Earth risks heading towards irreversible 'hothouse' state

Researchers suggest the tipping point could come once the Earth warms to 2 degree Celsius 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.

Doomed!Even if humans stopped emitting greenhouse gases, the current warming trend could trigger other Earth system processes, called feedbacks, driving even more warming.Photo: AFPOLIVER BERG

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 on Monday.

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 Celsius (7-9 Fahrenheit) higher than pre-industrial times, and sea levels that are 10 to 60 meters (30-200 feet) higher than today,” cautioned scientists in the Proceedings of the National Academy of Sciences. And that “could be only decades ahead,” they said.

Yet even if humans stopped emitting greenhouse gases, the current warming trend could trigger other Earth system processes, called feedbacks, driving even more warming.

These include permafrost thaw, deforestation, loss of northern hemisphere snow cover, sea ice and polar ice sheets.

Researchers say it's not certain that the Earth can remain stable.

“What we do not know yet is whether the climate system can be safely 'parked' near 2 C above preindustrial levels, as the Paris Agreement envisages,” said Schellnhuber. AFP

How they calculated this

The “Perspective” article is based on previously published studies on tipping points for the Earth. The scientists also examined conditions the Earth has seen in the distant past, such as the Pliocene period five million years ago, when CO2 was at 400 ppm like today.

During the Cretaceous period, the era of the dinosaurs some 100 million years ago, CO2 levels were even higher at 1,000 ppm, largely due to volcanic activity. AFP

How to stop it

• Change your lifestyle to be better stewards of the Earth.

• Fossil fuels must be replaced with low or zero emissions energy sources.

• There should be more strategies for absorbing carbon emissions such as ending deforestation and planting trees to absorb carbon dioxide.

• Soil management, better farming practices, land and coastal conservation and carbon capture technologies are also on the list of actions.