Vol. 121, No. 4 * Pages 329–477 * October - December 2017

The latest reanalysis at the European Centre for Medium-Range Weather Forecasts is the ERA5 system, which is produced in the framework of the European Union’s Copernicus Climate Change Service. ERA5 is primarily going to cover the satellite era, i.e. 1979 to near real-time and will be publicly available for the users during 2018. The present article provides information about the observation usage of ERA5 together with an impact assessment of the assimilated data. Though all this is based on some test (scout) ERA5 experiments, however, they are providing a good overview of the evolution of the Global Observing System. The impact assessment is based on the Degree of Freedom to Signal adjoint diagnostic tool. There is a continuous data amount increase from the beginning of the ERA5 period, which is reaching more than 30 times of the assimilated data amount today than that of the 1979s. The data increase is mostly attributed to the satellite measurements, particularly lately to the hyper-spectral infrared observations. Though at every period the satellite data amounts are larger than that of the conventional observations, their impact is not getting larger until the late 1980s. At the same time the per observation impact of the conventional observations always remain larger than the satellite ones, which means that the conventional observations, though small in quantity, still remain essential ingredients of the Global Observing System.

Climate change impacts determine the long term development possibilities in Hungary. Due to the different vulnerability and adaptive capacity of various regions, the impacts and problems should also be handled in a differentiated way. The key areas of climate safe planning are: water safety, food security, human health security, safety of infrastructure, energy security, natural environment. Successful adaptation to climate change is inconceivable without having a sound knowledge of the impacts of climate change. The National Adaptation Geo-information System (NAGiS) may be used by national, regional, and local decision makers and stakeholders. It provides information on the climate status of the country, on the impacts of strategic risks connected to climate change and other long-term natural resource management issues, and on the correspondent adaptation possibilities, based on indicators, analyses, and impact studies. Data layers of NAGiS were elaborated by the Geological and Geophysical Institute of Hungary and partner projects funded by the Adaptation to Climate Change programme of the EEA Grants. The main parts of the NAGiS are a map-visualization system with 650 data layers; a database containing the calculation results based on modeling (GeoDat with 910 data layers); and a meta-database to help finding relevant data. NAGiS can be a useful tool for climate safe planning, analyzing, decision-support activities in governmental strategic planning; or for municipalities in spatial planning, settlement planning, organizing public services. It can be used in climate policy, energy policy planning, transport, and energy infrastructure design and numerous other fields. The further development of NAGiS is financed by the Environmental and Energy Efficiency Operative Programme. Between 2016 and 2018, the project will elaborate a decision support toolbox for underpinning policy and municipal adaptation measures, based on the development of the databases, methodologies, and evaluation modules of NAGiS.

Extreme weather conditions have caused difficulties in the Hungarian drinking water management many times in the past. High demand for drinking water in dry summer periods and the accompanying reduction in water resources lead to insufficiency in the availability of a number of water supplies, therefore causing limitations in water access. In some other cases, as a result of excessive precipitation, floods and flash floods evolved over karstic areas, and several water supplies had to be excluded from operation in order to avoid the risk of infections.
The expected increase in the number of extreme weather conditions and further possible changes in future climate necessitates the analysis of the vulnerability of drinking water resources to climate change. Since 95% of the total drinking water supply in Hungary originates from subsurface layers, significance of groundwater resources is outstanding.
Our work was carried out in the frames of the NAGiS (National Adaptation Geo-information System) project with the aim to devise a methodology for the study and determination of the vulnerability of drinking water supplies to climate. Methods have been chosen according to the CIVAS (Climate Impact and Vulnerability Assessment Scheme) model that has been developed in the frame of the international climate research project CLAVIER (Climate Change and Variability: Impact on Central and Eastern Europe). The CIVAS model, being based on the combined evaluation of exposure, sensitivity, impact, adaptability, and vulnerability provides a unified methodical scheme to quantitative climatic impact assessment.
The investigation involves the analyses of climatic parameters primarily influencing drinking water supplies and hydrogeological characteristics of the geological media that significantly determines vulnerability. Apart from the expected environmental changes, societal and economic processes have also been taken into account. Climate vulnerability has been determined on the basis of the distribution and categorization of the chosen indicators.
Further effects, independent of climate change and caused by anthropogenic activity, result in similar phenomena. It is often difficult to differentiate between natural and anthropogenic effects that occur simultaneously; therefore, anthropogenic activity is necessary to be taken into account.
In the analyses we used data of two different climate models covering two separate future time periods. Results on the basis of both climate model projections suggest that a considerable number of regions in the area under investigation appear to be vulnerable to climate change to a certain extent, and vulnerability intensifies to the end of the 21st century.

