A body of experts convened by the United Nations has put out its most comprehensive look to date at how climate change is affecting our homes, health, livelihoods and infrastructure, as well as the natural systems upon which they all depend.

The picture is not cheerful. 195 governments approved a report showing how widespread and severe the impacts of human-caused global warming are, and how hard it will be for societies and ecosystems to manage if nations don't bring greenhouse gas emissions down sharply.

The I.P.C.C. report has complete coverage.

The report says that any further delay in concerted anticipatory global action will miss a brief and rapidly closing window of opportunity.

There are five main findings.

The last big survey of the impacts of climate change was put out by the Intergovernmental Panel on Climate Change. The report on the physical drivers of climate change was put out last year. There was limited evidence that nations needed more money to deal with the dangers than they were allocated. The panel said that global warming was having a relatively small effect on human health.

It is not the same eight years later.

Climate change is adding to ecological threats such as wildfires, heat waves and rising sea levels, and it is also endangering food and water supplies, according to a new report. It is harming people's physical and mental health, with increasing incidence of food and waterborne illness, respiratory distress from wildfire smoke and trauma from natural disasters. There is a funding shortfall for dealing with all this.

If global warming didn't go over 2 degrees Celsius, scientists thought the planet would be spared the most damaging effects of climate change.

It is clear that many of the harms will appear if the temperature goes past 1.5 degrees Celsius. We are at roughly 1.1 degrees. The report says that even if we cross 1.5 degrees, severe and irreversible damage could still occur.

The report says that the regions could suffer irreparably from past 1.5 degrees of warming. It is harder to arrest global warming if more carbon dioxide is released into the air.

The economic damage worldwide increases if temperatures continue rising beyond that, according to the report. More animal species are likely to go extinct. Billions of people would be at risk for the mosquito-borne disease by the end of the century, according to the report.

The report acknowledges some success in adjusting to the new dangers. It says that humanity's efforts have been fragmented and sometimes counter productive.

Flood risks are pushed down shore by societies building sea walls. Some of the fires that have been put out have ecological benefits.

The report says that changes are needed to safeguard human well-being, including stronger health and sanitation systems, more robust food supply chains, more resilient electricity grids and more forward-looking urban planning.

Icebergs that broke off of the melting Breidamerkurjokull glacier, seen in the distance, near Hof, Iceland.Credit...Sean Gallup/Getty Images

The report says that as global temperatures have risen, they are running up against limits to how much they can adjust.

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A world on fire. A United Nations report has concluded that the risk of devastating wildfires around the world could increase by up to 57 percent by the end of the century.

It is melting away. A new analysis of satellite images shows that the sea ice around Antarctica has reached a record low. Warming ocean temperatures may have played a role in the effect of climate change on sea ice.

The water supplies are being let down. Millions of people depend on glaciers for drinking water, crop irrigation and everyday use, and the world's glaciers may contain less water than previously thought.

According to the report, the costs of maintaining people's health, safety and well-being are prohibitive for some nations. Measures that are effective today for protecting water supplies, boosting agriculture and defending against climate-related harms will lose their effectiveness as warming continues. It is possible to develop new crop varieties that can be resistant to heat and dry weather.

The report suggests that communities try to work with nature rather than against it, and that increasing tree cover in cities to cool them is effective only to a point.

Developing countries have less resources to deal with climate shocks. Their infrastructure is often inadequate, their social safety nets are weak, and their people depend more on the natural world. Between 2010 and 2020, floods, droughts and storms killed 15 times as many people in developing nations as they did in the wealthiest countries, according to a report.

There are huge differences in exposure to these risks among different groups of people. Almost half of the world's population are highly vulnerable to climate change today, according to a report.