Apr 13

Volts podcast: Paulina Jaramillo on the IPCC's new climate-solutions report

Working Group Three in effect y'all.

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David Roberts
Volts is a podcast about leaving fossil fuels behind. I've been reporting on and explaining clean-energy topics for almost 20 years, and I love talking to politicians, analysts, innovators, and activists about the latest progress in the world's most important fight. (Volts is entirely subscriber-supported. Sign up!)
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In this episode, Carnegie Mellon professor Paulina Jaramillo discusses the IPCC's working group 3 report, “mitigation of climate change,” of which she was a co-author. It's the most comprehensive look to date at the economic sectors that emit greenhouse gases, the strategies and technologies that can reduce emissions, and the state of play in climate policy around the world.

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Full transcript of Volts podcast featuring Paulina Jaramillo, April 13, 2022

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David Roberts:

Anyone who’s followed climate change for a while has become accustomed to the cycle of reports from the Intergovernmental Panel on Climate Change (IPCC) — the dire warnings, the brief flurry of press coverage, and the rapid return to normal. It’s easy for them to blur together.

But the latest IPCC release is worth a closer look. It’s not about the science, or the impacts, but the solutions — how to fix the problem. (Technically it’s the third part of the sixth comprehensive assessment report, which is being rolled out in phases.) “Mitigation of Climate Change” is a comprehensive review of the economic sectors that emit greenhouse gases, the strategies and technologies that can reduce emissions, and the state of play in climate policy around the world.

The overall message is quite familiar: it’s still possible to meet the target of keeping global warming below 1.5° Celsius, but the window is getting extremely small and it would require immediate, coordinated global action. Even limiting temperature to 2°C requires massive action. But at the same time, the tools and technologies for tackling the problem have never been cheaper or more accessible. Our capacity to solve the problem is rising alongside its severity.

Paulina Jaramillo (CMU)

To dig into the report and its significance, I chatted with Paulina Jaramillo, a professor of engineering and public policy at Carnegie Mellon University, co-director of its Green Design Institute, and one of the co-authors of the WG3 report. We talked about how the report fits in with the IPCC’s other work, the kind of research it draws on, its major conclusions, and the usefulness of these kinds of reports going forward.

With no further ado, Paulina Jaramillo, welcome to Volts. Thanks for coming.

Paulina Jaramillo:  

Thank you for having me.

David Roberts:   

Can you set the scene for this Working Group 3 report and how it fits into the larger IPCC context?

Paulina Jaramillo:  

The Intergovernmental Panel on Climate Change (IPCC) is a UN-sponsored organization that works on providing information on climate change to decision makers. Every few years, they publish what we call assessment reports. We're in the cycle of the sixth assessment report – the sixth time the IPCC has put together a large report assessing the state of knowledge on climate change. 

There are three reports that come from three working groups. Working Group 1 is in charge of performing an assessment on the physical science of climate change: What do we know about how climate change happens? What is happening to the physical system as a result of climate change? The report from Working Group 1 for the sixth assessment report came out last August. 

Working Group 2 focuses on the impacts of climate change on natural and human systems, and what adaptation strategies could be available to mitigate these impacts. Their report came out in February of this year.

Working Group 3 focuses on mitigation: What can we do to reduce the greenhouse gas emissions that are driving climate change? That's the report that came out this week.

David Roberts:   

The IPCC has to cut off eligibility for research at a certain point so that it can gather it all and assess it, and by the time the IPCC report comes out, the science that it is summarizing is often three to five years old. The scientific research around mitigation is changing so quickly, in terms of our ability to do things and the cost of different technologies – how does Working Group 3 deal with that? How old is the mitigation research that's being summarized here? 

Paulina Jaramillo:  

The cutoff date for Working Group 3 was October 21 of last year, so it's not that long. The cutoff date for all of the working groups is a couple months before the report is due for submission. It's definitely not years, so that might be a misconception that is out there.

It’s true we don’t let in new research right up to the end; there was a lot of stuff that happened since November of last year. We edited and sent it out for comments to the government on November 3. 

