Humanity just lived through the hottest 12 months in at least 125,000 years, report says

Month after month since June, the world has been abnormally hot. Scientists have compared this year's climate-change fallout to "a disaster movie" - soaring temperatures, fierce wildfires, powerful storms and devastating floods - and new data is now revealing just how exceptional the global heat has been.

Two major reports published this week paint an alarming picture of this unprecedented heat: Humanity has just lived through the hottest 12-month period in at least 125,000 years, according to one, while the other declared that 2023 is "virtually certain" to be the hottest year in recorded history, after five consecutive months of record-obliterating temperatures.

"We have become all too used to climate records falling like dominoes in recent years," David Reay, executive director of the Edinburgh Climate Change Institute at the University of Edinburgh, told CNN. "But 2023 is a whole different ball game in terms of the massive margin by which these records have been broken."

The period from November 2022 to the end of October 2023 was the hottest 12 months, with an average temperature of 1.32 degrees Celsius above pre-industrial levels, according to an analysis of international data, published Thursday by the nonprofit research group Climate Central.

El Niño - a natural ocean and weather pattern in the tropical Pacific - is just beginning to boost temperatures, the report found. The strong, long-term trend of global warming is primarily driven by the burning of planet-heating fossil fuels.

"The key is this is not normal. These are temperatures we should not be experiencing," Andrew Pershing, vice president for science at Climate Central, said on a call with reporters. "We are only experiencing them because we have put too much carbon dioxide onto the atmosphere."

The vast majority of humanity was affected by unusual heat over this 12-month period, researchers found, with 7.3 billion people - 90% of the global population - experiencing at least 10 days of high temperatures "with very strong climate fingerprints."

In India, 1.2 billion people - 86% of the population - experienced at least 30 days of high temperatures, made at least three times more likely by climate change. In the United States, that figure was 88 million people, or 26% of the population.

Some cities were particularly hard hit. In the US, these were concentrated in the South and Southwest. Houston experienced the longest extreme heat streak of any major city on Earth, according to the report, with 22 consecutive days of extreme heat between July and August.

Only two countries, Iceland and Lesotho, experienced temperatures that were cooler-than-average over this period, the report found.

Climate Central's findings come on the heels of another analysis, published Wednesday by the European Union's Copernicus Climate Change Service, which said that 2023 is "virtually certain" to be the hottest year on record.

The prediction follows the report's finding that last month was the hottest October on record by a significant margin, beating the previous record set in 2019 by 0.4 degrees Celsius. The month was 1.7 degrees Celsius warmer than the pre-industrial average.

"October 2023 has seen exceptional temperature anomalies, following on from four months of global temperature records being obliterated," Samantha Burgess, deputy director of Copernicus, said in a statement.

Every month since June has smashed monthly heat records and every month since July has been at least 1.5 degrees Celsius above pre-industrial levels. The year to-date is averaging 1.43 degrees Celsius above pre-industrial levels, according to Copernicus - perilously close to the internationally agreed ambition to limit global warming to 1.5 degrees Celsius.

While scientists are most concerned about long-term temperature trends, the past several months above that threshold have been an alarming taste of what the world can expect as global warming accelerates.

"The likely impacts of this extra heat are well understood," Hannah Cloke, a climate scientist and professor at the University of Reading in the UK, told CNN. "We are already seeing its impact in more violent storms, heavier rains and floods, and more intense, frequent and longer heatwaves, droughts and wildfires."

In addition to unprecedented land temperatures, ocean temperatures continued to soar. They have consistently been at record-high levels since the beginning of May, according to Copernicus, fueling an explosive development of hurricanes and tropical storms around the planet, including Hurricane Otis, which slammed into Southern Mexico last month.

Antarctic sea ice also remained at record-lows for the sixth consecutive month, according to the report.

"Laid out so starkly, the 2023 numbers on air temperatures, sea temperatures, sea ice and the rest look like something out of a disaster movie," Reay said.

While the statistics in these reports are big and alarming, it's what's behind them that's truly terrifying, said Friederike Otto, senior lecturer in climate science at the Grantham Institute, Imperial College London. "The fact that we're seeing this record hot year means record human suffering," she said in a statement.

Even as 2023 draws to a close, the extraordinary heat shows little sign of letting up.

China saw more than 12 monthly temperature records broken on Monday, with temperatures reaching 34 degrees Celsius (93 Fahrenheit) in some places. While in the US, multiple heat records have fallen this week, with parts of Texas reaching 93 degrees Fahrenheit on Wednesday, beating previous November records.

And records are predicted to continue to be broken next year. "El Niño is really going to bite next year and that's going to lead to even more warming as we head into 2024," Pershing said.

The unprecedented global heat adds extra urgency to the upcoming UN COP28 climate conference in Dubai this December, where countries will take stock of their progress towards meeting the Paris Climate Agreement goal of limiting global warming to 1.5 degrees.

Scientists are clear that this means stopping burning oil, gas and coal. But a report published by the UN on Wednesday found that governments are planning to produce more than double the amount of fossil fuels than the limit that would cap global heating at 1.5C degrees.

"The only thing more remarkable than the magnitude of these increases in global temperature and sea ice loss," Reay said, "is our continuing failure to put the world on track to meet the Paris climate goals."

CNN's Robert Shackelford, Sara Tonks and Brandon Miller contributed to this report

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