Extreme weather is in the attention focus of many scientists and managers during the last decades. The leading aspect of these phenomena investigations in the recent years is the risk of material and human losses and damage mitigation. Especially, the interest is with regard to effects of weather extremities on natural systems and social processes such as land use practices, water resources management, emergency management, and planning. The main objectives of the investigations are clarifying of spectrum, space and time regularities of extreme weather events occurring in Ukraine as well as their intensity, duration, daily and seasonal variation, spreading, recurrence in the regions, and their changes analyzed. Applying statistical and geographical space-time analyses, the main regularities of the extreme weather events' occurrence have been described as well as the trends and intensity of the extreme weather regime changes in Ukraine have been calculated and assessed.
The aim of this study consists in assessment of impact of change of thermal regime, air moisture and weather phenomena on quantity and area of forest fires in the northern part of the Black Sea Region of Ukraine, their possible changes and consequences by the middle of XXI century with regard to modern climatic period for SRESA1B scenario and setting of some proportion of uncertainty of these changes. The study of regional peculiarities of climate change was performed on the basis of daily meteorological observations over the period of 1961-2013 in the context of Kherson region. To assess impact of weather conditions on fire safety data on number of forest fires and their area in the region over 1996-2013 (about 4 000 cases of fire) were used. The study was carried out using regression and correlation analysis. Calculation projections of climate characteristics’ change resulting in forest fires was performed for the period of 2021-2050 with relation to modern climatic period (1981-2010) using the data of regional climate model REMO with resolution of 25 km initiated by ECHAM5 global model calculation. It was found that number and area of forest fires in the northern part of the Black Sea Region of Ukraine is largely dependent on thermal regime, moisture and wind regime. Influence of temperature appears to be decisive and affects area of fires rather than their number. For example, increase of annual / summer average air temperature by 1°C can lead to increase of average area of fire almost by 110% and 90% respectively and increase of number of days with atmospheric drought and heat (maximum temperature above 30°C) by 10 days can cause increase of average area of fires by 130% and 80%. At the same time air temperature in September and October has a significant impact on number of fires: increase of monthly average air temperature by 1°C can lead to increase of number of fires by 20%. Climate change analysis conducted in Kherson oblast resulted in finding that over the recent decades the region faced a significant change of thermal regime, moisture and wind regime, recurrence of weather phenomena affecting number and area of forest fires. These changes led to increase of fire risks in the region. Evaluation of possible changes of these characteristics by the middle of the XXI century showed that the under SRES A1B scenario the region might expect further increase of temperature throughout the year, growth of number of hot days and duration of sultry period. Since these processes are accompanied by increase of duration of dry period these changes will significantly affect fire risk increase – number of forest fires and their area by the middle of the XXI century in Kherson region may significantly grow. Obtained results can be used to develop plans for adaptation to climate change.
<p>The last decade proved to be the warmest in Ukraine for the whole period of instrumental weather observations. Recent and projected future warming will cause changes in the duration of climatic seasons in Ukraine with corresponding shifts in dates of their start and end.</p> <p>As specified by the Expert Team on Climate Change Detection and Indices, climatic seasons are determined as periods from the first day after the start of a year to the first date after 1 July when at least 6 consecutive days mean daily temperature (t) exceeds (drops under) different thresholds. We analysed four climatic periods: warm period (t>0<sup>o</sup>C), growing season (t>5<sup>o</sup>C), active vegetation (t>10<sup>o</sup>C), and summer season (t>15<sup>o</sup>C).</p> <p>To assess these projected changes bias-adjusted daily data of EuroCORDEX were used from 34 regional climate models for RCP4.5 and RCP8.5 scenarios for 3 future periods: near-term 2021-2040, mid-term 2041-2060 and far-term 2081-2100. Data of ensemble mean for two scenarios firstly were compared with E-Obs v20.0e results in the base period 1991-2010 and showed different biases for different climatic seasons, but very similar behaviour for both scenarios and both variables (length and start of climatic seasons). The least biases (< 0.5 days) were obtained for growing season, while biases reached -10 days for length of warm season and were within 1-3 days for other two seasons.