Although carbon dioxide (CO2)
comprises only 0.03% of the Earth's atmosphere, its projected doubling
this
century may change the climate significantly.
Recent empirical estimates of climate sensitivity, DT2x – the
change in
global-mean near-surface temperature due to a doubling of the
pre-industrial CO2
concentration – indicate there is a 90% likelihood that 1.0°C ≤ DT2x ≤ 9°C.
Some have argued that little or nothing should be done until
such “deep”
uncertainty is significantly reduced.
However, a new study finds that hedging in the near term
effectively
“buys insurance” against future adjustment costs and is extremely
robust across
most possible futures, especially when compared with a wait-and-see
strategy
that would eschew mitigation over the first third of this century.