Energy

-LRB-

-RRB-

available

at

contentId

T.

M.

L.

Wigley

in

The

Carbon

Cycle

T.

M.

L.

Wigley

D.

S.

Schimel

Eds

-LRB-

Cambridge

Univ.

Press

Cambridge

-RRB-

pp.

G.

Shaffer

J.

L.

Sarmiento

J.

Geophys

Res

-LRB-

-RRB-

The

authors

thank

J.

Greenblatt

R.

Hotinski

and

R.

Williams

at

Princeton

K.

Keller

at

Penn

State

and

C.

Mottershead

at

BP

This

paper

is

a

product

of

the

Carbon

Mitigation

Initiative

-LRB-

CMI

-RRB-

of

the

Princeton

Environmental

Institute

at

Princeton

University

CMI

-LRB-

cmi

-RRB-

is

sponsored

by

BP

and

Ford

Supporting

Online

Material

SOM

Text

Figs

and

Tables

to

References

VIEWPOINT

Sustainable

Hydrogen

Production

John

A.

Turner

Identifying

and

building

a

sustainable

energy

system

are

perhaps

two

of

the

most

critical

issues

that

today

's

society

must

address

Replacing

our

current

energy

carrier

mix

with

a

sustainable

fuel

is

one

of

the

key

pieces

in

that

system

Hydrogen

as

an

energy

carrier

primarily

derived

from

water

can

address

issues

of

sustainability

environmental

emissions

and

energy

security

Issues

relating

to

hydrogen

production

pathways

are

addressed

here

Future

energy

systems

require

money

and

energy

to

build

Given

that

the

United

States

has

a

finite

supply

of

both

hard

decisions

must

be

made

about

the

path

forward

and

this

path

must

be

followed

with

a

sustained

and

focused

effort

In

his

State

of

the

Union

Address

U.S.

President

Bush

proposed

billion

in

research

funding

so

that

America

can

lead

the

world

in

developing

clean

hydrogenpowered

automobiles

Since

that

time

articles

both

pro

and

con

have

buffeted

the

whole

concept

The

hydrogen

economy

-LRB-

-RRB-

is

not

a

new

idea

In

Jules

Verne

recognizing

the

finite

supply

of

coal

and

the

possibilities

of

hydrogen

derived

from

water

electrolysis

made

the

comment

that

water

will

be

the

coal

of

the

future

-LRB-

-RRB-

Rudolf

Erren

in

the

suggested

using

hydrogen

produced

from

water

electrolysis

as

a

transportation

fuel

-LRB-

-RRB-

His

goal

was

to

reduce

automotive

emissions

and

oil

imports

into

England

Similarly

Francis

Bacon

suggested

using

hydrogen

as

an

energy

storage

system

-LRB-

-RRB-

The

vision

of

using

energy

from

electricity

and

electrolysis

to

generate

hydrogen

from

water

for

transportation

and

energy

storage

to

reduce

environmental

emissions

and

provide

energy

security

is

compelling

but

as

yet

remains

unrealized

If

one

assumes

a

full

build-out

of

a

hydrogen

economy

the

amount

of

hydrogen

needed

just

for

U.S.

