The Club PUBlication 11/13/2023

​Hottest year in the past 125,000
By SCOTT DANCE Washington Post

The Earth just endured its hottest 12 months in the modern era, and probably the hottest in 125,000 years, according to an analysis published Thursday.

That means nearly 3 in 4 people experienced more than a month's worth of heat so extreme that it would have been unusual in the past, but it became at least three times more likely because of human caused climate change, scientists at Climate Central found.

And it means that the planet is closer than ever to a global warming benchmark that scientists have predicted could irreversibly damage, if not destroy, entire ecosystems — 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, above preindustrial norms.

Data shows a surge of warming this year has pushed average planetary temperatures 1.3 to 1.4 degrees Celsius above 19thcentury levels.

In sharing the analysis, scientists professed hopes it would spur action and underscore its urgency as global leaders prepare to convene an annual United Nations climate change conference, COP 28, later this month.

"If we don't phase out fossil fuels now and stop burning them imminently, this will be a very cool year soon," said Friederike Otto, a senior lecturer in climate science at the Grantham Institute for Climate Change and the Environment at Imperial College London.

The Climate Central analysis looked at the influence of climate change on weather over the 12-month period from November 2022 through October 2023. The nonprofit climate science and news organization's leaders acknowledged they chose that period in light of the schedule for COP 28, which begins Nov. 30.

That meant the analysis included relatively cooler months in late 2022 and early 2023 as well as the dramatic surge in planetary heat observed during the past several months. July, August, September and October each brought record-high average global temperatures, all but guaranteeing that 2023 will be Earth's warmest calendar year on record.

Using what is known as attribution science, the analysis found that billions of people around the world have recently experienced extreme heat waves that likely would not have been as intense or as long-lasting if fossil fuel emissions had not warmed the planet so dramatically over the past century and a half.

It focused on temperatures so extreme that they are at least three times more likely today than they were before the Industrial Revolution.

During the past year, 9 in 10 people experienced at least 10 days of such heat, the analysis found. Nearly 3 in 4 people endured it for 30 days or more.

Scientists linked the warming climate to calamitous disasters around the world: hospitals overwhelmed with heat-related illnesses, thousands dead and millions displaced from floods, and 23 million without secure food supplies in Africa alone because of drought.

"The past year was quite extraordinary," said Joyce Kimutai, principal meteorologist at the Kenya Meteorological Department.

The analysis found that average temperatures during the past year have met or exceeded the 1.5-degree- Celsius warming threshold in nearly a dozen countries in Europe and northern Africa: Romania, Bulgaria, Bosnia, Moldova, Morocco, Switzerland, Austria, Hungary, Montenegro, Algeria and Ukraine.

That heat was most intense across Europe and Africa in recent months, with temperatures in both Switzerland and South Sudan averaging 2 degrees Celsius warmer than preindustrial levels from May through October.

As extreme as those hot spots may seem, the observations are in line with past global warming observations and projections, said Andrew Pershing, vice president for science at Climate Central.

"We should expect to set records because we live on a warming planet," he said.

"2023 is very consistent with that long-term trend."

Separate data that European scientists published Wednesday underscored how dramatically the warming trend has accelerated just in recent months.

The European Union's Copernicus Climate Change Service said that October brought record global warmth for a fourth consecutive month. Temperatures across the planet averaged 1.7 degrees Celsius above the norm for October during preindustrial decades, from 1850 to 1900.

And through the first 10 months of 2023, global temperatures are averaging 1.43 degrees Celsius above preindustrial levels, according to the Copernicus data. That is a tenth of a degree Celsius warmer than observed during the first 10 months of 2016, which holds the record as Earth's hottest ever measured.

And scientists said they don't expect the surge of warming to slow down.

When the planet surged to record warmth in 2016, it was on the tail end of an episode of El Nino, the global climate pattern known to release vast stores of Pacific Ocean heat into the atmosphere. Now, a strong El Nino is still building toward an expected peak this winter, meaning its influence could make for an even hotter 2024.

"El Ninoi going to push these temperatures higher," Pershing said. "We're going to continue to set these records as we move on into next year."

"If we don't phase out fossil fuels now ... this will be a very cool year soon."

Friederike Otto, senior lecturer in climate science at Imperial College London
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3 in 4 people experienced at least a month's worth of extreme heat in the past year.