Newswise — The heat waves that swept across Europe this summer made many people realize the importance of plants when it comes to cooling the environment. But how do the different types of Arctic vegetation affect the energy exchange between the Earth’s surface and its atmosphere? This is a very relevant question, because the region is of great importance for the climate. The Arctic is warming at more than twice the rate of the global average, causing permafrost to thaw and glaciers to melt on a regional scale. Globally, this warming translates into consequences far from the Arctic, such as cold damage to ecosystems in East Asia.
Difference in heat flux similar to that between glaciers and grasslands
An international team led by two researchers from the Department of Evolutionary Biology and Environmental Studies at the University of Zurich (UZH) has now taken a closer look at the land surface energy balance in the Arctic. According to their study, the diverse vegetation of the Arctic, which is ignored in climate models, is one of the key factors in the exchange of energy between the Earth’s land surface and the atmosphere. “Remarkably, in summer the difference in heat flux between two types of vegetation – such as a landscape dominated by lichens and mosses and another with shrubs – is about the same as between the surface of glaciers and green meadows,” says postdoc Jacqueline Oehri, first author of the study.
Vegetation types linked to data from 64 measuring stations
Arctic vegetation is very diverse and ranges from dry grasslands and wetlands to scrubland dominated by dwarf shrubs as well as heathland with mosses and lichens. The researchers linked this plant diversity to all available energy exchange data collected by 64 measuring stations in the Arctic between 1994 and 2021. They focused on the summer months between June and August, when sunlight, and therefore energy absorption, is particularly high. Depending on the type of vegetation, the surface or the air is heated to varying degrees. In addition, with the increase in the density of shrubs, the land warms up sooner after winter. “The dark branches of the shrubs emerge early from under the snow, absorb sunlight and transmit it to the surface long before the snow melts,” says Oehri.
Vegetation cooling can preserve permafrost in the tundra
“Our findings on energy fluxes in the Arctic are extremely relevant, because the preservation of permafrost depends to a large extent on heat flux in the ground,” says Gabriela Schaepman-Strub, a professor at UZH. The data from the study make it possible to integrate the effects of different plant communities and their distribution into climate forecasts. Researchers can thus use improved climate models to calculate whether, and to what extent, tundra vegetation in the Arctic plays a role in cooling the earth’s surface.
Precision models require additional measuring stations
“We now know which plant communities have a particularly pronounced cooling or warming effect through energy exchange. This allows us to determine how changes in plant communities, which occur in many parts of the Arctic, affect permafrost and climate,” says Schaepman-Strub. In particular, this requires improvements in data collection. Although the Arctic is changing rapidly and has a major impact on the climate dynamics of the entire planet, there are only a few reliable measuring stations in this region. In addition to calling for current stations to remain in operation, the study authors believe that new stations are needed in the types of Arctic landscapes that could only be partially analyzed due to incomplete data.
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