P. Hadjinicolaou

Climate change and impacts in the Eastern Mediterranean and the Middle East.

The Eastern Mediterranean and the Middle East (EMME) are likely to be greatly affected by climate change, associated with increases in the frequency and intensity of droughts and hot weather conditions. Since the region is diverse and extreme climate conditions already common, the impacts will be disproportional. We have analyzed long-term meteorological datasets along with regional climate model projections for the 21st century, based on the intermediate IPCC SRES scenario A1B. This suggests a continual, gradual and relatively strong warming of about 3.5–7°C between the 1961–1990 reference period and the period 2070–2099. Daytime maximum temperatures appear to increase most rapidly in the northern part of the region, i.e. the Balkan Peninsula and Turkey. Hot summer conditions that rarely occurred in the reference period may become the norm by the middle and the end of the 21st century. Projected precipitation changes are quite variable. Annual precipitation is expected to decrease in the southern Europe – Turkey region and the Levant, whereas in the Arabian Gulf area it may increase. In the former region rainfall is actually expected to increase in winter, while decreasing in spring and summer, with a substantial increase of the number of days without rainfall. Anticipated regional impacts of climate change include heat stress, associated with poor air quality in the urban environment, and increasing scarcity of fresh water in the Levant.

Model projected heat extremes and air pollution in the eastern Mediterranean and Middle East in the twenty-first century

The eastern Mediterranean and Middle East, a region with diverse socioeconomic and cultural identities, is exposed to strong climatic gradients between its temperate north and arid south. Model projections of the twenty-first century indicate increasing hot weather extremes and decreasing rainfall. We present model results, which suggest that across the Balkan Peninsula and Turkey climate change is particularly rapid, and especially summer temperatures are expected to increase strongly. Temperature rise can be amplified by the depletion of soil moisture, which limits evaporative cooling, prompted by the waning of large-scale weather systems that generate rain. Very hot summers that occurred only rarely in the recent past are projected to become common by the middle and the end of the century. Throughout the region, the annual number of heat wave days may increase drastically. Furthermore, conditions in the region are conducive for photochemical air pollution. Our model projections suggest strongly increasing ozone formation, a confounding health risk factor particularly in urban areas. This adds to the high concentrations of aerosol particles from natural (desert dust) and anthropogenic sources. The heat extremes may have strong impacts, especially in the Middle East where environmental stresses are plentiful.

Evaluation of interpolation techniques for the creation of gridded daily precipitation (1 × 1 km2); Cyprus, 1980–2010

High-resolution gridded daily data sets are essential for natural resource management and the analyses of climate changes and their effects. This study aims to evaluate the performance of 15 simple or complex interpolation techniques in reproducing daily precipitation at a resolution of 1 km2 over topographically complex areas. Methods are tested considering two different sets of observation densities and different rainfall amounts. We used rainfall data that were recorded at 74 and 145 observational stations, respectively, spread over the 5760 km2 of the Republic of Cyprus, in the Eastern Mediterranean. Regression analyses utilizing geographical copredictors and neighboring interpolation techniques were evaluated both in isolation and combined. Linear multiple regression (LMR) and geographically weighted regression methods (GWR) were tested. These included a step-wise selection of covariables, as well as inverse distance weighting (IDW), kriging, and 3D-thin plate splines (TPS). The relative rank of the different techniques changes with different station density and rainfall amounts. Our results indicate that TPS performs well for low station density and large-scale events and also when coupled with regression models. It performs poorly for high station density. The opposite is observed when using IDW. Simple IDW performs best for local events, while a combination of step-wise GWR and IDW proves to be the best method for large-scale events and high station density. This study indicates that the use of step-wise regression with a variable set of geographic parameters can improve the interpolation of large-scale events because it facilitates the representation of local climate dynamics.

