November 27, 2010 — andyextance

The amount of greenhouse gases in the atmosphere reached the highest level recorded since pre-industrial times in 2009, despite a fall in CO2 emissions during the year, scientists have underlined this week.

Writing in Nature Geoscience on Sunday, a group of UK, US and Australian scientists found that global CO2 emissions from burning fossil fuel in 2009 were 1.3 percent below the record 2008 figures. However, the World Meteorological Organization (WMO) on Wednesday underlined that the overall amount of “radiative forcing” from greenhouse gases – a measure of the warming energy that they contribute – actually rose by 1 percent in 2009. The WMO notes that reduced growth rates for concentrations of greenhouses gases like CO2 and nitrous oxide last year were accompanied by more rapid growth for methane.

Atmospheric levels of methane, which contributes around one-fifth of global radiative forcing, had been steady for a decade previously, but have been rising rapidly since 2007. The WMO’s 2009 Greenhouse Gas Bulletin says that although the reasons for this are unclear, it’s thought that it is down to natural emissions as regions like the Arctic warm. “Potential methane release from northern permafrost, and wetlands, under future climate change is of great concern and is becoming a focus of intensive research and observations,” said WMO Secretary-General Michel Jarraud.

The WMO bulletin says that in 2009 the atmospheric concentration of CO2 was 386.8 parts per million, methane was 1803 parts per billion (ppb) and nitrous oxide’s concentration was 322.5 ppb. These values are 38 percent, 158 percent and 19 percent greater than in 1750, respectively, before the industrial revolution began to intensify humanity’s burning of fossil fuels.

These figures will rise still further, with global CO2 emissions set to reach their highest ever levels in 2010, according to the University of Exeter’s Pierre Friedlingstein and colleagues. The 1.3 percent drop in 2009 that their Nature Geoscience paper documented was less than previously predicted, and unlikely to happen again this year.

“Despite this drop, the 2009 global fossil fuel and cement emissions were the second highest in human history at 30.8 billion tons of CO2, just below the 2008 emissions,” the team wrote. They also predicted that 2010’s economic growth will raise CO2 emissions from fossil fuel by more than 3 percent, a high growth rate similar to what was seen earlier in the decade through 2000 to 2008.

The financial crisis seen in Europe and North America was expected to have a knock-on effect reducing energy use, Friedlingstein explained. “The 2009 drop in CO2 emissions is less than half that anticipated a year ago,” he said. “This is because the drop in world Gross Domestic Product (GDP) was less than anticipated and the carbon intensity of world GDP, which is the amount of CO2 released per unit of GDP, improved by only 0.7 per cent in 2009 – well below its long-term average of 1.7 percent per year.”

The global financial crisis severely affected western economies, reducing their industrial activity and need for electricity, for example, and therefore cutting CO2 emissions produced in power generation. UK emissions were 8.6 percent lower in 2009 than in 2008, with similar figures seen in most other industrialised nations. Rapidly growing emerging economies recorded substantial increases in CO2 emissions, with China’s emissions increasing by 8 percent, and India’s by 6.2 percent, broadly agreeing with figures produced earlier this year. These countries are more “carbon intense”, producing more CO2 for the money earned in their economies. This and the increasing reliance on coal around the world contributed to the poor carbon intensity result.

The good news, however, is that the team finds CO2 emissions resulting from forests disappearing over the last decade have decreased by over 25 percent compared to the 1990s. This is thanks largely to reduced deforestation in tropical areas. “For the first time, forest expansion in temperate latitudes has overcompensated deforestation emissions and caused a small net sink of CO2 outside the tropics”, says Friedlingstein’s co-author Corinne Le Quéré, from the University of East Anglia and the British Antarctic Survey. “We could be seeing the first signs of net CO2 sequestration in the forest sector outside the tropics”, she adds.

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