E. Kostopoulou

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.

Study of CO surface pollution in Europe based on observations and nested-grid applications of GEOS-CHEM global chemical transport model.

Carbon monoxide (CO) is studied over Europe for 2001 using measurements from 31 rural-background stations and the nested-grid application of the global CTM GEOS-CHEM. The model reveals lowest (highest) biases in warm (cold) periods, tracking observations in most cases more closely than the global model. The role of CO production and destruction processes and the atmospheric conditions are investigated. A rotated Principal Component Analysis is applied to all stations, based on daily CO modelled concentrations in 2001, yielding three principal components (PCs) with stations of common characteristics. CO concentrations are studied for these groups in relation to the circulation patterns prevailing over Europe in 2001, at mean sea level and 850 hPa. The nested-grid model improves results in comparison to those calculated by the global model by up to ∼22% for first principal component subregion, where emissions are high and elevation is low. Improvement reaches∼17 and∼7%, respectively, for second and third principal component subregions, where emissions are lower and altitudes are higher. Better performance is achieved for patterns associated with westerly flow, whereas poor skills are revealed during stagnant conditions. During pollution events, the nesting model’s ability in capturing CO surface concentrations improves by up to ∼40% in comparison to the global simulation.

Temporal and Spatial Trends of the Standardized Precipitation Index (SPI) in Greece Using Observations and Output from Regional Climate Models

Water scarcity is becoming a serious threat, which may have negative environmental and socioeconomic impacts. Increases in the projected global temperature and changes in regional distribution and intensity of precipitation may alter the frequency, severity and duration of droughts. In this study, we use the Standardized Precipitation Index to identify drought events in the present and future climate. The index is initially calculated using data from meteorological stations of the Hellenic observational network, and subsequently using output from three regional climate models. The period of 1971–2000 is chosen as present climate and the future climate conditions are studied using the model timeseries up to 2100. The present-period was divided into two sub-periods and significant drought events were identified over the recent period of 1989–2000. Overall, we found that intense droughts occurred in continental Greece, whereas the islands, including Crete, experienced milder drought episodes. The years 1989 and 2000 were the driest on record for Greece, resulting in serious consequences for both urban and rural areas. The 21st Century projections did not suggest radical changes in the region’s rainfall patterns, although potentially intense drought events are expected to increase in the western parts of the country.

European CO budget and links with synoptic circulation based on GEOS-CHEM model simulations

The European carbon monoxide (CO) budget is studied in relation to the synoptic circulation throughout 2001, using the nested-grid configuration of the GEOS-CHEM global model and CO measurements from 31 rural background stations. To meet the aims of this study, a seasonal circulation type (CT) classification is developed for the Northern Hemisphere based on mean sea-level pressure (SLP) fields, as well as two upper atmospheric levels, over a 60-yr period. The highest contribution to the European surface CO concentrations is attributed to regional anthropogenic sources (up to ~80%), which become more important under the prevalence of anticyclonic circulation conditions. The corresponding contribution of the long-range transport (LRT) from North America (up to 18%) and Asia (up to 20%) is found highest (lowest) in winter and spring (summer and autumn). The transport of the CO towards Europe in winter is more intense under cyclonic circulation, while both cyclonic and anticyclonic patterns favour LRT during other seasons. Occasionally (mainly in winter and spring), LRT contribution is higher than the regional one (up to 45%). In the free troposphere, the LRT contribution increases, with the largest impact originating from Asia. This flow is favoured by the intense easterly circulation in summer, contributing up to 30% in the Eastern Mediterranean during this season. On the other hand, the regional contribution in the upper levels decreases to 22%. The contribution of CO chemical production is significant for the European CO budget at all levels and seasons, exceeding 50% in the free troposphere during summer.

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.

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.

Physical and Socio-economic Indicators

A set of physical and social indicators relevant to each Mediterranean case study has been developed within the context of the CIRCE case studies integrating framework. This framework approach provides a systematic means of structuring indicator selection and helps to provide a scientific basis for the assessment of climate-related impacts and vulnerability. A detailed set of criteria was developed to select and refine indicators through an iterative process of review and consultation. Indicators represent key issues related to climate variability and change for each of the case-study locations. Seven key indicator themes are identified: climate and atmosphere; marine and coastal systems; terrestrial ecosystems and biodiversity; freshwater systems; agriculture and forestry; human health and well being; and, the economy. A number of core indicators are common to all case studies (for identifying common/disparate trends), others are common across generic case studies (urban, rural, coastal), and some are case-study specific. Data and methodological challenges in the indicator assessment included: data availability and quality limitations; distinguishing impacts from vulnerabilities, and climate from non-climate influences; and, identifying thresholds and coping ranges. Despite these difficulties, the selected set of indicators proved a useful and accessible tool for monitoring trends and portraying key information to regional stakeholders.