In Central Europe, river flooding has been recently recognized as a major hazard, in particular after the 1997 Odra /Oder flood, the 2001 Vistula flood, and the most destructive 2002 deluge on the Labe/Elbe. Major recent floods in central Europe are put in perspective and their common elements are identified. Having observed that flood risk and vulnerability are likely to have grown in many areas, one is curious to understand the reasons for growth. These can be sought in socio-economic domain (humans encroaching into floodplain areas), terrestrial systems (land-cover changes -urbanization, deforestation, reduction of wetlands, river regulation), and climate system. The atmospheric capacity to absorb moisture, its potential water content, and thus potential for intense precipitation, are likely to increase in a warmer climate. The changes in intense precipitation and high flows are examined, based on observations and projections. Study of projected changes in intense precipitation, using climate models, for several areas of central Europe, and in particular, for drainage basins of the upper Labe/Elbe, Odra/Oder, and Vistula is reported. Significant changes have been identified between future projections and the reference period, of relevance to flood hazard in areas, which have experienced severe recent floodings.

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The surface warming has been widespread over the entire globe. Central Europe, including Poland, is not an exception. Global temperature increases are accompanied by changes in other climatic variables. Climate change in Poland manifests itself also as change in annual sums of precipitation. They have been slightly growing but, what is more important, seasonal and monthly distributions of precipitation have been also changing. The most visible increases have been observed during colder half-year, especially in March. A decreasing contribution of summer precipitation total (June-August) to the annual total is observed. Climate projections for Poland predict further warming and continuation of already observed changes in the quantity of precipitation as well as its spatial and seasonal distribution.

Abstract. Multi-model ensemble climate projections in the ENSEMBLES Project of the EU allowed the authors to quantify selected extreme-weather indices for Poland, of importance to climate impacts on systems and sectors. Among indices were: number of days in a year with high value of the heat index; with high maximum and minimum temperatures; length of vegetation period; and number of consecutive dry days. Agricultural, hydrological, and human health indices were applied to evaluate the changing risk of weather extremes in Poland in three sectors. To achieve this, model-based simulations were compared for two time horizons, a century apart, i.e., 1961-1990 and 2061-2090. Climate changes, and in particular increases in temperature and changes in rainfall, have strong impacts on agriculture via weather extremes -droughts and heat waves. The crop yield depends particularly on water availability in the plant development phase. To estimate the changes in present and future yield of two crops important for Polish agriculture i.e., potatoes and wheat, some simple empirical models were used. For these crops, decrease of yield is projected for most of the country, with national means of yield change being: −2.175 t/ha for potatoes and -0.539 t/ha for wheat. Already now, in most of Poland, evapotranspiration exceeds precipitation during summer, hence the water storage (in surface water bodies, soil and ground) decreases. Summer precipitation deficit is projected to increase considerably in the future. The additional water supplies (above precipitation) needed to use the agro-potential of the environment would increase by half. Analysis of water balance components (now and in the projected future) can corroborate such conclusions. As regards climate and health, a composite index, proposed in this paper, is a product of the number of senior discomfort days Correspondence to: M. Szwed (mszwed@man.poznan.pl) and the number of seniors (aged 65+). The value of this index is projected to increase over 8-fold during 100 years. This is an effect of both increase in the number of seniors (over twofold) and the number of senior-discomfort days (nearly fourfold).

There is a strong inter-annual and inter-decadal variability in time series of flood-related variables, such as intense precipitation, high river discharge, flood magnitude, and flood loss at a range of spatial scales. Perhaps part of this variability is random or chaotic, but it is quite natural to seek driving factors, in a statistical sense. It is likely that climate variability (atmosphere–ocean oscillation) track plays an important role in the interpretation of the variability of flood-related characteristics, globally and, even more so, in several regions. The aim of this review paper is to create an inventory of information on spatially and temporally organized links of various climate-variability drivers with variability of characteristics of water abundance reported in scientific literature for a range of scales, from global to local. The climate variability indices examined in this paper are: El Niño-Southern Oscillations (ENSO), North Atlantic Oscillations (NAO), Atlantic Multi-decadal Oscillation (AMO), and Pacific Decadal Oscillations (PDO). A meta-analysis of results from many studies reported in scientific literature was carried out. The published results were collected and classified into categories after regions, climate variability modes, as well as flood-related variables: precipitation, river flow, and flood losses.

On the basis of temperature observations at 60 meteorological stations in Poland, changes in the indices associated with the presence of extremely high air temperatures were examined. Indices associated with heat waves, such as the number of hot days (T max ≥30°C) in the summer months (June, July, August) and beyond the summer months (May, September), the number of extremely hot days (T max ≥35°C), the duration of the longest hot spell in the year, as well as the number of tropical nights (T min ≤20°C) were calculated. Spatial distribution of change rate in days per decade for the studied indices as well as the significance level of the observed trends is illustrated. Also current values of the studied indices (for 1991-2013) are examined and compared with the reference period, . For eight of 11 analysed indexes, increase has been detected in last decades with the help of the Mann-Kendall test at a significance level ≥0.05 or better, for a large group of stations. Statistically significant increases of the number of hot days in summer, the number of tropical nights in a year, and duration of the longest hot spell in summer were found for more than half of the stations. Distinct changes in the duration of heat waves were also noted. In 1961-1990, the longest hot spell lasted for 10 days while in 1991-2013, there were many hot spells longer than that, while the longest hot spell recorded in this period lasted for 17 days. Beyond summer, changes in the number of hot days were smaller. In May, a statistically significant increase was recorded for only three stations, while in September the downward trend was dominating and for eight stations it was statistically significant.

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The aim of this study was to estimate a likely number of additional fatalities in ten largest cities in Poland, recorded during heat waves in particularly hot summer seasons. In the period of 1989-2012, for which data on mortality were available, the most intense, long-lasting, summer heat waves occurred in 1992, 1994, 2006, and 2010. The numbers of fatalities in these years were compared to the numbers of fatalities in reference periods. These calculations were undertaken for days during heat waves and also for a longer interval including next 30 days after the end of the last sub-wave. An increase of mortality risk for people over 65 years of age and for those affected with cardiovascular diseases was noted. The total number of additional fatalities in ten largest cities in Poland could have exceeded 1070 in 1994. During the hottest days in the analyzed period, in some cities, the number of fatalities was more than three times higher than the mean value for the reference period. The results indicate that the increase of mortality during heat waves is a serious threat in Poland already in the present climate and will be even more severe in a warming climate.