Understanding Decarbonization
A new THB classroom series, Part 1
Recently, several THB readers have been in touch with requests. One request is to discuss climate mitigation policy in less technical terms, to be more broadly accessible to nonspecialists. The second request has been to expand my discussion of the practical feasibility of accelerating the decarbonization of the global economy — to focus on opportunities.
With this new THB series — Understanding Decarbonization — I hope to address both requests. The emphasis of this series will be educational and I’ll take on the role of professor, which seems pretty familiar!
Be warned — As I’ve told my students over the past decades, you can expect that I’ll ask you to do your part as well, which means to read what is offered, ask questions, and read more than what is on the syllabus! There will be no taking of the roll, nor quizzes, but there might be an occasional optional assignment.
As a starting point, today’s post establishes some terminology and basic background. If anything is unclear or you have further questions, just ask. I expect this new series to run for a while, as the topic is both fascinating and incredibly complex.
Let’s start with the big picture.
The figure below shows the decarbonization of the global economy from 1992, when the Rio Earth Summit took place introducing the U.N. Framework Convention on Climate Change, to 2024, the most recent year that data is available.
Decarbonization of the economy — carbon dioxide emissions per unit of GDP — is a far more meaningful metric than just emissions because it explicitly acknowledges the iron law of climate policy. People around the world want and expect economic growth to continue, so policies focused on reducing emissions must take place in that context.
Note that as a policy metric, decarbonization of the economy is explicitly counter to the notion of degrowth that is currently fashionable in some pockets of climate advocacy, especially among some academics. Degrowth posits that we can reduce carbon dioxide emissions by intentionally limiting or reducing the size of the economy. In effect, by making people materially less well off.
That is not going to happen.
Read more! Additional Background and details about decarbonization here. For a much deeper dive, see also The Climate Fix, Chapters 3 and 4.
Something else to notice about the figure above showing global decarbonization: The trend is almost a straight line. In fact, that straight line goes all the way back to the 1960s, long before climate policy.
That long-term trend tells us two important things.
First, decarbonization has been underway long before policy makers thought that reducing emissions should be a policy goal. There is thus something going on in the global economy that causes decarbonization, far beyond climate policy. In fact, as we will see as this series develops, decarbonization is a welcome side effect of intentional changes to the economy that make us wealthier and energy consumption less impactful on the global environment.
Decarbonization is a good thing, or more accurately, the consequences of the pursuit of good things. We will explore this underappreciated dynamic in more depth in this series.
Second, since the climate policy era began in 1992, there is precious little evidence of any acceleration in the long-term background rate of decarbonization. To reach targets for deep decarbonization, as a matter of simple math, that historical linear trend will going forward necessarily have to bend downward. In other words, there will need to be a future inflection point, as there has not been one yet.
Can there be? What would it take? How fast might it bend? We will explore questions like these together.
Let’s next break that global decarbonization curve into component parts.
The figure below shows the global decarbonization time series along with trends in decarbonization for the top 20 carbon dioxide emitting countries (in 2024), expressed as relative change from 1990 (set to 100 for each country).
You can see that there is a lot of variation in overall decarbonization by country — ranging from a 40% increase (Iran) to an 80% reduction (Poland) over 35 years. These differences reflect different starting points, different energy economies, different components of economic growth, different domestic and international energy policies, and much more.
The table below summarizes from the figure above the annual rate of decarbonization from 1990 to 2024 for each of the 20 countries. Negative values mean that the country is carbonizing (CO2 per GDP has increased) and positive values mean that the country has decarbonized (CO2 per GDP has decreased).
I have also included in red at the bottom of the table the rate of global decarbonization implied by a deep decarbonization target for 2050 (assuming here illustratively an 80% reduction in emissions from 2024). As you can see, no country has ever come remotely close to this implied rate of decarbonization.
Every day that passes means that implied rate ticks up, pushing the possibility of achieving net zero carbon dioxide emissions further into the future.
When might be a realistic date for reaching net zero, should the world actually take the goal seriously? We will explore this question also.
The table below looks at decarbonization rates from another perspective — It compares the 8 years before the Paris Agreement to the 8 years that followed. Such a comparison shows which countries may have accelerated their decarbonization after 2015. As you can see, there was no acceleration in global decarbonization in the 8 years following the Paris Agreement.
Whatever the Paris Agreement has achieved, accelerating the rate of global decarbonization is not among its consequences. Raise your hand if you had the UAE at the top of the table for leading the world in post-Paris acceleration of decarbonization! Expect more surprises as this series continues and we look carefully at data and some simple math.
I expect this series to be active here at THB for a while — There is a lot to cover!
Among the questions I plan on addressing:
What explains historical inflection points for specific countries in rates of decarbonization?
How do each of the elements of the Kaya identity (population, economy, energy intensity, carbon intensity) factor into prospects for accelerated decarbonization?
Why has decarbonization occurred in the background even before climate policy?
How fast can a country or the world actually decarbonize, in the real world versus in models?
Can we assess mitigation policy proposals and subsequent implementation based on plausible projected rates of decarbonization?
What would it take in terms of action in the real world to stay “on trend” into the future for the global rate of decarbonization? What might slow it down? Accelerate it?
What degree of climate change would be expected by staying “on trend”?
Let me know your questions to add to this list!
As part of the “classroom series,” I am also considering holding in-person “office hours” via a live stream, for paid subscribers to discuss the series and to ask questions. Let me know if this would be of interest. With a critical mass of interest, I’d be happy to add this to the syllabus.
Before you go — If you think that the idea of “classroom series” is a good innovation here at THB then please click that “❤️ Like” to let me know. As well, more likes mean that THB rises in the Substack algorithm and gets in front of more readers. Thanks!
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While I don’t agree that decreasing atmospheric CO2 is a good idea, I think we’d have a planet that supports more life at 1,000ppm, if decreasing CO2 (not carbon)is one’s objective, why not do
more of what works? More natural gas, nuclear and energy efficiency have led to the declines of CO2 emissions per unit of GDP.
For those who want to “decarbonize” why not do more of what has been proven to work?
It seems to me that the threshold question in any discussion of decarbonization is - to be blunt - "Why??" It's worth doing if and only if Al Gore and Michael Mann understand the realities of atmospheric physics around CO2 better than do the likes of Richard Lindzen and William Happer. If the latter are even half right, it's a further huge waste of resources that will have negligible effect on ambient temperatures going forward. And if we don't have the STEM chops to make up our minds about the physics, decarbonization puts the cart before the horse.
Happer and Lindzen, two authoritative voices who have been sidelined by means that Roger well understands, are fully qualified to have a professional opinion on the matter. They summarized their views in a 37-page comment submitted as part of the EPA's review of the Endangerment Finding. ( Download the pdf of the full comment here. ) Note the CV's at the end of the paper.
Roger's "Iron Law of Climate Policy" has a counterpart in an Iron Law of Climate Politics: In jurisdictions where the center-left has been able to put its climate policies into practice, nothing can change unless those responsible are allowed to pretend that they've accomplished something worthwhile for the climate. Exhibit A would be the Carney government in Canada, which is insisting on a massive Carbon Capture-and-Storage expenditure as its price for another pipeline that would allow Alberta to export more of its resources to Asia and the world.