ML I want to take as the starting point the presentation made by Stuart Kirk, the now-suspended Head of Responsible Investing at HSBC, at the FT Moral Money conference. What was his overarching thesis in your view?
RP His overarching thesis was that investors really don't need to worry about climate risk. He said that because the average HSBC debt portfolio loan is six years, what happens to the planet in year seven is actually irrelevant to their loan book. He said, somewhat flippantly, something like “who cares if Miami is under six meters of water”, which I think obscured more important points that any ESG investors should be aware of. In climate change, there's good guys and bad guys and he allowed himself to be painted as one of the bad guys. Kirk is the Head of Responsible Investing for a major bank, and he was at an investor conference where, almost always, people do not present themselves as brave truth tellers undermining their own industry. I get it from a mathematical, from a spreadsheet perspective, that if you're insuring your risk for the next year, then what happens in year 30, probably doesn't factor into that. When he talked about GDP, he raised a really important point. Under the Intergovernmental Panel for Climate Change, IPCC, its scenarios have some contradictions in the long term. On the one hand, all of the scenarios show that every one of us worldwide will all be much richer by 2100. At the same time, it says that in some regions, people won't be able to live there, it'll be uninhabitable. I call this the climate GDP paradox. Are we all going to be rich, or are we not going to be able to live in certain places?
ML Do you want to start by laying out your position on climate change? Are you fully orthodox or somewhat orthodox?
RP I was, I think, the first person in the United States to write a PhD dissertation on the role of climate science and supporting climate policy. Climate change is real, it's serious. Carbon dioxide emissions from the burning of fossil fuels is a, if not the, major driver in climate change. What I'm saying is boilerplate IPCC conclusions. I have strongly supported IPCC since the beginning. The Framework Convention on Climate Change defines climate change only as those changes caused by the emission of greenhouse gases into the atmosphere; IPCC has a much broader definition. There are broader human impacts on the climate system than just greenhouse gases.
ML What about on mitigation? Can you talk us through the Kaya identity?
RP The Kaya Identity was the basis for my book, The Climate Fix. It is the single most powerful tool that we have for understanding the challenge of emissions reductions. Kaya’s point was to generate profiles of future carbon dioxide emissions so they can be plugged back into climate models. It says there's four reasons why we have increasing carbon dioxide emissions: more people, more wealth, energy consumption, and energy production.
ML Tell us about the issues you raised in The Climate Fix. Did you look at some of the solutions for those different pieces of the formula?
RP In it I took issue with the way that we use scenarios. We're not going to get rid of people, we're not going to make people poor. What that means is we have only two instruments that we can use to achieve deep decarbonisation. One is energy productivity, the other is the carbon intensity of the energy that we produce. Whatever we do on efficiency, carbon intensity worldwide has to go down to close to zero. At the same time, we have to recognize that global energy consumption is going to increase. In that book I simply presented the magnitude of the challenge.
ML I think we have to start now by talking about hurricanes. When did you start working on hurricanes?
RP I started working on hurricanes in my postdoc. The paradox that we started with was that 1991 through 1994 was the most expensive period for hurricane impacts in history. It was also the quietest period for Atlantic hurricane activity in the last 50 years. So, we said, let's answer a question. If every hurricane season of the past happened with 1995 population, 1995 infrastructure, how much damage would there be? And we called that normalized hurricane damage. We were among the first people to offer an alternative to catastrophe models for understanding trends and damage.
ML You’ve repeatedly concluded that the significance of any human-caused climate change to hurricane impacts has been exceedingly small.
RP That's perfectly fair. From 1992 to today, there is no upward trend in land-falling hurricanes in the US. Globally, we have data from 1970, and again, there's no upward trend over that timeframe for hurricanes. Part of the issue is, I think, if you just started paying attention to hurricanes in the last 20 years, which is a lot of people a lot younger than me, you would think there's a lot more hurricanes. We can't substitute our experience for actual climate data.
ML Let's broaden to other types of weather related damages. With droughts, wildfires, flooding, heat waves, are we seeing a climate fingerprint?