The last couple of months are intense in trying to assess the literature. The deadline is for papers being published, but we could consider papers in our literature review while they were in the peer review process. We had access to some before they were published, if we had confirmation that they would be published by October of 2021. That also gave us some time to make sure that we considered those papers that were still in the peer review process.

David Roberts:   

What qualifies as mitigation research? Is it social science, political science, behavioral science, all the above?

Paulina Jaramillo:  

There are 17 chapters in the report. They cover the large integrated assessment models; work that is more specific to sectors; in this cycle, there's a chapter specifically on demand; later chapters involve political issues like financing. I was not involved with the financing chapter, for example, because that's not my area of expertise. 

I was involved with the transportation sector. That was a lot of papers looking at the technology: analyzing technologies, analyzing modeling, how those technologies can be integrated into the system, research on how much they will cost. It's system-level for the transport sector, and for a lot of the sectors. It's really the research on what the available technologies are. There's a lot of work in the research world about how much they might cost in the future and how they will perform. That's the literature for the sectoral models. 

On the demand chapter, there were a lot of social scientists involved because there is a lot of research on how humans behave and make decisions about energy and transport. A lot of that comes from human geography and social behavioral science. I'm not as much of an expert on that. 

There is also that chapter on financing, which I think is really interesting. Social scientists and political scientists work on, what are policy instruments that have worked? What are financing mechanisms that could be available? There's research on those issues as well, so those are the types of literature that the authors of those chapters looked into.

David Roberts:   

Is it fair to say that the scientific literature on policies and future costs is less firm than the physical science research? Every time there's a conclusion in the report, there’s a parentheses that indicates high, medium, or low confidence – are there more medium- and low-confidence results in this chapter than in the hard science chapters?

Paulina Jaramillo:  

I haven't actually done a comparison. If you look at the transport chapter, for example, we covered what the costs of alternative fuels could be. The cost of an electric vehicle compared to the cost of a gasoline vehicle varies a lot throughout the world, depending on the cost of buying the vehicle but also the electricity costs and the cost of diesel or gasoline, which we know changes a lot. It was more of an analysis of the realm of possibilities and how the costs compare. 

You can look for robustness and see, okay, in this whole set of possibilities, electric vehicles are increasingly cheaper than internal combustion engines. Not everywhere, but look at the body of literature and we find that the costs have dropped down so much for electric vehicles and wind and solar that there is consensus – and there's some variability by region, but there is robustness in the findings – that wind and solar are increasingly competitive with fossil fuels and electric vehicles are increasingly competitive with conventional vehicles. 

For some things, for example fuels for aviation, the costs of those things are really low confidence. My chapter doesn't have that much information about the costs of those fuels, because a lot of those technologies are early in their development stages so there's not much we can say about costs.

David Roberts:   

As long as I've been covering this, there've been a million technical policy solutions on the table that could solve this. Climate people say, “We have all the solutions we need, all we need now is political will.” Over time, I've come to see that political will is the main thing. Is there research on not just what policies would have what effects if they were implemented, but how we can move politics? How can we get policies across the finish line? It seems like that's the main thing we don't know and need help with. Was there any research in that direction, not just technical policies but political economy?

Paulina Jaramillo:  

First of all, the IPCC is very careful to not be prescriptive, very careful not to say “this is what should happen.” It’s about presenting the possibilities. 

Again, I am not as familiar with the literature. There is probably literature on political economy, and I think there are some issues covered in those chapters, but it is not the role of the IPCC assessment to say “these are the things that politicians should do.” 

I agree with you that that is a gap. I don't know if I will be involved with the IPCC again, but something that would make me more excited about being involved is if we were looking at what the barriers are to implementing these solutions in the real world, in places around the world. That has not been explicitly covered in the reports. I think that's because of the way the IPCC is structured, which I don't fully understand; it's above my paygrade. But I agree with you.

The IPCC also publishes special reports between the different assessments. Maybe we need a special report on barriers associated with governance and social systems – why are these things not happening, and what are the available options for making them happen?

