Dear denialists, I must apologise

You see, in my previous post I grievously underestimated how many climate change sceptics there are among Thought Leader readers. Perhaps my calling those sceptics “dim-witted” drew them out from their exhaust fumes. I’m not sure. But the point is, I must apologise: not for the insult, but for unwittingly creating the impression that there is debate about whether climate change is human-generated or not. Because there really isn’t.

Though parliaments and social groups may still be debating the reality of climate change, scientists in the climate science community have reached consensus: climate change is human-generated. In one study 3 146 actively publishing climate scientists were asked about climate change. A whopping 97% agreed that human activity, causing carbon emissions and deforestation, was driving climate change [1]. The IPCC, an intergovernmental, international panel tasked with reviewing research into climate change, agrees that climate change is “very likely due to the observed increase in anthropogenic (human) greenhouse gas concentrations” [2]. Furthermore, they state that the probability of climate change being caused by natural climatic processes is less than 5%.

Finally, the US National Academy of Science — another body based on the principle of peer-reviewed research — also attributes climate change to “human activities that have increased the amount of greenhouse gases in the atmosphere … on climate change, [the National Academies’ reports] have assessed consensus findings on the science … “[3].

Boring as that may have been to read, the point is quite obvious: the science is in; climate change is being driven by human actions. On this point there is consensus. Granted, scientists will not ever say they are 100% sure, but no scientist ever should. Even Newtonian physics and the theory of evolution are not referred to in the language of absolute certainty. There is always a small chance that some new finding will change the theory as it stands today.

That said, however, the relative certainty of climate scientists is quite phenomenal. According to the IPCC statements containing the word “most” translate to a likelihood greater than 50%, “likely” means at least a 66% likelihood, and “very likely” means a likelihood of at least a 90%. So, from their statement above, the IPCC links climate change to human actions with at least 90% certainty. Such certainty does not come easily in the fields of science, and it should not be taken lightly.

Now, I can just hear the charge that IPCC findings can’t be trusted — that the very basis of its climate change model is flawed. But this is not the case. While there were a number of mis-statements found in their research documents, hundreds and hundreds remain unchallenged, and are supported by a massive volume of research. Nonetheless, anticipating the confusion that theses mis-statements would cause — and how quickly sceptics would pounce on them — 250 climate scientists in the US signed a statement saying that their position on human-generated climate change was unchanged and “unequivocal” [4].

I could go on, but again the point I’m trying to make is simple: the science on climate change is settled. Though there may be debate on finer points, peer-reviewed research no longer questions the basis of human-generated climate change. Any substantial challenges that have come against the theory have been responded to, and either dismissed, or incorporated without any meaningful change to the overall theory. This consensus is as certain as science gets. And being confident in these findings isn’t some form of religious dogma; it’s a belief consistent with a mountain of peer-reviewed research.

Now, I am not a scientist, let alone a climate-change scientist. For this reason I’m unable to argue on the finer points of climate change, and frankly I don’t care to. But my failure to do so doesn’t make the findings of bodies like the IPCC any less valid. So when I don’t, or can’t respond to your theory that climate change is really caused by volcanoes or the like, you won’t have disproved climate change. It’s really not that simple — and seriously believing that one’s pet theory could possibly challenge a scientific consensus of this magnitude, must make one at least a little dim-witted.

[1] Intergovernmental Panel on Climate Change. http://www.ipcc.ch/organization/organization.htm. Accessed online 15/05/2010.

[2] IPCC Fourth Assessment Report: Climate Change 2007

[3]“A guide to facts and fiction about climate change”. The Royal Society. March 2005. http://www.scribd.com/doc/7989797/A-Guide-to-Facts-and-Fiction-About-Climate-Change. Retrieved 15/05/2010.

[4] IPCC Fourth Assessment Report: Climate Change 2007“Open Letter from U.S. Scientists on the IPCC”. http://www.openletterfromscientists.com/