Climate change: is the planet reaching a ‘point of no return’?

2021 is a “make or break year” in the fight against climate change, the UN has warned as the UK gears up to host crucial climate talks.

Originally due to be held in Glasgow in November 2020, COP26 will bring together world leaders to co-ordinate action to stop the rise in global temperatures. However, goals set by the group have been repeatedly missed, with UN Secretary-General António Guterres describing 2019’s climate talks, COP25, as “a lost opportunity” to agree on tougher measures on climate action.

An interim report published by the UN in February described a “red alert from the planet”, adding that “governments are nowhere close to the level of ambition needed to limit climate change to 1.5 degrees and meet the goals of the Paris Agreement”.

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And that message was echoed in an article published in Nature last year, when a group of leading scientists warned that the Earth’s climate is closer to reaching crucial “tipping points” than was previously thought.

Ice collapse

Evidence shows that the Antarctic ice sheets are becoming increasingly unstable, and that the Greenland ice sheets could collapse entirely if global temperatures rise by 1.5C - which could happen as soon as 2030 if current trends persist.

Collapsing ice sheets leads to higher sea levels, one of the most dangerous consequences of climate change.

Sea level rises are already having “devastating effects”, forcing mass migration of people to higher ground and coinciding with dangerous hurricanes and typhoons, says National Geographic.

Key services such as internet access - which rely on infrastructure in the path of rising seas - may also be hit as a result.

Biosphere boundaries

Climate change threatens to trigger biosphere tipping points, some of the consequences of which are already being felt.

Ocean heatwaves have caused coral bleaching and the loss of half of the shallow-water corals on Australia’s Great Barrier Reef. And there would be “a profound loss of marine biodiversity and human livelihoods” if the global average temperature rises by 2C, according to the report published in Nature.

Deforestation and climate change also risks destabilising rainforests such as the Amazon. The scientists say that “estimates of where an Amazon tipping point could lie range from 40% deforestation to just 20% forest-cover loss”.

About 17% has already been lost since 1970.

Global cascade

The biggest risk is a “global cascade” of tipping points “that led to a new, less habitable, ‘hothouse’ climate state”, says report author Tim Lenton, director of the Global Systems Institute at the University of Exeter.

Evidence suggests that exceeding one tipping point can increase the risk of exceeding others, with such links found for 45% of possible interactions.

Arctic sea-ice loss is amplifying warming in the area, which contributes to an influx of fresh water in the North Atlantic. This in turn contributes to a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), a large system of ocean currents that distribute heat and energy around the world and determine the climate we feel all around the globe.

A further slowdown of the AMOC could destabilise the West African monsoon, triggering drought in Africa’s Sahel region. The phenomenon could also dry the Amazon, disrupt the East Asian monsoon, and cause a heat build-up in the Southern Ocean, which could further accelerate Antarctic ice loss.

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Is it too late?

The scientists behind the Nature article says that the evidence suggests the world is currently in a state of “planetary emergency”.

“We might already have lost control of whether tipping happens,” they write. “A saving grace is that the rate at which damage accumulates from tipping - and hence the risk posed - could still be under our control to some extent.”

“To be honest, I think we know enough climate science to act, yet we are not acting decisively, so we need to put resources into action,” report author Lenton told Vice.

After the talks in 2019’s COP25 conference, Guterres said he was “disappointed” with the results, adding: “The international community lost an important opportunity to show increased ambition on mitigation, adaptation and finance to tackle the climate crisis.”

Other critical voices said there was a “disconnect” between “what the science requires” and what had been delivered, with Alden Meyer, strategy chief at the Union of Concerned Scientists, warning that“most of the world’s biggest emitting countries are missing in action and resisting calls to raise their ambition”.