Ep63: Glen Peters 'The Past, Present & Future of CO2 Emissions'

“If you want to put that into terms of how many facilities you would need to build, we're getting to a situation where you will have to build new facilities, maybe a million ton per year, every day from now to 2050.”: Glen Peters on the feasibility of carbon-removal technology. 


In this episode of Cleaning Up, Michael Liebreich talks to Glen Peters, Research Director at the Cicero Centre for International Climate Research in Oslo.

Michael and Glen begin by discussing the current trajectory for greenhouse gases and Glen’s thoughts on whether the target of limiting temperature increases to 1.5 degrees is achievable.

They then debate whether a new, higher target is needed and what the ramifications of a larger temperature increase could be.

Finally, they talk about unrealistic climate scenarios and Glen’s recent article for Nature.

This is an abridged transcript of the conversation, edited for clarity.


Michael Liebreich: What's your sense of the most likely trajectory in terms of emissions?

Glen Peters: In the 2000s emissions were growing quite fast with the emergence of China. Then we hit 2010 and emissions really started to slow down. If you look at the last 10 years or so, emissions have started to level out. Are emissions peaking? Have they peaked? Maybe, maybe not. Pre-corona, we were talking about emissions and peaks, and that most likely carbon dioxide emissions would be flattish for the next decade or two. There's some nuance and discussion about that, but more or less emissions were flattening out. If emissions continue on that path, let's say flat, maybe declining a little bit after 2050. Which would be consistent with our current policies more or less. Also, if we're raising ambition a little bit as time progresses, then we'll probably end up in the 2.5, maybe 3 degree range and in 2100, temperatures would still be rising, because we're not at zero emissions. That's a ballpark, where we're heading for an increase of 2.5 or 3 degrees by 2100 with rising temperatures afterwards.

ML: What could happen if temperatures increase by 2.5 to 3 degrees?

GP: That's certainly not a good outcome. In terms of impacts, I'm not so good at quantifying directly into hard numbers for different temperature levels. I think, particularly for me, coming from Australia, I often think about the extreme heat days, drying out the vegetation, things like bushfires becoming more prolific and so on. I think for countries like Australia changing rain patterns are a problem. Maybe you get a little bit more rain overall, but the seasonal shifts may be problematic. So, it would be disruptive. And of course, sea level rise, you would certainly lose some small island states to 2.5 degrees. It takes time for the water to come up but particularly with a surge we would probably lose some countries. It's a bad outcome for lots of people, definitely.

ML: How much certainty is there in climate forecasts? Could it be even worse than 2.5 to 3 degrees?

GP: The range is very big indeed. An increase of 2.5 to 3 degrees sounds small in some respects, but if you think about it in terms of a carbon budget, that's cumulatively about 1,000 billion tons of CO2. There are various layers of uncertainty. We divide them into different parts. There's the uncertainty in the emissions pathway: where will CO2 emissions go? There's the uncertainty in other emissions, like methane. And then there's the uncertainty in the climate response. On the optimistic side, let's say, emissions decrease by 5-10% trending downwards. Some of the challenges for that to happen are really in the developing countries. China's growing, India's growing, you might have the EU and the US trending down, but you've got emissions growing in the rest of the world. When you think about those different dynamics, getting emissions down by 2030 could be more challenging than we think. If you look at what countries have put forward as emission pledges in the various climate agreements then we’re looking at something like a 16% increase by 2030. So, let's say there's some uncertainty in the emissions pathway.

ML: What’s needed to hit 1.5 degrees, or to stay consistently at 1.5 degrees increase by 2100?

GP: The point I'm trying to make here is that there would be a need for a rapid short term decline in emissions in 1.5 degree scenarios. Then when you start to get to 2040-2050, then you start to get to the hard to mitigate sectors, industry, long distance transport, and so on. Most integrated assessment models find that it's more cost effective to start deploying carbon dioxide removal. That could range from things like reforestation to growing trees for bioenergy with carbon capture and storage. Another technology, which is becoming increasingly discussed, is when you just suck carbon directly out of the air, direct air capture. Those technologies are used at scale in a lot of these scenarios. Just to give you an idea of the scale: some scenarios use around 5 billion tons of CO2 removal by around 2050. If you want to put that into terms of how many facilities you would need to build, we're getting to a situation where you will have to build new facilities, maybe a million ton per year every day from now to 2050. These are the sorts of scales that we're getting to, which are astronomical.

ML: At what point do we admit that we’ve missed the 1.5 degrees target? Should we refocus on making sure that we keep to 2 degrees or 2.5 degrees?

GP: So essentially, we need a reframing. I think part of the problem is that we've framed the climate problem around these targets and it’s “1.5 degrees or die”. If you shift away from 1.5 degrees to something else then it's like we’ve given up and now it becomes “two degrees or die”. There is a better way to frame it and the IPCC actually tried this in the 1.5 degree report. There are more increments of warming, so every tenth of a degree matters, every year matters, every bit that you can mitigate matters. I think it's very important to get out of this narrative of threshold. We have to get the emissions down as fast as we can. There are political considerations and technological considerations, there's bringing along a population who may have other interests. You need to bend the curve, get emissions down as fast as you can. Hopefully, that takes us down somewhere around the two degree mark, maybe we end up better off and we get down to 1.8 degrees, or maybe a little bit worse off at 2.2 degrees. We have a problem with the narrative being set up in a way that if we crossed 1.5 degrees then we should give up, or it's too late, this is very problematic. Looking at the world where we are today and looking at the way these scenarios go down to 1.5 degrees, it's like an immediate and dramatic change: it would be COVID19 every year, in a sense. It would be very dramatic changes, rapid changes, all countries involved, no matter how rich or poor you are, your emissions would need to go down dramatically in the very short term. It's just not feasible.

ML: You wrote a piece in Nature arguing that whilst we may not meet the 1.5 degrees target, things are not quite as bad as framed in the public discourse. Why did you write that article?

GP: If you think back to some of the earlier reports like the IPCC fifth assessment report, which came out in 2014, then there were essentially four pathways that we looked at in terms of climate. The high end, which is the RCP 8.5, two in the middle, and the low end, which is a two-degree type scenario. But also in that report was the Working Group Three report which had 1200 scenarios staining that range. I think from around that time, people were starting to become a bit more clued up, there was a lot more variation in what the high end could be. This high end scenario, RCP 8.5, is a scenario which has no climate policy. It's also a scenario which assumes no climate impacts. So, we can go to RCP 8.5, and it has no impact on the system. And if you look there's quite a big range of scenarios that have no climate policy. There are scenarios with no climate policy, where emissions are essentially flat throughout this century. And I think this nuance never really entered into the discussion. In the last 10 years, we've seen emissions start to potentially level out, maybe even peak, maybe not but we're getting there. So there's been climate policy in place, and people are starting to realise this. There's now this tension between these scenarios without climate policy, these scenarios with climate policy, and it was a good time to have that discussion. And so that's what we really wanted to get out in that article.