The use ofdifferent high resolution climate models in Europe

One of the most urgent challenges to agrometeorological risk management in Europe today is timely adaptation to climate change effects, tte prerequisite for intelligent, effective and efficient adaptation of agriculture to climate change is a good understanding of regional impacts. Regional modelling of climate development provides the essential basis in this regard, tte use of different high resolution cli mate models linked to impact/crop models enables us to quantify the uncertainties of predictions and analyse how these uncertainties are transferred from the climate models into the crop models. Major scientific progress has been made in this field recently.

PRUDENCE was a recent EU project (PRUDENCE, 2005) using four Atmosphere General Circulation Models (AGCM) namely NCAR CCM3 (Italy), HadAM3H AGCM (United Kingdom), ECHAM AGCM (Germany) and eight Regional Climate Models (RCM), namely HIRHAM (Danmark), PROMES (Spain), ICTP RegCM (Italy), ARPEGE (France), CHRM (Switzerland), LM and CRCM-2 (Germany) and RCA (Sweden) to quantify the uncertainties associated with climate predictions and impacts of future climate changes on Europe. PRUDENCE is providing improved model representation of climate change scenarios by utilising high-resolution models (at spatial scales of -50 km) for current (1961-1990) and future (2071-2100) climate, characterising the level of confidence in these scenarios, and assessing the uncertainty resulting from model formulation. Future scenarios correspond to the IPCC A2 and B2 CO2 emissions (IPCC, 2001). For temperature, GCMs and RCMs behave similarly, except that GCMs exhibit a larger spread, tte differences between GCM and RCM precipitation responses for some regions are significant, tte spread of precipitation during summer period is larger for RCMs than for GCMs. For both, however, in terms of precipitation, the bias is twice as large as the response to climate change, when observed climate is used as a cross validation.

tte scenarios indicate that European regions undergo substantial warming in all seasons in a range of 1 - 4 °C (B2 scenario) and 2.5 - 5.5 °C (B2 scenario) by 2071-2100. Over Northern and Eastern Europe, the warming is stronger in winter, and the reverse happens over Western and Southern Europe with stronger increases in summer (IPCC, 2007). Within Europe, the warming is estimated to be greatest over western Russia and southern countries (Spain, Italy, Greece), and less pronounced along the Atlantic coastline.

Across all scenario simulations, the results agree on a general increase in winter precipitation in Northern and Central Europe and on a general decrease in summer precipitation in Central and Southern Europe, a bit smaller in central Scandinavia (Raisanen et al. 2004). Over all, there is an annual increase in Northern Europe and an annual decrease in Southern Europe. Increased Atlantic cyclonic activity could lead to stronger precipitation (up to 15-30 %) in winter over Western, Central and Northern Europe, and in response to anticyclonic circulation to reduced precipitation in winter over Southern Mediterranean regions (Giorgi et al. 2004). In summer, a blocking situation caused by enhanced anticyclonic circulation over the Northeastern Atlantic could lead to decreases in precipitation (up to 30-45 %) over Western and Central Europe and the Mediterranean. Precipitation changes for spring and autumn are less pronounced than for winter and summer.

Notable changes are also projected for temperature and precipitation extremes in Europe. According to IPCC (2007), yearly maximum temperature is expected to increase much more in Southern and Central than in Northern Europe. According to EEA (2004), cold winters, which occurred on average once every 10 years in the period from 1961 to 1990, are likely to become rare in Europe and will almost entirely disappear by 2080. In contrast, by 2080 nearly every summer in many parts of Europe is projected to be hotter than the 10 % hottest summers in the current climate (EEA, 2004). Under high emission scenarios every second summer in Europe will be as hot or even hotter than 2003 by the end of the 21st century (Goodess 2005). In southern Europe, these changes are projected to occur even earlier. Extreme daily precipitation will even increase in most of those areas where the mean annual precipitation decreases (Raisanen et al. 2004). Risk of drought is likely to increase in central and southern Europe.

Uncertainty in projections of future precipitation is larger in comparison with temperature, ttis applies particularly to regional precipitation patterns and seasonal distribution of precipitation. But it should be stated that scientific confidence in the ability of climate models to estimate future precipitation is steadily increasing (IPCC 2007).

Climate change poses many challenges to agrometeorological risk management in Europe today, since extreme weather events, such as hot spells, heavy storms, intense rainfall and droughts, can severely disrupt crop production all over Europe. Especially the precipitation reduction in central, eastern and southern Europe is expected to have severe effects, e.g. more frequent droughts, with considerable impacts on crop production and availability of water resources.

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