Heatwaves the new normal: WMO Secretary-General
WMO – Without human-caused climate change temperatures of 40 degrees Celsius in the United Kingdom would have been extremely unlikely, according to a rapid analysis from a group of internationally renowned scientists at World Weather Attribution.
“We have broken an all-time high in the UK”, said WMO Secretary-General Prof. Petteri Taalas. “Heatwaves will happen more frequently because of climate change. The connection has been clearly demonstrated by the Intergovernmental Panel on Climate Change.”
“In the future, this kind of heatwaves are going to be normal. We will see stronger extremes. We have pumped so much carbon dioxide in the atmosphere that the negative trend will continue for decades. We haven’t been able to reduce our emissions globally,” said Taalas. “I hope that this will be a wake-up call for governments and that it will have an impact on voting behaviors in democratic countries”, he said.
On July 18, the 40°C threshold was breached for the first time ever in the UK and breaking the previous maximum temperature record of 38.7°C set in 2019, according to the UK’s Met Office. Local records were broken in 46 stations across the country. Minimum temperatures were also extremely high with 25.8°C provisionally being recorded in Kenley in Surrey, breaking the previous record from 1990 by 1.9°C.
The unprecedented temperatures occurred during a widespread and long-lasting heatwave in Europe, accompanied by drought, wildfires and stress on health systems.
The heatwave was very well forecast, and the Met Office issued a top-level Red Alert, complementing a Level 4 Heat-Health warning by the UK Health Security agency – used when a heatwave is so severe and/or prolonged that its effects extend outside the health and social care system. At this level, illness may occur among the fit and healthy, not just in high-risk groups.
Scientists from South Africa, Germany, France, Switzerland, New Zealand, Denmark, United States of America and the United Kingdom, collaborated to assess to what extent human-induced climate change altered the likelihood and intensity of the heatwave.
Using published peer-reviewed methods, they analysed how human-induced climate change altered the likelihood and intensity of this heat wave in the region of the red alert warning. To capture the duration of the event as well as the record temperatures we look at maximum temperatures as well as the highest two-day averages observed.
While Europe experiences heatwaves increasingly frequently over the last years, the recently observed heat in the UK has been so extreme that it is also a rare event in today’s climate. The observed temperatures averaged over two days were estimated to have a return period of approximately 100 years in the current climate, according to World Weather Attribution.
The likelihood of observing such an event in a 1.2 °C cooler world (pre-industrial era) is extremely low, and statistically impossible in two out of three stations analysed by the study.
According to IPCC, temperatures will rise more quickly in European areas than elsewhere. In the Mediterranean, a worrisome combination of climatic impact-driver changes (warming; temperature extremes; increase in droughts and aridity; precipitation decrease; wildifire increase; mean and extreme sea levels; snow cover decrease; and wind speed decrease) is expected by mid-century if global warming exceeds 2°C.
The IPCC Special Report on Extremes also shows that heatwaves will be more frequent, longer and more intense in the 21st century. Early warning systems and reinforced health systems will be needed.
