The science is clear: global warming is real

A new word, ‘warmist’, has entered the vocabulary of discussion about climate change. It is often intended to mock and to imply that those who promote the fact that the climate of the earth is warming are members of some weird cult. It joins another word ‘denialist’ that is applied by some to those who refuse to accept that there is a human cause of climate change and disruption.

These words are unhelpful. Of course there is a fair debate to be had about the uncertainty of some of the precise details of climate prediction. But that is a far cry from the way in which extreme opponents of the conclusions of the science of climate change denigrate both the science and the scientists involved. This includes personal abuse of scientific leaders including the Met Office Chief Scientist and successive Presidents of the Royal Society.

Scientists are used to argument and to debate, and indeed science proceeds by posing questions driven by scepticism and uncertainty. One of the fundamental methodologies of science is to reduce uncertainty by means of experiment and observation. However, there is a difference between robust debate and unwarranted personal attacks.

Questions can be divided into 2 types, those for which there is an answer, even if we don’t know what it is, and questions for which there is no right or wrong answer and where different people will hold different views. The question of whether humans are causing climate warming is an example of the first type of a question, not the second. There is a correct factual answer. For this type of question Daniel Moynihan’s quote is apposite;

…you are entitled to your own opinions but not to your own facts.

As with any science which aims to understand and predict the future state of a complex system, there are uncertainties in climate science. That humans are emitting carbon dioxide and other greenhouse gases on an unprecedented scale, and the fundamental physics that carbon dioxide warms the Earth’s atmosphere, are not among these uncertainties. Climate scientists may not be able to quantify the precise impacts of climate change in a specific locality in fifty years time, but they do know we are performing a very risky experiment if we carry on emitting carbon dioxide at the rate we are today.

Climate change poses very serious risks, and responding to these is one of the biggest challenges facing today’s policy-makers. For this reason, there has been unprecedented rigour and global collaboration in the analysis and measurement of climate change. There is no equivalent of the Intergovernmental Panel on Climate Change in any other area of science. It is widely expected that the Panel’s ‘Fifth Assessment Report on the Physical Science Basis of Climate Change’, which will be published later this month, will present even greater confidence in the evidence that the climate is warming as a result of human activities.

This message may be unpalatable. The response should not be to shoot the messengers however - or to be abusive to them, which appears to be acceptable to a minority of commentators. How we respond is for all of us to determine. As John Holdren, scientific adviser to President Obama, put it in a lecture at Imperial College last year, we have 3 choices in responding to climate disruption, we can mitigate, we can adapt or we can suffer. The reality is that we shall have to do all 3. But unless we are very serious in our response, we and the other living inhabitants of the planet will suffer greatly.

Jointly written by Sir Mark Walport, the current Government Chief Science Adviser, and his 3 predecessors: Sir John Beddington (2008 to 2013), Sir David King (2000 to 2007) and Lord May (1995 to 2000).