Climate change is expected to exert considerable influence on natural ecosystems all over the world, though not all ecosystems are equally vulnerable to the changes. In this paper, an assessment framework of vulnerability of natural habitats to future climate change is presented, examining Hungary, Central Eastern Europe as a case study. A climate change impact, adaptation and vulnerability (CCIAV) assessment following IPCC traditions was applied, which operationalizes the concepts of exposure, sensitivity, potential impact, adaptive capacity, and vulnerability for natural ecosystems. Potential impact was quantified for the periods 2021–2050 and 2071–2100 based on regional climate models ALADIN-Climate and RegCM. Although the potential impact of future climate change was predominantly negative on the most climate sensitive forested habitat types of Hungary, for some of the grassland types we experienced positive predicted responses. Loess steppes and annual saline vegetation may thus partially benefit from climate change. The most climate vulnerable Hungarian regions are the Transdanubia (West Hungary) and the Northern Mountains (North Hungary) in terms of natural vegetation.

Several natural habitats are expected to be sensitive to climate, and their vulnerability to future climate change can be further increased by their insufficient capacity to adapt to the changes. Therefore, it is increasingly pressing to set up methodologies for assessing sensitivity and adaptive capacity of natural ecosystems for enhancing detailed climate change impact, adaptation, and vulnerability assessments. In this paper, we first provide a methodology to quantify the sensitivity of a natural habitat based on habitat distribution models. Next, we selected the 12 most climate sensitive habitats of Hungary as a case study. We also developed a composite adaptive capacity index, which was applied to the selected habitats and used as an input in the climate change impact, adaptation, and vulnerability assessment described. Our adaptive capacity index consists of three main components describing the naturalness, diversity, and connectivity of the studied natural habitats. According to our results, adaptive capacity of the climate sensitive habitats of Hungary is generally lower than it needs to be to cope with the predicted climate change of the 21st century.

It is a well-known fact that the characteristics and frequency of different hydrological processes (particularly the extremes – both droughts and floods) are definitely sensitive to climate change. Since extreme hydrological conditions often result in severe socio-economic impacts, it is essential to estimate reliable future tendencies, for which cooperation of experts in hydrology and climate modeling is a key step. In this study, the DIWA hydrological model is applied for the Upper Tisza Basin; the necessary meteorological time series are provided by the RegCM4 regional climate model simulation and the CARPATCLIM dataset. The calibrated DIWA model is run for the past and two future time periods. The comparison of the runoff characteristics concludes that an increase in winter and a decrease in summer are projected in the target watershed area.

This research focuses on the objective assessment of the pyrological regime in climate change conditions. The present state (1981–2010) of climatic characteristics determining the natural fire danger in Ukraine is investigated. For all physicogeographical zones, the change in the pyrological regime, its significance throughout the current climatic period were estimated. Since the beginning of the 21st century, there has been an increasing tendency in fire danger. It resulted in increasing number of forest fires and theirs areas. In most regions of Ukraine, authenticity of such changes is 90–99%.
The impact of climate change on the number and area of forest fires in the country (e.g., in the Kherson region) is discussed. The article presents the quantitative relationships of the level of fire danger in the region with the thermal regime, humidity and wind regimes. The decisive influence of air temperature on the degree of natural fire danger is proved. The effect is most marked by the area of fires and much less by their numbers.
Possible changes of climatic characteristics and extreme weather conditions in Ukraine in 2021–2050 relative to the current climatic period for the scenario SRES A1B and their impact on forest fires were found.