Assessing Shifts of Mediterranean and Arid Climates Under RCP4.5 and RCP8.5 Climate Projections in Europe

José I Barredo,Alessandro Dosio,Achille Mauri,Giovanni Caudullo

doi:10.1007/s00024-018-1853-6

Abstract

The Mediterranean basin is the richest biodiversity region in Europe and a global hotspot of biological diversity. In spite of that, anthropogenic climate change is one of the most serious concerns for nature conservation in this region. One of the climatic threats is represented by shifts of the Mediterranean climate and expansion of the arid climate. In this paper, we present an assessment of changes in the spatial range of the Mediterranean climate in Europe and the conversion into arid climate under different greenhouse gas forcings, namely RCP4.5 and RCP8.5. We used 11 simulations in two future 30-year periods of state-of-the-art regional climate models from EURO-CORDEX. Our results indicate that by the end of the century under RCP8.5 the present Mediterranean climate zone is projected to contract by 16%, i.e. an area (~ 157,000 km2) equivalent to half the size of Italy. This compares with the less severe scenario RCP4.5 that projected only a 3% reduction. In addition, the Mediterranean climate zone is projected to expand to other zones by an area equivalent to 24 and 50% of its present extent under RCP4.5 and RCP8.5, respectively. Our study indicates that expansion of the arid zone is almost always the cause for contraction of the Mediterranean zone. Under RCP8.5 the arid zone is projected to increase by more than twice its present extent, equivalent to three times the size of Greece. Results of this study are useful for identifying (1) priority zones for biodiversity conservation, i.e. stable Mediterranean climate zones, (2) zones requiring assisted adaptation, such as establishment of new protected areas, implementation of buffer zones around protected areas and creating ecological corridors connecting stable Mediterranean zones.

Highlights

The Mediterranean basin is the richest biodiversity region in Europe and a global hotspot of biological diversity (Myers et al 2000)
We present an assessment of changes in the spatial range of the Mediterranean climate domain (MCD) in Europe and the conversion into arid climate under two different Representative Concentration Pathways (RCPs) adopted by the IPCC in its Fifth Assessment Report, namely RCP4.5 and RCP8.5 (Moss et al 2010; van Vuuren et al 2011)
When assessing the simulations independently all of them projected a shrink of the present extent of the MCD under both RCP4.5 and RCP8.5 (Fig. 2a)

Summary

Introduction

The Mediterranean basin is the richest biodiversity region in Europe and a global hotspot of biological diversity (Myers et al 2000). The Mediterranean region is considered a climate change global hotspot (Giorgi 2006). Temperatures in the Mediterranean basin have increased by * 1.3 °C relative to the 1880–1920 period, compared with an increase of * 0.85 °C globally (Guiot and Cramer 2016) posing challenges to adaptation policies in the Mediterranean region. Mediterranean ecosystems are sensitive to changes in water availability, the lower bound of precipitation of the Mediterranean climate type limits with the upper bound of the arid climate type (Hantel 1989; Kottek et al 2006; Peel et al 2007). Spatial shifts of the Mediterranean climate affect the availability and distribution of suitable habitats for wild species, contributing to reductions in endemic species range sizes (Benito Garzon et al 2008; Keenan et al 2011; Maiorano et al 2013; Thuiller et al 2005)

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