Thread by @Duncan_BBR

I really wish the ubiquitous GHG #decoupling charts were better news than they are (as it would make things much easier) but unfortunately they fall foul of the 'fallacy of composition' and are fostering a dangerous complacency about climate change efforts. 🧵

TL/DR: decoupling charts show some countries are now reducing emissions while still growing GDP, but the climate challenge is to reduce absolute global emissions to near zero before it is too late. The former does not at all guarantee the latter.

In the difficult debate about whether economic growth is the solution or problem for climate change, people often seek reassurance that 'growth is the solution' by citing the 'decoupling' of GHG emissions from GDP growth already underway in some countries, of this basic form:

For example, this frequently posted FT chart shows that GHG emissions are now going down while GDP goes up… in 28 countries representing 29% of global emissions and 16% of global population.

Equally, this chart tells a similar story for 25 countries representing 24% of global emissions and 12% of global population. Encouragingly, a footnote says 'there are more than these 25 countries…' True, but they still only represent a minority of population and emissions.

(NB. I appreciate very much OWID's work and skill in making data so accessible, my issue is with their interpretation of piecemeal decoupling evidence.)

The point in all this is *not* that decoupling is directionally unhelpful. It is obviously better that emissions decouple rather than continue to rise with GDP. However there are 2 major problems and one technical problem.

(The technical problem - to deal with first - is to be careful to use 'consumption-based' data as, obviously, a country can seem to 'decouple' simply by offshoring the manufacturing emissions of its consumption. Helpfully, OWID offer adjustments and most people are now aware.)

The first major problem is that such charts fall foul of the 'fallacy of composition' - what may be true of some parts is not necessarily true of the whole. (The fallacy is an ever-present logical trap because *sometimes* what is true of some parts proves true of the whole.)

The chart designers are obviously trying to make a reassuring case that growth is sufficiently consistent with emissions reductions that there is no need to resort to growth-compromising actions, but they can only marshal evidence for a minority of emissions and population.

For a *global* climate change problem, the scope that matters is *global* emissions and total global emissions are continuing to rise.

The second major problem is that 'decoupling' charts mask the 'race against time' nature of the climate challenge. Are decouplings for the illustrated countries occurring fast enough that even if all countries were reducing at that rate, we would avoid key tipping points?

As crystallized by 'net zero' initiatives and Paris Agreement targets, the climate challenge is to avoid breaching key thresholds that may lead to irreversible changes, which requires a drastic downturn in absolute global emissions of this sort of pace and magnitude.

Put together, the leap the decoupling narrative makes is that evidence that some countries are reducing their emissions at a rate that may or may not be consistent with avoiding thresholds implies the whole world will reduce emissions adequately before it is too late.

If the cost of failing the experiment were not that high, it might be permissible to wait and see if jumping to this conclusion proved correct, but the stakes are very high indeed. For climate change, *we are the experiment*.

The harm of the decoupling narrative is it encourages a complacency that sustainability will not require us to do anything that might interrupt economic growth - so effective policies that happen to be growth-compromising (e.g. meaningful carbon prices) are deemed unnecessary.

Put another way, the decoupling narrative strengthens the hand of those arguing against climate mitigation policies because it creates an umbrella story that 'growth will save the day' so nothing need be done that might adversely affect profits and stock prices.

To concretely grasp the disconnect between the decoupling story and the physical basis of the climate change problem, let's take Krugman's tweet that suggests because UK emissions (1% of total) are decoupling there is no need to take 'degrowthers' seriously.

It will help to have a clearer version of Krugman’s chart (LHS, same data; longer forward timeframe). He is trying to reassure people that economic growth can be counted on to reduce emissions (turning down is good). I wish, too, but the chart needs 4 (!) modifications...

First, a small detail noted above is that a production-based picture of UK emissions (LHS) is slightly more flattering than a consumption-based view (RHS) which is arguably a truer measure of UK ‘responsibility’ (black arrow has not rolled over as much).

Second, as a global problem, climate change risk is determined by total global emissions (making redundant the production/consumption distinction and the per capita metric). The global emissions curve is still heading upwards (RHS):

Third, temperature is really the issue (for which emissions are long lead drivers). Per the Paris Agreement, the challenge is to avoid global temperature increases, so to glean the sense of looming risk we should really focus on temperature (RHS):

Fourth, the reason to avoid global temperature rise is because we are fast approaching climate ‘tipping points’, such as melting of ice sheets, which may be irreversible in nature and trigger runaway warming beyond remedy. Hence, we ought to keep tabs on where they are (RHS):

These 4 steps highlight the profound disconnect between economists' piecemeal, threshold-denying and time-abstracting optimism for decoupling and ecologists' concerns about climate change rooted in their attention to nonlinear biophysical dynamics.

Needless to say, these two different worldviews induce very different emotional responses… which is a key aspect of the sustainability challenge: it is increasingly more a psychological than a technical challenge (thread continues...)

The economic rationale that 'decoupling' will work fast enough in all cases stems from a theory known as the Environmental Kuznets Curve, which denies the possibility of thresholds *by assumption*! In contrast, ecologists and scientists acknowledge systems thresholds can exist.

Krugman is an Economics Nobel Prize winner - an award which progressively resembles a prize for Unsustainably Narrow Thinking given the discipline's ongoing failure to recognize the nonlinear biophysical foundations of the economy. The 'Ceteris Paribus' Prize, perhaps?

Mainstream economics continues to keep at arms' length - by dismissing as 'heterodox' - the insights of a now long line of its fellow 'ecological economists' - Boulding, Schumacher, Georgescu-Roegen, Costanza, Daly, Jackson, Raworth, Spash, Steinberger, etc. etc.

Yet, the conceptual superiority of ecological economics is that it explicitly recognizes the authority of the 2nd Law of Thermodynamics. Indeed, other scientists peering into economics from outside might view that economics has its orthodoxy and heterodoxy the wrong way around.

The disregard of biophysical dynamics by mainstream economics is coming to define - and stain - the whole field. Today's students increasingly aren't 'buying' traditional economic theories because those theories don't seem to correspond to the world they are growing up in.

Krugman and other prominent economists have the power to make a real difference on climate change by addressing and remedying the historical marginalization of ecological economics' insights. Effectively a 'truth and reconciliation' moment that could really shift minds.

In fact, leading economists ought to have a strong personal incentive to do this work because if the discipline of which they are visible stewards continues to downplay real world biophysical risks, it will likely keep drifting into disrepute with every rise in temperature.

The upshot of all this is that #decoupling is one way in which the deeply difficult reality of the climate crisis is being denied. If the first line of denial is to deny climate change as a phenomenon, the second line is to deny that responding to it need not interrupt growth.

None of this is easy but what is being lost while this debate runs is time. There are many more things that could be done if there was wider acceptance that economic growth and climate protection might actually be in tension and that interrupting growth is humanly possible. END

For higher resolution images, this thread is also posted as a blog here:

bothbrainsrequired.com/2023/05/25/get…