Professor Kevin Anderson:

I have to disagree slightly with Professor Sweeney's final comments. From a modelling point of view, the scientists have done a fantastic job. The models are remarkably robust. Let us draw a very clear distinction between the modelling that the scientists do, which is basically lots of physics, and the modelling that goes on in these other huge models that use integrated assessment models, which is where we shoehorn in anything that can be quantified. There is a whole load of economics in it and right at the core is always a general equilibrium, which is basically a market economic growth model. One cannot question that so everything has to fit around it.

There is a simple climate model into which are plugged in theories on transitions and how technologies change. These things are really uncertain. One thing that is always missing is behaviour, and equity is almost completely ignored in these models. These models are part of the problem. Adding more data to them will not make them better. It just makes them worse. This is a deeply political problem that needs to be informed by science, including the excellent climate models. The voices we are missing in this, from an academic point of view, are less those of the scientists.

I heard the term "mitigation denial" used. I know climate scientists who are mitigation deniers. They deny the levels of mitigation that are necessary because they are not politically palatable. The funding we have requires us to do research that fits with the politics of the day. Look at how quickly net-zero has become a new term. Going back five years, it was not in the IPCC's AR4 or even AR5 reports but now it is everywhere. One cannot talk about climate change without talking about net-zero but most people do not even know what it means, although they use it.

We have to be careful about assuming that scientific expertise is what we need to guide good policymaking. Maybe we need to bring in more people from the social sciences and the humanities. I am an engineer. There are other people out there who have a useful contribution to make, as does wider civil society. Some of the work and ideas embedded in the Climate and Ecological Emergency Bill that is being developed in the UK at the moment, across parties, is looking at ongoing citizens' assemblies informed by experts as an ongoing process of thinking about these issues. It would be a bit like the House of Lords but rather than just being comprised of select elites it would be a much more random choice of people. That might help inform the policymaking process.

I am cautious about adding more quantitative expertise into models because all we will get from that is more high-tech options for the future and less understanding of the potential for major political change today. That is what we are talking about here. We are talking about political leadership akin to the big shifts we have seen in society from time to time, not about the incremental change that we see in between. It is not managerial politics we are after now but political leadership. There is no way that can be usurped by quantitative models so I would be cautious about that route.