A scientist who spearheaded findings of rising greenhouse gas emissions is rebuking a Forbes columnist who incorrectly claimed that temperatures have been “flat” to question the manmade causes of climate change.
Tuesday, the Associated Press reported that National Oceanic and Atmospheric Administration (NOAA) data showed a dramatic rise in atmospheric carbon dioxide levels in 2012. Pieter Tans, who heads NOAA's greenhouse gas measurement group, told AP that “The prospects of keeping climate change below” 2°C (3.6°F) by 2100, as world leaders agreed to do, “are fading away.” He added that the carbon jump is “just a testament to human influence being dominant.”
Rather than using the news to evaluate the costs associated with our addiction to fossil fuel and discuss the steps we must take to avert the worst consequences of climate change, James Taylor of the industry-funded Heartland Institute used it to deny science. Taylor claimed that global temperatures are “essentially the same today” as they were in 1995 despite a contemporaneous rise in carbon emissions, and that this was a “devastating rebuke to assertions that rising atmospheric carbon dioxide levels are causing a global warming crisis.”
But Tans told Media Matters in an email that Taylor is “factually wrong” even using his short-term example -- 2012 was actually warmer than 1995 by about 0.16°C -- and that Taylor cherry-picked a date that had higher temperatures than surrounding years:
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.
In any case, long-term temperatures trends, a far more relevant indicator of climate change, aren't “flat” at all: each of the 12 years since the turn of the century have ranked among the 14 warmest on record. But Taylor obscured the long-term temperature rise by using a short period of data, as seen in this graphic from Skeptical Science:
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.