Why we have a scientific consensus on climate change
Posted on 23 March 2011 by Thomas Stemler
A short piece for the general audience of RTR radio, Perth, Australia.
(listen to the original audio podcast)
Recently a research group analysed the current literature on climate science. Their aim was to find out how many of the active researchers in the field agree on man-made climate change. The answer is, 97 out of 100 agree that the climate is changing and that we are causing it.
From my own experience, such a high proportion is quite unusual. As scientists we are trained to be professional sceptics, who doubt everything and who moreover love a good debate. Therefore putting 3 scientists together in a room sometimes results in an argument with 5 different opinions.
While this is the more enjoyable side of science, the more important one is that being sceptic lets us identify errors and improve our understanding of nature.
Climate science is a very special science. It includes experts who study the dynamics and data from the atmosphere, the oceans, glaciers, and so on. Some of us specialise in building models, others use them to make predictions.
So how come that 97 % of the experts agree that the current warming is not natural but a consequence of burning fossil fuels?
First, it is because all our data show that the global mean temperature is increasing, that the glaciers and the arctic ice are melting and therefore sea levels are rising.
Second, we know that burning fossil fuel releases CO2 into the atmosphere. The properties of CO2 were first studied by John Tyndall in the late 1850s. Tyndall was an experimental physicist interested in how different gases absorb heat. John Tyndall's observations were remarkable. His pioneering work eventually inspired physicists to develop the theory of quantum mechanics, but his results about CO2 also led Arrhenius in 1896 to the conclusion that burning fossil fuel will result in global warming. So climate science is a very old science indeed; we have known about CO2 for more than 150 years.
Nowadays we know how much CO2 we put into the atmosphere by using it as our global garbage bin for fossil fuel. All our climate observations show a global increase in temperature. This increase is consistent with the well established properties of CO2.
Taking this into account it is no longer surprising that 97% of the professional sceptics working in the area of climate science agree that we are currently witnessing man-made climate change. The only question remaining is, what do we do? Ignore the facts or generate energy from other sources?
Dr Thomas Stemler is a physicist who is currently an Assistant Professor of Mathematics at the University of Western Australia. He is an expert in forecasting of complex nonlinear dynamical systems.
This podcast is now available on iTunes (or search for "Climate Podcasts from the University of Western Australia" in the iTunes store). Alternatively, you can subscribe to the stream via feedburner.
[DB] To get a proper perspective, you should read this.
[DB] You keep insisting on a simple answer to a complex question and then reject the answers given you without an obvious demonstration that you've objectively tried to understand them.
If your aim is not to understand the science of climate change but to simply offer up non-science-based rhetoric with no sourced links to substantiate your contrarian positions, then other websites exist to serve that purpose.
[Dikran Marsupial] You said it would be desirable to "precise what is not enough understood to justify keeping on doing research". The statements of uncertainty in the IPCC WG1 provide you with exactly the precis you want, it is a bit daft to then complain that the IPCC report doesn't provide "certitude". Science isn't about "certitude" it is about assessing the plausibility of the competing hypotheses that remain after you ignore the ones that are inconsistent with the observations. I have pointed out to you repeatedly that there is no proof of any theory regarding causality in the real world, it is fundamentally impossible. If you want certitude, stick to mathematics, or politics (where words like "proof" and "certainty" have weaker connotations).[DB] Then it is clear you simply do not understand how science works nor the meaning of scientific consensus. This would be a step towards greater understanding in both matters. I suggest reading it.
[DB] The linked post I gave you contained a parable; one based on a National Academy of Science statement (a reference which should have answered much of your questions about scientific consensus and warming attribution). Ironic, you being a teacher failed to note that. As a teacher then, you were given homework to do (you blew off the reading assignment). Your grade is based on you doing the work assigned to you; that is incumbent on the student, is it not?
"Feed a man a fish and he'll be fed...for a day
Teach a man to fish and he'll never be hungry again."
So either contribute to your own edification on this by doing the homework given you or cease wasting the valuable time of those well-meaning people who are trying to help you.
Your choice.
[Dikran Marsupial] Stating that all things not being equal does not make it true. If you want to show that point was wrong, you need to specify what conditions are not equal and why they invalidate the hypothesis. Also while CO2 is rising exponentially, the forcing is logarithmic in CO2, and hence the expected warming trend is linear (once internal climate variability is considered). That is the expected correllation and it is pretty much what is observed, so that point is at best pedantry over the exact meaning of "correlation". Lastly, of course it is simplistic, this is a blog for discussion of the science for the general public, of course it is going to be simplistic. Also being simplistic doesn't make it wrong. For a less simplistic explanation, quantification, see the IPCC WG1 scientific basis report. DBs logic is fine.
[DB] In case anyone's curious about the correlation of warming and carbon dioxide, r = 0.874 for ln CO2 and dT 1880-2008.