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Weather station data is insufficient for predicting biodiversity

Weather station data is insufficient for predicting biodiversity

We have been doing it all wrong with how we predict the future effects of climate change on biodiversity, state researchers in an article published recently in the scientific journal ‘Global Ecology and Biogeography'.

It is common practice among ecologists: if you want to know the faith of biodiversity in a changing climate, you first link the distribution of species to the climate at that location. To accomplish this, you use climate models based on the network of weather stations across the world. For many organisms, however, it turns out this approach is unlikely to be valid.

Jonas Lembrechts from the University of Antwerp and an international team of researchers, including Juha Aalto from the Finnish Meteorological Institute, studied the relationship between the tundra vegetation and the local climate in Northern Scandinavia. Researchers noted temperature differences of several degrees Celsius between global weather station models (at 2 meters in the air) and the temperature just below the soil surface, right there where small tundra plants are growing.

"Especially in winter, the differences are huge," Juha Aalto explains. "When the local weather station shows average temperatures dropping far below minus 10 °C, plants at the soil surface could still be comfortably at around 0 °C, as the snow cover in the tundra acts like a blanket. Many organisms are thus blissfully unaware of extreme conditions like that." Consequently, the distribution of most tundra species also relates more strongly to the soil than to air temperatures, the study shows.

"Interestingly," Lembrechts says, "this relationship was much stronger for small plant species like grasses, while it was not visible for trees." The former indeed experience a much stronger mismatch between the temperatures they experience, and the climate reported from weather stations.

This information has important implications for the question how biodiversity, and further cold-region ecosystems, will react to climate change. The reaction will not be linear, as has often been expected, as the temperatures at the vegetation level are driven by other factors, for example changes in snow cover. The researchers point out that this uncertainty on how climate change will look there where it matters for biodiversity needs to be solved urgently if we want to be able to predict what will happen in the future.

In winter, plants safely under a blanket of snow do not experience the extreme temperatures we feel – and our weather stations record. Dovrefjell, Norway. Photo: Jonas Lembrechts. 

Further information

Research professor Juha Aalto, Finnish Meteorological Institute, tel. +358 504 090 963, juha.aalto@fmi.fi                      

Publication: Lembrechts, L. , Lenoir, J., Roth, N., Hattab, T., Milbau, A., Haider, S., Pellissier, L., Pauchard, A., Ratier Backes, A., Dimarco, R., Nuñez, M., Aalto, J., Nijs, I. (2019). Comparing temperature data sources for use in species distribution models: from in-situ logging to remote sensing. Global Ecology and Biogeography 28: 1578–1595. doi: 10.1111/geb.12974

Related publication: Aalto, J., Scherrer, D., Lenoir, J., Guisan, A., & Luoto, M. (2018). Biogeophysical controls on soil-atmosphere thermal differences: implications on warming Arctic ecosystems. Environmental Research Letters 13: 074003. doi: 10.1088/1748-9326/aac83e. Open access.


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