The target

I like Tim’s Lenton’s style, and his substance. He has his detractors — and his latest essay in Nature is a little light on supporting data — but he’s almost always worth reading. This one is probably a doomed to be ignored because it advocates focusing climate policy efforts on the complex issue of radiative forcing instead of politician-friendly temperature rise, but he’s probably right. A teaser:

Ongoing negotiations for a new climate treaty aim to establish a target to limit the global temperature rise to 2 °C above the average temperature before the industrial revolution. But that is not enough.

The target is linked to the United Nations Framework Convention on Climate Change (UNFCCC), which aims to “prevent dangerous anthropogenic interference with the climate system”. But that noble objective is nearly 20 years old and is framed too narrowly, in terms of the “stabilization of greenhouse gas concentrations in the atmosphere”. Long-term goals to limit temperature or concentrations have so far failed to produce effective short-term action, because they do not have the urgency to compel governments to put aside their own short-term interests.

Extrapolating from the same reasoning, others have reached similar conclusions. James Hansen would have us try to bring atmospheric CO2 levels down to no more than 350 ppm, and many small island states would like to reduce to the temperature target to 1.5 °C, both of which logically follow from worrying more about radiative forcing. But again, does anyone really expect to be able to convince even educated politicians about just what radiative forcing is?