Ariel Conn: Hi Everyone and welcome to episode 18 of Not Cool, a climate podcast. I’m your host, Ariel Conn. Today, we’re joined by Glen Peters, who will talk about, among other things, our carbon budget. We’ll learn what the carbon budget is and why it’s hard to calculate, why some causes of carbon emissions are harder to address than others, how the phrase “carbon footprint” is so often misused and why it’s also hard to calculate, how responsibility for emissions is attributed to different countries, and much, much more.

Glen is a Research Director at the CICERO, the Center for International Climate Research in Oslo. Most of his research is on past, current, and future trends in energy consumption and greenhouse gas emissions. He studies human drivers of global change, the global carbon cycle, bioenergy, scenarios, sustainable consumption, international trade and climate policy, emission metrics, and too much more. Those are his words, not mine.

So Glen, thank you so much for joining us today.

Glen Peters: Thank you. It's good to be with you.

Ariel Conn: You have done a lot of work on the global carbon budget. I think my very first question for you is just what is the global carbon budget?

Glen Peters: Yeah, it's a good first question. In the global carbon budget, we try and look at all the sources of carbon into the atmosphere and the sort of sinks of carbon into the atmosphere and try and understand where carbon is going. You could think about it a bit like a bathtub, where you try and look what's going into the bathtub and see what's going out of the bathtub and make sure they match. The carbon budget generally has two components: the source component, so what's going into the atmosphere; and the sink component, so the components which are more or less going out of the atmosphere.

So in terms of sources, we have fossil fuel emissions; so we dig up coal, oil, and gas and burn them and emit CO2. We have cement, which is a chemical reaction, which emits CO2. That's sort of one important component on the source side. We also have land use change, so deforestation. We're chopping down a lot of trees, burning them, using the wood products and so on. And then on the other side of the equation, sort of the sink side, we have some carbon coming back out in a sense to the atmosphere. So the land sucks up about 25% of the carbon that we put into the atmosphere and the ocean sucks up about 25%. So for every ton we put into the atmosphere, then only about half a ton of CO2 remains in the atmosphere. So in a sense, the oceans and the land are cleaning up half of our mess, if you like.

The other half just stays in the atmosphere. Half a ton stays in the atmosphere; the other half is cleaned up. It's that carbon that stays in the atmosphere which is causing climate change and temperature increases and changes in precipitation and so on.

Ariel Conn: Is that number usually about half? Or is it increasing?

Glen Peters: It's a pretty robust number, and this is one of the great mysteries of the carbon cycle. Mystery is not really the right word, but it's quite curious that no matter how much we're putting in the atmosphere, this fraction that stays in the atmosphere, about 50%, has remained relatively constant. So if we go back 50 years in time for example, we still had about 50% stay in the atmosphere. Today when we emit, there's about 50% that stays in the atmosphere, but then there's a question of will this continue forever if we start to see the impacts of climate change — changing precipitation, maybe for example the land sink is not as good, so maybe tropical forests don't take up as much carbon. Then we may see this share drop and more stay in the atmosphere.

We know — there is some evidence that it may change, so when there's an El Nino and it causes hotter and drier weather in the tropics, less carbon is taken up by the forests, and so we see a greater increase in the atmosphere. This is sort of natural variability, but this natural variability gives us an idea of what may happen if temperatures increase.

Ariel Conn: One of the terms that I saw come up a lot is the carbon budget imbalance. What is that and how does that relate to what we've just been discussing?

Glen Peters: The carbon budget is like a balance, so you have something coming in and something going out, and in a sense by mass balance, they have to equal. So if we go out and we take an estimate of how much carbon have we emitted by burning fossil fuels or by chopping down forests and we try and estimate how much carbon has gone into the ocean or the land, then we can measure quite well how much carbon is in the atmosphere. So we can add all those measurements together and then we can compare the two totals — they should equal. But they don't equal. And this is sort of part of the science, if we overestimated emissions or if we over or underestimated the strength of the land sink or the oceans or something like that. And we can also cross check with what our models say.

So this carbon imbalance is basically the balance between what we think is happening and whether those two things agree. And they don't, but the good thing is that sometimes we overestimate the balance, sometimes we underestimate it — which means that they're sort of bouncing above and below zero, if you like, so it averages out. Just like the weather, we can have hot years, dry years, and so on and so forth. So when you think about the global climate, we also have some years that are a little bit warmer, some years that are a little bit cooler, and this is propagating to natural variability in the carbon cycle. First of all, we can't perfectly measure everything; and second, our models can't protect all the natural variability that happens.

But if you average over a longer time period, over decades or whatever, this carbon imbalance averages out to zero, which is nice. It means that on average, we've got the science right. It's just some of the details we're missing. It's like we're not sure whether it's going to rain next Thursday or not. So it's that sort of variability that we can't detect. But the big scale changes in the system we can detect well.

