Europe is warming almost three times faster than the global average, and the climatologists’ explanation is as surprising as it is paradoxical: cleaner air. A new study reveals that reductions in industrial pollution in recent decades have inadvertently removed an aerosol “shield” that reflected solar radiation and masked the true extent of the greenhouse effect. Without this protective barrier, the old continent is now feeling the full force of climate change, making extreme heat waves the new normal.
A study published in the journal Geophysical Research Letters tries to explain why temperatures in Western Europe rose much faster than climate models predicted.
According to the researchers, the average summer temperature in Western Europe has risen by around 2.3 degrees Celsius since 1980, while the global average has risen by only 0.8 degrees Celsius over the same period.
This difference has surprised climatologists, who have searched for years to explain why Europe is warming almost three times faster than the planet as a whole.
The unexpected role of cleaner air
The explanation proposed by the new study does not call into question the effect of greenhouse gases, but adds an important piece of the puzzle.
For decades, coal-fired power plants, industry, and other sources of pollution have emitted significant amounts of sulfate aerosols into the atmosphere. These particles reflect some of the solar radiation back into space and have had an unintended cooling effect on the climate.
Basically, the aerosols acted as a fine curtain that reduced the amount of solar energy reaching the Earth’s surface, writes sciencex.com
With the introduction of stricter environmental regulations and the reduction of industrial emissions, the concentration of these particles has decreased significantly.
The consequence is that some of the warming caused by greenhouse gases, which until now was “hidden”, has become visible.
The authors of the study show that the reduction in aerosol pollution contributed to the increase in summer warming in Europe, over and above the effect produced solely by the increase in the concentration of carbon dioxide and other greenhouse gases.
How does the heat stay locked over Europe
Researchers have also identified the atmospheric mechanism that amplifies this phenomenon.
These are Rossby waves, natural oscillations of the jet stream – the strong flow of air that circulates at high altitude in the northern hemisphere.
Under certain conditions, these waves become almost stationary and block the normal circulation of air masses.
The result is the appearance of real “heat domes”, which prevent the penetration of cold air and maintain extremely high temperatures for several days or even weeks.
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According to the study, the reduction of aerosols has favored the formation of these persistent atmospheric configurations, which explains the frequency and intensity of heat waves in recent years.
Why climate models have underestimated warming
One of the important conclusions of the research is that many climate models used so far correctly captured the influence of greenhouse gases, but underestimated the impact of changes in atmospheric circulation.
Comparing climate simulations with actual observations, the researchers found that the models reproduced only about half of the additional warming observed in Europe.
The reason is that they estimated too weak an effect of Rossby waves on summer temperatures.
When the scientists recalibrated the models to better reflect the behavior of these atmospheric waves, the simulated temperatures became much closer to those recorded in reality.
The discovery could lead to improved regional climate forecasts and more accurate estimates of the frequency of future heat waves.
A paradox of environmental policies
The study’s authors emphasize that the results do not mean that reducing air pollution is the wrong move.
On the contrary, lowering the concentration of aerosols has brought major benefits to the health of the population, reducing the number of respiratory and cardiovascular diseases associated with pollution.
But this development also had an unexpected side effect: it eliminated a factor that partially masks global warming.
In other words, Europe today breathes cleaner air, but feels the effects of climate change more intensely.
What it means for the future
The researchers warn that the effect produced by the reduction of aerosols will diminish gradually, since their concentrations have already decreased considerably.
In the coming years, the main driver of warming will remain the accumulation of greenhouse gases in the atmosphere.
That is precisely why the authors of the study believe that strategies for adapting to climate change must take into account both the reduction of pollution and the risk of increasingly intense heat waves.
The conclusion of the research is that cleaner skies do not cause climate change, but make the warming already produced by greenhouse gas emissions more visible. Without the particles that reflected some of the solar radiation, Europe is now feeling the full intensity of this phenomenon, and extreme summers could become the new normal.