RP We can't talk about extreme weather as one big category. Extreme weather involves phenomena and we have to take them phenomenon by phenomenon. The IPCC defines a change in climate as a statistically detectable change over 30 years or more of data. The IPCC concluded that with respect to heat waves, in many parts of the world, though not North America, they have detected a statistically significant increase in heat waves. So yes, it is absolutely the IPCC position that that increase can be attributed to greenhouse gas scores. The IPCC does not weigh in on wildfires, or forest fires per se, because they are multi-causal. But what they do focus on is what's called fire weather, which is a combination of hot and dry conditions. They have found an increase in fire weather in a number of places around the world. However, the events that we see on the media the most - hurricanes, flooding, meteorological and hydrological drought, and tornadoes - the IPCC does not have confidence in either detection or attribution.
ML In East Africa right now there is a drought. There are certainly those who are saying that is climate change.
RP This is a really important point. So, we went from talking about 30 year plus trends in events to raising a particular drought in the Horn of North Africa. There is a relatively new area of science that has developed that's called event attribution. It's early days in that sort of science. These are interesting, provocative studies, they certainly generate headlines. But I'm not sure that they have the stature of 30-year, 40-year, 80-year datasets, looking at drought, floods, tropical cyclones, and so on. I'm not ready to substitute models for evidence quite yet. If your study says there's an event that's 30 times more likely than it used to be, then the proper question would be to say, well, why haven't we seen an increase of 30 times over the last 50 years, or whatever the data set happens to be?
ML Stuart Kirk also claimed that we actually now have fewer deaths from floods, droughts, storms, wildfires, and extreme temperatures. There’s been a lot of population growth, but it looks like deaths from those causes have been going down.
RP From about 100 years ago to today, the total number of deaths caused by extreme weather have decreased. And also, the proportion of deaths as a proportion of the population by several, two-three orders of magnitude. This is what makes it so difficult to attribute climate change singly to human impacts, because at the same time that the climate is changing - and yes, it is changing – so too is society, and so too is our ability to deal with the vagaries of weather.
ML Professor Michael Mann argued on Democracy Now that climate change is already costing far more lives than COVID-19.
RP Professor Mann probably needs to brush up on his disaster statistics and maybe stick to physical science. To try to assert that climate change through these four or five extreme events exceeds the number of deaths versus COVID is simply irresponsible. It's wrong. The adding up of deaths related to natural disasters is a very imprecise science. Over the long term, what is clear though is that the reduction is so sufficiently large, that, unfortunately, a few thousand here and there in the recent years doesn't detract from that incredible decline of millions of deaths over the better part of a century.
ML What did it feel like when John Holdren, the President’s Scientific Adviser, said that you were outside the scientific mainstream?
RP I am I think the first and only scientist who has been attacked by the US Presidential Science Advisor in the history of the position. I have to say that being attacked by the White House, being attacked by a member of Congress, being investigated by my university… That was a dark, difficult time.
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ML Roger, you recently wrote a paper with Justin Ritchie, entitled Distorting the View of Our Climate Future, the Misuse and Abuse of Climate Pathways and Scenarios. You said that climate science research and assessments under the umbrella of the IPCC have misused scenarios for more than a decade, especially the treatment of an unrealistic extreme scenario as the world's most likely future. I have inveighed against the scenario RCP 8.5. I consider it to be wildly implausible.
RP Going back 30 years, the IPCC has used an approach to looking into the future called a scenario analysis, and scenario analysis dates to the 1960s. The most extreme scenario of its scenario set goes by the name RCP 8.5, which was later identified as the single reference scenario. That scenario, overeggs the pudding, it's not a plausible scenario anymore. Yet in the most recent IPCC report, that scenario features more than any other. Every one of us who engages in research, we make mistakes. The problem is, what do you do when you find out that you're going in the wrong direction? So, for me, that is a signal that there are some self-correction issues in the scientific community. And one way to call attention to that is to write articles that call it out.
ML RCP 8.5, has got a successor scenario which is SSP5 8.5. To get there, you have to burn a lot of coal: 7 to 10 times as much coal as currently. It's not just slightly implausible, it is by now wildly implausible. Nobody in my world, the energy world, is planning or thinking about or would consider or conceive of a return to coal to liquids, and yet, that was what was driving the RCP 8.5 scenarios. If it's not 8.5 where are we currently headed?
