New research has narrowed the predicted likely range of global warming for a given increase of CO2. Previously, a doubling of CO2 above pre-industrial levels would have been predicted to increase global surface temperatures by 1.5‐4.5°C, a measure of “climate sensitivity”. The new research, assessing available evidence, places climatic sensitivity within the middle or upper part of this range: 2.6‐4.1°C.
With lower climate sensitivity increasingly unlikely, attempts to build hopes upon it are even more untenable. The need to radically reduce net carbon emissions, as well as to mitigate the climate crises impacts, are more important than ever.
Indeed, 2020 is set to be the warmest or second-warmest year on record. And this is despite El Niño, a multi-year climatic cycle, not currently boosting global temperatures. As well as heatwaves, and dangers from Siberia, as covered last issue, this drove record-low levels of Arctic sea ice in July.
Earlier this year, scientists first observed warm water below the Thwaites glacier in Antarctica: simultaneously explaining its rapid decrease to date, and raising further warnings of Thwaites’ potential collapse. Thwaites is roughly the size of the UK and its ice melt already accounts for 4% of global sea-level rise. If it were to collapse into the sea, that would raise sea levels by almost two-thirds of a metre. Worse, Thwaites acts as a plug for other glaciers and icecaps. If these, too, were released, they could together raise sea levels by two to three metres.
Current sea-level rise of around 20cm already seriously increases coastal flooding. Rises on the scale of metres would hit many of the worlds most populous areas, and food-producing regions.
The political impact of the Covid-19 crisis presents opportunities for a remaking of society on a more socially just and environmentally sustainable basis, for a “green recovery”. Yet globally, and in the UK, we are currently seeing instead a “fossil-fuel reboot”. It is down to the workers’ movement, and to environmentalists working within the labour movement, to fight for and win the recovery we need.