Modelling nitrogen in the Yeşilirmak River catchment in Northern Turkey: Impacts of future climate and environmental change and implications for nutrient management

Recent research in catchments of rapidly developing countries such as Brazil and China suggests that many catchments of the developing world are already showing signs of nitrogen pollution reminiscent of past experiences in developed countries. This paper looks at both the individual and combined effects of future climate change and other likely environmental changes on in-stream nitrate concentrations in a catchment in Northern Turkey. A model chain comprised of simulated future temperature and precipitation from a Regional Circulation Model (RCM), a conceptual hydrological model (HBV) and a widely tested integrated catchment nitrogen model (INCA-N) is used to model future changes in nitrate concentrations. Two future periods (2021-2050 and 2069-2098) are compared to the 1961-1990 baseline period in order to assess the effectiveness of several possible interventions available to catchment authorities. The simulations show that in the urbanised part of the catchment, the effects of climate change and other environmental changes act in the same direction, leading to peak nitrate concentrations of 7.5 mg N/l for the 2069-2098 period, which corresponds to a doubling of the baseline values. Testing different available policy options reveals that the installation of wastewater treatment works (WWTWs) in all major settlements of the catchment could ensure nitrate levels are kept at near their baseline values for the 2021-2050 period. Nevertheless, a combination of measures including WWTWs, meadow creation, international agreements to reduce atmospheric N concentrations and controls on agricultural practises will be required for 2069-2098. The approach presented in this article could be employed in order to anticipate future pollution problems and to test appropriate solutions, some of which will necessitate international co-operation, in other catchments around the world.

Assessment of climate change extremes over the Eastern Mediterranean and Middle East region using the Hadley Centre PRECIS Regional Climate Model

Regional-scale climate projections based on the Hadley Centre PRECIS climate model have been used to assess future changes of rainfall and temperature extremes in the Eastern Mediterranean and Middle East region (EMME). Model output was evaluated by comparison with stations located in the western part of the study region. The area of interest is particularly vulnerable to extreme climate events such as droughts and heat waves. Extreme climate indices were calculated for three future 30-year time slices and compared to the reference period (1961–1990). Overall, model projections for the different future time periods reveal a continual and gradual future warming trend while conditions characterised as exceptional hot summers during the control period are found to become “typical” by the end of the twenty-first century. In agreement with previous studies, our results point to a drying tendency in the study domain, and indicate a decline in annual precipitation by 5–30% by the end of the twenty-first century relative to the reference period. The model projects larger precipitation reductions in the northern EMME, while the number of days with heavy precipitation is expected to decrease in the high-elevation areas of the region.

Enhanced near-surface ozone under heatwave conditions in a Mediterranean island

Near-surface ozone is enhanced under particular chemical reactions and physical processes. This study showed the seasonal variation of near-surface ozone in Nicosia, Cyprus and focused in summers when the highest ozone levels were noted using a seven year hourly dataset from 2007 to 2014. The originality of this study is that it examines how ozone levels changed under heatwave conditions (defined as 4 consecutive days with daily maximum temperature over 39 °C) with emphasis on specific air quality and meteorological parameters with respect to non-heatwave summer conditions. The influencing parameters had a medium-strong positive correlation of ozone with temperature, UVA and UVB at daytime which increased by about 35% under heatwave conditions. The analysis of the wind pattern showed a small decrease of wind speed during heatwaves leading to stagnant weather conditions, but also revealed a steady diurnal cycle of wind speed reaching a peak at noon, when the highest ozone levels were noted. The negative correlation of NOx budget with ozone was further increased under heatwave conditions leading to steeper lows of ozone in the morning. In summary, this research encourages further analysis into the persistent weather conditions prevalent during HWs stimulating ozone formation for higher temperatures.

