University of Tartu research award went to Centre for Climate Research for discovery about anthropogenic air pollution

The University of Tartu research award 2024 went to an extraordinary discovery by researchers of the Centre for Climate Research of the Institute of Physics – an international study led by Associate Professor in Climate Physics Velle Toll revealed that in industrial hot spots, anthropogenic air pollution causes snowfall and reduces cloud cover. The research contributes to a better understanding of the impact of pollution particles on clouds, which is the most ambiguous component of the climate impact of human activities.

“Right now, when we have just experienced the hottest year in the world's recorded history, and again the warmest January on record, every new piece of information on the climate impact of human activity is invaluable. It is a huge recognition to the entire university that our climate researchers are leading such world-class research,” said Academic Secretary Tõnis Karki on behalf of the evaluation committee.

Global warming resembles a tug-of-war between the two opposing consequences of human activity: anthropogenic greenhouse gases warming the Earth's climate and air pollution particles cooling it. When it comes to global warming, there has been much talk about greenhouse gases, the effects of which researchers agree on: since the second half of the 20th century, at least 90% of warming is due to anthropogenic greenhouse gases. Velle Toll noted that the extent of the cooling effect of air pollution particles – aerosols – on the climate is still unclear, although it is known to partly offset warming.

This is exactly what the research group of the Centre for Climate Research studies: to what extent the impacts of anthropogenic aerosols on clouds offset global warming caused by anthropogenic greenhouse gases. The physicists discovered that anthropogenic aerosols act as seeds for ice formation in the atmosphere, causing snowfall, reducing cloud cover and affecting solar and thermal radiation fluxes. When there are fewer clouds, the phenomenon causes more solar energy to be absorbed by the ground.

Toll explained that the discovery of his research group underlines the need for further research. “If it turns out that the effects of aerosols acting as seeds for ice formation occur beyond the immediate vicinity of factories, the phenomenon could affect not only industrial areas but the Earth's climate as a whole,” said Toll.

New knowledge helps to compile more reliable climate projections and shape research-based climate policy

“We know from previous research that aerosols make the clouds brighter, cooling the climate. If we could more accurately determine the magnitude of the cooling effect of aerosols on the climate, we would be able to compile even more accurate and reliable climate projections,” explained Toll.

“The broader aim of our research is to investigate whether the cooling effect of aerosols is stronger than previously thought and whether the climate change ahead is faster than projections based on current climate policy indicate,” said Toll. If this effect is strong, it would also mean that global warming so far has been caused by a smaller-than-expected human influence and that the Earth's climate is very sensitive to human influence.

Recipients of the research award are Associate Professor in Climate Physics Velle Toll (head of the research group), Research Fellows in Climate Physics Hannes Keernik and Heido Trofimov, Specialist in Climate Physics Jorma Rahu, Professor of Climate Science Piia Post and Engineer Tanel Voormansik.

The University of Tartu research award is given to recognise a university’s academic staff member or working group who has stood out by an extraordinary achievement in basic or applied research in the previous year. This time, there were five nominations for the research award.

At the beginning of 2024, the previous Laboratory of Atmospheric Physics of the Institute of Physics was replaced by the Centre for Climate Research, focusing on the strength of the climate impact of human activities. The centre’s staff also compile climate projections and promote climate awareness in education.