The University of Helsinki’s most cited researchers in the fields of geosciences and pharmacology.
Markku Kulmala (b. 1958), professor of physics, has been the world's most cited geoscientist since 1 May 2011. He has reached this position thanks to his groundbreaking research on the formation of small particles in the atmosphere as well as on the interaction between the climate and forests. Kulmala has developed completely new hypotheses, provided evidence for them and built a research infrastructure around them, the most central components of which are the SMEAR I and II stations in Värriö and Hyytiälä respectively, both established in the 1990s.
At the turn of the millennium, Kulmala first formulated the hypothesis that the atmosphere must contain molecule clusters and particles of 1—3 nanometers in diameter. He then proved their existence as well as the fact that they largely consist of organic by-products of photosynthesis.
The forests of the world produce such aerosols, which serve as condensation nuclei for droplets and contribute to the creation of clouds. The clouds then reflect sunlight back into space, thus cooling the climate.
These phenomena form the foundation of Kulmala’s hypothesis regarding the feedback mechanism between climate change and forests – namely, that forests slow down climate change. The studies conducted at the SMEAR II station have proven his hypothesis to be correct.
In the feedback mechanism, photosynthesis increases when the amount of carbon dioxide in the atmosphere increases. Photosynthesis creates hydrocarbons as by-products, which then react in the atmosphere, forming fairly stable aerosol particles. These particles serve as condensation nuclei for clouds, which refract sunlight back into space.
As the amount of aerosol particles increases, the refraction becomes more intense in the lower atmosphere. As a result, pine needles located under the tops of coniferous trees receive more photons, which enables them to photosynthesise even more, which binds even more carbon dioxide from the atmosphere, generating even more aerosol particles.
During the past few years, Kulmala has focused on the connections between air quality and climate change as well as potential solutions to improve the air quality in China.
Kulmala and his wife are part of a peer support network for couples and families through the NGO Parempi avioliitto.