13 July 2009

Two Decades of No Warming, Consistent With . . .

Over at Real Climate they are busy giving climate skeptics reason to cheer:
We hypothesize that the established pre-1998 trend is the true forced warming signal, and that the climate system effectively overshot this signal in response to the 1997/98 El Niño. This overshoot is in the process of radiatively dissipating, and the climate will return to its earlier defined, greenhouse gas-forced warming signal. If this hypothesis is correct, the era of consistent record-breaking global mean temperatures will not resume until roughly 2020.
Imagine, twenty-two or more years (1998 to ~2020) of no new global temperature record. What would that do to the debate?

Real Climate does say something very smart in the piece (emphasis added):
Nature (with hopefully some constructive input from humans) will decide the global warming question based upon climate sensitivity, net radiative forcing, and oceanic storage of heat, not on the type of multi-decadal time scale variability we are discussing here. However, this apparent impulsive behavior explicitly highlights the fact that humanity is poking a complex, nonlinear system with GHG forcing – and that there are no guarantees to how the climate may respond.
As I've argued many times, uncertainty is a far batter reason for justifying action than overhyped claims to certainty, or worse, claims that any possible behavior of the climate system is somehow "consistent with" expectations. Policy makers and the public can handle uncertainty, its the nonsense they have trouble with.