Future Trends of Suitability

This section focus on the impacts of anthropogenic climate change on the potential distribution of tree species in Europe. Following our approach for current species and forest formations habitat suitability mapping, future climate scenarios are used to assess potential geographical shifts of tree species. For this objective, bioclimatic factors are implemented for producing future scenarios habitat suitability maps.

Climate change projections are simulated by Global Climate Models (GCM). GCM provide scenario-driven data of climatic variables representing different socio-economic futures resulting on different GHG emission. The IPCC’s Special Report on Emissions Scenarios (SRES) (Nakicenovic and Swart, 2000) describes the relationships between the forces driving GHG emissions and their evolution during the 21st century.

IPCC scenarios represent different demographic, social, economic, technological and environmental developments that diverge in increasingly irreversible ways. Within the IPCC SRES report (Nakicenovic and Swart, 2000) several storylines exists: we used the A2a and B2a story-line scenarios. Both A2 and B2 storyline describe a "regionalisation" leading to a heterogeneous world development opposed to "globalization" tending to an homogeneous world development described in the A1 and B1 storylines.

•A2a describes a highly heterogeneous future world with regionally oriented economies. The main driving forces are a high rate of population growth, increased energy use, land-use changes and slow technological change.

•The B2a is also regionally oriented but with a general evolution towards environmental protection and social equity. Compared to A2, B2 has a lower rate of population growth, a smaller increase in GDP but more diverse technological changes and slower land-use changes.

GHG emissions from the two scenarios will affect global climate change in different ways, with A2a having a more drastic effect compared to B2a.

We used A2a and B2a scenario data from three GCM:
•HADCM3 (Hadley Centre Coupled Model version 3) (Collins et al., 2001)
•CCCMA (Canadian Centre for Climate Modelling and Analysis) (Kim et al., 2003)
•CSIRO (Commonwealth Scientific and Industrial Research Organisation) (Gordon and O’Farrell, 1997).
•From the previous three GCM we computed an average ensemble (ENS) model.

Future climate conditions are modelled for years 2020, 2050 and 2080.
An example of the modelled future climatic conditions in Europe is shown in figure 1. An overall increase in average temperature is observed across Europe. According to the different models, annual mean temperature in Europe will increase between 2.8 and 4.8 degree C towards the end of the century. Changes in precipitation are variable in the different model realisations. CSIRO scenarios A2a and B2a show precipitation increase higher than 25mm/year. CCCMA and ENS B2a show a slight increase of ~10mm/year. HADCM3 A2a shows a decrease in precipitations of 20mm/year. The other scenarios show slight variations of around -1 and +5 mm/year.

Figure 1 - Changes in European mean annual accumulated precipitation and mean temperatures for the next century according to different models and IPCC scenarios.

A series of tree species habitat suitability maps has been implemented using the Random Forest algorithm as described in the Tree Species Habitat Suitability section. The maps cover the different combinations of model/scenario/period indicated above.

Maps available here.

•Collins, M., Tett, S., Cooper, C. (2001): The internal climate variability of hadcm3, a version of the Hadley centre coupled model without flux adjustments. Climate Dynamics, 17, 61–68.
•Gordon, H.B., O’Farrell, S.P. (1997): Transient climate change in the CSIRO coupled model with dynamic sea ice. Monthly Weather Review, 125, 875–907.
•Kim, S.J., Flato, G., Boer, G. (2003): A coupled climate model simulation of the last glacial maximum, Part 2: Approach to equilibrium. Climate Dynamics, 20, 635–661.
•Nakicenovic, N., Swart, R. (2000): Special Report on Emissions Scenarios. Cambridge University Press, Cambridge, United Kingdom, 612.


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