A multi-model, multi-scenario, and multi-domain analysis of regional climate projections for the Mediterranean

Abstract

Observation and model-based studies have identified the Mediterranean region as one of the most prominent climate change "hot-spots." Parts of this distinctive region are included in several Coordinated Regional Downscaling Experiment (CORDEX) domains such as those for Europe, Africa, the Mediterranean, and the Middle East/North Africa. In this study, we compile and analyze monthly temperature and precipitation fields derived from regional climate model simulations performed over different CORDEX domains at a spatial resolution of 50 km. This unique multi-model, multi-scenario, and multi-domain "super-ensemble" is used to update projected changes for the Mediterranean region. The statistical robustness and significance of the climate change signal is assessed. By considering information from more than one CORDEX domains, our analysis addresses an additional type of uncertainty that is often neglected and is related to the positioning of the regional climate model domain. CORDEX simulations suggest a general warming by the end of the century (between 1 and 5°C with respect to the 1986-2005 reference period), which is expected to be strongest during summer (up to 7°C). A general drying (between 10 and 40%) is also inferred for the Mediterranean. However, the projected precipitation change signal is less significant and less robust. The CORDEX ensemble corroborates the fact that the Mediterranean is already entering the 1.5°C climate warming era. It is expected to reach 2°C warming well within two decades, unless strong greenhouse gas concentration reductions are implemented. The southern part of the Mediterranean is expected to be impacted most strongly since the CORDEX ensemble suggests substantial combined warming and drying, particularly for pathways RCP4.5 and RCP8.5.

21st Century Projections of Extreme Precipitation Indicators for Cyprus

“…The presented results are in general agreement with other studies for the eastern Mediterranean [4][5][6][7], nevertheless, here we provide a higher level of detail for the region. Moreover, the range of changes for Cyprus, presented in the current study, is within the range of previous studies for the island, which are, however, driven by an outdated set of global climate models and scenarios.…”

“…Large multimodel and multiscenario ensembles are expected to add value and provide a more representative range of possible futures [7,49]. In this respect, downscaling of multiple global models and future pathways or scenarios are needed.…”

“…The broader region of the Mediterranean, and particularly the eastern part of the basin, is a well-known climate change hotspot [1,2]. According to most future scenarios and climate projections, a combined drying and warming is expected for the 21st century [3][4][5][6][7]. While the climate projections for temperature are quite robust and their signal is significant, this is not the case for precipitation, which is found to be mainly driven by internal climate variability [5,7].…”

Assessing Multidomain Overlaps and Grand Ensemble Generation in CORDEX Regional Projections

“…This knowledge gap is of particular relevance for vast regions of the world for which a number of RCM simulations coming from overlapping CORDEX domains are available (see Figure 1). One of these regions is the Mediterranean, a hot spot for climate change where projections indicate summer temperature increases of up to 7 K by the end of the century (Zittis et al, 2019) and a reduction of 10-40% in mean precipitation. The most comprehensive analyses of RCM projections over this region are those carried out by Giorgi and Lionello (2008)-who used CMIP3 and PRUDENCE results-and by Zittis et al (2019)-who used CMIP5 and CORDEX results.…”

“…One of these regions is the Mediterranean, a hot spot for climate change where projections indicate summer temperature increases of up to 7 K by the end of the century (Zittis et al, 2019) and a reduction of 10-40% in mean precipitation. The most comprehensive analyses of RCM projections over this region are those carried out by Giorgi and Lionello (2008)-who used CMIP3 and PRUDENCE results-and by Zittis et al (2019)-who used CMIP5 and CORDEX results. The latter considered a grand ensemble formed by all overlapping CORDEX domains over the target area trying to make the most of all available information.…”