Study says global warming has intensified heat waves in Europe, China and North America

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The heatwave that hit North America and Europe in July would have been “virtually impossible” without climate change, the researchers said, adding that extreme weather events would occur with greater frequency.

The World Weather Attribution Research Group, an academic collaboration, said human-induced warming has made the recent extreme heat in China “at least 50 times greater”.

Events such as simultaneous and record-breaking temperatures in July can now be expected approximately “once every 15 years in North America, once every 10 years in southern Europe and approximately once every five years in China,” the WWA said in a report Tuesday. The group found that about 75 percent of the recent extreme weather events it assessed were made more likely or severe because of climate change.

If the world warms 2C more than pre-industrial levels, “events like the (recent heatwave) which occur every two-five years” will become more frequent, said the team of six researchers from the UK and the Netherlands.

The 2016 Paris Agreement commits countries to strive to limit temperature rise to 1.5C above pre-industrial levels. However, according to the United Nations, the world has already warmed by at least 1.1C, and current climate pledges put it on track for a temperature rise of between 2.4C and 2.6C by 2100.

“The result of this attribution study is not surprising,” said Friedrich Otto, senior lecturer in climate science at the Grantham Institute for Climate Change and the Environment and author of the report. “The world hasn’t stopped burning fossil fuels, the climate continues to warm and heat waves are becoming more severe.”

Scientists are clear that with each degree of warming extreme weather events, including heatwaves, will become more frequent and intense.

The WWA, which assesses the impact of climate change on weather-related disasters including floods, fires and heatwaves, found 38 of its 52 studies found that events became more likely or severe because of warming.

Following Warmest June on record globallyExtreme heatwaves were experienced in July over large parts of the US, Mexico, Europe and China. The World Meteorological Organization said preliminary data indicated that early July was “the warmest week on record”.

Temperatures in California’s Death Valley exceeded 50C, while parts of China and Europe also reached record highs. Heat-related deaths have been reported in countries including the US, Mexico and Italy, and wildfires have raged in parts of Greece, leading to the evacuation of tourists on some islands such as Corfu and Rhodes.

The WWA said heatwaves are no longer rare, but they would have been “extremely rare” without anthropogenic or human-caused warming.

The WWA found that recent heat waves were about 2.5C warmer than they would have been without climate change in southern Europe, 2C warmer in North America and 1C warmer in China.

“Unless the world rapidly stops burning fossil fuels, these events will become more common and the world will experience heat waves that are even hotter and longer lasting,” the researchers said.

Scientists analyzed the data and computer model simulations to compare today’s climate with past weather patterns.

They looked at average maximum temperatures over seven days in southern Europe, over 18 days over the western US, Texas and northern Mexico, and over 14 days over lowlands in China – when heat in each region was at its most dangerous.