Early human impact on the climate in Europe

Long before the industrial revolution humans have cut down forest to make room for arable land and pasture, or to improve the possibilities for hunting. Such changes in the vegetation impact the local climate, and therefore there are reasons to believe that human activities have impacted the climate in Europe as early as 6 000 years ago.

– Simulations with climate- and vegetation models show that manmade changes in the vegetation have made the summer climate in southern Europe up to half a degree warmer, says Gustav Strandberg, climate researcher at SMHI.

The vegetation, like it was 6000 years ago, has been simulated with a model that describes the vegetation based on the prevailing climate at the time.  Such simulations show the vegetation as it could have been if humans had not interfered. Additionally, the vegetation was reconstructed with the help from pollen data from lake sediments. Pollen that has been stored in the seabed reveals the previous vegetation in the area. The reconstruction describes the vegetation as it was, including the impact of forest fires and human activity. Through climate simulations with the climate models, and with different descriptions of the vegetation, we get information about how the vegetation impacts the climate.

The results show that the climate in Europe is sensitive to changes in the vegetation. Which means that it is important to have a realistic description of the vegetation in climate simulations, and also in simulations of the future climate. Because the climate models are sensitive in different ways, more models need to be used, as well as different descriptions of the vegetation.

Gustav’s research was published earlier this year and will be presented on the Swedish Climate Symposium in Norrköping, May 16-18th 2022.

gustavs papaer

Composite maps of LPJ-GUESS simulated potential natural vegetation cover using climate inputs derived from different climate models (L1 e RCA4, L2 - HCLIM, EC-Earth) and reconstructed vegetation cover (R) of Europe at 6 ka. Legend: ET = evergreen forest; ST = summergreen forest; OL = open landcover; BL = bare ground.