This Year Is ‘Virtually Certain’ to Be Hottest in Human History, Researchers Say

This year is “virtually certain” to be the hottest year in recorded history, the World Meteorological Organization announced on Thursday at COP28, the United Nations climate summit in Dubai where delegates from nearly 200 countries, including many heads of state and government, have gathered.

The organization said 2023 has been about 1.4 degrees Celsius, or about 2.5 degrees Fahrenheit, above the global average preindustrial temperature from 1850 to 1990. The past nine years have been the warmest nine in 174 years of recorded scientific observations, with the previous single-year records set in 2020 and 2016. This comes in addition to record greenhouse gas concentrations, sea levels and concentrations of methane.

“It’s a deafening cacophony of broken records,” Petteri Taalas, the secretary general of the World Meteorological Organization, said in Dubai.

Although data for the end of the year is still to come, the organization issued a draft of its State of the Global Climate report early in order to inform the talks in Dubai, where diplomats and leaders are trying to negotiate plans to accelerate the global transition away from the fossil fuels that are dangerously heating Earth.

Mr. Taalas said he hoped the report would signal to negotiators in Dubai the urgent need to hash out an ambitious deal to mitigate climate change. “We are not at all going in the right direction,” he said later in an interview. “We are going in the wrong direction.”

The provisional findings were in line with what scientists had predicted, with month after month in 2023 breaking global average temperature records.

By emphasizing the changes the planet is already undergoing, the scientific community wants to make sure leaders at COP28 understand the urgency of climate change and the weight of their decisions, said Brenda Ekwurzel, director of climate science for the Union of Concerned Scientists. Dr. Ekwurzel was not involved in the World Meteorological Organization’s report, but contributed to a similar report in the United States.

“The decision makers within the international negotiations are in the driver’s seat of future climate change,” she said.

The Northern Hemisphere summer was disastrously hot for much of the world’s population, with July coming in as Earth’s hottest month on human record. Scientists found that extreme temperatures in North America and in Europe would have been “virtually impossible” without the influence of climate change from the burning of fossil fuels.

The true cost in lives and economic losses won’t be clear for some time. But research examining past years reveal the steep price of global warming in general. More than 61,000 people are estimated to have died in Europe alone because of heat waves in 2022. In Africa, climate change has led to more hunger, malaria, dengue fever and flooding, Mr. Taalas said.

More intense, concentrated bursts of rainfall are one effect of climate change. In September, a powerful storm dumped torrential rain over the Mediterranean, rupturing two dams in Libya and killing thousands in the city of Derna. Earlier in the year, the exceptionally long-lived Tropical Cyclone Freddy hit southern Africa, forming in early February and making final landfall in Mozambique and Malawi in mid-March. The storm killed more than 600 and displaced more than 600,000 in Malawi.

Another intense storm, Tropical Cyclone Mocha, hit Southeast Asia in May. The cyclone displaced more than 1 million people, including many Rohingya refugees who had already been displaced once from Myanmar and were living in the world’s largest refugee camp, Cox’s Bazar, in Bangladesh.

In less dire circumstances, high temperatures prevent people from working as many hours as they would normally. One study estimated that, in 2021, the United States agriculture, construction, manufacturing and service sectors lost more than 2.5 billion labor hours to heat exposure. A separate assessment found that, in 2020, productivity losses from extreme heat cost the American economy about $100 billion.

Those figures don’t account for what’s lost to other climate-related disasters. This year’s record-breaking heat contributed to a rash of wildfires around the world, particularly in Canada, where more than 45 million acres burned and hundreds of thousands evacuated their homes in the country’s worst recorded fire year by far. Smoke from the long-lasting fires affected millions more in cities far away.

Nature has also paid a price, particularly in the ocean, which has absorbed 90 percent of global warming so far. Sea surface temperatures reached new heights this year, especially in the Atlantic. In July, a buoy off the coast of Florida recorded a temperature of 101 degrees Fahrenheit. Coral reefs in the region suffered mass bleaching.

“Record global heating should send shivers down the spines of world leaders,” the United Nations secretary general, António Guterres, said Thursday in a video message to the conference in Dubai. “Today’s report shows we’re in deep trouble. Leaders must get us out of it, starting at COP28.”