János Mika

In many regions, water availability influences grape yield fluctuations more than thermal conditions. This study analyzes dryness indices calculated from observed and simulated RCM data to establish statistical relationships with observed yield data, considered an indicator of food safety. Five dryness indices were analyzed: the number of days without rain, the maximum number of consecutive dry days, climatic water balance, dryness index, and vineyard water indicator. These indices were analyzed for three periods: 1986–2005 (recent past), 2016–2035 (near future) and 2081–2100 (distant future). After this analysis, quadratic regression connections were established between the indices and available wine grape yields in the 22 wine regions of Hungary for 2005–2021 without information on grape varieties and for 2017–2021 with data on grape varieties. Linear agro-technological trends were extracted from these wine grape yield series, whereas the residuals exhibited significant quadratic regression in slightly over 50% of the indices and regions, according to the F-test for the 17 year series. For the short series, these proportions are 29 and 27% for the selected seven white and seven red wine grapes. According to the most significant quadratic regressions, combined with the projected dryness indices, we can expect less average yields with higher interannual variability in the future.

Daily Peczely circulation types are investigated over 140 years (1881–2020). After presenting monthly mean frequencies and durations of the 13 circulation types, two further questions are investigated: (i) How do the circulation types influence local weather extremes?; (ii) Are there significant trends in the frequency of the original and the grouped circulation types in the recent monotonically warming 50 year period (1971–2020)? The answers are as follows: (i) Four local weather extremes were investigated in nine grid-points of the Pannonian Basin and analyzed in the central months of the seasons. It was established that high precipitation and wind maxima occur in almost all circulation types and months, whereas for both high temperature maxima and low temperature minima, there are six circulation types, where no extremity occurred in one, two, or three investigated months. (ii) In the last 50 years, 37% of the linear seasonal frequency trends have been significant. However, these trends are rarely significant in the shorter monotonously warming (1911–1940) and cooling (1941–1970) 30-year periods. Therefore, the significant trends of the last 50 years are unlikely to be the direct consequences of the monotonous hemispherical warming. Since these hemispherical temperature trends are most likely caused by different sets of physical reasons, the reality of the presented circulation frequency trends needs to be validated by climate models.

Tanulmányunk lényege két szakértői összesítés egyfelől arról, hogy az időjárási szélsőségek, másfelől a hazánkban várható éghajlatváltozás milyen hatással vannak a címben jelzett három tájtényezőre, azaz a hidrológia és vízkezelés, a természetes ökoszisztémák, valamint a mezőgazdaság és élelmiszer-ellátás folyamataira. Ezt a két, egyenként 12, illetve 9 sort és mindkétszer három-három oszlopot számláló táblázatot annak a kérdésnek a tisztázása követi, hogy mit mondhatunk a szélsőségek és a klímaváltozás kapcsolatáról. Ez utóbbi összesítés alapján megállapíthatjuk, hogy az időjárási szélsőségek nem azért veszélyesek, mert egyöntetűen fokozódnak, mert ez nem áll fenn, hanem azért mert rendszeresen bekövetkeznek.