SerpApi.Org
Britain’s scorching heatwaves are being driven by cleaner skies after pollution was stripped from the atmosphere, new research suggests.
Temperatures in Europe have warmed twice as much as the rest of the world since the 1980s, figures show, with the continent now 2.3C warmer than it was in the pre-industrial era. The global average is 1.3C.
The steep temperature rise in western Europe has outstripped expectations and has left experts puzzled as to their cause and concerned about the increase in deadly heatwaves.
Now Spanish researchers and the Met Office have concluded that most of the extra heat experienced in Britain and Europe is linked to the fall in particle emissions in recent decades.
The signing of the Montreal Protocol in 1987, which was championed by Margaret Thatcher, was designed to protect the Earth’s ozone layer and led to a general reduction in aerosols and particulates being emitted into the atmosphere.
Scientists now believe the reduction in some pollutants allows more of the sun’s heat to reach the Earth’s surface and also changes how air circulates globally to increase the chance of prolonged hot weather in Europe.
Prof Markus Donat, of the Barcelona Supercomputing Centre, said: “On the one hand, the cleaner air lets more sunlight reach the surface.
“On the other hand, we think that this additional energy causes atmospheric circulation changes that bring even more heat to Western Europe.”
Aerosols, particularly sulphates, reflect sunlight back into space which cools the planet. But when they are absent the Earth absorbs more heat, particularly at the poles, and shrinks the temperature difference between the poles and the equator.
A significant difference between the temperature at the poles and the tropics is crucial for keeping the jet stream moving.
The jet stream, the fast current of wind high in the sky that controls the weather, blows from west to east and flows in giant curves around the world in what are known as Rossby Waves, which are caused by the planet’s rotation.
Normally these waves undulate constantly, but the smaller temperature contrast created partly by the lack of sulphates in the air is causing them to virtually stall, locking in weather patterns and leaving Europe trapped under sweltering heat domes and high temperatures.
Experts believe this year’s heatwave was driven by the phenomenon, as well as scorching European summers of 2003, 2006, 2015, 2018 and 2019, which brought tens of thousands of excess deaths and widespread agricultural losses.
The scientists found that while the removal of sulphates made heatwaves more potent in Europe, if their emissions had not been curbed the overall impact of global warming would have been worse.
British temperature records for June were broken three times last month, with the mercury soaring to 37.3C at Santon Downham in Suffolk on June 26, exceeding figures reported on June 24 and 25.
Pedro Roldán‐Gómez, of the Barcelona Supercomputing Centre, said: “Now that the sulphates are disappearing over Europe we can see the full impact of the carbon dioxide emissions.
“From 1980, Europe warmed around 1C more than the average of extratropical areas of the Northern Hemisphere, and around 1.5C more than the global average.
“Most of this excess warming over Europe can be linked to the reduction of particle emissions.
“The increase of quasi-stationary Rossby Waves over Europe, is exactly what we are seeing in the heatwaves of this summer.”
The study found that although current climate models had factored in changes to the jet stream, they had got it the wrong way round, assuming it would cut heat in Europe by four per cent. In fact, atmospheric circulation changes boosted excess warmth by 29 per cent.
Overall, up to the 1980s, temperatures in Europe increased more slowly than the rest of the world, while particles in the atmosphere acted as a sunshade, but since then they have been rising faster than the rest of the world.
Now that sulphate emissions have stabilised, experts said that excess warming in Europe may now also slow down, as temperature increases only depend on greenhouse gases.
However, as Asia continues to cut emissions, the unmasking effect may continue elsewhere.
The new research was published in the journal Geophysical Research Letters.