High-Resolution Simulations of Recent Past Extreme Precipitation Events Over Cyprus

Besides global warming, climate change is expected to influence precipitation amounts and distribution. While global climate projections typically address the long-term, and weather forecasts the short to medium range up to weeks, decision-makers and stakeholders also need guidance on inter-annual to decadal time scales. In this context, the BINGO H2020 project aims both at reducing the uncertainty of near-term climate predictions and developing response strategies. One of the main objectives is to provide decadal predictions with a specific focus on extreme events. The projected precipitation distribution will eventually drive hydrological impact models. In this study we present the dynamical downscaling of the ERA-Interim (EI) dataset for validation purposes. Extreme rainfall periods were identified and simulated in very high horizontal resolution (up to 4 km) using the WRF model. In a later stage, future periods of extreme precipitation or droughts will be identified from the output of the MiKlip decadal prediction system and will be downscaled in order to assess the climate change impact on water resources in Cyprus. Our simulations seem to capture reasonably well rainfall during an extreme event (November 2014) over the eastern Mediterranean. It is also found to improve the EI precipitation that was found to be underestimated.

Land-atmosphere coupling: The feedback of soil moisture on surface temperature in the Eastern Mediterranean and Middle East

Future climate projections suggest that beside changes in mean climate there will also be shifts in extremes (i.e. droughts, floods, heat waves), partly due to enhanced interannual variability. In the already warm Eastern Mediterranean and Middle East (EMME) it is crucial to investigate possible changes in extreme temperature and try to understand all the relative mechanisms and feedbacks that cause or intensify severe heat events. One of these feedbacks is the soil moisture – atmosphere interaction. In general, when there is no sufficient water content in the soil, evapotranspiration is low, leading to higher near surface air temperatures, due to less evaporative cooling. In the present study, we explore this interaction, for the summer season. We identify sub-regions sensitive to this feedback in the EMME domain using the classical hydrology framework which defines evapotranspiration regimes as a function of soil moisture and latent heat flux. Moreover, we use the correlation of temperature and evapotranspiration as a diagnostic of this coupling. The data used cover the period 1951–2099 and come from the Hadley Centre’s regional climate model PRECIS, driven by the A1B emissions scenario. Finally, we discuss possible alterations of the relationship between soil moisture and surface temperature throughout the twenty-first century.

Exploration of 12-km ERA-Interim Simulations from CORDEX Over the Levant

We investigate the performance of the 12-km horizontal resolution simulations that are increasingly becoming available from the CORDEX simulations, as part of the Phase I CORDEX regional climate model runs (which mainly contain climate downscaling simulations at a grid spacing of about 50 km). In this preliminary work we evaluate 12-km CORDEX simulations driven by the ERA-Interim re-analyses for the period 1980–2010 with a focus in the Levant, broadly defined as the region encompassing the eastern Mediterranean. The 12-km modelled climatology, variability and trends of temperature and precipitation are compared with station measurements from different locations in the region and their performance is assessed. Biases of a few degrees are assigned to the model while the inter-annual variability and longer-term trends is reproduced nicely.

Impacts of Climate Change Over the Eastern Mediterranean and Middle East Region Using the Hadley Centre PRECIS RCM

The Eastern Mediterranean and Middle East (EMME) region is a vulnerable region regarding global warming and therefore likely to be greatly affected by climate change and its associated impacts. This study uses daily climate projections based on the Hadley Centre PRECIS regional climate model (RCM) to assess climate change impacts in the Eastern Mediterranean and Middle East. The PRECIS RCM uses boundary and initial conditions from the HadCM3Q0 global climate model, employing the IPCC SRES A1B emission scenario. The control run represents the base period 1961–1990 and is used here as reference for comparison with future projections. We study the future period 2040–2069 specifically chosen for the needs of policy makers, so as to assist their planning in the mid-term future. Using daily PRECIS output, we examine climatic changes with the aim to identify regions in the study area that are likely to undergo significant changes in impact sectors, such as thermal comfort, energy demand, and agriculture. More specifically, vulnerable regions per sector of interest are identified, using appropriately constructed indices and impact models.