David Roberts:   

At this point, six IPCC reports in, we've got a giant mountain of scientific evidence that the problem is bad and getting worse; we've got a mountain of possible policies that we could implement to solve it; and the latter are not being applied to the former. It's that disconnect that’s the main thing now.

Paulina Jaramillo:  

That is a common frustration of scientists that work on climate. The challenge there is that it is very political. It is very different in different countries around the world. So ultimately, it requires political will. 

Friends and family ask me “what can I do to help?” and there are personal decisions people can make. But the climate problem requires systemic solutions. I would argue that the most important things people can do are to engage in the political process and mobilize so that action is taken. 

It isn't just at the federal level. In fact, in the absence of federal activity on climate, a lot of what is happening in terms of climate mitigation is happening at the local and even state levels.

David Roberts:   

There's a whole part of the report on that, right? Is that new as well?

Paulina Jaramillo:  

It's been a while since AR5 and I have to be honest, I've always focused more on the technical parts. But I do think there's a lot more about that in this report, because there's been a lot of action on local levels in recent years.

David Roberts:

I go back and forth on whether I'd want to see a comprehensive assessment of that. On one hand, that's what we really need – to figure out how to make the things we know need to happen, happen. On the other hand, I worry that if I saw the results, it would reveal that no one knows how to make things happen, and if they knew they would be doing it.

Paulina Jaramillo:  

We talk about uncertainty on mitigation, which may be higher than some of the others, although the uncertainty on impacts is pretty significant, too. But when we're talking about political processes, we're talking about a human system with a lot of players.

David Roberts:   

That's low certainty across the board there.

Paulina Jaramillo:  

And it can change every four years at the federal level.

David Roberts:   

Let's take a step back and discuss the big picture findings. There are two trajectories we can talk about: One is where we’re headed based on current policies that are in place, and the second is where we’re headed based on the nationally determined contributions (NDCs) that each country has offered up in Paris. Lots of countries are not doing what they would need to do to hit their professed targets, but nonetheless, where would we end up if we stayed with current policy, and where would we end up if everybody did what they say they're going to do?

Paulina Jaramillo:  

With current policies, emissions would continue to increase. And that's with the current policies extended beyond 2030; a lot of the policies are to 2030. Under the current path, we're headed to around 3.5°C.

David Roberts:   

The action we've taken so far has helped shrink the range of possible outcomes. We have acted enough now to make the 5°-6°C scenarios, the species-ending type of mega-apocalypse, extremely unlikely. That said, 3.5°C would still be super bad. How do you explain the difference in possible outcomes to civilians?

Paulina Jaramillo:  

Even 2.5°C and 3.5°C would be catastrophic. Maybe not everywhere in the world, because of adaptation, but the Working Group 2 report says we need to emit below 2°C, and ideally below 1.5°C, to avoid the really catastrophic. After a certain level of bad, everything is just bad. Yes, we have gone from possibly getting to 5°C to going to 2.5°C or 3.5°C – that's still bad.

David Roberts:   

It's difficult to rank catastrophes in your head. There's such a wide range from 3°C up to 6°C of catastrophe, it's difficult to keep them straight. But as the previous IPCC report was all about, even the difference between 1.5°C and 2°C is super bad, especially for certain parts of the world.

Paulina Jaramillo:  

I'm originally from Medellín, Colombia. The last time I was there, a while ago, I remember saying, “Oh my god, traffic has gotten so bad here.” Some of my friends were like, “It's worse in Bogotá.” And I was like, “Yeah, that doesn't mean this isn't bad.” Just because it's worse somewhere else doesn't mean it's good here. 

This is the message. Just because the projections for no action are slightly better than they were years ago – they're still bad.

David Roberts:   

So current policies lead us to somewhere between 2.5°C and 3.5°C, which, as we were saying, is super bad. What about if countries do what they have pledged to do in Paris? How big of a difference does that make? 

