Top climate change scientist explains how to ‘get the work done’

The science is unequivocal: anthropogenic climate change from burning fossil fuels is undeniable and is happening at an alarming rate. We need to reach net zero globally by 2050 and decarbonise rapidly by 2030. A report from the World Meteorological Organisation predicts that one year in the next five will almost certainly be the hottest on record, and there’s a high chance that the world will cross the critical 1.5C global warming threshold by 2027.

That means radically reducing fossil fuel use, whilst scaling renewable energy, decarbonising industry, and protecting and restoring our natural ecosystems. Delivering this requires immediate, bold action from governments and the private sector if we are to protect ourselves from the worst consequences of climate change.

Supporting this effort, are the world’s foremost climate scientists, The Intergovernmental Panel on Climate Change (IPCC) – a UN scientific group of experts and the authoritative source of expertise on climate change. They provide policymakers with comprehensive assessments on the causes, impacts, and how to respond to climate change. Formed of three Working Groups: Working Group I deals with the physical scientific basis of climate change; Working Group II deals with impacts, adaptation and vulnerability; and Working Group III deals with the mitigation of climate change.

Professor Jim Skea is co-chair of Working Group III, and the UK’s candidate to be the overall chair of IPCC. In a recent conversation, I discussed with him the crucial role of climate science in policy-making, and how to ensure climate negotiations between countries are based on the science.

There’s no doubt that the conversation around climate change, which has intensified since the IPCC began over 30 years ago, is finally being taken seriously. But as we look ahead to key climate targets in 2030 and beyond, what does the future hold for climate science and how will it inform urgent action now?

“I think the attitude to climate change has changed over time. When we started 25 or 30 years ago, climate change was something for the future, something you projected, it wasn't something that was happening now. I think the realisation has come in the last five to 10 years. You only need to look out of the window or decide what clothes you're going to wear on the outside, or if you're living in vulnerable parts of the world, to really see the impact.

“Climate change is happening now and we have evidence the world has warmed by more than 1C. Already we can see the impacts. Climate change is here and now, and it will get worse. And that's where the light bulb turned on for me fully in terms of understanding what the implications of climate change could be. If we see bad things now, they could get much worse in the future, unless we take much more radical action.”

“At the moment, we're about three months towards the end of the latest IPCC cycle – this cycle has lasted nearly eight years. It’s a substantial effort, and we're trying to make sure at the moment that the final IPCC products are put together. It's the culmination of all the activities we've had over the last seven or eight years.

“In this cycle, we, in Working Group III, convened a group of about 250 authors, who together wrote 17 chapters overviewing the latest climate science on how to reduce climate emissions. We then had to go through these chapters with governments worldwide, to nudge, steer and shape them towards a final product. The summary for policymakers, which is usually around 30-40 pages, requires agreement word for word, line for line, with all the world's governments. The culmination of these efforts is a week-long meeting to agree with governments – and every word and every line is fought over.

“Right now, we are wrapping it up. We ran a workshop on scenarios for the future, which is an important topic for the next cycle. What we're trying to do is set everything up, so that whoever takes over from us after the elections in July, is in a good place to build on the knowledge that we built up during the last cycle.”

“This is something that varies a lot between the working groups of IPCC. When it comes to Working Group I on the physical science, governments cannot argue with the scientists – they don't know enough, the scientists are truly authoritative. In Working Group III when we get on to mitigation, which takes us more into the policy space, a lot of the government people know an awful lot about mitigation. So, it's a very different dynamic when you are trying to approve reports. We need to stick to the science. The obvious risk we as co-chairs are guarding against is governments trying to alter the report’s wording to align with their interests, away from the underlying science. This is high-stakes for governments because what they agree in the IPCC will lock them in as they enter climate negotiations.

“Some of the things need to be phrased extremely carefully. And we need to ensure we don't diverge from the underlying science. So, somebody like me will be wielding the gavel, the chair in the middle of the meeting looking at a sentence, and if governments propose something, we always turn to the experts to ask, “is this true to the underlying science?” And if it’s not, we won’t approve it and we will not gavel it down. Governments being in the room is important as they help craft the messages that will be most compelling to policymakers back in their home country. But of course, it's a delicate balancing act to do that sometimes. We are always driven by two principles: is it communicable and is it true to the underlying science?”

“The Global Stocktake currently taking place under the Paris agreement is really important. It’s divided into two phases: the technical, which will come to an end in September; and the political phase. From a scientist and IPCC point of view, the technical phase has been the most important, and we have been heavily involved.

