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It's official: This summer was the hottest on record

By Rachel Koning Beals

'The dog days of summer are not just barking, they are biting,' United Nations Secretary-General Antonio Guterres says

The globe just experienced its hottest summer on record. That means searing temperatures not only put portions of the population at risk right now, but rising global sea temps chipped away at Antarctic ice to compound worrisome issues in the future, like warming oceans that fuel hurricanes, and eroding coastlines.

Persistent global warming from burning fossil fuels like coal and oil, along with the shorter-term impact from an early showing of an El Niño event, drove the thermometer higher from Texas to New York to Spain to China.

"The dog days of summer are not just barking, they are biting," United Nations Secretary-General Antonio Guterres said in a statement issued Wednesday. "Climate breakdown has begun."

August was about 1.5 degrees Celsius (2.7 degrees Fahrenheit) warmer than pre-industrial averages. The translated to a record string of days without a break below 90 degrees F for Phoenix and hot and humid conditions above 100 degrees F over many days in areas of Texas, as well as a couple of hot spells in the U.S. Northeast. Extreme heat impacts the youngest and oldest in the population, people who are pregnant, and those with asthma or other underlying health conditions. It also traps pollution closer to the ground, which can aggravate respiratory conditions.

The temperature data was issued Wednesday by the U.N.'s World Meteorological Organization. WMO leans on temperature recordings from the European Union-funded Copernicus Climate Change Service (C3S) and five other international datasets for its climate-monitoring activities and its periodic State of the Climate reports.

Copernicus, a division of the EU's space program, has records going back to 1940, but in the United Kingdom and the United States, global records go back to the mid-1800s and additional weather and science agencies are expected to soon report that the summer was a record-breaker.

The 1.5 C mark is also significant because it's the threshold that the world is trying not to pass as it embarks on climate-change policy, although scientists are more concerned about rises in temperatures over decades, not a few months' change.

Still, the year so far, from January through August, is the second warmest on record behind 2016, when there was also a powerful warming El Niño.

July was notably hot, bringing extreme heatwaves in several parts of the Northern Hemisphere, including the Southwest U.S. and Mexico, Southern Europe and China, where the all-China heat record was broken in Sanbao on July 16.

In Europe, the hottest ever day in Catalunya, Spain, was recorded and highest-ever records of daily minimum temperature were broken in other parts of the country. In the U.S. parts of Nevada, Colorado and New Mexico tied their all time high, while parts of Arizona and the Cayman Islands marked their highest ever night time temperatures.

Related:July 2023 is the hottest month ever recorded. Blame global warming and El Niño

"The northern hemisphere just had a summer of extremes -- with repeated heatwaves fueling devastating wildfires, harming health, disrupting daily lives and wreaking a lasting toll on the environment," said World Meteorological Organization Secretary-General Prof. Petteri Taalas.

But the rest of the globe had its own issues, with a far reach. Global sea surface temperatures are at unprecedented highs for the third consecutive month and Antarctic sea ice extent remains at a record low for the time of year, the report said.

It is warming ocean temps that are creating in part longer-lasting hurricanes that suck up warm water and dump it further inland, bringing flooding risk on top of the typical high wind damage that comes with tropical storms. Plus, it is rising ocean temps and rising levels of oceans that degrade coastlines vital to a diverse ecosystem and marked as desirable real estate.

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"In the southern hemisphere Antarctic sea ice extent was literally off the charts, and the global sea surface temperature was once again at a new record. It is worth noting that this is happening before we see the full warming impact of the El Niño event, which typically plays out in the second year after it develops," Taalas said.

Read:Hurricane Idalia: Florida storm is 2023's costliest U.S. disaster so far

August as a whole saw the highest global monthly average sea surface temperatures on record across all months, at 20.98 degrees Celsius Temperatures exceeded the previous record, set in March 2016, every single day in August.

Antarctic sea ice extent remained at a record low level for the time of year, with a monthly value 12% below average, by far the largest negative anomaly for August since satellite observations began in the late 1970s, the report said. Arctic sea ice extent was 10% below average, but well above the record minimum of August 2012.

The weather agencies are also trying to look ahead.

A report in May from WMO and the U.K.'s Met Office predicted that there is a 98% likelihood that at least one of the next five years will be the warmest on record and a 66% chance of temporarily exceeding 1.5 degrees C above the 1850-1900 average for at least one of the five years. This does not yet mean that we will permanently exceed the 1.5deg Celsius level specified in the Paris Agreement which refers to long-term warming over many years, but the repeat years for new high-temp marks worries scientists tracking climate change and its costs.

"What we are observing, not only new extremes, but the persistence of these record-breaking conditions, and the impacts these have on both people and planet, are a clear consequence of the warming of the climate system," said Carlo Buontempo, director of the Copernicus Climate Change Service.

Some observers argue it may be too late to soundly limit warming to 1.5 degrees C, but that efforts should be redoubled to keep the atmosphere from heating up much past that level.

Climatologist Andrew Weaver told the Associated Press that the numbers announced by WMO and Copernicus come as no surprise because major nations aren't showing enough alarm, even when temperatures like those this summer put the population on alert.

"It's time for global leaders to start telling the truth," said Weaver, a professor at the School of Earth and Ocean Sciences at the University of Victoria in Canada. "We will not limit warming to 1.5 C; we will not limit warming to 2.0 C. It's all hands on deck now to prevent 3.0 C global warming -- a level of warming that will wreak havoc worldwide."

The Associated Press contributed.

-Rachel Koning Beals

This content was created by MarketWatch, which is operated by Dow Jones & Co. MarketWatch is published independently from Dow Jones Newswires and The Wall Street Journal.


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09-09-23 1508ET

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