</p> <p>In general by the end of the century, under the RCP4.5 scenario in Ukraine, all analysed climatic season lengths may be the same as in the middle of the century under the RCP8.5 scenario.</p> <p>By the end of the century, for the RCP8.5 scenario, the changes in the climatic seasons range from 40 to almost 70 days, increasing from east to west. As a result, in the coldest in Ukraine region winter is projected to last only from 10 to 30 days, and the vegetation will last throughout the year not only at the southern coast of the Black Sea but also the steppe part of the Crimea and some southern parts of Odesa region. There are almost no differences between scenarios for growing season length, start and end days in the near-term. The area with the longest growing season (from 240 to 260 days) will extend almost 200 km to the north. &#160;</p> <p>Under the RCP8.5 scenario, the length of active vegetation at the end of the century can range from 200 to 240 days, and in the Crimea and the south of Odesa region - 240-285 days, and summer length can vary from 140 days in the north to over half-year in the Crimea and southern Odesa. At the end of the 21<sup>st</sup> century, projected summer in Polissya will be as in the Crimea now - 140-160 days. Such climatic conditions were not observed in Ukraine previously. Increasing the length of the growing season and the period of active vegetation will strengthen the agro-climatic potential of Ukraine and contribute to obtaining higher yields of crops if corresponding measures in providing enough water supply will be implemented.</p>
<p>Climate change is one of the major challenges for future development in every country including Ukraine where actual warming already has impacted many sectors, population, and ecosystems. Recently, the International Initiative of Coordinated Downscaling Experiment for Europe (Euro-CORDEX) has provided RCM data for 0.1<sup>o</sup> grid. This detailed RCM projection dataset is an excellent basis for estimation of exposure and vulnerability to climate change of different objects and for updating projections for a new National Communication of Ukraine to UNFCCC as well as for Strategy of Ecological Safety and Adaptation to Climate Change in Ukraine.</p><p>The study is focused on the estimation of the essential and special climatic characteristics and their changes in the near future (2021-2040) as well as to the middle (2041-2050) and end (2081-2100) of the century over the base period 1991-2010 for three scenarios: RCP2.6, RCP4.5, and RCP8.5. We used bias-adjusted RCM data for daily maximum, mean, and minimum temperature and precipitation provided via ESGF web-portal. We applied a multi-model ensemble approach with further bias-correction by delta-method for multi-year monthly values of the essential characteristics as well as calculated climatic indices using a gridded observational dataset of E-Obs v.20.0e. Ensembles for RCP4.5 and RCP8.5 consisted of 34 RCMs while for RCP2.6 only data of 3 RCMs were available. That is why RCP2.6 is only indicative, while the other two scenarios results have a high confidence level and quartiles and percentiles of the ensemble range are estimated.</p><p>More consistent temporally and spatially results were obtained for temperature projections. Increases relative to the baseline were in the range of 0.5-1.5&#186;C for all the RCPs with a bit higher warming in the North of the country in 2021-2040. In 2041-2060, the increases were 1.0-2.0&#186;C under RCP2.6 and 1.5-2.5&#186;C under RCP8.5, with RCP4.5 in between. By the end of the century 2081-2100 the differences between scenarios became much pronounced: from 1-2&#186;C for RCP2.6 to 4-6&#186;C for RCP8.5.</p><p>Precipitation changes are much complex with high variability across the seasons and the territory. In winter precipitation tends to increase relative to the baseline in most of the country for all the RCPs. In early spring (March) there is a relative decline in the near-future period, especially in RCP2.6 and RCP8.5 but not in RCP4.5. In later periods the decline becomes less and in the higher RCPs, there is a relative increase. Later spring rainfall changes show a decline in RCP2.6 but an increase for the other RCPs. The summer months show a relative decline with all the higher RCPs getting drier over time. In the fall relative changes are mixed, with declines in some months and increases in others.</p><p>Based on these two essential climatic characteristics other important indices were calculated and analyzed: length of vegetation season, tropical nights, summer days, water deficit, aridity/humidity index, etc.</p><p>Obtained projections of climatic characteristics were(will be) used for further agriculture, forest, and human health impact assessments, that will be the basis for the development of adaptation measures to climate change in the frames of the National Adaptation Plan of Ukraine. &#160;</p>
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