Paulina Jaramillo:  

It still doesn't help us get to 1.5°C or even 2°C, with current conditions. I’m going to read you a specific sentence, and then we can talk about what it means: “With unconditional and conditional elements in the nationally determined contributions, emissions would be 53 (with a range of 50 to 57) or 50 (with a range of 47 to 55) gigatons of CO2 equivalent, which leaves a median estimate of emissions gaps of 14 to 23 gigatons of CO2 equivalents to limit warming to 2°C, and 25 to 30 more gigatons to limit warming to 1.5°C.” 

Even with these NDCs, the gap is big. The NDCs really are not enough.

David Roberts:   

The NDCs that, to be clear, countries are not even meeting yet. 

Paulina Jaramillo:  

This is a better line from the report: The estimates are that “projected global emissions from aggregated nationally determined contributions place limiting global warming to 1.5°C beyond reach and make it harder after 2030 to limit warming to 2°C.” That's very striking. 

David Roberts:   

I wrote a post a few years ago for Vox saying that it is still technically possible to hit 1.5°C – you can stick a bunch of policies into a model and get the model to output 1.5°C – but at this point, it would involve basically a sharp heel turn by every institution in every country in the world simultaneously, which has no historical precedent. Do you accept the conclusion that 1.5°C is effectively pragmatically out of reach at this point? And if you do or don't, what does that mean to you? What would it mean to decide that 1.5°C is out of reach?

Paulina Jaramillo:  

I actually had a colleague write to me after the report came out and say, “I don't know why we're still talking about 1.5°C. That's just not going to happen.” Not because we don’t have the tools; the report clearly says we have the tools to make this happen if we act now. 

Sometimes I get that feeling of, this isn't going to happen. But I have two kids, and I'm dedicating my life to figuring out how to make it happen, so a part of me has to maintain a level of optimism. And even if 1.5°C doesn't happen, there is a little bit of a better chance to be able to get 2°C.

David Roberts:   

Can you envision us coming in under 2°C? Does that seem a little bit more achievable to you?

Paulina Jaramillo:  

Yes. It still requires action and political will pretty quickly. It's a little bit more – I don't know if “likely” is the right word, because I can't put probabilities on these things happening, but maybe a little more tenable. 

Sometimes I think we're not going to do anything, and those days are very depressing. The only way I can function is by keeping some optimism that we can do at least something about 2°C.

David Roberts:   

Well, in the name of optimism, you mentioned that the review of the mitigation literature found some themes in which you have high confidence. What are a few of the big solutions that we are very confident are going to have to play a big role in mitigation?

Paulina Jaramillo:  

The power system is probably where we have the most developed options. For the first time, the report had a section on demand-side mitigation options. There is no doubt that we need to address demand, and demand-mitigation options can reduce demand for services in developed countries. Developing countries are a different ballgame.

David Roberts:   

I'm curious how the demand chapter addressed emerging countries. On the one hand, you want to be very careful about limiting demand when so many people are in poverty and have so little; on the other hand, there are ways of shaping demand even as it grows to make it less than it might otherwise be. 

Paulina Jaramillo:  

That's the key message that sometimes gets lost. There is a figure in the summary for policymakers that looks at the potential reductions in emissions that could happen through demand-side mitigation. A very important thing that we have to understand about that figure is that these are not reductions compared to today; these are reductions compared to what emissions could be in 2050 if we don't do anything. 

In the transport chapter, we specifically say that demand-side mitigation strategies can help reduce demand for transportation services in developed countries and limit the growth of demand in developing countries, which suggests it's not about saying that demand won't grow in developing countries. Because there are going to be 3.5 billion more people in developing countries by 2050. Just because of population growth, demand is going to grow. What these strategies can do is limit the growth associated with those changes.

That is important, because it reduces the need for technologies. If we didn't have those demand-side mitigation strategies, we would need even more technologies and expand into technologies that maybe are less well-developed. That's an important message on the demand side that I want to clarify. 

There are definitely opportunities for reducing demand from current levels in developed countries. That means investments in urban form, for example – having more dense, mixed-use cities where people live close to where they work and where they shop. That can reduce distance of travel; it can also make biking and walking much more viable. If you live 30 miles from your work, you're not going to bike or walk to work. But if you live 2 miles from work, or even 5, you might. If you have more public transport, that helps reduce emissions. That’s a demand-side strategy.