Ariel Conn: Okay. A minute ago, you mentioned sort of the chemical processes involved with cement. And that's been one of the things that's been sort of interesting for me, starting this process of interviewing people and trying to learn more about climate change, was seeing that cement seems to have this huge carbon footprint. And I was wondering if you could talk a little bit about why that is.

Glen Peters: Every sector you can look at in different ways, so the biggest probably single sector, if you like, is production of electricity. So cement is certainly an important sector, one of the most important ones. It's about 5% of global emissions, or something like that, and it's growing relatively rapidly. And it will grow more or less in line with, let's say, growth in developing countries as they're building infrastructure, new buildings, new roads, and so on. And it's also very hard to find alternatives to cement. But the emissions from cement essentially come from two areas. So the first is a chemical reaction, so when you produce the cement, you're taking limestone, basically, and taking the CO2 out of that, so you get a high level of CO2 through a chemical reaction. That's about 5% of global emissions. And also to do this process requires a lot of energy, a lot of heat, so you burn a lot of fossil fuels in the process of producing cement as well. I'm not sure of the exact number, but it's basically another 5%. 

So in total, cement is probably give or take, rounded numbers here, about 10% of global emissions. But the process emissions, the chemical part, is about 5%, and that's the part that you most often see in emission statistics or in a report or something like that. But the good news, if you like, is that the chemical reaction produces quite a pure CO2 stream — quite a high concentration of CO2 — which means that it's quite suitable for carbon capture and storage. The mitigation options for cement are in a sense quite obvious, but that will increase the cost, which no one really likes.

So there's lots of sectors which let's say are easy to mitigate, and some sectors which let's say are hard to mitigate. If you think about electricity generation, maybe a good US example is there's a shift away from coal to gas and to renewables, so there's some sort of obvious and easy technologies where we can straight away shift production of electricity to different sources and have less emissions. There's also various behavioral things we could do. We could use less energy or have different travel habits and so on, which can reduce emissions. So these are, let's say in quotes, some of the easier things. Cement is usually classed as one of the harder things to mitigate, but this is more cost related. It's not so easy to use a different material and it's not so obvious how you could produce it differently to get the same product but lower emissions.

But when you produce the cement, it does have a very high concentration of CO2, so if you just put a bag over the top of the cement factory if you like, and capture the CO2, then you can reduce the emissions. It just costs a lot, that's the problem.

Ariel Conn: And so I've been using this term carbon footprint a lot. But can you explain how that's actually defined?

Glen Peters: Yeah. The carbon footprint is often misused. Basically you would say it's the total emissions associated with an activity, and that could be very broadly defined. So it could be an individual, what's my personal carbon footprint? When you talk about that, you would think about all the things that I do in my life, including the emissions in the supply chain to produce the products that I consume and to drive a car or whatever. You could also think about the carbon footprint of a business or a company or a country, just sort of the way you define the carbon footprint will slightly change because of the difference in scale. But overall, it's all the direct and indirect emissions associated with the activity that you're thinking about. Individual consumption is an easy one. All the emissions that I emit in my daily life, from driving a car or taking an airplane to using electricity, plus also the emissions to produce products which I consume, like food. Meat would be a big one. TV: the emissions to produce a TV; and so on and so forth.

Also services surprisingly have a large part of the carbon footprint, so going out for dinner or the hairdresser, or the gym, or the movies. None of these things are completely free of emissions when you consider the electricity use and so on. All the emissions associated with the activity is essentially the carbon footprint.

Ariel Conn: How do you deal with overlap? Like if I, say, go to the hairdresser, what's more important to calculate: my carbon footprint in that activity, or the carbon footprint of the hairdresser itself?

Glen Peters: This is a good question that us carbon footprint nerds discuss all the time. So it's quite a technical point and it relates a little bit to how you do the calculation as well. There are quite a few potential areas for, let's say, double counting. And so getting a consistent carbon footprint that is comparable across different activities can be very hard unless you account for this double counting. So if you were going to the hairdresser, for example, generally that would include, let's say, you going to the hairdresser, let's say you took a bus; and it would include the emissions associated with the hairdresser, so you know to produce the scissors, to use electricity for the hairdresser to have lights on, and so on and so forth. Those things would be included in the carbon footprint, your carbon footprint, which means then essentially you're saying that the hairdresser has no carbon footprint because you've taken their emissions.

But if you allocated in a different way, then you might want to consider the hairdresser's carbon footprint. Then you're considering a slightly different activity and it's not really comparable to your personal carbon footprint. So you get all these quite detailed complications on how to avoid double counting. But if you do it correctly and you're careful, you can set it up so it's done consistently. You'll always have some problems, but overall if it's done correctly, then it shouldn't be too much of an issue. Maybe some of the more problematic areas is when you go up to a national level, then the risk of double counting becomes much larger.

A car for example: a car could be your personal car that you drive to work or for a holiday or something, but a car could also be used by, let's say, your hairdresser. Maybe the hairdresser's a mobile hairdresser and drives around. Then that car used by the hairdresser is a part of their business activity and it's not really a personal footprint. So separating transportation and cars into cars associated with personal activities and cars associated with business activities is a quite important split. The same happens with electricity: how much electricity goes directly to the household, how much electricity goes to industry to produce products that then I consume. So you get all these complications, but when you have a method, you can sort through these things and make sure you don't do any double counting.

