A new study has revealed the most intense heat waves in history around the worldand surprisingly some of them went almost unnoticed decades ago.
The research, led by the University of Bristol (UK) and published in Science Advances, also shows that heat waves are expected to be more intense in the future as climate change worsens.
Last summer’s heat wave in western North America broke a record, with a Canadian all-time high of 49.6°C at Lytton, British Columbia on June 29, an increase of 4.6°C from the previous peak. The new results reveal another five heat waves around the world that were even more severe, but went unreported.
Lead author Dr Vikki Thompson, a climatologist at the University of Bristol, said in a statement that "the recent heat wave in Canada and the United States shocked the world. However, we have seen that even greater extreme situations have occurred in recent decades. Using climate models, we also found that extreme heat events are likely to increase in magnitude over the next century, keeping pace with the average local temperature.".
Heat waves are one of the extreme weather events most devastating. The Western North American Heat Wave It was the deadliest weather phenomenon in history. of Canada, with hundreds of fatalities. Associated forest fires also caused extensive damage to infrastructure and loss of crops.
But the study, which calculated the extreme degree of heat waves in relation to local temperature, showed that the three hottest on record in the respective regions were produced in Southeast Asia in April 1998which reached 32.8 °C, in Brazil in November 1985, with a maximum of 36.5 °C, and in the southern United States in July 1980, when temperatures rose to 38.4 °C .
Dr Vikki Thompson, from the university’s Cabot Institute for the Environment, stresses that "the western North American heat wave will be remembered for its widespread devastation. However, the study exposes several major weather extremes in recent decades, some of which went largely unnoticed, likely because they occurred in poorer countries. It is important to assess the severity of heat waves based on local temperature variability, as both humans and the natural ecosystem adapt to it, so that in regions where there is less variation, a lower absolute extreme can have more detrimental effects".
The team of scientists also used sophisticated climate model projections to anticipate heat wave trends for the remainder of the century. The models indicated that intensity levels of heat waves will increase in line with rising global temperatures.
Although the highest local temperatures are not necessarily the ones that cause the greatest impacts, they are often related. Improving understanding of climate extremes and where they have occurred can help prioritize actions to help tackle extreme weather in the most vulnerable regions.
Co-author Professor Dann Mitchell, Professor of Climate Science at the University of Bristol, recalls that "climate change is one of the biggest global health problems of our time, and we have shown that many heat waves outside the developed world have gone virtually unnoticed. The heat burden on mortality at the country level can be in the thousands of deaths, and countries that experience temperatures outside their normal range are the most susceptible to these shocks.".