Sombre reminder of climate disarray

Yet another reminder of the perilous disequilibrium of earth's climate
has come our way, via the Royal Society and the Tyndall Centre for
Climate Change Research. Two of the sharpest brains at Tyndall, Dr Alice
Bows and Prof  Kevin Anderson  (both at Tyndall North here in
Manchester),  have  put together an assessment of the politically driven
aim to restrict global average temperature increase to 2 degrees
centigrade. They find this aim to be seriously defective, and in a
closely argued and densely referenced 20 page paper they offer their
reasoning.

Their assessment of our capacity to restrain temperature to bearable
limits focuses on (a) the recent acceleration of 21st century CO2
emissions, well beyond the bounds of the working assumptions of the IPCC
4th Assessment Report (AR4) (2007) and of the Stern Report (2006); (b)
the neglect in current political thinking of the powerful role played by
deforestation and by other greenhouse gases; (c) the implied naivety of
the generalised (and politically useful?) belief that the route to a
stable atmospheric concentration of CO2 (and the other greenhouse gases)
can be attained without detailed attention being paid to the emission
"route" through  which this supposedly ideal, or at least tolerable,
concentration will be attained. This route necessitates defining a peak
year for emissions, and then defining a steeply decreasing year-by-year
curve  in emissions down to a near-zero "no-regrets" minimum.
They show with rigorous argument and calculation that it will be much
much harder - and possibly politically impossible - to hold the
anticipated temperature increase below 2 degrees, and show that a more
honest assessment of the way things industrial and political are going
is that an increase of the order of 4 degrees is likely - and that
society should plan for the appropriate adaptation.
The politically possible and the physically necessary demands in carbon
emissions are thus in unreconcilable conflict. The extremely steep
annual drops in emissions needed by the biosphere and its human
inhabitants do not seem to be achievable.

"Reframing the climate change challenge in light of post-2000 emission
trends" by Kevin Anderson and Alice Bows.

Phil. Trans. R. Soc. A
doi:10.1098/rsta.2008.0139
Published online