Ariel Conn: Something else that I've been confused by that I think is sort of along the same lines is — I hear at least — things like how high China's emissions are. But a lot of China's emissions, I think, are production. So if they're producing things that are consumed by US citizens, who's causing — I don't know, I don't really want to say blame, but —

Glen Peters: We can blame someone. I know what you're saying. We have troubles with what word we use there as well. It's more of an allocation issue.

Ariel Conn: Yes, I like that. Allocation. Who should that be allocated to?

Glen Peters: The way emission inventories are usually done or emissions are usually estimated is what is called a territorial perspective. Emissions are allocated to the place that they physically occur, so if there's a factory in the US, then the emissions are allocated to the US — regardless of who consumes those products. And this is a sort of reasonable accounting system. It makes a lot of sense. It's much easier to monitor and to keep track of what's going on. But then when you start to zoom in, get to a smaller scale, such as if you look at the individual carbon footprint, your personal carbon footprint, in your house you're probably not producing electricity and have a big coal power plant or something like that. So your emissions will look like zero, essentially. 

So then you want to start to estimate your carbon footprint, and then some of those emissions in a factory in the US will get allocated to you. This is sort of moving to consumption. So when you go to the national level, the territorial emissions, the way emissions are usually calculated: the emissions coming directly from a chimney in that country. And then some of those emissions — let's say in the US it's produced products which are then exported to China — you can do an accounting scheme and carbon footprint at the national level where China then would get the emissions that occur in the US to produce products that they consume in China will get allocated to China and vice versa. This is usually discussed the other way, in the sense that the US consumes a lot of products which are produced in China, so China is getting the emissions; the US is having the benefits of the consumption. It's the same for the EU and also developing countries as well.

So about a quarter of Chinese emissions are to produce products which are exported. So when you shift to a carbon footprint, China's emissions go down around about 20% or something like that. It makes a pretty significant difference, and it's sort of a consequence of trade, that we trade with other countries; but then you sort of have to think a little bit about what are the implications of that. So in the US, if you consider the US states, you don't usually get worried if a product is produced in one state and exported to another state. That's not a problem, even if it's across the US; no one seems to get worried about that.

But then all of a sudden if it's China, that's a different country, then we start to worry about this trading relationship and the effect it may have on emissions and so on and so forth. There's lots of reasons that you might discuss it from a policy perspective, but it's a different form of accounting and different allocation. When you allocate to consumption, there's a little bit more uncertainty. It may give a better reflection of your emissions as a country, but it also has some policy complications in how you would implement policies.

Ariel Conn: Can you talk a little bit about some of the equity issues that we see, especially when considering things like the question of is it fair to blame China if I'm the one who's asking them to produce this product that I can then buy, and how it deals with other countries as well?

Glen Peters: Yeah. It's pretty easy when you think of a carbon footprint and you look, "Well, there's a lot of emissions coming from China and China's using a lot of coal,” and so on. Then it's easy to think, "Well, therefore we just stop importing products from China." But that does come with some implications for China, so the population and the growth in China is often dependent, or can be partly dependent, on the growth in trade and growth in exports. So if you just cut someone off and say, "We're not importing your products anymore," then there's a whole group of people that will suffer loss of income, etc. etc. etc. That'll have big equity implications. And it just comes back to things that are going on with the US and China and the trade war. Very many similar issues arise when you have a trade war and tariffs go up and you stop trading with another country, then there's a whole lot of people that lose out because they can't sell their products; they lose their jobs.

So if you take consumption based accounting too far and start to think, "Well, therefore we have to stop importing stuff and produce everything locally," then that will have huge equity dimensions associated to it. There's other issues as well, such as whether you could even produce stuff locally and if you did produce stuff locally, whether it would have lower emissions. And quite often by trading products, then the whole idea is that someone that could produce something more efficiently would produce it. So it's not clear that you would reduce emissions that much, if at all, by not trading with other countries. Lots of complex questions get into policies that might be relevant to consumption-based emissions or carbon footprint emissions, particularly the equity one.

Ariel Conn: Are there other things that we can do to try to encourage producers to be more efficient? Aside from not buying from them.

Glen Peters: That's essentially the process that's been happening. So through climate negotiations and the Paris Agreement that's trying essentially to get more and more countries on board, more countries involved in mitigation, and then countries have to put forward emission pledges. So therefore countries like China and India, South Africa, Brazil, etc. — they all have to put forward emission pledges and try and meet those pledges. So it's sort of pushing the countries in the right direction. Completely inadequate in how fast it's going, but within 30 years of climate negotiations, this is the only pathway that's actually making some progress, which sort of indicates a lot of the challenges there.

