An international group of folks put together an interim report analyzing “Deep Decarbonization Pathways”. Decarbonization refers to the process of using less carbon within an economy. The intent of the report was to show ways forward to keep global mean temperatures below 2C. Readers of this blog know that I no longer think such a goal is achievable given the scope and scale of decarbonization. We have not moved from a “business-as-usual” approach and have run out of time to reduce GHG emissions prior to relevant limits to meet this goal. I argue the exact opposite of what the authors describe in their summary:
We do not subscribe to the view held by some that the 2°C limit is impossible to achieve and that it should be weakened or dropped altogether.
Thus the main problem with this report. They’re using a threshold that was determined without robustly analyzing necessary actions to achieve it. In other words, they a priori constrain themselves by adopting the 2C threshold. Specifically, a more useful result would be to ascertain what real-world requirements exist to support different warming values in terms real people can intuitively understand. The report is not newsworthy in that it reaches the same results that other reports reached by making similar assumptions. Those assumptions are necessary and sufficient in order to meet the 2C threshold. But examination unveils something few people want to recognize: they are unrealistic. I will say that this report goes into more detail than any report I’ve read to date about the assumptions. The detail is only slightly deeper than the assumptions themselves, but are illuminating nonetheless.
An important point here: the authors make widespread use of “catastrophe” in the report. Good job there – it continues the bad habit of forcing the public to tune out anything the report has to say. Why do people insist on using physical science, but not social science to advance policy?
On a related note, the report’s graphics are terrible. They’re cool-color only, which makes copy/paste results look junky and interpretation harder than it should be. So they put up multiple barriers to the report’s results. I’m not sure why if the intent is to persuade policy makers toward action, but …
Let’s start with the reports projected CO2 emissions trajectories:
Like I said, the graphics are terrible. That aside, what does this show us? It shows us that global emissions peak in 2020 – only six years from now. Individual countries peak at different times withing the next 16 years (by 2030). By 2050, total emissions from these 15 countries are 1/2 their 2020 value.
What effect do these reductions have in aggregate?
There are different ways to measure the effect, tons of CO2 per capita is one (one few people understand). By 2050, energy-related CO2 emissions per capita are 56% below their 2010 value. This is an interesting graph for a couple of reasons. Note the time axis starts in 2000. Why? Because prior to 2000, this metric’s value was fairly constant. There is, of course, a wide range of emissions by country – from 4 for China to 20 for the US. What would US emissions have to do to achieve a 15-country mean of 2 by 2050? They would have to plummet. And other countries’ would have to decrease (e.g., western European) or not grow (e.g., China and India). How will China’s economy grow for the next 35 years yet emit fewer emissions given how many fossil fuel plants China built in the past 10 years? The report assumes widespread technological deployment to accomplish this. I think the assumed deployment is wildly optimistic:
CCS is carbon capture and sequestration, something that is easily much more of a buzzword than a viable technology. To date, there is not one utility-scale example of a fully functional CCS system. That says nothing about a cost-effective system that utilities would want to deploy of their own volition. With expensive new technologies necessary to achieve these emissions cuts, governments will have to enact policies telling utilities to use CCS. This will increase consumer’s energy bills. How long do you think people will let that happen? And the report assumes scale-deployment of CCS by 2025 to 2030. That’s 10 to 15 years from now. Again, utility-scale CCS isn’t feasible today. How will it be feasible in 10 to 15 years? Only massive R&D investment could accomplish this. The report recommends this approach, but I don’t think any country will actually allocate sufficient resources.
Indeed, the report’s assumption of CCS, unrealistic renewable, or nuclear deployment underlies requisite US emission reductions (from the report’s US section):
High CCS scenario. The numbers in bubbles are grams of CO2 per mega-joule of energy (gCO2/MJ), or more units that nobody actually understands. This graphic shows historical and projected US energy portfolio. First of all, note that the US will likely need to supply twice as much energy in 2050 as 2010 – so regardless of source, the US needs more power plants of some type. This scenario eliminates coal and natural gas without CCS by 2050. What would have to happen to actually achieve that? There are about 5,000 fossil fuels plants across the US. Most of those are coal – all of them have to be shut down by 2050 in this scenario. Every existing natural gas plant has to be retrofitted with CCS technology. Wind and solar continue their current growth, which you can see results in a continued minority of energy supply by 2050. What the report doesn’t show is post-2050. In order to achieve <2C warming, we have to stop using natural gas soon after 2050.