David Roberts:   

There is a longstanding argument in the climate world about the possible contributions of electrifying vehicles vs. urban form. What are the relative roles of those two? Are they equally potent, or is electrification going to be a much bigger part?

Paulina Jaramillo:  

In the transport sector we do not directly quantify; we have a discussion about them. There is a lot of uncertainty, and it’s actually very different in different parts of the world. 

The US has cities that are well developed, so there's a legacy system. People already live in the suburbs. In cities in the developing world, where cities are growing, these interventions could be very powerful. We’re talking about having the opportunity to build the cities with these concepts in mind, and that will drive behaviors that will remain. 

We talked about walking infrastructure; we can talk about walking behaviors. We have walking behaviors in the US because of the ways our cities have been built over centuries. By 2050, the top 10 largest cities will be in developing countries; what we build in those cities now will lock in that type of behavior. 

In those cities, these strategies have a lot of potential, because populations are going to be higher, incomes are going to grow. Demand will probably be higher than it is now, but it will be lower than if they follow the path of the cities of the United States.

David Roberts:   

These concepts of density, robust transit, multimodal transportation, walkability – do they have any purchase in those areas where those cities are being built right now? Are cities being built that way at all?

Paulina Jaramillo:  

Karen Seto at Yale University, who was the coordinating lead author for the urban chapter, would be better equipped to deal with this question. There are definitely places in the world where walkability and density are growing in popularity. 

David Roberts:   

Is it fair to say that large-scale clean electrification is necessary now, that there's no way around it? 

Paulina Jaramillo:  

Here we have to be careful and talk about two things. One is decarbonizing power generation – how we generate electricity. The other is, we use a lot of energy for heating and for transportation that is not electrical energy – should we transition to electrical energy for those? 

There is consensus that electrification of space heating, of transportation, of cooking, has the potential to reduce emissions from those energy services. They will only reduce emissions if we decarbonize the power sector, so we need to decarbonize the electricity system. Without decarbonization, electrification would not provide benefits. 

But it is clear that electrification of end uses offers a large potential for mitigating emissions. It is much easier – not easy, but easier – to think about decarbonizing power plants than decarbonizing every natural gas furnace. Replacing those furnaces with electricity is the way you can decarbonize. 

The evidence is there for electrification of those end uses. It's very important. We say in the transport chapter that electrification offers the largest potential for reducing emissions in land-based transportation.

David Roberts:   

There are a lot of cases – planes, big ships, big trucks – that seem questionable whether they can be electrified. Is there a consensus currently on how much of the transportation sector can be electrified?

Paulina Jaramillo:  

Passenger transport can definitely be electrified, and it currently accounts for 75 percent of emissions from land-based transport, which accounts for a very large share of general transport. 

It isn't just personal vehicles. It isn't just the automobile. It’s also electrifying buses and rail. In developing countries, it's electrifying motorcycles, two- and three-wheelers, which is already happening. In developing countries, a lot of transport happens through motorcycles, and the evidence is that electrification of those is happening pretty rapidly. 

For land-based heavy duty trucks, there are opportunities for electrification. It will be more for trucks that don't travel very long distances: garbage collection trucks, trucks that operate in mines, trucks that operate for shorter distances. 

Long-distance hauling is where there's a lot more uncertainty about the possibility of electrification. That's where the transport chapter discusses the role of hydrogen and derivatives, and biofuels to a certain degree. Biofuels open up a lot of questions related to other impacts, but there are some countries where biofuels will likely remain an important component. 

Shipping and aviation are totally different beasts, hard to decarbonize. Electrification may play a role in short flights and ferries. For aviation, a lot of it is moving people – so in some places where there is rail infrastructure, shifting from flying to high speed rail can help reduce emissions. Countries like the US that have rail infrastructure could potentially really improve the rail infrastructure for passenger transport, and if it becomes comfortable and economically viable and convenient, maybe that reduces some demand for aviation. 

