The dangers of climate change are mounting so rapidly that they could soon overwhelm the ability of both nature and humanity to adapt, creating a harrowing future in which floods, fires and famine displace millions, species disappear and the planet is irreversibly damaged, a major new scientific report has concluded.
The report released Monday by the Intergovernmental Panel on Climate Change, a body of experts convened by the United Nations, is the most detailed look yet at the threats posed by global warming. It concludes that nations aren’t doing nearly enough to protect cities, farms and coastlines from the hazards that climate change has already unleashed, such as record droughts and rising seas, let alone from the even greater disasters in store as the planet keeps heating up.
Written by 270 researchers from 67 countries, the report is “an atlas of human suffering and a damning indictment of failed climate leadership,” said António Guterres, the United Nations secretary general. “With fact upon fact, this report reveals how people and the planet are getting clobbered by climate change.”
In the coming decades, as global temperatures continue to rise, hundreds of millions of people could struggle against floods, deadly heat waves and water scarcity from severe drought, the report said. Mosquitoes carrying diseases like dengue and malaria will spread to new parts of the globe. Crop failures could become more widespread, putting families in places like Africa and Asia at far greater risk of hunger and malnutrition. People unable to adapt to the enormous environmental shifts will end up suffering unavoidable loss or fleeing their homes, creating dislocation on a global scale, the authors said.
To avert the most catastrophic impacts, nations need to quickly and sharply reduce emissions of carbon dioxide, methane and other greenhouse gases that are dangerously heating the planet, the report said.
Even so, the world’s poorest nations are increasingly struggling with climate shocks and will likely require hundreds of billions of dollars per year in financial support over the next few decades to protect themselves — support that wealthier nations have so far been slow to provide.
“This report is terrifying; there is no other way of saying it,” said Simon Stiell, the environment minister of the Caribbean nation of Grenada. “We need to see enhanced action and increased climate finance provision for adaptation. The scale of this crisis requires nothing less.”
Global temperatures have already increased by an average of 1.1 degrees Celsius, or 2 degrees Fahrenheit, since the 19th century, as humans have pumped heat-trapping gases into the atmosphere by burning coal, oil and gas for energy, and cutting down forests.
Many leaders, including President Biden, have vowed to limit total global warming to no more than 1.5 degrees Celsius compared with preindustrial levels. That’s the threshold beyond which scientists say the likelihood of catastrophic climate impacts increases significantly.
But achieving that goal would require nations to all but eliminate their fossil-fuel emissions by 2050, and most are far off-track. The world is currently on pace to warm somewhere between 2 degrees and 3 degrees Celsius this century, experts have estimated.
If average warming passes 1.5 degrees Celsius, even humanity’s best efforts to adapt could falter, the report warns. The cost of defending coastal communities against rising seas could exceed what many nations can afford. In some regions, including parts of North America, livestock and outdoor workers could face rising levels of heat stress that make farming increasingly difficult.
“Beyond 1.5, we’re not going to manage on a lot of fronts,” said Maarten van Aalst, the director of the Red Cross Red Crescent Climate Center and an author of the report. “If we don’t implement changes now in terms of how we deal with physical infrastructure, but also how we organize our societies, it’s going to be bad.”
Poor nations are far more exposed to climate risks than rich countries. Between 2010 and 2020, droughts, floods and storms killed 15 times as many people in highly vulnerable countries, including those in Africa and Asia, as in the wealthiest countries, the report said.
That disparity has fueled a contentious debate: what the industrialized nations most responsible for greenhouse gas emissions owe developing countries. Low-income nations want financial help, both to defend against future threats and to compensate for damages they can’t avoid. The issue will be a focus when governments meet for the next United Nations climate summit in Egypt in November.
In northern Kenya, where drought has been ravaging crops and pastures, “people are still dying by the day,” said Fatuma Hussein, a program manager with Power Shift Africa, a think tank. “They are not even able to provide food for their animals or themselves.”
Some herders are moving their livestock to wetter regions, Ms. Hussein said. But vulnerable countries will not manage without support from rich nations, she said.
In Central America, climate adaptation measures that are effective today may no longer be feasible in the years ahead, said Debora Ley, an energy specialist based in Guatemala who contributed to the report. Between rising seas, droughts, and mudslides worsened by deforestation, Dr. Ley worries that some communities in the region may face collapse. “You can live somewhere, but if you’re prone to floods for six months out of 12 in a year, then can you really consider that habitable?” she said.
The report, which was approved by 195 governments, makes clear that risks to humans and nature accelerate with every additional fraction of a degree of warming.
