Most climate policy discussions seem to focus on decarbonisation of the electricity sector, but industry, transport, and buildings also play an important role.
Climate policy is full of unhelpful distractions.
We often fall into the trap of focusing on the global picture. Climate is, after all, a global problem.
To solve the climate problem, we need to work in smaller units. Country level is perhaps the first step, as we have highlighted when discussing the political economy of carbon dioxide removal. Non-state actors, units smaller than that of a country, also play a role: cities, business, households.
Something we rarely discuss is sectors, and sectors are particularly important for business.
Just the other day I had occasion to find a figure of global greenhouse gas emissions, say 1990-2015, by sector. Do you think I could find a decent figure? No. I may not be the best at Google in the world, but if such a figure is not the first hit, then there is something wrong…
It is scandalous, really. One of the most important problems facing society, and it is really hard to find information at a level that might be useful to actors!
Fortunately for me, I was asked to give a presentation at the Zero conference, in a session on industry. This allowed me to do something I had wanted to do for a while, look into the sector level results in global emission scenarios.
Sector-level scenario results
To look at sector-level results, I have used the emission scenarios assessed by the IPCC in its Fifth Assessment Report (Working Group 3, Chapter 6), which disaggregate electricity, industry, transport, and buildings (residential and commercial). Individual models may have more detail, but this is the detail available in the scenario database. The new emission scenario database, the so called shared socio-economic pathways, does not currently contain this level of detail, meaning we need to rely on old scenario results.
There were about 1200 scenarios assessed by the IPCC, and I decided to simplify these to instead show the median scenario in different climate categories. This leaves five indicative scenarios, with different median temperature increases at the end of the century. Some may not like this, but I find it is useful simplification for communication purposes.
It is worth noting a few key factors:
- The scenarios with a 66% probability of staying below 2°C (blue) have a median temperature of about 1.6°C in 2100, one could argue this is “well below 2°C” as specified in the Paris Agreement;
- The scenarios with a 50% probability of staying below 2°C (green) hit zero emissions around 2100, consistent with the International Energy Agency;
- The emission pledges to the Paris Agreement take us to 2.5-3°C, an area where we have very few scenarios.
Fossil fuel and industry emissions have rather steep and continuous declines once climate policy is implemented, reaching net-zero emissions by about 2070. From 2070 onwards, global carbon dioxide emissions are net negative, meaning emissions are removed from the atmosphere at the global level.
While carbon dioxide emissions go negative by about 2070, the carbon dioxide removal actually starts at the facility level from about 2020. The scale of carbon dioxide removal grows rapidly, until it reaches sufficient scale to offset continued positive (residual) emissions by about 2070.
Carbon dioxide removal is a fascinating topic, but it is not something I plan on discussing at length here.
Carbon dioxide emissions from energy supply (essentially electricity generation) are about 40% of total emissions, give or take. When climate policy is implemented, mitigation begins quickly taking emissions below zero by about 2050 for indicative 1.6°C scenarios, 2060 for 2°C, and 2070 for 2.4°C.
A surprise to most people, is that carbon dioxide removal is needed whenever temperatures are stabilised, this is the power of cumulative emissions.
If we miss the Paris goal of “well below 2°C” and end up at 2.5°C, then we still need large scale carbon dioxide removal.
Most carbon dioxide removal happens in electricity generation, as scenarios generally achieve large-scale negative emissions with bioenergy with carbon capture and storage (BECCS). BECCS has a great quality in that it produces electricity and removes carbon dioxide at the same time. Other technologies exist, but they generally require energy as input.
Carbon dioxide emissions from industry are about 20% of the global total, give or take. Industrial emissions are mitigated strongly, but never get to zero. There are two reasons for this. First, as I just mentioned, most models only have carbon dioxide removal in the energy sector. Second, in the cost-effective setting, models find large-scale carbon dioxide removal is cheaper than deeper short-term mitigation in the energy demand sectors.
Mitigation in the industry sector is often viewed as harder than the electricity sector. In the energy sector, one can shift from fossil fuels to renewables. While, in the industry sector, there is often no obvious alternative to avoid the required chemical or physical processes. Carbon capture and storage can also be applied to the industry sector, and this may be a niche and high-value application.
I could repeat the above figures for transport and the building sector, but they basically look the same. The only exception, is that the transport sector has less mitigation leading to higher residual emissions in 2100.
Instead, I show the total fossil fuel and industry emissions by sector as area graphs, for two extreme cases. First, in a world without any climate policy (unlikely today, but a useful reference point). Second, for a world that stays “well below 2°C”.
The heavy lifting in terms of the total contribution to mitigation is done in the electricity sector. Industry and building go close to zero, while transport has more persistent residual emissions in 2100. These residual emissions in 2100 mean that we need carbon capture and storage.
The negative emissions in the electricity sector are needed to offset ongoing positive emissions, but also to offset non-CO2 emissions like methane and potentially offset past emissions.
The fact that the electricity sector provides all the carbon dioxide removal should be a cause for some concern. It will certainly lead to distributional concerns within countries, as some sectors will have more perceived effort than others.
As I have discussed before, these emission scenarios have large-scale carbon capture and storage (CCS). The figure below, is an illustrative “well below 2°C” scenario. At the end of the century, it has CCS of 20 billion tonnes carbon dioxide per year, about half today’s annual emissions or about 20,000 average sized CCS facilities.
Unfortunately, the scenario database does not provide information on industrial CCS, so we are unsure how large it may be in the scenarios. Further, the CCS flows are estimated using energy consumption data, as the scenario database only reports total aggregated CCS flows.
The figure highlights that, in the average scenario, the main use of CCS is for bioenergy and hence carbon dioxide removal. Even though this does vary by individual scenario, the bigger picture is important. CCS should not be thought of as allowing continued use of fossil fuels, but rather, as a way of removing carbon from the atmosphere. Despite the framing, the outcome may, nevertheless, be the same.
The sector-level results of emission scenarios generally receive less attention than the global and country level results. The same is true of historical emission estimates. This makes sense for climate negotiations, but for implementation, sector-level results are probably more useful.
This blog post is just scratching at the surface, to highlight the importance of sector level results. One can dig a lot deeper, and the IPCC basically has a report that digs deeper.
You can also have a look at my presentation from the Zero Conference.