Some aviation and shipping will remain. We can’t take a train from the US to Europe. Africa is a huge continent and the rail infrastructure is basically nonexistent. We need to find solutions for aviation and those solutions are much less well developed. Hydrogen would be important for those sectors, and it has to be electrolytic hydrogen – hydrogen produced with electricity that is produced with low-carbon sources. 

For aviation, there's this idea that we need drop-in fuels, converting hydrogen to synthetic fuels that can be used in the current technologies. But synthetic fuel production for electrolytic hydrogen is very early in development. 

The other thing we point out in the chapter is that in most if not all of the scenarios that limit warming to 1.5°C or 2°C, emissions from transport do not go to zero, even by 2100.

David Roberts:   

Even by 2100, we can't imagine clean hydrogen-derived fuels taking care of shipping, aviation, and long-haul transport?

Paulina Jaramillo:  

This is based on the models, and the models have a lot of assumptions about what costs will look like and how the technology develops. It's not impossible that we say “we really have to do something, we have to invest heavily in these developing technologies and decrease the costs and that will allow us to have those technologies.” 

The models that have studied these do not incorporate that level of technology development and cost reduction, because the model will not choose things that are not available to choose. In these models, those technologies are not available, because they're not cheap enough – the development is delayed. So you wouldn't reduce emissions to zero. 

But, the model suggests that even if transport does not go to zero, you could still meet the 1.5°C or 2°C target. The way it does that is through carbon dioxide removal. The models have characterized carbon dioxide removal. They have cost characterization and performance characterization, and when they run the models, those technologies are deployed to address those vestigial emissions that are very hard to reduce from some of the sectors.

David Roberts:   

You could imagine that in the next IPCC report, five years from now, the mitigation chapter could find that these hydrogen-derived fuels have been further developed and commercialized, have gotten on a learning curve and are headed down. That could theoretically change huge parts of these models. Having convenient, carbon-free liquid fuels would be a game changer in a number of areas, and it seems like we're right on the verge of having them. Do you think five years from now when we come back to look at this again that that'll be an area of radical change?

Paulina Jaramillo:  

I guess it depends on what we decide. 

I will point out that these zero-carbon synthetic fuels depend on carbon dioxide removal technologies. The only way we can produce synthetic fuels that are zero carbon is if we can produce hydrogen from low-carbon electricity. For it to be zero, it would have to be through biomass gasification and carbon capture, using that captured carbon dioxide with the hydrogen to produce the synthetic hydrocarbons. So even those technologies rely on CDR.

David Roberts:   

Some people have said, “The IPCC keeps saying these things are possible, but that's because these models keep tucking in more and more carbon dioxide removal toward the end, which is like a Get Out of Jail Free card that allows you to emit more on the front end.” There’s an argument that we shouldn't be assuming that large-scale CDR will be possible and we should be planning as though it weren't. Is it fair to say that any model that shows us hitting 1.5°C is going to involve a lot of carbon dioxide removal?

Paulina Jaramillo:  

Yes. In the press conference, Jim Skea, the co-chair of Working Group 3, said carbon dioxide removal is inevitable. 

I have gotten into some discussions over the last couple of days on Twitter about carbon dioxide removal. There is this concern that carbon dioxide removal is just an excuse to allow us to continue burning fossil fuels. That's not the case. That's not what these reports suggest. These reports suggest that we have to reduce emissions now – and, we might still need carbon dioxide removal. They're not mutually exclusive. We need to stop burning fossil fuels, and we most likely still need carbon dioxide removal.

The other thing is, the report has a taxonomy of different mechanisms for carbon dioxide removal, which includes afforestation – trees.

Ideally, planning that CDR technologies will not be available is probably a good idea, but the model suggests that that's just not possible. Unless there's a technology that can produce energy with no carbon that we haven't thought about, and it suddenly appears and becomes competitive – I can't see any of those technologies. Personally, from what I know, with all the potential drawbacks of and concerns about carbon dioxide removal, not investing in those technologies … I mean, we have to hedge the risks.

