Last month broke records as the hottest June in observed history, marking the first-ever 12-month period where Earth’s average temperature surpassed 1.5 degrees Celsius above the pre-industrial baseline, according to the Copernicus Climate Change Service.
“This is more than a statistical oddity and it highlights a large and continuing shift in our climate,” said Carlo Buontempo, director of the Copernicus Climate Change Service. The report indicated that over the past year, the planet’s average temperature was 1.64 degrees Celsius above the 1850-1900 reference period.
Despite current anomalies, Buontempo added, “more records will be broken … This is inevitable unless we stop adding [greenhouse gases] into the atmosphere and the oceans.”
Other global temperature datasets concur with this 12-month streak, though some await finalization. “Global heating is continuing apace,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies in New York, noting that differences of a few tenths of a degree shouldn’t distract from the overall trend.
The 1850-1900 period is used as the reference for pre-industrial conditions, as it marks when direct temperature measurements became routinely available, explained Julien Nicolas, a senior climate scientist with Copernicus. Under the 2015 Paris Agreement, 196 countries pledged to limit warming to well below 2 degrees Celsius, pursuing efforts to prevent it from exceeding 1.5 degrees Celsius above that baseline.
Nicolas emphasized, “The 1.5 and 2 degree limits set in the Paris Agreement are targets for the average temperature over a twenty or thirty-year period.”
Since the Paris accord, Earth’s average monthly temperature first exceeded the 1.5-degree threshold in January 2016, staying above it through March of that year. The three months with the highest anomalies were November 2023 at 1.74C, February 2024 at 1.77C, and December 2023 at 1.78C.
Despite these spikes, Schmidt noted that the milestone isn’t as significant due to uncertainties about the exact pre-industrial baseline temperature. “The exact point at which we first cross 1.5 degrees Celsius may be exciting, but it’s not very important nor does it have much climate significance,” he said.
Former NASA climate scientist James Hansen suggested that mainstream climate institutions like the IPCC may be lagging behind in acknowledging the warming rate. “If IPCC doodles for another 10 years before it admits that we have reached more than 1.5 degrees of warming, we will be far above that level by that time,” he warned. Hansen noted that the rate of warming has accelerated to 0.32 degrees Celsius per decade since 2010.
The recent El Niño played a role in the rapid temperature increase, though Hansen argued it’s too large to be driven solely by El Niño. His research suggests a reduction in industrial aerosol pollution, which reflects solar radiation, contributed to recent temperature records.
Climate scientist Michael Mann from the University of Pennsylvania noted that the global average sea surface temperature recently dropped, indicating a temporary slowdown of warming as we head into La Niña. “What will remain is the steady long-term warming that will continue as long as human-generated carbon emissions continue,” Mann said.
Kevin Trenberth, a climate scientist in New Zealand, said the 12-month streak with temperatures more than 1.5 degrees Celsius above the pre-industrial level is “not meaningful for science but it is meaningful societally and because of the Paris Agreement. It’s not unexpected and it will get worse.”
World Meteorological Organization Secretary-General Celeste Saulo highlighted that the frequency of exceeding the 1.5-degree level on a monthly basis is increasing, as seen in the latest Copernicus report.
Original Story at insideclimatenews.org