Tropics in trouble as rising heat, humidity push populations to the edge: study

Rising temperatures and humidity will make the world's tropics increasingly unliveable by pushing more people to the thresholds of their physical tolerance and beyond, a new international study finds.

A family cools off in a stream during a heat
wave last month in Islamabad, Pakistan. 

As of 2000, about 30 per cent of the world's population lived in regions where the climate exceeds deadly threshold levels – based on temperature and relatively humidity levels – for at least 20 days a year, researchers publishing in the Nature Climate Change journal estimate.

Even with the most optimistic scenario for greenhouse gas emissions reductions, that share will rise to about 48 per cent by the end of the century. If so-called business as usual emissions continue, that share would climb to 74 per cent by then, the paper found.

Read Peter Hannam’s story in The Sydney Morning Herald - “Tropics in trouble as rising heat, humidity push populations to the edge: study.”