There are other means that you could use. Some of these are directed maybe at the US. So the US has decided to pull out of the Paris Agreement. Then you could think countries could punish the US by putting trade sanctions on the US to try and encourage the US to get back into the Paris Agreement. Of course, as we see in the whole China-US thing now, these things just lead to retaliation. It may not be that effective overall. You can change your habits as an individual a little bit by where you purchase. Countries can implement policies which would encourage purchasing of cleaner products through, let's say, procurements. You could do some things with trade policy, but then it's a very risky territory to go, because countries may retaliate. And there's big equity dimensions, which we often forget about.

Ariel Conn: Is there anything else equity related that you think is important to consider?

Glen Peters: Pretty much any climate policy does have equity dimensions, which is something that's easy to forget. There's been a lot of discussion and arguing about aviation, so Greta Thunberg traveling over to the US by boat instead of flying brought up a lot of discussions about aviation and so on, which is fair enough. But it's also important to remember that there are huge inequities in a sector like aviation, just as there are in many other sectors. It's generally the privileged that fly, but when you try and take away someone's privilege, you may disadvantage other people. There may be some people that may need to fly for various personal reasons and so on, so even though aviation is a very high impact sector and has a very individual impact, there might be a whole range of equity reasons or issues that you need to be careful of when you're pushing on that sector.

But the same applies to any sector: with transportation, electricity consumption, climate policies in general try to increase energy prices. Therefore you change your behavior and reduce your energy use. But this could all increase costs, which has a big impact on those with lower income. So there's a whole range of issues that you need to take care of when you implement policies.

Ariel Conn: The one other thing that has often crossed my mind is I hear a lot about trying to reduce your consumption because the production of materials and goods has a lot of emissions. And I think that's great and I'm trying to reduce my consumption, but I wonder if we're all reducing our consumption, what impact does that have on the people whose jobs it is to produce? 

Glen Peters: This gets into a question of growth and whether the economy needs to grow and so on, which is a whole new discussion one could have. But also if you change your behavior so you're producing less material products, you're still going to spend your money.

Ariel Conn: True.

Glen Peters: So you might spend it on something else. So a lot of these issues are often distributional issues. If you take a US example with the coal miners, so a lot of coal power plants and therefore coal mines are being shut down because of solar wind and cheap gas. There might be enough jobs in the US, but those jobs may not be in the right place, so those people would technically have to move, but it's where they've grown up or lived for 50 years. There's quite often other issues that make it hard for people to be able to move or to change jobs. So even if the economy restructures so you consume less material stuff but produce more services, it involves a lot of disruption to existing jobs and so on, which is really hard for people that lose out. 

This is also true at the international level, climate policies will affect different countries differently. Middle Eastern oil countries will get a big hit, so they're naturally going to be resistant to strong climate policies. So you really need to think about how can you get those countries on board so you're not always fighting with them. Likewise, how do you get coal miners on board when they lose their jobs or when their industry is facing a dark future — how do you get them on board for strong climate policy. These are some of the more difficult questions getting into the politics of how you manage a transition.

Ariel Conn: Okay. I want to step back real quick to the carbon budget, where we started. You've been working on the carbon budget for quite a few years. In the time that you've been working on it, what have you seen change, if anything?

Glen Peters: When you look back, it's not a surprise. It's sort of hard to think what it was like 10 years ago. But certainly emissions have grown rapidly and continue to grow, so that's maybe not a surprise, but it's a sort of important aspect of the carbon budget. And a bit of a consequence there is that relative emissions from fossil fuels keeps growing in the carbon budget. We used to think that emissions from fossil fuels were the most certain part of the carbon budget, but now emissions from fossil fuels are so big that the actual uncertainty is quite important to things like the budget imbalance that we were talking about before.

The continued growth in fossil fuels is important. Maybe one component of the carbon budget that is continually uncertain is land use change. It's very hard to estimate emissions from land use change, so you have to know what land use has changed from which type to which other type. If I go from crop lands to forest, it's called aforestation, so I'm growing a new forest. Or if you go from forest, let's say the Amazon, to pastures for cattle, or if you go to crops to grow soybean, there can be different carbon implications depending on those land use changes. And it also depends on the type of carbon that you're cutting down or changing when you go from the land use change. So if you're in the Amazon and creating more crop land by cutting down the forest, the implications would be different compared to if you were in Russia cutting down the forest and changing the land.

The relative carbon densities, as we would say, to go from one land use to another is quite important and we don't have perfect data what's going on in the soil. There's a lot of carbon in the soil, a lot of uncertainty about what's happening when we change from one land type to another. And actually, just tracking the areas can be quite hard to estimate, what area in this country has changed from forest to cropland or something like that. To make it even more complex, you can have multiple land use changes, so you could go from a forest to cropland and then that cropland may become a pasture, then that pasture is left and it becomes a forest again, and then someone cuts down the forest and converts it into cropland. So over a 10 or 20 year period, you could have all these factors happening, which is changing the carbon balance. It is really hard to estimate what's going on with land use emissions, and this is the biggest uncertainty I think in the carbon budget, or one of the more important ones.

