Climate change is causing widespread loss and damage to lives, livelihoods, homes and natural habitats – with more severe effects to come, the UN has said.
Already some of the impacts of global warming are irreversible, as nature and humans are pushed to the limits of their ability to adapt to rising temperatures, the Intergovernmental Panel on Climate Change (IPCC) said.
It has issued a “dire warning” over the grave and mounting threat global warming poses to physical and mental health, cities and coastal communities, food and water supplies, and wildlife across the world.
Any further delays to curb greenhouse gas emissions and adapt to already inevitable climate change mean humanity will miss a “brief and rapidly closing window” to secure a liveable and sustainable future, the report warns.
UN secretary-general Antonio Guterres described the report as “an atlas of human suffering and a damning indictment of failed climate leadership”, warning that nearly half of humanity is in the climate danger zone and many ecosystems are at the point of no return.
The assessment is the second in a series of three reports from the IPCC in the latest review of climate science, which take place every seven years or so for governments.
It has been released after its summary was approved line by line in a process involving representatives of 195 governments and scientists, which overran by a day as delegates continued to haggle over the text.
The report now published looks at the existing and future effects of climate change, efforts and limits to adapt to rising temperatures and vulnerable communities and natural systems.
It finds that climate change caused by humans has led to increasing heat and heatwaves, rising sea levels, floods, wildfires, heatwaves and drought, causing death, food and water scarcity, and migration.
Health impacts have been felt worldwide: people have died and suffered illness from extreme heat, diseases have emerged in new areas, there has been an increase in cholera, and worsening mental health, with trauma inflicted by floods, storms and loss of livelihoods.
Global warming has caused substantial damage and increasingly irreversible losses to natural systems, such as mass die-offs of corals and trees, and the first climate-driven species extinctions.
Different weather extremes are happening at the same time, causing “cascading” effects that are increasingly hard to manage.
The report also warns of the closeness of irreversible “tipping points” where melting of ice sheets in Antarctica, thawing of permanently frozen areas of the Arctic, or the loss of Amazon rainforest become unstoppable.
Some 3.3 billion to 3.6 billion people live in situations where they are highly vulnerable to climate change, the report warns.
The consequences of global warming, which has reached 1.1C above pre-industrial levels already, are not felt evenly around the world, with countries in sub-Saharan Africa and small island states among the most at risk.
But even in the UK and Europe people face coastal and inland flooding, heat extremes, damage to habitats, water scarcity and loss of crop production, as well as knock-on effects on food supplies and prices.
There will be “unavoidable increases” in climate hazards in the next two decades with global warming of 1.5C above pre-industrial levels, the bleak 35-page summary for policymakers says.
Letting temperatures climb above that, even temporarily, will lead to additional severe impacts, with the risks increasing more quickly at lower temperatures than previously thought.
Accelerating efforts to adapt to climate change – which are currently patchy and insufficient – is urgently needed.
But the report warns there are limits to how much people and nature can cope with, becoming more limited at 1.5C of warming, and impossible in some regions at 2C, making curbing emissions to limit temperature rises also crucial.
The report, which comes just over 100 days after world leaders agreed new efforts to limit warming and to deliver finance for adaptation at the Cop26 climate summit in Glasgow, calls for adequate funding to help those most at risk.
Safeguarding nature, including conserving 30%-50% of the world’s land, freshwater and sea habitat, will reduce carbon and climate impacts, as well as protecting wildlife and the natural systems people rely on for food and water.
The report sets out what can be done to adapt to rising temperatures, from restoring wetlands and avoiding building in flood plains, to planting more trees in cities for cooling, and nature-friendly farming and more plant-based diets to reduce pressure on land.
But it warns against “maladaptation” – efforts to adapt such as hard sea walls which can cause more problems – and geoengineering schemes that could cause a host of new risks.
Hans-Otto Portner, co-chairman of the team that produced the report, said: “The scientific evidence is unequivocal: climate change is a threat to human wellbeing and the health of the planet.
“Any further delay in concerted global action will miss a brief and rapidly closing window to secure a liveable future.”
IPCC chairman Hoesung Lee said: “This report is a dire warning about the consequences of inaction.
“It shows that climate change is a grave and mounting threat to our wellbeing and a healthy planet.”
And he said: “It emphasises the urgency of immediate and more ambitious action to address climate risks. Half measures are no longer an option.”