If global warming reaches 1.5 degrees Celsius, up to 8 percent of the world’s farmland could become unsuitable for growing food by the end of the century, the authors wrote. Coral reefs, which buffer coastlines against storms, will face more frequent bleaching from ocean heat waves and decline by 70 to 90 percent. The number of people around the world exposed to severe coastal flooding could increase by more than one-fifth without new protections.
At 2 degrees Celsius of warming, the amount of land globally burned by wildfires is expected to rise by more than one-third. Between 800 million and 3 billion people globally could face chronic water scarcity because of drought, including more than one-third of the population in southern Europe. Crop yields and fish harvests in many places could start declining.
At 3 degrees of warming, the risk of extreme weather events could increase fivefold by century’s end. Flooding from sea level rise and heavier rainstorms could cause four times as much economic damage worldwide as they do today. As many as 29 percent of known plant and animal species on land could face a high risk of extinction.
To date, many nations have been able to partly limit the damage by spending billions of dollars each year on adaptation measures like flood barriers, air-conditioning or early-warning systems for tropical cyclones.
Understand the Latest News on Climate Change
Struggling to adapt. The dangers of climate change are mounting so rapidly that they could soon overwhelm the ability of both nature and humanity to adapt unless greenhouse gas emissions are quickly reduced, according to a major U.N. report. Here are five takeaways from the report.
The biggest climate case in a decade. The U.S. Supreme Court will hear arguments in a dispute that could restrict or even eliminate the E.P.A.’s authority to control the pollution that is heating the planet. A decision by the court, with its conservative supermajority, could shred President Biden’s climate agenda.
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, as climate change further intensifies what the authors of the document described as a “global wildfire crisis.”
Melting away. Sea ice around Antarctica has reached a record low in four decades of observations, a new analysis of satellite images shows. While warmer ocean temperatures may have played a role, the precise effect of climate change on Antarctic sea ice remains unclear.
A megadrought and rising sea levels. An intense drought in the American Southwest has become so severe that it’s now the driest 22-year period in the region in 1,200 years. Scientists are also warning that coastal sea levels in the U.S. will rise by about a foot or more on average by 2050.
Over the past half-century, the number of deaths worldwide from storms, floods and other extreme weather events has fallen by more than half because of improved early warning systems and disaster management, the World Meteorological Organization has found. Investments in public health have meant fewer people are succumbing to diseases like cholera, even as rising temperatures and heavier rainfall have facilitated their spread.
But those efforts are too often “incremental,” the report said. Preparing for future threats, like dwindling freshwater supplies or irreversible ecosystem damage, will require “transformational” changes that involve rethinking how people build homes, grow food, produce energy and protect nature.
Some of the planet’s most vulnerable nations have been digging deep into their coffers to cope with climate threats. Ethiopia aims to spend $6 billion a year on a range of adaptation measures, which amounts to 5.6 percent of its annual economic output, according to government information compiled by Power Shift Africa. South Sudan, one of the world’s poorest countries, is preparing to spend $376 million a year until 2030 to address climate-fueled flooding.
A decade ago, wealthy nations pledged to deliver $100 billion per year to the developing world by 2020 to shift to cleaner sources of energy and adapt to climate change. But they have fallen short by tens of billions of dollars, with only a fraction of the funds spent on adaptation.
John Kerry, President Biden’s special envoy for climate change, acknowledged in an interview Monday that wealthy, heavily polluting nations were not doing enough.
“Every country needs to do more in terms of mitigation and they need to do more in terms of addressing both adaptation and resilience, no question about it,” he said.
At the same time, many communities are still acting in ways that increase their vulnerability, the report said. One reason flood risk is growing along the coasts, for instance, is that millions of people are moving to low-lying areas that are endangered by sea level rise. And some adaptation measures have unintended consequences. For example, sea walls protect certain places but can also redirect flooding into populated areas elsewhere. Irrigation can help protect crops against drought but can also deplete groundwater resources.
Instead, the report recommends that leaders pursue more farsighted strategies. As oceans rise, coastal communities could relocate inland while discouraging additional development along vulnerable shorelines. Improvements in basic services like health, roads, electricity and water could help make poor and rural communities more resilient against climate shocks.
“If we act now, we have a lot of choices,” said Edward R. Carr, a professor of international development at Clark University and an author of the report. “Ten years from now, hell of a lot of less. Thirty years from now, I don’t know.” He added, “We’ll always have choices. But they’ll be less good choices, and they’ll be much harder choices to make.”
Somini Sengupta contributed reporting.