Many of the impacts of global warming are now simply "irreversible" according to the UN's latest assessment. But the authors of a new report say that there is still a brief window of time to avoid the very worst.

 

 

The Intergovernmental Panel on Climate Change says that humans and nature are being pushed beyond their abilities to adapt. Over 40% of the world's population are "highly vulnerable" to climate, the sombre study finds. But there's hope that if the rise in temperatures is kept below 1.5C, it would reduce projected losses.

 

Just four months on from COP26, where world leaders committed themselves to rapid action on climate change, this new UN study shows the scale of their task.

 

The report is a stark account of the fierce consequences that the world is already experiencing, like growing numbers of people dying from heat.

 

But the authors say that there is still a brief window of time to avoid the very worst.

 

"One of the things that I think is really, really clear in the report is that yes, things are bad, but actually, the future depends on us, not the climate," said Dr Helen Adams, a lead author on the report from King's College, London.

 

The report shows that extreme weather events linked to climate change like floods and heatwaves are hitting humans and other species much harder than previous assessments indicated.

 

The new study says that these impacts are already going beyond the ability of many people to cope.

 

While everyone is affected, some are being hit much harder. This outcome very much depends on where you live.

 

Between 2010 and 2020, 15 times more people died from floods, droughts and storms in very vulnerable regions including parts of Africa, South Asia and Central and South America, than in other parts of the world.

 

Nature is already seeing dramatic impacts at the current level of warming.

 

Coral reefs are being bleached and dying from rising temperatures, while many trees are succumbing to drought.

 

The report highlights the increasing impacts that are expected as the rise in global temperatures, currently around 1.1C, heads to 1.5C.

 

Continued and accelerating sea level rise will increasingly hit coastal settlements pushing them towards "submergence and loss".

 

Under all emissions scenarios, the IPCC expects a billion more people to be at risk from coastal specific climate hazards in the next few decades.

 

If temperatures rise to between 1.7 and 1.8C above the 1850s level, then the report states that half the human population could be exposed to periods of life-threatening climatic conditions arising from heat and humidity.

 

Commenting on the summary, UN Secretary General Antonio Guterres described it as an "atlas of human suffering". He has no doubt as to where the blame lies.

 

"The facts are undeniable. This abdication of leadership is criminal. The world's biggest polluters are guilty of arson of our only home."

Health a growing concern

 

Diseases will likely spread more quickly in the coming decades, say the study's authors.

 

There is a particular risk that changing climactic conditions will ease the spread of mosquito-borne dengue fever to billions more by the end of this century.

 

As well as the physical health impacts, this report, for the first time, states that climate change may be exacerbating mental health issues, including stress and trauma related to extreme weather events and the loss of livelihoods and culture.

 

Warming threats to species

 

About half of the living organisms assessed in the report are already moving, to higher ground or towards the poles. While up to 14% of species assessed will likely face a very high risk of extinction if the world warms by 1.5C, this will rise to up to 29% of species at 3C of warming. For creatures living in areas that are classed as vulnerable biodiversity hotspots, their already very high extinction risk is expected to double as warming rises towards 2C, and to go up tenfold if the world goes to 3C.

 

Some researchers have speculated that going over 1.5C for a short period would be acceptable if temperatures came back down below the level soon afterwards.

 

This report says there are dangers with this approach.

 

"In any overshoot there's an increasing risk of hitting tipping points and triggering feedback, in the climate system, like permafrost thawing," said Linda Schneider from the Heinrich Boll Institute, who was an observer at the IPCC discussions.

 

"That would make it a lot more difficult, it could make it impossible to get back below 1.5C."

 

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