Just published, my new article on #mitigationdeterrence from #carbonremoval (in #ClimaticChange ) link.springer.com/article/10.100…
What is this about, and why do I think it important?
A thread 1/15
What is this about, and why do I think it important?
A thread 1/15
Most climate scientists are so concerned about the risks of climate change that they typically support 'all of the above' ... in other words, behaviour change, energy efficiency, decarbonization, low-carbon technology and carbon removal (not unreasonable on the face of it) 2/15
Our previous work in @NatureClimate rdcu.be/b3FEB shows that such responses are not simply additive, and while some may interact positively, galvanising more action, others - especially promises of future technological solutions - tend to undermine emissions cuts 3/15
If that undermining effect - which we call #mitigationdeterrence - were marginal in scale, it might be a reasonable price to pay for increasing our armory with new weapons (such as Direct Air Capture or Enhanced Weathering). 4/15
Even so, we should still want to look for tools to minimise any undermining effect, and if the effect might be large, we might also wish to consider not pursuing certain options if they seem particularly vulnerable to #mitigationdeterrence. So its scale is important 5/15
This article is a first effort to quantify the risk of #mitigationdeterrence, exploring plausible worst case scenarios, so we can make those judgements. 6/15
How can one quantify such a problem? I do it by estimating the 'carbon at risk' in IPCC SR1.5 pathways. I identify three possible types of #mitigationdeterrence that could contribute. 7/15
First I examine how much carbon removal is a substitute for otherwise anticipated emissions reduction. It turns out that about 70% of promised carbon removal is a substitute, and only about 30% increases overall abatement. 8/15
So if carbon removal fails for some reason, overall abatement falls. There is so much carbon removal in the average 1.5degC pathways, that this effect alone could lead to 50-229 Gt-C additional emissions by 2100. 9/15
That doesn't take account of any side-effects or rebounds from carbon removal, such as indirect land-use change (which might occur even if the carbon removal project failed). Such effects might add 34-135 Gt-C to unabated emissions by 2100. 10/15
Finally I consider how much of remaining emissions cuts in the pathways costs more than the promised carbon removal, on the basis that there will be an incentive to keep emitting in the hope that even more carbon removal capacity will become feasible (another 182-297 Gt-C) 11/15
The point is not to argue against the development of carbon removal, but to note that the risk of even scientifically valid projections can be counterproductive, unless we take action to mitigate these effects 12/15
In the worst case, the total carbon at risk is 371-545 Gt-C - substantially more than the carbon removal itself is projected to remove, and (depending on climate sensitivity), adding up to 1.4degC additional warming 13/15
So to ensure pursuit of carbon removal is helpful and additional, rather than risking further undermining and delay to climate action we need to acknowledge this problem link.springer.com/article/10.100… and seek tools to minimise it frontiersin.org/articles/10.33… 14/15
Thanks to the Research Councils for funding this work, and to my colleagues at Lancaster including Andy Jarvis, @NilsMarkusson @szerszynski @Bankfieldbecky and @DTyfield 15/15