Ariel Conn: It seems like you hear a lot about the discussion between whether we should be having forests or crops and pastures and stuff like that, but I don't really hear much about the impact of turning the land into a city or a town or something like that. Does that impact the land use debate?

Glen Peters: It does. The land uses involved are relatively small — the urban area, city area, compared to let's say the forest area. So there's that scale difference. And quite often, you may not get a city emerge in the middle of the forest. But the city might grow and it takes up the hinterland around it: so for example you have a town which becomes a bigger town, and so the farmland around that town is converted into housing, and then it grows bigger. And so you keep taking over the cropland and pasture land that was around the town, so the town expands. This will push agricultural production to other areas, which then might cause deforestation or other types of land use change. So there will be come direct link, in that expanding a city may impact on forests or woodland of different types. And there's also an indirect effect, that even if you expand your city into cropland or pasture land, then you may cause some additional agricultural activity in another area, which might cause some deforestation. So, it's a complex picture.

Ariel Conn: Okay. One last question for the carbon budget. As you said, you've been doing this for 10 or 15 years. Do you still think it's a valuable calculation?

Glen Peters: It's actually, I think, been a very useful thing to do for the carbon cycle community, and there's several reasons for that. So when every year you come back and make sure that you've got balance and things are working and try and understand what's happened in the last year, you're sort of in a sense forced to learn about things that are happening. If you didn't re-estimate the carbon budget every year — let's say you only did it every five years — then many things would happen and you would maybe not follow up so closely the annual changes and what's causing annual changes. So I think the fact that we do the carbon budget every year forces us to think about things like annual variability: we have to explain to people why the emissions go up or down this year; why did the atmospheric concentration of CO2 — so the amount of CO2 in the atmosphere — so why did that go up or down; how did it relate to natural variability, this El Nino I mentioned before. 

And also it gives a new opportunity every year to communicate what's happening. So, one advantage of doing the carbon budget is we have a release every year; we can have a new story, a new narrative, a new way to engage with people focusing on what's happened in the last year, which is much closer to home compared to what happened five years ago. I think it's been a very useful tool to get the scientific community to work together, but also to communicate the science to a broader audience.

Ariel Conn: Okay. Another phrase that I've seen crop up in some of the papers of yours that I was looking at was greenhouse gas inventories. Could you explain what those are?

Glen Peters: Inventories are basically a report that certain countries — not all countries — certain countries have to do every year, more or less, to give statistics on their emissions. So before, I was talking about the territorial emissions, how much emissions have been released in different countries, in factories and so on and so forth. So every year the statistical offices or environmental agencies in those countries will compile the energy statistics and convert them into estimates of CO2. And so an emission inventory is basically a catalog or a database report of all the emissions that have happened in a country — usually by sector and type of activity, sometimes also by region. And so it's essentially our latest estimate of emissions into the atmosphere.

I mentioned only some countries need to report this. So through the United Nations Framework Convention on Climate Change, countries have to report what their emissions are, but essentially it's only developed countries have to regularly report what their emissions are and developing countries have less stringent reporting requirements. And this is a bit of a problem for people like me that are trying to estimate global emissions. We have quite good quality reports from one set of countries and then quite disparate information from another set of countries, so this is a sort of problematic issue when you're trying to get climate action to happen. If someone's not reporting something very well, then it's quite hard to identify where they can reduce their emissions and to track whether they're actually doing what they said they would do.

Ariel Conn: How do you deal with that?

Glen Peters: There's some organizations that compile statistics at the international level. For example, International Energy Agency is maybe the best example; it compiles energy statistics for a whole range of countries — they essentially try and cover the world. They might have to make some estimates where there's some missing data, and then you can make various assumptions and convert that data into emissions. And you can do a pretty good job there, but they're in no way as detailed as, let's say, a bottom up approach to it may be. If you think about the International Energy Agency, they'll have a bunch of people working on emissions at the global level and energy statistics at the global level. But within a country, particularly if you go to a rich country, you've probably got even more people working just on that country.

So there's a lot of knowledge within a country on what's happening with energy and emissions in different sectors and obscure sub sectors, like what are the emissions in refrigeration and so on — there'll be experts in countries on these sorts of things. And these statistics are compiled; you could say because it's coming from the country, it could be biased, but there's a review process which goes on. So people will pick up, "Well, you've been telling us some stories about the refrigeration. Could you please improve that estimate?" Or something like that. So, we have these global data sets that can give us a global picture, also every country at the global level. But the sort of national statistics gives a lot more information that allows us to verify things, to see whether something we saw in the international statistics made sense, and so on.

So it's a very important way to get much more accurate information. We generally push the developing countries, to try and get them to also do national reports. So they have these inventory reports every year that we can go in and see what's going on in China or India or South Africa or whatever that country may be. But of course, they find it's a lot of work. They may not see it's in their best interest to report detailed statistics, in case it means they may need to reduce their emissions. So it's a constant struggle.

Ariel Conn: We've touched on this a little bit earlier, but could you also talk about the difference between measuring production versus consumption?

