News That Rising Emissions Could Lead To Dire Warming Should Prompt Action, Not Denial
by MAX GREENBERG, March 7, 2013
Taylor is factually wrong about the global temperature. According to the NASA GISS web site the year 1995 was 0.16 deg.C cooler than 2012. He could have compared to 1994 or 1996, in which case the difference from 2012 would have been 0.31 and 0.25 C cooler respectively. Therefore it makes sense to not compare individual years, but to take a 10-year smoothed average. In that case 1995 was cooler than 2012 by about 0.28 C. The second decimal depends a little on your smoothing technique.
The link between CO2 and warming is firmly grounded in well known chemistry and physics. We know that, as we add greenhouse gases to the atmosphere, additional heat will be retained in the atmosphere. The increase since pre-industrial times is currently 2.8 Watt m-2 averaged over the entire Earth, 1.8 of which is due to CO2 alone. The earth does two things with the extra heat. The majority is radiated to space in parts of the spectrum where the greenhouse gases do not absorb, and the rest goes into heating the oceans. More heat is radiated to space as the earth and atmosphere become warmer. The warming of the earth surface and the atmosphere is slowed down by the oceans. The latter take decades and longer to catch up with the new radiation balance. Eventually, if greenhouse gases stop increasing, a new steady state will be established with, on average, warmer oceans, warmer land surfaces and a warmer atmosphere. That is unavoidable and well understood. The questions that climate scientists are working to answer are about feedbacks that could either greatly amplify the warming from greenhouse gases, or dampen the effect. Unfortunately amplification appears stronger overall than damping.