Hothouse Earth: planet dangerously close to climate tipping point

Published by Charline Fernandez on August 7, 2018August 7, 2018

August 7th, 2018

Scientists have warned that the planet is at risk of entering a Hothouse Earth scenario where large parts of the world become uninhabitable even if the Paris Agreement are met.

In 2015, the Paris Agreement was signed to maintain global average temperature well below 2°C above pre-industrial levels. The current average temperature is over one degree above pre-industrial levels and rises at 0.17 degree each decade.

A new study published yesterday in Proceedings of the National Academy of Sciences (PNAS) found that we are now at risk of crossing the 2°C “planetary tipping point”.

This could trigger the likes of events such as permafrost thaw or loss of Arctic summer sea ice that would see temperatures rise to four or five degrees above pre-industrial levels.

Sea-level would also be between 10 and 60 meters higher than today under Hothouse Earth condition, the study finds.

Global map of potential tipping cascades. Map: Stockholm Resilience Center.

These tipping points can lead to abrupt change, falling like a “row of dominoes” according to the report’s co-author and incoming co-director of the Potsdam Institute for Climate Impact Research, Johan Rockström, and are “impossible to stop”.

“Places on Earth will become uninhabitable if Hothouse Earth becomes the reality,” Mr Rockström said.

Speaking on RTE’s Morning Ireland show this morning, Joseph Curtin, a senior fellow for climate and energy policy at the Institute of International and European Affairs, explained that as sea-ice melts, the sea directly absorbs more of the sun’s energy, creating more warming.

“Even at two degrees, these tipping points would kick in and we could describe it as runaway warming. [The tipping points] could be triggers,” he said.

“It doesn’t really change the imperative that we need to manage the situation. We need to reduce greenhouse gas emissions dramatically as soon as we possibly can,” Mr Curtin added.

The study finds that reducing emissions is not the only solution to avoid a Hothouse Earth situation, and calls for increased policy for the likes of biodiversity conservation, carbon storage through forestry, as well as agricultural and soil management.

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