World Records Second-Hottest May in History

Last month was Earth’s second-warmest May on record – surpassed only by May 2024 – concluding the second-hottest spring (March-May) ever recorded in the northern hemisphere, the EU’s Copernicus Climate Change Service (C3S) announced in its monthly bulletin.

Global surface temperatures averaged 1.4 degrees Celsius higher than the pre-industrial period 1850-1900, when humans began burning fossil fuels on an industrial scale, according to C3S.

This triggered a period of exceptional heat during which 21 of the past 22 months saw global average temperatures 1.5C above pre-industrial levels – though scientists warned this period is unlikely to last.

“While this may offer the planet some respite, we expect the 1.5C threshold to be exceeded again in the near future because the climate system’s temperature continues to rise,” said C3S Director Carlo Buontempo.

Greenhouse gas emissions drive warming

The primary cause of climate change is greenhouse gas emissions from burning fossil fuels. Last year was the hottest ever recorded on the planet.

In a separate study published today by the World Weather Attribution team of climate scientists, human-caused climate change triggered record heatwaves in Iceland and Greenland last month, approximately 3C warmer than would otherwise have occurred, contributing to massive additional ice melting across Greenland.

From 15-21 May, ice melted 17 times faster than the historical average in Greenland, the World Weather Attribution team announced. In Iceland, temperatures exceeded 26C on 15 May, occurring for the first time on this island at the Arctic’s edge.

Iceland breaks temperature records

“Temperatures observed in May in Iceland break all records, exceeding by more than 13C the average of maximum daily temperatures for May during 1991-2020,” according to the WWA study.

During May, 94% of weather stations recorded new temperature records, according to the local meteorological institute.

In eastern Greenland, the warmest day had temperatures 3.9C higher compared to the pre-industrial era, WWA highlighted.

“A heatwave around 20C doesn’t seem like an extreme phenomenon for most people worldwide, but it’s truly a significant problem for this region… and this affects the entire world massively,” said Friederike Otto of Imperial College London, one of the study’s authors.

Arctic warming accelerates globally

The Arctic is warming four times faster than the rest of the world, according to the scientific journal Nature. “Even countries with cold climates are experiencing unprecedented temperatures,” said Sarah Kew, a study co-author and researcher at the Royal Netherlands Meteorological Institute.

The massive ice loss in Greenland has global implications for sea level rise, with the island’s ice sheet containing enough water to raise global sea levels by approximately 7 metres if completely melted.

Climate scientists emphasise that whilst individual months may occasionally fall below the 1.5C threshold, the long-term warming trend continues unabated due to ongoing greenhouse gas emissions.

C3S records begin in 1940 and are compared with global temperature records dating from 1850, providing comprehensive data on climate trends spanning more than 175 years.