transportation

needs

would

be

about

million

tons

per

year

-LRB-

-RRB-

One

must

question

the

efficacy

of

producing

storing

and

distributing

that

much

hydrogen

Because

energy

is

required

to

extract

hydrogen

from

either

water

or

biomass

so

that

it

can

be

used

as

an

energy

carrier

if

the

United

National

Renewable

Energy

Laboratory

Golden

CO

USA

E-mail

jturner@nrel.gov

States

chooses

a

hydrogen-based

future

it

needs

to

think

carefully

about

how

much

energy

we

need

and

where

it

is

going

to

come

from

In

addition

sustainability

must

be

a

hallmark

of

any

proposed

future

infrastructure

What

energy-producing

technologies

can

be

envisioned

that

will

last

for

millennia

and

just

how

many

people

can

they

support

-LRB-

-RRB-

Technologies

for

Hydrogen

Production

Hydrogen

can

be

generated

from

water

biomass

natural

gas

or

-LRB-

after

gasification

-RRB-

coal

Today

hydrogen

is

mainly

produced

from

natural

gas

via

steam

methane

reforming

and

although

this

process

can

sustain

an

initial

foray

into

the

hydrogen

economy

it

represents

only

a

modest

reduction

in

vehicle

emissions

as

compared

to

emissions

from

current

hybrid

vehicles

and

ultimately

only

exchanges

oil

imports

for

natural

gas

imports

It

is

clearly

not

sustainable

Coal

gasification

could

produce

considerable

amounts

of

hydrogen

and

electricity

merely

because

of

the

large

size

of

available

coal

deposits

-LRB-

-RRB-

Additionally

because

of

its

relatively

low

cost

it

is

often

cited

as

the

best

resource

for

economically

producing

large

quantities

of

hydrogen

However

the

energy

required

for

the

necessary

sequestration

of

would

increase

the

rate

at

which

coal

reserves

are

depleted

converting

the

vehicle

fleet

to

electric

vehicles

and

generating

that

electricity

from

clean

coal

or

making

hydrogen

as

a

possible

energy

carrier

would

accelerate

that

depletion

Couple

that

to

a

modest

economic

growth

rate

of

and

U.S.

coal

reserves

drop

to

years

or

so

-LRB-

-RRB-

which

is

not

at

all

sustainable

That

leaves

solarderived

wind

nuclear

and

geothermal

energy

as

major

resources

for

sustainable

hydrogen

production

The

hydrogen

production

pathways

from

these

resources

include

electrolysis

of

water

thermal

chemical

cycles

using

heat

and

biomass

processing

-LRB-

using

a

variety

of

technologies

ranging

from

reforming

to

fermentation

-RRB-

Biomass

processing

techniques

can

benefit

greatly

from

the

wealth

of

research

that

has

been

carried

out

over

the

years

on

refining

and

converting

liquid

and

gaseous

fossil

fuels

Some

of

these

processes

require

considerable

amounts

of

hydrogen

and

many

of

these

fossil-derived

processes

can

be

adapted

for

use

with

a

large

variety

of

biomassderived

feedstocks

Biomass

can

easily

be

converted

into

a

number

of

liquid

fuels

including

methanol

ethanol

biodiesel

and

pyrolysis

oil

which

could

be

transported

and

used

to

generate

hydrogen

on

site

For

the

high-biomass-yield

processes

such

as

corn

to

ethanol

hydrogen

is

required

in

the

form

of

ammonia

for

fertilizer

Although

biomass

is

clearly

-LRB-

and

necessarily

-RRB-

sustainable

it

can

not

supply

hydrogen

in

the

amounts

required

It

remains

to

be

seen

in

a

world

that

is

both

food-limited

and

carbon-constrained

whether

the

best

use

of

biomass

is

for

food

as

a

chemical

feedstock

or

as

an

energy

source

Because

the

direct

thermal

splitting

of

water

requires

temperatures

of

C

and

produces

a

rapidly

recombining

mixture

of

hydrogen

and

oxygen

-LRB-

-RRB-

a

number

of

thermal

chemical

cycles

have

been

identified

that

can

use

lower

temperatures

and

produce

hydrogen

and

oxygen

in

separate

steps

The

one

that

has

received

the

greatest

attention

involves

sulfuric

acid

-LRB-

-RRB-

at

C

and

hydrogen

iodide

-LRB-

HI

-RRB-

at

C

-LRB-

-RRB-

The

next

generation

of

fission

reactors

includes

designs

that

can

provide

the

necessary

heat

however

a

number

of

critical

material

properties

must

be

satisfied

to

meet

the

required

stability

under

the

operating

conditions

of

HI

AUGUST

VOL

SCIENCE

Downloaded

from

on

May

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O B O O O O O B O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O B O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O 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