In other words, the forest is a significant balancing factor. Its impact on the climate is several tens of percent greater than it would be as a carbon sink alone. “Carbon sinks such as forest, forest growth and forestry land are essential in removing carbon dioxide from the atmosphere. Whenever there is photosynthesis, carbon dioxide is sequestered from the atmosphere, and it is im- portant to ensure that it stays out.” No other place in the world has a time series as long as the Hyytiälä station. It provides unique information about the feedback loop, which further enhances the ability of forests to sequester carbon. ESSENTIAL TO UNDERSTAND THE ENTIRE CHAIN How big are the carbon sink and carbon storage of the soil and trees? Kulmala says we still need more information about aspects such as the volume of carbon that forests of different ages absorb in different parts of the world. We also need to know where wood-based products end up: are they long-lived, or will they soon be burned, re- turning their carbon dioxide to the atmosphere? “We must enhance our understanding of the entire chain. In terms of climate change, the key question is how quickly carbon returns to the atmosphere. If we want to curb climate change, we must increase sinks and reduce “It can mean lengthening felling cycles by a few years. Or it can mean using wood for products that are as long- lived as possible, and for products that replace plastic or other fossil-based products.” From a global perspective, it is absolutely vital to reduce forest fires. emissions at the same time,” Kulmala says. Small things can help increase carbon sinks. METROPOLITAN AIR QUALITY STUDIES IN CHINA According to Markku Kulmala, Finnish atmospheric com- petence is of world-class quality by any standards. “The knowledge and measurement of interactions be- tween the atmosphere and forests, as well as the related competence, are unique here. They can not be found at this level anywhere else.” Kulmala hopes to see this competence spread around the world. “There should be a measurement station like a SMEAR station in each main ecosystem and in each metropolis. Worldwide, we would need a few hundred of them – but preferably a thousand.” Finland currently has five stations, Estonia one and China two. “Three stations are under construction in China, and one each in Russia, South Africa and Kenya. In addition, there are preliminary Arctic stations in Greenland and
Markku Kulmala has been involved in the stations’ histo- ry from the outset, and the related work has made him and Finland number one in atmospheric sciences research. He established the stations with Pertti Hari , Professor Emer- itus in Forest Ecology. The first one was set up at Värriö, a fell in the eastern part of Finnish Lapland, in 1990–1991. SMEAR II, the most famous of the five stations in Fin- land, is part of many international measurement net- works. It was set up in 1995–1996 at the University of Helsinki’s Hyytiälä forestry field station in the Tampere region. It has produced a steady stream of data for re- search purposes. “When we initiated our measurements, it was clear we needed long time series. We just didn’t realise all the things they could be used for,” Kulmala admits. The stations provide researchers with continuous meas- urement data. One of the things that they help explain is the impact of the forest ecosystem on the formation of particulates. “The collection of data on forests is particularly impor- tant, because the forest ecosystem has a major impact on the atmosphere. Measurements help us identify various feedback loops between the two.” The SMEAR II station keeps tabs on greenhouse gases like carbon dioxide, methane, nitrous oxide, other gases including ozone, carbon monoxide, sulphur dioxides, ni- trogen oxides, various hydrocarbons, photosynthesis and its by-products – more than 1,200 variables. “We offer the widest scope of measurements worldwide. A normal air pollution station measures ten variables, as does a normal weather station.” THE CLIMATE IMPACT OF FORESTS Thanks to the Hyytiälä station, Finnish forests are the world’s best measured. “We examine natural processes as extensively as possi- ble so that we can answer questions like climate change. Without these measurements, we would not possess all the knowledge we do about carbon sinks – for example, that a coniferous forest in southern Finland, including its soil, absorbs 300 grams of carbon per square metre annually,” Kulmala explains. In many ways, forests and the soil are significant carbon sinks, removing carbon dioxide from the air. Like the soil, trees absorb carbon as they grow, but they also perform many other tasks. Photosynthesis generates hydrocarbons, and if you wan- der in the forest on a sunny day in the early summer, you can actually smell these hydrocarbons, known as terpenes. Terpenes react with atmospheric ozone and UV radiation, forming nanoparticles that contribute to the mitigation of climate change.
Markku Kulmala Academician, Academy Professor, Professor of Aerosol and Environmental Physics at the University of Helsinki, and Director of the Atmosphere and Climate Competence Center (ACCC). For many years he was the world’s most cited geophysicist.
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