Glen Peters: Production is more or less synonymous with territorial emissions, so production emissions are the emissions that occur within the country. It's a little bit different by territorial, but this gets into very obscure economic definitions related to companies that may be registered in one country but have activities in another country and so on. Whereas consumption emissions essentially are a carbon footprint, so a consumption emission will look at the emissions within the country; they will take out the emissions to produce products which are exported, but they will include the emissions in other countries to produce emissions from products which are imported. So it basically matches to a carbon footprint at the very aggregated national level. They sort of give different information. They allocate emissions a different way and give different information, and that's why they're both quite useful.

Ariel Conn: So a lot of what you're talking about sounds complicated. I guess I'm curious: how much uncertainty is there in what you're doing? How confident are you in a lot of the numbers that you work with and how much uncertainty are we dealing with?

Glen Peters: The uncertainty, it's always a relative question. So when you go to a rich, well developed country, the uncertainty in these estimates of emissions may be let's say a few percent. If you go to a developing country like China or India or something like that, you may get 10, 20% uncertainty. If you go to a least developed country, so very poor countries where they have very poor statistical infrastructure, the uncertainty may be even higher. But generally these countries don't have much emissions overall, so their high relative uncertainty doesn't really affect the global total that much. But there's also this question then of how does uncertainty change? Is it so uncertain that we can't tell if a country's emissions are going up or down or anything like that?

And I think the uncertainty in both developed and developing countries is low enough that we have a good idea what emissions are doing in terms of trends — whether they're going up or down or whatever. So there is uncertainty; it'd be much nicer if the uncertainty was lower. But I don't think the uncertainty is problematic in the sense that it's too large that we could avoid acting or something like that. So certainly the uncertainty is low enough that we can make good policy with the data.

Ariel Conn: And when you talk about, “We can figure out whether or not emissions are going up or down,” what is happening with emissions right now? Are they going up or down?

Glen Peters: They're going up — although that needs a little bit of nuance, I suppose. Over the last decades, emissions have been going up one, two percent per year over a long term trend. We did have this little bit exciting period — 2014, '15, '16 — where emissions were more or less flat and everyone got very excited about that. But since then — 2016, '17, '18, probably this year — emissions are rising again. So the last 10 years emissions have gone up about one percent per year. Overall, emissions globally are going up. There was a slight slow down, but I think that was more of an aberration than anything else. And then when you go to the country level, the general rule of thumb is the developed countries’, the wealthier countries' emissions are flat or going down; and in the developing countries, where they're growing their economies, emissions are generally going up.

Ariel Conn: That was something that I thought I was picking up on in some of the stuff that I was looking at, which is it seems like growing an economy increases emissions just generally. Is that the case?

Glen Peters: It doesn't have to be the case, but in the past that's generally been the case. So when you grow your economy, you grow your energy consumption. You have some efficiency improvements, but generally the growth in the economy is faster. So energy use will generally go up, and when energy use is going up — if you're producing energy with fossil fuels: coal, oil, or gas — then your emissions will go up. So broadly speaking, if the economy's growing, it's putting upward pressure on energy use and upward pressure on emissions. Countries where emissions have gone down — so US is an example, the EU is an example — they also have been able to slow or stop the growth in energy consumption. Their economies are growing slow enough so that the efficiency improvements are greater than the growth and energy consumption has gone down slightly.

And when your energy consumption is going down, then it's easy to replace, let's say, coal with renewables. You don't have to expand your energy system. So instead when you put out solar or wind, that solar or wind can displace existing fossil power plants, like coal, instead of adding on top of a growing energy consumption. So there's a general pattern that if you have got slow enough economic growth, you can slow down your growth in energy consumption, then you can get your emissions to go down. If you're growing your economy fast, then your energy consumption is going up, and it's very hard to build solar or wind fast enough to be able to produce energy for that growth. Overall, though, growing the economy puts upward pressure on emissions.

Ariel Conn: Part of the Paris Agreement relies on negative emissions. And I was hoping you could talk quickly about what that means and whether it seems feasible.

Glen Peters: Mainly we've been talking about historical emissions: so what's happened in the past. But if we want to keep temperatures below, let's say, two degrees or one and a half degrees or something like that, then we need to reduce our emissions quite dramatically. The emissions would need to go to zero. And emissions will actually need to go negative, so that means that we'll have to take more carbon out of the atmosphere than we put in. So when you think about it in terms of the carbon cycle, we already put in carbon to the atmosphere and then take out some carbon naturally through forests and oceans. But most of these scenarios that are consistent with different temperature goals, like two degrees or one and a half degrees — you have to artificially take carbon out of the atmosphere. And this is what's called negative emissions.

So you can do these negative emissions in different ways. You can grow a lot more forests. If you take cropland and turn it into a forest, then that will take up some carbon. You can use it with bio energy, where you burn the bio energy but then capture the carbon before it goes back into the atmosphere and then bury the carbon. This is called bio energy with carbon capture and storage, which is quite a weird technology in a sense. Or you can have direct air capture, which is basically a machine that sucks carbon straight out of the air. It takes a huge amount of energy, but you can suck carbon directly from the air.

