The planet would warm by a searing 10°C if all fossil fuels are burned, according to a new study published in Nature Climate Change, leaving some regions uninhabitable and wreaking profound damage on human health, food supplies and the global economy.
The Arctic, already warming fast today, would heat up even more – 20°C by 2300 – the new research into the extreme scenario found.
“I think it is really important to know what would happen if we don’t take any action to mitigate climate change,” said Katarzyna Tokarska, at the University of Victoria in Canada and who led the new research.
If recent trends in global emissions continue, about two trillion tonnes will be emitted by the end of the century.
The new work considers the impact of emitting five trillion tonnes of carbon emissions. This is the lower-end estimate of burning all fossil fuels currently known about, though not including future finds or those made available by new extraction technologies.
The researchers used a series of sophisticated climate models and found this rise in CO2 would lead to surface temperatures rising by an average of 8°C across the world by 2300. When the effect of other greenhouse gases is added, the rise climbs to 10°C.
The heating predicted by the models was not uniform across the globe. In the Arctic, the higher CO2 levels led to 17°C of warming, with another 3°C from other greenhouse gases, across the year. These rises are higher than indicated by previous, less comprehensive models, which are less accurate at modelling how the oceans take up heat. In February, parts of the Arctic had already recorded temperatures 16°C above normal.
The warming caused by burning all fossil fuels would also have enormous impact on rainfall. The new research shows rainfall decreasing by two-thirds over parts of Central America and northern Africa and by half over parts of Australia, the Mediterranean, southern Africa and the Amazon.
Source: The Guardian, 23 May 2016