David Roberts: 

There's an already famous graph from the report showing the relative potential contribution to decarbonization of a long list of technologies. Among the power sector technologies, it's very clear that wind and solar are the big contributors, 2-5 times more than their nearest competitors. In the climate world there are still some people who say renewables can't do it – it's going to have to be nuclear-based or we're never going to get there. Would you say at this point that it's pretty high confidence that any decarbonized world is going to have at its heart an electricity system primarily based on wind and solar?

Paulina Jaramillo:  

There is no doubt that wind and solar are going to be a massive contributor to mitigation. One thing to keep in mind is that there are a lot of underlying technical, operational issues surrounding the operations of a power system that that figure doesn't necessarily capture. It’s more like: if we figure out how to manage a power system with wind and solar, this is what you could expect to reduce. 

The energy chapter talks about this also. It says, “Electricity systems powered predominantly by renewables are becoming increasingly viable. In some countries and regions, electricity systems are already predominantly powered by renewables. It will be more challenging to supply the entire energy system with renewable energy.” 

Large shares of renewables in the power system are definitely possible. We probably have the tools. Those things require storage technologies that have to be deployed. But the power sector is the easy one. The energy sector isn't just the electricity sector – it’s also the energy that is used in buildings, in transportation, in industry. There are opportunities for electrifying a lot of that. Wind and solar can provide a large share of the electricity, but there are some end uses that will be much harder. 

I guess you could do everything with hydrogen. Everything is either electricity or hydrogen produced with renewables. A lot of that is going to be needed, but then you're really increasing the demand for electricity, so the need for these other low-carbon resources starts showing up. 

The other thing about this figure is that it doesn't show that we can reduce all of our emissions with wind and solar energy. If we only use wind and solar energy, that isn't enough to meet all the energy demand. 

I've done power system modeling, and been involved in a lot of the work and in the controversy with certain work from a certain professor. I often think this whole discussion about nuclear and renewables feels like “you can only do one of them.” A lot of the energy models will say we need everything at our disposal.

David Roberts:   

Isn’t it fair to say that it’s most likely we’ll have electrification based on a system that is primarily powered by wind and solar? Where these other sources – nuclear, geothermal, storage, transmission – are supplements meant to make the system balanced, safe, and reliable, but the workhorses of the system are going to be wind and solar?

Paulina Jaramillo:  

Another caveat is that wind and solar resources are also geographically different. Your statement is probably accurate for the United States. The report points out that a lot of places are operating very high-renewable energy systems. They're mostly hydropower systems. 

I remember hearing at some point that the US Great Plains Midwest region is like the Saudi Arabia of wind. Not everywhere will have access to that same level of resources. The electricity system isn't an integrated system; you're not connecting the entire earth. Interconnection is going to be important, but interconnecting Africa and the Americas, probably not. There is a big role for wind and solar in Africa, particularly solar. 

It is fair to say that with wind- and solar-based power systems, we can get very large levels of emission reduction, and we'll probably need to get to those large levels. But some other technologies will be needed, and the contribution of those other technologies will vary regionally.

David Roberts:   

These are meant to be long-term, forward-looking reports: after 2030 and 2050, even to 2100. But two things have happened recently that have roiled the energy world. One is, of course, Covid, the lockdown and the economic disruption. The second is the Ukraine war, the subsequent imperiling of natural gas supply and the flurry of efforts to accelerate the transition off of Russian gas. Do you think either of those two are going to have long-term effects on the trajectories that you're looking at in these IPCC reports, or are they ultimately going to look like bumps that get averaged out in the long term? 

Paulina Jaramillo:  

Covid is really uncertain, because we have seen a rebound of emissions after the lockdowns were lifted. We saw very quick reductions from emissions from transportation, for example, but those went up again last year. I hope that maybe companies are being more flexible and workers have an opportunity to work from home a couple days – that could reduce emissions from the transportation sector. But that's uncertain. 

On Russian gas, it's a very large opportunity to do something that is in the benefit of climate mitigation – to not find other sources of natural gas, but to transition to electrification of heating, with renewables or other low-carbon sources for the electricity.

David Roberts:

You see lots of voices out there right now using the war to the opposite effect, saying “this shows that we're transitioning too fast and we still need robust domestic natural gas production.” I know you're not a fortune teller, but which of those arguments do you think will triumph in the end?

