A recent issue of the journal Nature carried two scientific
reports that underline the challenge for governments — and for
fossil fuel reliant countries and companies — if the world
agrees to keep greenhouse gas emissions within limits deemed
safe by scientists. Looking at the broad period beginning
roughly from the industrial revolution to the year 2500, one of
the reports argued the need to limit cumulative carbon dioxide
to about 1 trillion metric tons, on the basis that the
accumulation of long-lived greenhouse gases, like CO2, mainly
determines maximum projected warming. But with more than that
amount of carbon dioxide already released since industrial
times, “it may well turn out that we can only afford to release
less than the same again, possibly much less, with many times
that amount in fossil-fuel reserves remaining underground,”
according to a commentary by the authors of the reports
published by Nature online on April 30. The commentary warns
that “having taken 250 years to burn the first half-tri