10 Hydrological Impacts of Climate Changes in Romania
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the flood risk in these seasons [120, 122]. Regarding precipitation extremes, during
1961–2010, significant increasing trends were detected over large areas in both the
frequency of very wet days and maximum daily amount during autumn, and in the
maximum duration of dry spells, during summer [123].
The snow-related parameters recorded substantial changes in Romania in the last
decades. During the period 1961–2010, general decreasing trends were found in:
mean snow depths, number of days with snow cover, number of days with snowfall
and continuous snow cover duration. These changes are related mainly to the recent
warming and to the slight decrease in winter amounts of precipitation [125]. In the
previously mentioned period, the trend analysis of the data recorded at 104 w.s. in
Romania showed significant downward trends for the number of days with snow pack
at 40% of the stations, and for the mean snow depth, at 20% of the analyzed stations
[114]. The most dramatic change concerns the number of snowfall days, which tends
to decrease at 82% of the locations. The intra-Carpathian, western and northeastern
regions are the most affected by the changes in snow-related parameters.
During 1961–2007, upward trends in the annual reference evapotranspiration were
detected in almost 3/4 (72%) of the total of 57 w.s. investigated in Romania, of which
30% is statistically significant. The highest frequency of the positive trends, as well as
their absolute maximum magnitude were found during summer in almost the entire
country, while in autumn negative trends of the reference evapotranspiration were
identified at more than 80% of the locations (but only 20% are significant, mostly in
the southern half of the country) [115].
10.3.2 Climate Changes Projections
In order to estimate the future climate in Romania, several studies were made, based
on different climate models (both global and regional) and scenarios. Most of the
studies were conducted by researchers from the National Meteorological Administration, within European research programs/projects (e.g., ENSEMBLE, SEERISK,
ORIENTGATE, etc.).
It is worth noting that all scenarios used for Romania indicate an increase of mean
annual air temperature, with different intensities, depending on the time interval
and type of scenario considered. The magnitude of the warming varies all over the
year, with higher increases projected for summer and winter, and lower increases
for autumn [119, 122]. In summer, on the whole country, according to the RCP8.5
scenario, the temperature could rise during 2021–2050 by up to 3 °C (Fig. 10.4a)
and by up to 5 °C for 2061–2090 when compared to 1961–1990 (Fig. 10.4b).
Using Global Climate Models—GCMs (available in CMIP 3 and CMIP programs), as well as regional models (available in the EuroCORDEX program) and
based on simulations with 6 regional models of EuroCORDEX program (considering RCP 8.5 scenario), it was estimated that, for the 2021–2050 period relative to
1971–2000, the average air temperature will rise by up to 2.5 °C in winter, and by
up to 4.6–4.9 °C in summer. In winter, the warming is higher in extra-Carpathians
317
the flood risk in these seasons [120, 122]. Regarding precipitation extremes, during
1961–2010, significant increasing trends were detected over large areas in both the
frequency of very wet days and maximum daily amount during autumn, and in the
maximum duration of dry spells, during summer [123].
The snow-related parameters recorded substantial changes in Romania in the last
decades. During the period 1961–2010, general decreasing trends were found in:
mean snow depths, number of days with snow cover, number of days with snowfall
and continuous snow cover duration. These changes are related mainly to the recent
warming and to the slight decrease in winter amounts of precipitation [125]. In the
previously mentioned period, the trend analysis of the data recorded at 104 w.s. in
Romania showed significant downward trends for the number of days with snow pack
at 40% of the stations, and for the mean snow depth, at 20% of the analyzed stations
[114]. The most dramatic change concerns the number of snowfall days, which tends
to decrease at 82% of the locations. The intra-Carpathian, western and northeastern
regions are the most affected by the changes in snow-related parameters.
During 1961–2007, upward trends in the annual reference evapotranspiration were
detected in almost 3/4 (72%) of the total of 57 w.s. investigated in Romania, of which
30% is statistically significant. The highest frequency of the positive trends, as well as
their absolute maximum magnitude were found during summer in almost the entire
country, while in autumn negative trends of the reference evapotranspiration were
identified at more than 80% of the locations (but only 20% are significant, mostly in
the southern half of the country) [115].
10.3.2 Climate Changes Projections
In order to estimate the future climate in Romania, several studies were made, based
on different climate models (both global and regional) and scenarios. Most of the
studies were conducted by researchers from the National Meteorological Administration, within European research programs/projects (e.g., ENSEMBLE, SEERISK,
ORIENTGATE, etc.).
It is worth noting that all scenarios used for Romania indicate an increase of mean
annual air temperature, with different intensities, depending on the time interval
and type of scenario considered. The magnitude of the warming varies all over the
year, with higher increases projected for summer and winter, and lower increases
for autumn [119, 122]. In summer, on the whole country, according to the RCP8.5
scenario, the temperature could rise during 2021–2050 by up to 3 °C (Fig. 10.4a)
and by up to 5 °C for 2061–2090 when compared to 1961–1990 (Fig. 10.4b).
Using Global Climate Models—GCMs (available in CMIP 3 and CMIP programs), as well as regional models (available in the EuroCORDEX program) and
based on simulations with 6 regional models of EuroCORDEX program (considering RCP 8.5 scenario), it was estimated that, for the 2021–2050 period relative to
1971–2000, the average air temperature will rise by up to 2.5 °C in winter, and by
up to 4.6–4.9 °C in summer. In winter, the warming is higher in extra-Carpathians