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The effects of climate change are worse than we thought, an unflinching new UN report finds

Trees scorched by the Caldor Fire smoldered in the Eldorado National Forest, Calif. on Sept. 3, 2021.Jae C. Hong/Associated Press

Climate change is changing our world more quickly than anticipated, and its effects are even more widespread and horrific than previously thought, according to an urgent new report from the world’s top climate scientists.

Extreme heat, sea-level rise, and disasters like storms and wildfires are threatening people and ecosystems, the analysis from the United Nations’ Intergovernmental Panel on Climate Change shows, and they’re leading to cascading consequences like food and water insecurity and increased disease.

“I have seen many scientific reports in my time, but nothing like this,” UN Secretary-General António Guterres said in a statement.

The report, released Monday, shows that no corner of the Earth is safe from the climate crisis. Yet the effects are not evenly distributed: Poor and vulnerable people face the greatest risks.


If the world is to minimize irreversible effects, we must make unparalleled changes to every aspect of society. We can avert global catastrophe, but only if we move at full tilt.

The report was compiled by 270 scientists from 67 countries who reviewed thousands of studies. Unlike a previous analysis released by UN climate scientists in August, the new report focuses not on the physical science of climate change, but on how climate change is affecting our world. It’s the first report of its kind since 2014.

Here are four major takeaways.

A man rode his bike along a flooded Sausalito/Mill Valley bike path during the "King Tide" in Mill Valley, Calif.JOSH EDELSON/AFP via Getty Images

It’s worse than we expected

The authors state unequivocally that climate change is already disrupting nature and society.

Many impacts, including the increased severity of wildfires and heat waves and the rate of ice sheets melting, are on the high end of what scientists forecasted under our current level of warming.

“That high end happens to be pretty daunting,” said Edward R. Carr, director of Clark University’s Department of International Development, Community, and Environment, who co-authored the report.

These shifts are unleashing cascading effects, according to the report. Due to changes in cycles of evaporation and precipitation worldwide, it said, roughly half of the world’s population is already experiencing severe water shortages at some point during the year. Warmer and wetter conditions are making diseases like dengue and lyme more transmissible. And in some regions, high air temperatures are threatening people’s ability to work outside, which puts entire economic sectors at risk.


Climatic changes have contributed to the loss of hundreds of animal populations and have even driven some species to extinction. Approximately half of all Earth’s species have changed where they live, moving toward the poles or to higher elevation, the report said. Biodiversity loss, it notes, threatens humans, since we depend on plants and animals for food, insects to pollinate our crops, and plants to protect us from flooding.

Earth is also losing its ability to cope with greenhouse gas emissions. The Amazon rainforest — a crucial source of carbon sequestration — may already be producing more carbon than it’s sucking up. The same goes for permafrost in northern North America and northern Siberia.

All regions are affected, including New England. The report said southern New England has lost 78 percent of its lobster population and found that winter sports like skiing are becoming unviable.

Giant tabular icebergs are surrounded by ice floe drift in Vincennes Bay in the Australian Antarctic Territory. Australia's CSIRO's atmospheric research unit has found the world is warming faster than predicted by the United Nations' top climate change body, with harmful emissions exceeding worst-case estimates. (Photo by Torsten Blackwood - Pool/Getty Images) Photographer: Pool/Getty Images AsiaPacTorsten Blackwood/pool/file

More warming will make things worse

Without massive efforts to curb emissions and adapt to the changing world, things will get much worse. Weather events and temperatures that are outliers today will become commonplace, and much of life on the planet will face mortal risk, the report said.


If the world warms by 1.5 degrees Celsius by the end of the century, the world will experience four times more extreme weather events by the century’s end than it did in 2020, the report said. If the world warms by twice that much, the increase will be five-fold.

The report forecasted the long-term impact under several warming scenarios. If the world warms by 2 degrees by 2100, it said up to 3 billion people will experience chronic water scarcity due to droughts. If the world warms by 4 degrees, that number rises to 4 billion people, and that’s not even considering population growth.

Under 2 degrees of warming, by 2100, up to 18 percent of all species on land will be at high risk of extinction. Under 4 degrees, of warming, half of all known species will face that threat.

Survivors washed salvaged clothes in a makeshift tent put up where their home used to be before it was flattened by Super Typhoon Rai, in Loboc, Bohol province, the Philippines.EZRA ACAYAN/NYT

Poorer communities bear the brunt

Climate change is affecting all parts of the Earth, but not evenly. Poor people, especially in the global south, face far graver threats, the report said.

“There’s more focus on justice than in previous reports,” said Shyla Raghav, vice president of climate strategy at Conservation International. “That some people are more impacted is not even a question.”

From 2010 to 2020, for instance, the mortal threat some people in small island countries, sub-Saharan Africa, and south Asia faced from floods, droughts and storms was 15 times higher than that faced by the world’s least vulnerable.

Many places that face the greatest dangers also have the fewest resources available to respond. For the first time, the UN body called out colonialism as a cause of this imbalance.


“Inequality and marginalization anywhere leads to horrific impacts from climate events,” Erin Coughlan de Perez, a climate scientist at Tufts University and report co-author, said.

This inequality is seen not only between regions but also within them, the assessment said. In the US, poor neighborhoods of color are often most vulnerable to extreme heat because they tend to have more abundant asphalt, buildings, and highways, all of which absorb and radiate heat.

“It’s a catastrophic harmony,” Robert Johnston, director of the George Perkins Marsh Institute at Clark University, who did not work on the report, said of the intersecting challenges.

We need transformative solutions immediately

The dire assessment says the growth in climate damages is far outpacing our efforts to adapt to them.

“We are used to coping strategies,” Giacomo Fedele, an adaptation-focused climate scientist at Conservation International who participated in the peer review of the report, said. “Those won’t work.”

Just as we can’t mitigate global warming by changing a few light bulbs, we can’t adapt to it by making a few tweaks. We need transformative solutions.

For instance, in some regions, people are planting crops a few weeks earlier to account for the shift in rainy season. Solutions like this won’t suffice in the long term, the report said. Instead, some regions may need to consider completely reshaping their agricultural practices to prioritize crops that don’t need much water to grow.


Leaders will also have to consider much larger changes to cope with sea rise and erosion, the report said. noting that adaptation efforts must be paired with radical action to cut carbon pollution.

“The more we emit, the more we’ll have to adapt. The less we adapt, the more suffering there will be,” said Raghav.

Helpfully, some strategies aid both adaptation and mitigation. Restoring wetlands and marshes can help sequester carbon emissions and also protect people from floods.

Radically changing society to adapt to climate change may be daunting, but it’s our only option.

“We can either transform our actions or face the transformations done to us by the changing world,” said Carr.

Dharna Noor can be reached at Follow her on Twitter @dharnanoor.