Science

Large parts of Europe are warming twice as fa

image: The figures on the left and right show the warming in Europe of the summer half of the last four decades, subdivided for clear skies and all air conditions, respectively.
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Source: Paul Glantz/Stockholm University

Warming during the summer months in Europe has been much faster than the global average, according to a new study by researchers at Stockholm University published in the journal Journal of Geophysical Research Atmospheres. As a result of human greenhouse gas emissions, the climate across the continent has also become drier, especially in southern Europe, leading to worse heat waves and an increased risk of fires.

According to the UN’s Intergovernmental Panel on Climate Change (IPCC), warming over land areas is significantly faster than over oceans, averaging 1.6 degrees and 0.9 degrees respectively. It means that the global budget for greenhouse gas emissions to stay below 1.5 degrees of global warming has already been used up. Now the new study shows that the emissions budget to prevent a warming of 2 degrees over large parts of Europe during the summer half-year (April-September) has also been used up. Measurements even show that the warming during the summer months in large parts of Europe has already passed two degrees over the past four decades.

“Climate change is serious because, among other things, it leads to more frequent heat waves in Europe. These, in turn, increase the risk of fires, such as the devastating fires in southern Europe in the summer of 2022,” said Paul Glantz, associate professor in the Department of Environmental Science, Stockholm University, and lead author of the study.

In southern Europe, a clear so-called positive feedback is visible, caused by global warming, ie the warming is amplified by drier soil and reduced evaporation. In addition, there has been less cloud cover over large parts of Europe, probably due to less water vapor in the air.

“What we are seeing in southern Europe is consistent with what the IPCC has predicted, which is that a greater human impact on global warming would lead to arid areas on Earth becoming even drier,” says Paul Glantz.

Impact of aerosol particles

The study also includes a section on the estimated impact of aerosol particles on temperature rise. According to Paul Glantz, the rapid warming in Central and Eastern Europe, for example, is primarily a result of human emissions of long-lived greenhouse gases, such as carbon dioxide. But as emissions of short-lived aerosol particles from coal-fired power stations, for example, have declined sharply over the past four decades, the combined effect has led to an extreme temperature rise of more than two degrees.

“The airborne aerosol particles, before they started to decrease in Europe in the early 1980s, masked the warming caused by human greenhouse gases during the summer half-year by an average of just over one degree. As the aerosols in the atmosphere decreased, the temperature increased rapidly. Human emissions of carbon dioxide are still the biggest threat, as they affect the climate for hundreds to thousands of years,” says Paul Glantz.

According to Paul Glantz, this effect is a harbinger of future warming in areas where aerosol emissions are high, such as India and China.

Background Facts – The Greenhouse Effect and the Aerosol Effect

Fossil combustion leads to the release of both aerosol particles and greenhouse gases. While their source is common, their effects on climate differ.

About the greenhouse effect
Greenhouse gases are largely unaffected by solar radiation, while efficiently absorbing infrared radiation, leading to re-emissions to the Earth’s surface. The earth absorbs both solar radiation and infrared radiation, which causes the lower part of the atmosphere to warm up in particular.

Time-Space: Greenhouse gases generally have a long lifetime in the atmosphere and this is especially true for carbon dioxide where human emissions affect the climate for hundreds to thousands of years. It also means that greenhouse gases spread evenly all over the planet.

About the aerosol effect
Unlike greenhouse gases, aerosol particles affect incident solar radiation, ie they scatter some of the sunlight back into space and provide a cooling effect. Human emissions of aerosols can enhance this cooling effect.

Time-space: Airborne human aerosol particles have a lifespan of about a week, meaning that they mainly cool the climate locally or regionally and in the short term.

According to the Paris Agreement, all parties must commit to drastically reducing their greenhouse gas emissions, but it is also important to also reduce concentrations of aerosol particles, because aerosol particles in polluted air, in addition to their effects on climate, cause about eight million premature deaths every year around the world.


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