Newswise – Warming during the summer months in Europe has been much faster than the global average, shows a new study by researchers at Stockholm University published in the Journal of Geophysical Research Atmospheres. Due to human emissions of greenhouse gases, the climate across the continent has also become drier, particularly in southern Europe, leading to more severe heat waves and an increased risk of fires.
According to the UN’s Intergovernmental Panel on Climate Change (IPCC), land is warming much faster than the oceans, with an average of 1.6 degrees and 0.9 degrees respectively. This means that the global greenhouse gas emissions budget to stay below 1.5 degree warming on earth has already been exhausted. Now the new study shows that the emissions budget to avoid a 2 degree warming over large parts of Europe in the summer semester (April-September) has also been used. In fact, measurements reveal that warming during the summer months in large parts of Europe over the past four decades has already exceeded two degrees.
“Climate change is serious because it leads, among other things, to more frequent heat waves in Europe. These, in turn, increase the risk of wildfires, such as the devastating fires in southern Europe in the summer of 2022,” says Paul Glantz, associate professor in the Department of Environmental Sciences at the Stockholm University and lead author of the study.
In southern Europe, a clear, so-called positive feedback caused by global warming is evident, i.e. the warming is amplified due to drier soil and a decrease in l ‘evaporation. Additionally, there was less cloud cover over large parts of Europe, likely due to less water vapor in the air.
“What we see in southern Europe is consistent with what the IPCC predicted, that increased human impact on the greenhouse effect would lead to dry areas of the Earth becoming even drier,” says Paul Glantz.
Aerosol Particle Impact
The study also includes a section on the estimated impact of aerosol particles on temperature increase. According to Paul Glantz, rapid warming, for example in central and eastern Europe, is above all a consequence of human emissions of long-lived greenhouse gases, such as carbon dioxide. But as emissions of short-lived aerosol particles from, for example, coal-fired power plants have fallen dramatically over the past four decades, the combined effect has led to an extreme temperature increase of more than two degrees.
“Airborne aerosol particles, before they began to decline in the early 1980s in Europe, masked the warming caused by human greenhouse gases by just over a average degree for the summer semester. As the aerosols in the atmosphere decreased, the temperature rose rapidly. Human emissions of carbon dioxide remain the greatest threat as they affect the climate for hundreds if not thousands of years,” says Paul Glantz.
According to Paul Glantz, this effect is a harbinger of future warming in regions with high aerosol emissions, such as India and China.
Historical background – The greenhouse effect and the aerosol effect
Burning fossils results in the release of aerosol particles and greenhouse gases. Although their source is common, their effects on the climate differ.
About the greenhouse effect
Greenhouse gases are largely unaffected by solar radiation while they effectively absorb infrared radiation, causing re-emission towards the Earth’s surface. The Earth absorbs both solar radiation and infrared radiation, which leads in particular to the warming of the lower part of the atmosphere.
Space-time: Greenhouse gases are generally long-lived in the atmosphere, and this applies above all to carbon dioxide, whose human emissions affect the climate for hundreds or even thousands of hours. years. It also means that greenhouse gases are distributed evenly across the planet.
About the aerosol effect
Unlike greenhouse gases, aerosol particles affect incoming solar radiation, i.e. they reflect some of the sunlight back into space, causing a cooling effect. Human aerosol emissions can enhance this cooling effect.
Space-time: Human aerosol particles suspended in the air have a lifespan of about a week, which means that they mainly cool the climate locally or regionally and in the short term.
According to the Paris Agreement, all parties must undertake to drastically reduce their greenhouse gas emissions, but it is also important to also reduce the concentrations of aerosol particles because, in addition to their effects on the climate, aerosol particles in polluted air cause around eight million premature deaths worldwide each year.
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