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Tracking carbon emissions from many different angles

Glen Peters is an expert in how humans are shaping global change – with a focus on how policies, economic shifts and other factors can drive or curb the growth in greenhouse gas emissions. There has been some good news on that front in recent years: The latest Global Carbon Budget, an annual report released by the Global Carbon Project, for example, found that fossil fuel emissions hadn’t increased in 2016. It marked the third year in a row of flat growth in the carbon dioxide that humans add to the atmosphere.

In a new paper, Peters, Senior Research Fellow at the Center for International Climate and Environmental Research – Oslo (CICERO), and his colleagues argue that raw emissions numbers only get at part of the picture. It’s important, they say, to look not just at whether emissions are changing, but why. Such an understanding will be central to international efforts to limit temperature increases from climate change to 2 degrees Celsius.   

This study, published today in Nature Climate Change, lays out a series of indicators that Peters and his colleagues say scientists can measure to track the world’s progress on meeting climate goals. They include carbon dioxide per unit energy, or the emissions produced to get a given amount of power. In an interview, Peters discusses how such a “mixed bag” of indicators might help nations to pick the best climate policies for reducing their emissions.  

Peters is a member of the Scientific Steering Committee of the Global Carbon Project, a global research project of Future Earth. The paper published in Nature Climate Change includes multiple authors from the Global Carbon Project network.

Daniel Strain: We’ve seen some good news about emissions recently, but in your paper, you try to temper some of that optimism. Why is that?

"Future reducations will need some work," says Glen Peters. Photo: Monica Bjermeland/CICERO

Glen Peters: If we go back to the early 2000s, emissions were growing about 3% per year, and very strongly in China, around 10% per year. And now, some of these emissions have really backed off in the last few years.

And that’s good news. We’re heading in the right direction in a sense. But we have to look at the reasons for why that's happening. Is the slowdown in China driven purely by climate policy or energy policy, or are there other economic factors? And we find that there are certainly other economic factors that are playing a significant role: the slowdown in construction, which makes for less production of steel and cement. The emission changes are not really driven by a growth in renewables.

These changes are good and welcome, but we still need to be cautious and realise that these things don’t come for free. Future reductions will need some work.

DS: So a lot of the hard work is still ahead of us?

GP: When you look forward to, say, mid-Century, emissions need to be getting close to zero, which is a completely fundamental change in the energy system.

There is no easy tinkering-around-the-edges way to get there. Every country can get a few percent here and a few percent there by doing the “easy stuff,” but then the next phase gets much harder. Then you have questions like “do we continue to build internal combustion engines?”

DS: You focus in your paper on tracking changes in emissions. Why is that a difficult task?

GP: If we just take a developed country, let’s say the U.S. or Europe, they have pretty good emissions statistics, maybe one or two years behind the current year. In the U.S., the data availability has made it easier to look at the causes of and changes in emissions. 

But even in a developed country, you do have some inconsistencies in statistics – such as between emissions statistics, energy statistics and economic statistics. They can have different definitions. So depending on how you do your analysis, you can get different answers, for example, in what’s causing the reduction in coal use in the U.S. Is it renewables? Is it gas? Is it lingering effects from the recession?

DS: But that’s for developed countries.

GP: When you move to developing countries, let’s say China and India or smaller African countries, then the statistics are much weaker. Quite often, they don’t estimate their own emissions, so you need to rely on third-party sources, industry or different institutions, to provide those statistics. You get a lot of inconsistencies, let’s say, between the energy data, the emissions data, the economic data.

So one clear recommendation in this context is you really need a set of consistent and updated data. If I want to analyse emission targets in China, what CO2 data do I use? What GDP data do I use?

DS: So what do we need to track when it comes to emissions?

GP: In the paper, we outline a hierarchy of indicators. Those indicators themselves are very aggregated. The carbon intensity or carbon per unit energy indicator, that’s dependent on a whole range of different things at the national level. Using the U.S. as an example, maybe one state is replacing coal with gas and another state with renewables, but when you look at the indicators at the national level, you’re just looking at the big mix.

Then maybe you need to tease those apart, to go into deeper details: What’s causing the carbon per energy to change? Then you could keep going to deeper and deeper levels. What is the growth rate of renewables? What is the share of research and energy expenditures in terms of total GDP? If that goes up over time, then you’d expect in the future that there will be new technologies available that will drive down emissions in 10 years.

DS: It seems like the list of possible indicators might be endless.

GP: Of course, ultimately, there’s an end, but there is no one unique indicator that will tell you everything you need, so you use different indicators in different contexts. You need a mixed bag of indicators.

DS: What are the next steps when it comes to examining diverse groups of indicators?

GP: You can start to dig through the data of specific countries. In this paper, we did a snapshot of recent trends. But if you update this every year, then you can start to see that if China implemented a policy, we may see the impact in the statistics with a particular indicator changing. Maybe another country implemented a policy, and we didn’t see any changes, and that's also important information.

DS: In terms of policies and new technologies, the one that you focus a lot on in the paper is Carbon Capture and Storage, or CCS. Why is that?

GP: Nearly all scenarios that keep temperature below 2 degrees use a large amount of CCS. The CCS can be applied to industry, such as cement and steel, power generation, such as from coal, and significantly carbon neutral bioenergy to remove carbon from the atmosphere. CCS therefore allows relatively high levels of fossil fuel consumption in the emission scenarios, contrary to many people’s perceptions.

Unfortunately, the deployment of CCS has consistently lagged expectations, and some fear it may never be able to meet expectations in scenarios. Many scenarios require around 4,000 facilities with CCS in 2030, and this is a long stretch from the tens currently proposed. We need much more emphasis on the development of CCS and, in parallel, a deeper exploration of emission pathways consistent with 2 degrees that do not depend so heavily on CCS.