RP The reason the climate science community holds so fast to RCP 8.5 is because the needs of climate research are better served by an extreme scenario, even though the needs of policy might be served by a much more plausible scenario. People may be surprised to learn that in the IPCC community and in the science community, there is no one who is tasked with the responsibility for assessing scenario plausibility. Scenarios are so important, and they're so central to everything we talk about in climate science impacts and policy, that someone needs to have that responsibility. Deep decarbonisation is an enormous challenge. But the world in 2022, is much better positioned for that challenge than we would have thought in 2005. We cannot develop scenarios in 2005 and still be using them 17 years later.
ML I broke energy Twitter at one point by saying that the papers that use RCP 8.5 should be withdrawn or resubmitted after correction. It's very hard to know what to call them other than junk science.
RP One of the issues that boggles my mind all the time is there are there are 1000s of studies that use RCP 8.5 as a business as usual. But the implication is that this is the trajectory we're on. If people knew that RCP 4.5 was considered policy success in large parts of the literature… Today, much of the literature looks at RCP 4.5 as an upper bound based on current policies. Try explaining that one to a policymaker. At this point in the climate debate, I often think that these scenarios get in the way more than they help. If I was in charge, I would say, for policy purposes, forget about these scenarios. The reality is we're here where we are today. And we can have some certainty about what the world looks like today. We want to retire all that coal, we want to retire all that natural gas, and all that oil. Those are the scenarios that we should be looking at. Temperature targets are fine, but most people don't know what they mean. They certainly don't know how they translate into how our energy infrastructure must change over the next 50 years.
ML There's still a scenario called SSP3 8.5 being used in papers. Not even the modellers in the most tortured modelling runs can even produce that scenario…
RP SSP3-8.5 doesn't exist in the scenario world, but it exists in some of the impacts world. It's actually an important scenario that's being used in the US government's regulations employing the social cost of carbon. So, these are not trivial scientific issues that eggheads debate, these have real world consequences. One reason why it's hard to get them corrected, is because there’s sort of an intellectual lock-in between policy, politics and science.
ML A paper in Nature, November 21, claimed over 60% of top climate scientists thought that the world will warm over three degrees by 2100. I've looked at some of the people who answered that questionnaire: they are not experts at all. The issue here is, what do you call a climate scientist?
RP Even experts in energy systems going back 50 years are not great prognosticators of where the energy systems are going. I don't put a lot of weight into long term speculative predictions, because historically, nobody's good at that. These are deeper issues in what sort of expertise is privileged in these discussions. At some point, I have to think that the disparity between the physical sciences expertise in climate and the energy systems expertise has to spill out into the open because there is an increasing gap between the views of those two communities.
ML Central banks are throwing scenarios at the financial system with huge interest rate shocks buried in the small print. What are the central banks assuming in their stress tests?
RP There's an entire industry and sub-industry of consultants and contractors, unfortunately, including some of the same institutions that provide scenarios for the IPCC, who are funded to produce scenarios to drive these stress tests. You will find that many of these scenarios don't pass test of plausibility. So, if the point is to generate stress tests for plausible worst case scenarios, someone has to have the task. It has to be someone independent, someone who doesn't have a stake in the game. Stress testing itself creates risks for the financial system. If this was the fossil fuel industry, people would be going nuts. If you learned that Exxon was in charge of funding a side project for IPCC scenarios, your eyebrows would go up pretty high. We have to ensure that whatever we do with stress testing, it's all conducted with scientific integrity. Governments in particular have to be sensitive to the fact that they're creating a new infrastructure of institutions. Those institutions should follow basic principles of democratic governance, and I don't think they are right now.
ML Many would argue that the only way we're going to get action is by raising the alarm, and if that means exaggerating the science, so be it. Message unity is key, and that we should keep quiet. What do you say?
RP Once you recognize that success in deep decarbonisation requires a sustained effort over the better part of a century, alarm doesn't work. What works is a low level of pressure applied continuously. One of my mentors once said, “if you want to turn around a battleship, you don't kick it, you lean on it, you have a tugboat and you push it, and eventually it gets moving.” For me, the best way to ensure continued legitimacy and trust is to be open, honest and call things like we see them. I am not a big fan of ends-justifies-the-means argument. I think that the science is plenty strong enough to survive course corrections on climate change.