Global Warming

Earth risks tipping into 'hothouse' state - study

The planet urgently needs to transition to a green economy because fossil fuel pollution risks pushing the Earth into a lasting and dangerous "hothouse" state, researchers warned.

If polar ice continues to melt, forests are slashed and greenhouse gases rise to new highs – as they currently do each year – the Earth will pass a tipping point.

Crossing that threshold "guarantees a climate 4-5°C higher than pre-industrial times, and sea levels that are 10-60m higher than today", cautioned scientists in the Proceedings of the National Academy of Sciences. And that "could be only decades ahead", they said.

"Hothouse Earth is likely to be uncontrollable and dangerous to many," said the article by scientists at University of Copenhagen, Australian National University and the Potsdam Institute for Climate Impact Research in Germany.

Rivers would flood, storms would wreak havoc on coastal communities, and coral reefs would be eliminated – all by century's end or even earlier. Global average temperatures would exceed those of any interglacial period – meaning warmer eras that come in between Ice Ages – of the past 1.2 million years. Melting polar ice caps would lead to dramatically higher sea levels, flooding coastal land that is home to hundreds of millions of people.

Researchers suggest the tipping point could come once the Earth warms to 2°C over pre-industrial times. The planet has already warmed 1°C over pre-industrial times, and is heating up at a rate of 0.17°C per decade.

"A 2°C warming could activate important tipping elements, raising the temperature further to activate other tipping elements in a domino-like cascade that could take the Earth System to even higher temperatures," said the report.