Climate change and the scientific consensus

I found Kylie Beach’s recent essay in Eternity on the nature of the scientific debate to be winsome and useful. David Robertson thinks otherwise and expresses several ideas in his response piece. There are three key ideas I took away, and I want to respond to each of these in separate short essays. This present piece deals with the science of climate change.

Science involves the careful taking of measurements, formulating theories, and attempting to match those measurements or data with theories in the simplest possible fashion. In climate science, for example, this involves collecting data about the atmosphere both directly (for example, via thermometers), remotely (satellites), and via proxy (tree rings, ice cores, etc.). Data needs to be quality controlled so that it is useful (e.g. taking into account a measurement site moving a change in its surrounds), and techniques need to be calibrated (e.g. the relationship between tree rings and temperature). Data can then be plotted and trends measured. The repeatability of the results by different research groups using similar but slightly different techniques points to the robust nature of the results. By this, we know we with very high confidence that temperatures have been rising since the start of the Industrial Revolution. We also can say with good confidence this stands out compared to previous interstadials, the warm periods between ice ages.

It is a truism to say that the results of science are never settled, but what result would change the observed data? Let us move on to theory, then. Given it is certain that the planet is warming, how would we identify the cause? By proposing theories as to what could drive the change and testing them. What is required is not simply correlation – a match between observations and theory, but causation – a physical link between observations of different sorts. The Earth has warmed during periods of the sun’s inactivity. Therefore, it is not the sun warming the planet. Changes in the Earth’s orbit produce a see-saw pattern in global temperature, and now predict the Earth should be slowly cooling. It is not. Therefore, these changes are not driving the warming.

How much longer do we give airtime to sceptics?

American Eunice Foote showed in 1856 that the atmosphere absorbed heat, and in 1859 John Tyndall demonstrated this was due to carbon dioxide and water vapour. Svante Arrhenius from 1900 started to examine how carbon dioxide emissions and the resulting water vapour feedbacks (extra evaporation) would influence the temperature. This is causation. The correlation between carbon dioxide emissions and temperature is now well known. Computer models can now validate past temperature increases, and the Intergovernmental Panel on Climate Change (IPCC )report shows how different the world would be now without past emissions. Models increase in complexity over time. In that regard, science is not settled. However, no update in science has improved the outlook for our future. The biggest source of uncertainty is us and our emissions. Yes, we can change the world for the better.

David tells us that humility does not command that we listen to climate scientists. To whom then? He cites three people. Michael Schellenberger is a journalist. Bjorn Lomborg has a degree in political science and lectured in statistics. Steve Koonin is a theoretical physicist. None of these people is a climate scientist. David tells us that the website skepticalscience.com attacks sceptical scientists. Actually, run by real climate scientists, it presents new data, summarises new research, and critiques the work of sceptics, showing it for what it is.

The truth is, 97 per cent of papers in the field affirm the consensus science. The remaining 2-3 per cent contain errors.

I’d like to finish with a cautionary tale. Dr Richard Muller is a physicist who once thought that climate science was flawed. So much so, he started a consultancy to find all of the errors in how the data was analysed. After collecting a team of top-notch physicists, Mueller concluded that not only could he reproduce the results of other research centres, but that the only theory that could account for the observed warming was the greenhouse gas theory. He notes in this interview that he wrote a graduate textbook on changes in the Earth’s orbit. One might argue that for a physicist to challenge the work of climate scientists lacked humility. However, he did have the humility to change his mind when confronted with the data. The independent work continues at Berkley Earth.

I presented this video as part of a presentation to a church group. One sceptic politely waited until I had finished, told me how disappointed he was in Muller. He was attending a conference the very next week, where they would be sharing their datasets—a parallel universe.

How much longer do we give airtime to sceptics? I have a friend who is a flat earther. Do we provide them with airtime every time Bezos sends someone into space? Do we allow Holocaust deniers time in discussions about history, or put inventors of perpetual motion machines alongside engineers? To attack the consensus and claim victimisation, exclusion, or censorship of “the other side of the debate” is a nice rhetorical flourish, but it does not represent the true situation. It is not humble. It says, “My opinion matters as much as the next person’s”. But you are not entitled to your opinion, only what you can argue for. This is something experts can do.

This is the first of a three-essay response by Mick Pope to a recent article by David Robertson, written in response to an article by Kylie Beach. You can read Part 2 of Mick’s response here, and Part 3 shortly.

Pope is a forecast meteorologist with twenty years of experience in the Australian Bureau of Meteorology. He also is a university professor with a PhD in tropical meteorology and is part of the ISCAST (Christians in Science and Technology) network.

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