This is the high-renewables scenario. Again, all coal plants are shut down by 2050. In this scenario, natural gas also declines. There is some nuclear growth. Wind supply grows exponentially for 35 years. Look, you can model this type of thing, but implementing it in the real world is something else. Based on my calculations, reducing US emissions 90% by 2050 (a metric that exceeds Kyoto Protocol thresholds) requires deploying more than 1 million 2.5MW wind farms, installing a new multi-billion dollar electricity transmission system, and developing and deploying a utility-scale energy storage system. This report goes one more level of detail down into the problem, but leaves many critical questions unanswered.
This is the high-nuclear scenario. Like the two previous scenarios, coal disappears by 2050; natural gas declines a little, and wind grows as in the high-CCS scenario. Here, nuclear grows exponentially for the next 35 years. What that means in reality is the US has to build about 1,500 nuclear power plants by 2050. There are 62 operating nuclear power plants in the US today. 62. We need 24 times that number in the next 35 years. There are 435 nuclear power plants installed worldwide – even in previous nuclear-happy countries like France and Germany. But the report modeled building more than 3 times as many nuclear power plants as operate worldwide in just 35 years. I can’t take that seriously.
Clearly, these scenarios are more illustrative than anything. We will likely implement some combination of them whether we strive for the <2C goal or not. But the trade-offs are clear: for every nuclear power plant we don’t build, we have to build some combination of renewable energy or deploy technology that doesn’t exist today.
The report models decade-over-decade energy-related CO2 emissions reductions that exceed historical best rates by a factor of eight. That is an assumption that simply goes too far to be credible. This report joins others that academia generates but pointedly ignores real-world requirements to achieve.
To summarize, the national deep decarbonization pathways produced by the DDPP Country Research Teams are based on a number of assumptions and enabling conditions:
- All countries take strong, early and coordinated actions to combat climate change.
- All countries operate in a supportive global policy environment that is firmly directed at the 2°C limit.
- There is ample public-private partnership and cooperation to enable the rapid development, demonstration, and diffusion of the requisite low-carbon technologies in all key sectors.
- Open global markets ensure the global diffusion of low-carbon technologies and their cost reduction through scale and learning effects.
- Major global cooperative efforts speed technology development and improve the reach and performance of low-carbon technologies, ranging from renewables to nuclear power to CCS to energy efficiency.
- Financial flows are re-directed from high-carbon to low-carbon portfolios and projects.
- Financial support is provided implicitly to countries with lower capacities to implement mitigation policies and finance low-carbon investments, though such support is not modeled in this phase of the project.
Low-carbon technologies become available and affordable to all countries, for example through a technology cooperation mechanism and fund.
This report also keeps energy poor populations energy poor:
Asian, African, and Latin American buildings are assumed to have 1/3 the carbon intensity of OECD nations in 2050, according to the IPCC 2C scenario. How will the developing world pay for more expensive carbon-free energy when they can’t afford cheap carbon energy? The answer is easy: they won’t. Instead, the energy poor remain that way while the energy wealthy maintain their energy status. And people wonder why the IPCC approach hasn’t worked.
I understand the desire to hold to an agreed-upon warming threshold. It was difficult for so many countries to agree to any value. Based on my own research and discussions with experts, I don’t think <2C warming is achievable any more. Beyond what this report has to say, pathways that keep the world <2C warming have to include net carbon removal just after 2050. Not just reducing carbon emissions, but actually removing carbon from the atmosphere – permanently. Not just zero-carbon, negative carbon. Is that doable?
Not achieving that goal it is not my fault and it isn’t the author’s fault. It is our collective fault for decades of inaction. That conclusion does have serious consequences for ecosystems and human systems. I think we need to spend more resources to figure out what such a world looks like, what effects might occur, and plan for them accordingly. I don’t think the public will react positively when it’s clear the planet will pass 2C and activists are still talking about 2C as if it is a viable target. There are risks associated with changing the target, but how do they compare with missing the 2C target, as is increasingly likely? None of this is easy. If it were, it wouldn’t still be such a problem.