A combination of these technologies — there are another few different types of technologies at the smaller scale — you're able to take carbon out of the atmosphere in theory and help get stabilized temperatures at two degrees or something like that. So whether I think this is realistic, it's important to point out a couple of things. So even if you want to reach some of these aggressive climate targets, you need to reduce your fossil emissions anyway. And then on top of that, you need to take some carbon out of the atmosphere, so you need some negative emissions. It's a question of how much we can have and how much do we need. I have no doubt that we'll have some negative emissions, but whether we can have a sufficient scale that it would be really meaningful at a global level, I think you could debate about.

There's a whole range of issues related to using land for bio energy, or for forests even — then that's going to put new water stress, new fertilizer stress, etc. It's going to cause additional stresses on the land that you may not want; issues with food security, that's a huge issue if you're using cropland and pastures for forests or for bio energy. So there's a whole range of issues that will make it hard to see those technologies come at scale. But according to most model runs, we need to figure out how to make this technology work. So we just basically have to find a way.

Ariel Conn: I mentioned not wanting to blame per se, but what countries right now are the biggest emitters?

Glen Peters: In a sense, that's a data question, right? So who are the biggest emitters — it's an obvious question. China is the biggest emitter, in aggregate terms: it's about a quarter of global emissions. US and the EU — European Union — are both similar, around about 12 or so, 13%; don’t have these numbers on the top of my head. India is much smaller, it's around the 5, 6% mark, from memory. So those four countries — region for Europe — they account for about 60% of global emissions. And then there's another 100 or whatever, 150 countries, that are the rest; but even though those countries are smaller, they are all important. Everyone needs to reduce their emissions.

Just because a country's big doesn't mean that a country that's small shouldn't do anything. But also it's important to point out that even though, let's say, China and India are two of the biggest emitters, they also have very large populations. So if you look at it at a population-adjusted level, it's quite different. The US and Australia will be two of the worst. Europe is, on a global average, not so bad. China actually has higher per capita emissions than the global average and than Europe, so China is certainly no saint when it comes to per capita emissions. But India does have quite a lot lower per capita emissions than many other countries. And it's a growing economy; there's a lot of people in poverty; they have made huge strides to get people out of poverty. But still, they need to grow their economy, give people the energy that they need to have a decent life. And so they're going to have increased pressure on energy use, therefore emissions in the future.

So let's say in Europe and in the US, we've reached a high standard of living where — a luxurious position where we can actually stabilize and even reduce our energy use. But that sort of has to happen at a faster speed to give more space to countries like China and India to develop. But also if they just develop on a high carbon pathway by using coal and so on, then all climate targets that we've ever dreamed of will just be blown out of the water. So China and India and other developing countries can't repeat the mistakes that the rich worlds made in having a fossil fueled growth. They will need a solar and wind powered growth or different technologies. Otherwise we'll certainly blow any climate budget that we might have.

Ariel Conn: I hear a lot about China's coal use. How bad is it actually? And what are they doing that's right? What are some of the steps they're taking that we want to see more of? And same with India, I guess.

Glen Peters: China is, I think, more than half global coal use. The Chinese energy system is basically based on coal — very coal dependent country. And that's fueled a lot of its growth. And a lot of the coal infrastructure in China is quite young, which is more of a problem. So the US has a very old infrastructure; it's easy to retire old coal power plants. China already has an energy system very heavily dependent on coal. India is the same; they both have the same problem. So China is very dependent on coal, although China is taking a few steps. How many of these steps they would have taken anyway you could discuss, but let's say China's got a huge growth in solar and wind. A lot of the caustic lines in solar and wind around the world are because of the production capacity of China.

China's made leaps and bounds in deploying solar and wind, but still their coal use is, let's say, stable — maybe growing a little bit. But it's not so related necessarily to the solar and wind. So China is certainly doing a lot on the solar and wind side, but it's maybe not affecting energy use as much as some people would like to think. There's a lot of local air pollution problems in China, and so there's a lot of activity trying to shut down inefficient power plants or inefficient factories to reduce the air pollution, but this also has climate benefits. And China is generally trying to shift its economy to one that's more based on services and less based on manufacturing products, which are then exported.

One big issue with China is they have a huge investment program, and when the economy's quiet, they generally try to invest in new infrastructure. So people may have heard about all these, let's say, ghost cities that they have in China, where they've built new cities but basically no people live in them. These are a way of sort of stimulating the economy, but it's also very bad for emissions. So China is taking some very positive steps, but also there's many of the old infrastructure that is continuing along. So China's emissions growth has slowed down dramatically, but still it's a question mark of whether it's sort of peaked or whether it will keep rising slightly into the years ahead. China's a very interesting place where there's so many contradictions going on.

