Some of the folks I follow on Twitter engage in periodic arguments about climate change, whether or not it is happening and the influence of human activity on this change. I don’t engage in these arguments personally because I don’t really know enough about this issue (I admit to being wishy washy in this as in most things). But with 40-odd years in science and engineering and 20 years working in complex systems, I think I do know enough to say that many of the statements made by climate change believers and non-believers prove nothing at all.
Basically, the earth’s climate is an immensely complex, dynamic system that is influenced by a huge number of variables. We do not understand the relationships between many of these variables (e.g. El Nino and sunspots). Therefore, our climate models are gross simplifications of reality. If we had thousands of years of data, we could maybe refine these models but at best we have just over 100 years of data so our model validation is necessarily limited. However, observations suggest that the earth’s climate is becoming warmer and current climate models suggest that human activities (agriculture and industry) are contributing to this via methane (primarily cow’s farts but also some industrial leakage) and CO2 emissions from burning carbon-based fuels.
This suggests to me that we should take actions to reduce methane and CO2 emissions because it is possible that the climate models are right and if they are, the consequences are severe. We will run out of carbon-based fuels eventually anyway so it makes sense to look at alternative means of energy production so long as these don’t do more harm than good to the environment.
However, it is also possible that the climate change models are wrong and that there is some other factor which we don’t understand and can’t control that is affecting the earth’s climate. Unfortunately, politicians especially in the US, make the incorrect assumption that because this is possibly the case then it must necessarily be true and nothing needs to be done.
Turning now to the twarguments about climate change there are 3 positions taken that are not really justificable.
1. The vast majority of climate scientists believe that climate change is dominated by human influences so it must be true. Science is not about democracy. If the ‘vast majority’ of scientists suddenly decided that Einstein was wrong on the basis of some incomplete physics models, then it would not mean that this was true. Scientists are human and those who have built their career on climate modelling (and depend on government grants) are loath to admit failings (and some climate scientists have behaved very badly e.g. Climategate scandal).
A book that all scientists should read is ‘The Structure of Scientific Revolutions’ by Thomas Kuhn. He points out that the history of science is dominated by paradigm shifts where the vast majority of scientists believe one thing and reject all evidence to the contrary. This only changes when some (often younger) scientists take a contrary position and finally convince the community of a new position.
2. Event X (say extent of Antarctic sea ice or slower temperature growth than predicted by models) contradicts other observations that the earth is warming so it can’t be true. This is also a pretty weak position. There is no need for warming to be uniform for it to be damaging and warming takes place over many years. This is simply another piece of data that should be added to the dataset to allow models to be refined.
3. The influence of greenhouse gases is proven so these have to be the major contributors to climate change. It is certainly true that gases such as methane and CO2 are greenhouse gases and trap heat. But we know so little about natural climatic cycles that we simply cannot know whether or not these are dominant. As I said, it makes sense to me to take a risk-averse position on this but the notion that it has been proven that our current observed climate changes are necessarily a result of gas emissions resulting from human activities is simply nonsense. These do correlate with human industrial activity and population growth but correlation is not causality.
The public have a right to know about scientific thinking and climate issues are incredibly important. The current journalistic presentations on these issues are mostly utterly simplistic and consequently, it is perhaps unsurprising that these twarguments go on. Sadly, too many scientists are unwilling to admit the complexity of this issue and communciate directly with the public in terms they can understand. Until we do this, we will not have public understanding of climate science and pantomime arguments (oh yes it is, oh no it isn’t) will continue.