A probabilistic risk assessment for the vulnerability of the European carbon cycle to weather extremes: the ecosystem perspective

[摘要] Extreme weather events are likely to occur more often under climate changeand the resulting effects on ecosystems could lead to a further accelerationof climate change. But not all extreme weather events lead to extremeecosystem response. Here, we focus on hazardous ecosystem behaviour andidentify coinciding weather conditions. We use a simple probabilistic riskassessment based on time series of ecosystem behaviour and climateconditions. Given the risk assessment terminology, vulnerability and risk forthe previously defined hazard are estimated on the basis of observedhazardous ecosystem behaviour.

We apply this approach to extreme responses of terrestrial ecosystems todrought, defining the hazard as a negative net biome productivity over a12-month period. We show an application for two selected sites using data for1981–2010 and then apply the method to the pan-European scale for the sameperiod, based on numerical modelling results (LPJmL for ecosystem behaviour;ERA-Interim data for climate).

Our site-specific results demonstrate the applicability of the proposedmethod, using the SPEI to describe the climate condition. The site inSpain provides an example of vulnerability to drought because the expectedvalue of the SPEI is 0.4 lower for hazardous than for non-hazardous ecosystembehaviour. In northern Germany, on the contrary, the site is not vulnerableto drought because the SPEI expectation values imply wetter conditions in thehazard case than in the non-hazard case.

At the pan-European scale, ecosystem vulnerability to drought is calculatedin the Mediterranean and temperate region, whereas Scandinavian ecosystemsare vulnerable under conditions without water shortages. These firstmodel-based applications indicate the conceptual advantages of the proposedmethod by focusing on the identification of critical weather conditions forwhich we observe hazardous ecosystem behaviour in the analysed data set.Application of the method to empirical time series and to future climatewould be important next steps to test the approach.

[学科分类] 地球化学与岩石