Climate change is upon us and humanity is far from ready, the United Nations climate panel warned in a major report on Monday.

Noting that nearly half the world’s population was already vulnerable to increasingly dangerous climate impacts, the report calls for drastic action on a huge scale: A third to a half of the planet needs to be conserved and protected to ensure future food and fresh water supplies. Coastal cities need plans to keep people safe from storms and rising seas. And more.

“Adaptation saves lives,” UN Secretary-General Antonio Guterres said with the report’s release. “As climate impacts worsen – and they will – scaling up investments will be essential for survival... Delay means death.”

The report is the latest in a series by the Intergovernmental Panel on Climate Change (IPCC) detailing the latest global consensus on climate science. This report, however, focuses on how nature and societies are being affected and what they can do to adapt.

On nearly all counts, the report makes clear that climate change is impacting the world far faster than scientists had anticipated. Meanwhile, countries have failed to rein in planet-warming carbon emissions, which continue to rise.

“Unchecked carbon pollution is forcing the world’s most vulnerable on a frogmarch to destruction,” Guterres said in a video address Monday. “The facts are undeniable. This abdication of leadership is criminal.”

Mitigation

While governments need to drastically curb their emissions to prevent runaway global warming, they can also work to limit suffering by adapting to the conditions of a warmer world, the report says. That will take a lot of money - to finance new technologies and institutional support. Cities can invest in cooling areas to help people through heat waves. Coastal communities may need new infrastructure or to relocate altogether.

“In terms of transformational adaptation, we can plan it and implement it now, or it’ll be thrust upon us by climate change,” said Kristina Dahl, a climate expert at the Union of Concerned Scientists, who was not involved in writing the report.

But in some cases, the report acknowledges, the costs of adapting will be too high.

The report’s release three months after global leaders met at a climate summit in Glasgow, Scotland, highlighted the urgency of efforts to contain global warming to within 1.5 degrees Celsius (2.7 degrees Fahrenheit) of pre-industrial temperatures.

Breaching that threshold will deliver irreversible damage to the planet, it says. And every increment of warming will cause more pain.

“Adaptation is not a get-out-of-jail-free card. There are limits to adaptation,” said Maarten van Aalst, director of the Red Cross Red Crescent Climate Centre and a report co-author. “We should reduce greenhouse gas emissions because if we don’t, it’s going to get really bad.”

Limiting global warming to close to 1.5 degrees Celsius may not prevent losses to nature, societies or economies, but will substantially reduce them, the report says.

Having already warmed 1.1 degrees Celsius, the planet is expected to hit the 1.5 degrees Celsius threshold within two decades.

Social justice

Societies will fail to adjust well to a warming world if they aren’t socially inclusive in tackling the task, the report warns. Solutions need to consider social justice and include indigenous populations, minorities and the poor, it says.

“It’s the poor and most marginalized who are most vulnerable,” said Timon McPhearson, an urban ecologist at The New School in New York and one of the report’s 270 authors. That includes people living in developing countries in Africa, South Asia and small island nations, as well as marginalized communities in wealthy nations such as the United States.

Without inclusive economic development in Africa, for example, climate change is expected to push 40 million more people into extreme poverty by 2030. Providing social welfare or jobs that also protect the environment - for example uprooting invasive trees that deplete water supplies - can go a long way towards helping vulnerable populations, said report co-author Christopher Trisos, a climate risk researcher at the University of Cape Town.

But time is running out to make the society-wide transformations needed, the authors warn. The decisions society makes in the next decade will set the climate path to come.

“There is a brief and rapidly closing window to secure a liveable future on the planet,” said Hans-Otto Portner, co-chair of the IPCC working group that generated the report. “We need to live up to this challenge.”