A historic and deadly heat wave has been scorching western Europe, killing hundreds in Spain and Portugal. Temperatures spiked into the triple digits from Spain to the British Isles, fueling wildfires raging across the continent. It’s the latest in a series of heat waves that have blistered the continent since May.
Heat waves are becoming more intense and frequent around the globe due to global warming, especially in Europe; scientists say heat waves there are intensifying faster than in almost any other part of the planet, including the United States.
Scientists continue to look for answers to why heat waves in Europe have been increasing comparatively faster than in other regions. “We do not understand why we have such an increase [in temperature] that the models do not predict,” said scientist Robert Vautard of the Climate and Environment Sciences Laboratory in France.
The current temperatures in England and Wales are caused in part by a “cutoff low” – a region of low-pressure air – that has remained off the coast of Portugal for days. Low-pressure zones draw neighboring air towards themselves – in this case, warm air from North Africa. “It’s pumping hot air northward,” said Kai Kornhuber, a researcher at Columbia University.
Another possible cause is changes in the global jet stream. Europe’s climate is moderated by the jet stream, a current of fast-moving air that runs across the northern hemisphere.
Sometimes the jet stream splits in two – what’s referred to as a “double jet.” Though double jets are normal, global warming may be making them occur more often. Dim Coumou, a scientist at Vrije Universiteit Amsterdam, published research linking frequent and persistent double jets to European heat waves.
“We showed that especially for Western Europe, the increased frequency in this particular jet state can explain … the increase in heat waves here,” said Coumou. During a double jet, airflow is more sluggish across most of Europe. This creates an area of weak winds which allow heat to persist and allowed the cutoff low to stall off the coast of Portugal.
Coumou added that the ongoing droughts in Europe are very likely causing current heat waves. Wet soils act as a barrier to extreme heat, according to climate scientist Sonia Seneviratne of ETH Zurich.
When soil is moist, some of the sun’s energy is used to evaporate the water, meaning less energy goes towards heating the air. However, when soils are too dry, all the energy goes towards baking the surface, adding to the heat.
There are also indications that a slowdown in one of the world’s major ocean currents, the Atlantic Meridional Overturning Circulation (AMOC), could be contributing to current heat waves. Climate models have long shown that the AMOC will slow as the climate warms. An AMOC slowdown would cool the North Atlantic, meaning the jet stream would channel more warm air from the equator into Europe. However, climate physicist Levke Caesar of Maynooth University warned that “The North Atlantic is not particularly cold at the moment, which might indicate [that] in this case, the AMOC did not play a big role.”
More research is needed to determine exactly what is causing Europe to heat up so fast. But for now, it’s clear that summer in Europe will only get hotter.
Heat waves are becoming more intense and frequent around the globe due to global warming, especially in Europe; scientists say heat waves there are intensifying faster than in almost any other part of the planet, including the United States.
Scientists continue to look for answers to why heat waves in Europe have been increasing comparatively faster than in other regions. “We do not understand why we have such an increase [in temperature] that the models do not predict,” said scientist Robert Vautard of the Climate and Environment Sciences Laboratory in France.
The current temperatures in England and Wales are caused in part by a “cutoff low” – a region of low-pressure air – that has remained off the coast of Portugal for days. Low-pressure zones draw neighboring air towards themselves – in this case, warm air from North Africa. “It’s pumping hot air northward,” said Kai Kornhuber, a researcher at Columbia University.
Another possible cause is changes in the global jet stream. Europe’s climate is moderated by the jet stream, a current of fast-moving air that runs across the northern hemisphere.
Sometimes the jet stream splits in two – what’s referred to as a “double jet.” Though double jets are normal, global warming may be making them occur more often. Dim Coumou, a scientist at Vrije Universiteit Amsterdam, published research linking frequent and persistent double jets to European heat waves.
“We showed that especially for Western Europe, the increased frequency in this particular jet state can explain … the increase in heat waves here,” said Coumou. During a double jet, airflow is more sluggish across most of Europe. This creates an area of weak winds which allow heat to persist and allowed the cutoff low to stall off the coast of Portugal.
Coumou added that the ongoing droughts in Europe are very likely causing current heat waves. Wet soils act as a barrier to extreme heat, according to climate scientist Sonia Seneviratne of ETH Zurich.
When soil is moist, some of the sun’s energy is used to evaporate the water, meaning less energy goes towards heating the air. However, when soils are too dry, all the energy goes towards baking the surface, adding to the heat.
There are also indications that a slowdown in one of the world’s major ocean currents, the Atlantic Meridional Overturning Circulation (AMOC), could be contributing to current heat waves. Climate models have long shown that the AMOC will slow as the climate warms. An AMOC slowdown would cool the North Atlantic, meaning the jet stream would channel more warm air from the equator into Europe. However, climate physicist Levke Caesar of Maynooth University warned that “The North Atlantic is not particularly cold at the moment, which might indicate [that] in this case, the AMOC did not play a big role.”
More research is needed to determine exactly what is causing Europe to heat up so fast. But for now, it’s clear that summer in Europe will only get hotter.