Paulina Jaramillo:  

The pragmatic in me says that the fossil fuel vision will prevail. The optimist in me hopes that that's not what happens. 

This is really affecting Europe. The fallout on US gas prices is because it's a global market, not because the US is importing a lot of oil from Russia. But in Europe, the optimist in me hopes that they will push for electrification of end uses so that they can reduce demand for natural gas – not that they just start building massive LNG terminals so that they can import gas from the US. That would be my hope.

David Roberts:   

There are a lot of arguments about whether the IPCC report process is still useful. Early on, when there was a lot more uncertainty around the science and the public didn't understand it very well, there was definitely an argument for synthesizing things. But now, it's very clear that climate change is happening, harming us, and going to harm us worse. We’ve got a mountain of reports to that effect. And we know pretty well that we have a bunch of tools and policies and technologies that we could use to solve it if we wanted to. We have a mountain of reports on that, too. 

So what's your read on whether the IPCC is still useful, in effect repeating that every five years? Are there ways that the IPCC process could be revised or updated that you think would make it more useful? 

Paulina Jaramillo:  

It's not necessarily the process, but the scope of what the IPCC produces. There were times writing this report where I was like, “but we already know this.” 

I was in an event with Andy Revkin and a couple of the other lead authors, and we talked about two assessments that I personally think would be important and useful, and maybe the IPCC could be the one that takes on doing that type of assessment. 

One is, we keep talking about the costs of climate mitigation. The impacts chapter talks about the costs of the impacts of climate change. But climate mitigation also has a lot of other co-benefits, and there isn't a report that focuses on quantifying the value of those co-benefits.

David Roberts:   

That's such a huge piece. I've tweeted this probably 100 times now, but the reduction in particulate air pollution alone would pay for the whole damn thing.

Paulina Jaramillo:  

We mention it. It is discussed. There is a whole table on the intersection between climate mitigation and the Sustainable Development Goals. Air quality shows up as a benefit, but what is the actual value of those benefits?

David Roberts:   

One of the things the mitigation report emphasizes, which is important, is that it is not the case that decarbonizing will necessarily impoverish emerging countries. The report says in no uncertain terms that radical decarbonization is commensurate with the UN Sustainable Development Goals. You can do these together.

Paulina Jaramillo:  

Part of it is because of the avoided costs, but also just highlighting those co-benefits much more prominently and quantifying them would really help with the message. 

The other assessment, that we already talked about, is why isn't this happening in the real world, and what needs to happen in the real world for mitigation to take place? 

Those two could be special reports or a refocus of the working groups, but it’s not out of the realm of what the IPCC could do.

David Roberts:   

Were you involved in the previous IPCC report and do you plan to be involved in the next one? 

Paulina Jaramillo:  

This was my first time. I actually got promoted to coordinating lead author, so on my first time in the IPCC, I was also involved in the approval of the summary for policymakers. It was really interesting, but also super intense. 

Will I do it again? Through the process, there have been times where I have told my kids and friends, “I'm never doing this again.” This is done on a voluntary basis, and it's not like I don't have responsibilities in my day job. It's a lot of time, and it's not an easy process. 

If there was focus on the two things that I just mentioned to you, I would consider doing it again. But I can't say yes for sure. And I'm going to avoid saying never.

David Roberts:   

This is an aspect of these IPCC reports that doesn’t get enough press and isn’t appreciated enough by the public: everybody doing this is doing it on their own time, unpaid. It's an enormous pro-social thing and I feel like it should be celebrated just on those grounds. It's remarkable that people are willing to work this hard and put this much time to save the Earth.

Paulina Jaramillo:  

Most of us work in research settings where there is the flexibility to use some of our time on this type of work. But I still have to supervise PhD students, and write proposals to fund those PhD students, and teach, so – there definitely is a limit.

David Roberts:   

Well, I really appreciate your work on the report, and I appreciate you coming and taking the time here with us today.

Paulina Jaramillo:  

Excellent. Thank you very much for having me. I look forward to hearing the podcast.