GLOBAL GREENHOUSE gas emissions in 2017 were 32,500Mte (million tonnes). Britain’s were 375Mte and Scotland’s about 10 per cent of these. Thus Scotland contributes about 0.113 per cent of the global total. What is this likely to mean in terms of a contribution to increased global temperatures, and so how much could Scotland’s ‘decarbonisation’ contribute to climate change amelioration?
The UN climate model which predicts end of century temperature rises of up to 4°C has in practice been found to be rather poor when its short term predictions are tested against observed changes. Danish statistician and environmentalist Bjørn Lomborg has used it, not to predict absolute temperature changes, but relative changes resulting only from changes in carbon dioxide emissions. These should be more reliable as this effect is believed to be better understood than many other factors such as cloud cover.
Specifically, Lomborg has used the model to estimate the impact of having all the signatories to the much-vaunted Paris climate agreement fulfil their (non-binding) commitments by 2030 and continue to honour them until the end of the century. The model predicts that the reduction in whatever temperature rise would otherwise have occurred would be a mere 0.17°C.
The impact of all the EU commitments, including Britain’s, would be 0.053°C. Britain’s share of EU emissions in 2017 was 11.2 per cent, so it seems reasonable to pro rata this temperature reduction, making our national contribution to saving the planet 0.00594°C. The UK commitment is to an 80 per cent reduction in emissions so if 100 per cent reduction were possible this would increase the amelioration to 0.00742°C.
So what of Scotland? Since our emissions are about 10 per cent of the UK’s, we are responsible for around 0.000742°C of whatever temperature rise may occur by the end of the century. This is the amount by which complete elimination of all our greenhouse gas emissions from all sources could reduce the postulated increase in global temperature. It is also an amount which is so small as to be literally unmeasurable.
Jack Ponton, FREng
Picture: Charles Harris