Cold comfort: climate may take decades to respond to carbon cuts.

Study on impact of Covid-19 lockdowns on temperature suggests next generation may benefit.

It seems logical that if we dramatically cut greenhouse gas emissions the global temperature will go down, but sadly this is not the case – at least for decades. The climate takes up to 25 years to react to changes in the composition of the atmosphere, up or down.

Scientists looking to see if they might detect something cheerful as a result of the drop in carbon dioxide or other emissions because of Covid-19, found that the temperature reductions were so small they would not be measurable.

Theoretically, it might have been possible to see the opposite, an increase in temperature because less sulphur dioxide was being pumped into the atmosphere from coal-fired power stations. This polluting gas reflects sunlight back into space and so cools the atmosphere, but the effect of a reduction was so slight in both cases any effects would have been lost in the natural variability of weather.

The message seems to be that if we continue business as usual atmospheric heating will soon reach dangerous levels. However, if we ever did manage to cut greenhouse gas emissions sufficiently, the temperature would become stable but we would not see reductions for a long time. We could perhaps take comfort from the fact that the next generation would benefit.

13 July 2020

The Guardian