Originally published at Skeptical Science on November 26th, 2015
The first part of this three-part series looked at the staggering magnitude and the daunting deployment timescale available for the fossil fuel and bioenergy carbon capture and storage technologies that many 2°C mitigation scenarios assume. In this second part, I outline Kevin Anderson’s argument that climate experts are failing to acknowledge the near-impossibility of avoiding dangerous climate change under current assumptions of the political and economic status quo, combined with unrealistic expectations of untested negative-emissions technologies.
In plain language, the complete set of 400 IPCC scenarios for a 50% or better chance of meeting the 2 °C target work on the basis of either an ability to change the past, or the successful and large-scale uptake of negative-emission technologies. A significant proportion of the scenarios are dependent on both. (Kevin Anderson)
Kevin Anderson has just written a provocative article titled: Duality in climate science, published in Nature Geoscience (open access text available here). He contrasts the up-beat pronouncements in the run-up to the Paris climate conference in December 2015 (e.g. “warming to less than 2°C” is “economically feasible” and “cost effective”; “global economic growth would not be strongly affected”) with what he see as the reality that meeting the2°C target cannot be reconciled with continued economic growth in rich societies at the same time as the rapid development of poor societies. He concludes that: “the carbon budgets associated with a 2 °C threshold demand profound and immediate changes to the consumption and production of energy”.
His argument runs as follows: Integrated Assessment Models, which attempt to bring together, physics, economics and policy, rely on highly optimistic assumptions specifically:
o Unrealistic early peaks in global emissions;
o Massive deployment of negative-emissions technologies.
He notes that of the 400 scenarios that have a 50% or better chance of meeting the 2 °C target, 344 of them assume the large-scale uptake of negative emissions technologies and, in the 56 scenarios that do not, global emissions peak around 2010, which, as he notes, is contrary to the historical data.
I covered the problems of the scalability and timing of carbon capture and storage and negative emissions technologies in a previous article.
From Robbie Andrew, adjusted for non-CO2 and land-use emissions.Note that thesemitigation curves assume no net-negative emissions technologies deployed in the latter part of the century.