Whereas India is much more clear patterned. Their stage of development is a little bit behind China. They're growing their economy more strongly. A lot of coal still going in, although it's starting to slow down; a lot of renewables, particular solar, going in. Whether that's fast enough to meet their incremental energy needs is a question, but certainly India's making some progress in terms of deploying solar and wind; slowing down a little bit on the coal side, but emissions are still growing very strongly.

This is sort of a pretty common picture you have when you look at different countries. Their stage of development has a big role to play in what their emissions are, because you're trying to put up your infrastructure, you're trying to build power plants and roads and bridges and factories and schools and hospitals. And when you're doing those things, then your emissions will go up.

Ariel Conn: What policies would you most like to see enacted to help address these problems?

Glen Peters: This is the most common question that I never have a good answer for. There's the very standard answer that you can give, which is basically you need to have a price on carbon, policies to reduce carbon emissions. But it's very easy to say that; it's very cheap to say just have a carbon price and everything will be okay. In reality, there are political realities, there are social realities, there are elections. So it's not very easy, necessarily, to put a price on carbon. So I'd just say, broadly speaking, you just need to roll out whatever policies you can find that you can get through your government or whatever that will help emissions go down, or encourage emission reductions in the future through investment in innovation and things like that.

You will find a patchwork, I think in any country, of different policies — based on what's possible to achieve in different countries. So different sectors will have different policies. Europe is a classic example, where certain sectors are within the emissions trading system; certain other sectors are outside of that system, but then they have other policies which address them. Although not all sectors are treated equally in the sense that some sectors get less attention than others. So that's certainly a problem. Yeah, there's maybe no answer, but basically to implement whatever policies you can implement.

Ariel Conn: Maybe this is an equally hard question, I'm not sure. What actions do you think are most important for individuals to take?

Glen Peters: For individuals, it's quite easy, in a sense, to a certain degree. Aviation is probably the number one. So if you go on a plane, that's probably going to be the biggest part of your footprint. Maybe if you have one or two flights within your country, let's say the US, in a year, then it might be similar to your driving emissions if you drive a car. But if you're taking international flights, or if you fly more than once or twice a year, that will completely dominate your carbon footprint. So there's a very big scope for individual behavior there. 

The next one on the list would be food: particularly red meat consumption has a huge footprint because of the methane emission when cows and sheep and so on basically burp. Just slight shifts in your diet can have a big impact. You don't necessarily need to become a vegan or something like that, but slowly shifting your food patterns away from red meat to a more plant based diet, and also white meats instead of some red meats, and so on: that can make a big difference.

Driving a car is pretty important, sometimes underrated. Each individual car trip might be quite small, but you might take hundreds and hundreds of small car trips every year — so when you add them all together, it's actually quite significant. So individuals have quite a bit of scope on things that they can do, but then they can only go a certain distance. So with the car transport and the aviation, if you don't have alternatives — if you can't take a bus or you can't ride or it's too far or a whole range of other reasons — then you may not have the capacity to be able to change your behavior. Also electricity, for example: if you don't have your electricity system cleaning up over time, then that's a little bit out of your hands, so there's not awfully much you can do. So the individual behavior is somewhat also limited by government action as well. So I guess you could say individuals could then lobby governments to do better action. But clearly aviation, food, transport, particularly driving, etc. will be big items.

Ariel Conn: All right. And then looking at all these issues that we're dealing with, what gives you hope?

Glen Peters: The hope is sort of abstract, but there's pleasant surprises. We have had some pleasant surprises, let’s say with solar or batteries or things like that. But I think we need some pleasant surprises, so things that actually turn out better than we had hoped, or maybe behavioral change will become more accepted than we hoped, or maybe voters in different countries will change their habit and vote differently. It's a little bit hard to sort of pinpoint exactly, but some things might happen that we didn't expect to happen, and after that things might happen much more easily and faster. So I'm hoping for some pleasant surprises.

Ariel Conn: I think that's everything on my end. Is there anything that you think is important that we didn't get into?

Glen Peters: I think you've covered pretty much everything there is to do with emission statistics. Some are quite technical, but you've touched on just about everything, I think.

Ariel Conn: All right. Well, thank you so much.

Glen Peters: It was a pleasure, thank you.

Ariel Conn: So far on the Not Cool podcast, we’ve most talked about the impact of carbon, with only some mention of greenhouse gases more broadly. But for as large as the carbon impact is, it’s not the entire cause of climate change. On the next episode of Not Cool, we’ll be joined by Ilissa Ocko, a Sr. Climate Scientist for the Environmental Defense Fund, who focuses on many of those other gases and aerosols that end up in the atmosphere and impact our climate.

Ilissa Ocko: We know around 90% of the excess heat that has been trapped has gone into the oceans. And so then that warming that came from methane in the atmosphere is now in the ocean, where it can last a lot longer. So even though methane is a short-lived climate pollutant, it doesn't have short-lived impacts.

Ariel Conn: As always, if you’ve been enjoying these episodes, please take a moment to like them, share them, and maybe even leave a good review. I hope you’ll join us for episode 19 with Ilissa.