“I'm a humble scientist, so I can’t speculate where the political phase is going in the next six months or so. We know it's incredibly important, but we don't quite see the political landing ground now. For IPCC, one of the considerations moving forward, is already thinking about the second Global Stocktake in 2028, and whether IPCC can produce useful products in advance of that second Global Stocktake. It's a big consideration for IPCC as it considers its activities over the next two to three years.

“When we think about scoping the next cycle, we're not thinking about the policy audience in 2023, we’re thinking about the policy audience towards the end of the 2020s and early 2030s where it will be much clearer where we are with respect to 1.5C warming. There may even have been one or two years when global warming exceeded 1.5C. This question of implementation is going to be a critical issue. IPCC traditionally thought about the longer term – years 2100 and 2050 – but we are going to need to think much more about 2025, 2035, and 2040. What does implementation look like? What can we actually achieve?”

“At the end of the last cycle, there were quite a few emerging issues One of them is the carbon dioxide removal – taking carbon out of the atmosphere. It's evident that unless we bring carbon dioxide emissions to net zero, global warming will not stop. The word ‘net’ in net zero emissions is significant because some kinds of carbon dioxide emissions are unavoidable or will be very difficult to remove. To get to net zero they will need to be compensated by means for taking carbon dioxide out of the atmosphere.

“One broad way of distinguishing between the different approaches is between the kinds of engineered solutions on what are being called ‘nature-based solutions’. There can be a robust and almost tribal debate between people who favour different approaches. It is a slight source of exasperation to me that people appear to spend more energy saying what solutions we should not employ to deal with climate change rather than thinking about the positive side of each contribution, because frankly, the Paris targets are so ambitious we can't really leave as to anything off the table.

“Nature-based solutions is a deeply controversial phrase within IPCC. Some governments do not like the phrase nature-based solutions – their argument is not with the word ‘nature’, but with the word ‘solutions’. They think the name nature-based solutions implies that nature can do it all and therefore we can leave it to the engineered reductions– so we have to choose our words very carefully.

“I'm not going to take any one side – I think the targets we've set out and the kind of the one-way street that the human race is on in terms of climate change means we need to deploy everything to some degree. We can enjoy making some choices about the degree to which the different options should be exercised, but we're going to need everything. For me, it's a little bit of a sterile debate. We need to think about how we can do each of them well, rather than saying one of them is completely off the table.”

“There are some studies now that are able to assign a percentage probability that a specific climate event, flooding event, or extreme temperature event, was due to human-induced actions on the climate. And that will be quite a controversial area because it will take it into discussions of losses and damages – new issues that are important to vulnerable parts of the world, especially to the small island developing states. These are some of the key issues that are going to need to be opened up. We've solved the big question in the latest report, it unambiguously said it is unequivocal that human beings have caused climate change – the word unequivocal is really important. That question is settled. But there are so many other scientific questions that need to be dealt with as we move into the future.

“The question of attribution of climate change raises questions of responsibility. The idea of responsibility is a very difficult one for IPCC to deal with because it is quite subjective. One thing that we did in Working Group III in this cycle was to document historic information going back to 1850 for all regions of the world. But that's where we stopped – there are all sorts of different legal interpretations of what responsibility might be. That's a very subjective kind of question. And that's when we have to pass it over to the policymakers, who of course, are not going to agree with each other – we totally understand the very different perspectives. But we felt it was our job to put the basic information out there into the public domain to allow a more informed debate among the policymakers.”

“Concepts like net-zero have really been helpful in guiding and motivating action – these two words ‘net zero’ really capture the imagination of political leaders, and have been helpful to define the end goal. The biggest challenge now, both for the scientists and policymakers, is much more attention to implementation and closing the gaps between where we need to be, what we promised to do, and what we're actually doing on the ground. Unfortunately, it’s much harder to find a simple, organising principle that will get us going in the short term, because we're really going down into local action on the ground, like assembling wind turbines, insulating homes, improving public transport. There are just so many things that need to be done.

“I think the key thing if we were to be serious about moving on climate change, is to mainstream climate across all kinds of policy-making and areas of activity. We can lock ourselves into future carbon dioxide emissions with the wrong kinds of planning decisions and infrastructure investments. Every investment decision should be screened for its implications for climate change. We don't always need visionary leaders, we need all members of society, citizens, and communities, who are working on the ground to make things happen.”