209 CUPRINS

and Founda et al. [9]. Barnett et al. [1] have concluded that the most probable cause of
the observed warming of the atmosphere since 1970 is a combination of internally and
externally forced natural variability and anthropogenic sources.
The cumulative Tmax excess above certain threshold during heat waves and the
peak temperature are used to characterize heat waves in both compared countries and
their duration. According to Kyselý [14], the cumulative Tmax excess (ΣΔTmax >30)
is probably the most appropriate variable to characterize the severity of heat waves.
The period of June–July–August was chosen since heat waves both in CR and RM
occur during these three months.
Regarding the analysis of heat waves in the middle part of Polabí (CR), we can
mentioned, that the absolute maximum temperatures were recorded in Hradec Králové
on July 30, 1994 (Tmax = 37.8 °C), i.e. in that summer when the longest and most
severe heat wave has been recorded since 1961 (Table 4a). However, on the whole
territory of the Czech Republic, the absolute maximum air temperature was observed
on the 27 th of July, 1983 (40.2°C) at the Prague-Uhrineves weather station [14].
The 2006 summer heat waves with the highest number of tropical days and peak of
maximum heat wave temperature reached 36.1 °C (the highest summer temperature in
the Czech Republic). The longest heat wave in the summer of 2006 started on the 12 th
of June and lasted to the 17 th of June, and after a break, it resumed on the 6 th of July
and lasted until the 13 th of July.
In Moldova, the longest cumulative heat wave duration (that lasted totally 24 days
with very short breaks of 1-2 days), as well as the highest number of heat waves (three)
were recorded in 2007 (Table 4b). This was followed by heat waves recorded in 1992
(13 days) and in 2002 and 1999 with a total heat wave duration of 12 days. The most
severe heat wave in Chişinău (as measured in terms of the cumulative Tmax excess
above 30 °C) was recorded in 2007 (127.2 °C) and heat waves that were by more than
2.5 times less severe occurred in 2008 and 2002 (~47 °C). In Moldova, the frequency of
heat waves has increased by four times, their duration and severity (by 5 and 10 times
respectively) simultaneously increasing.
An overwhelming percentage (76.2%) of the heat waves in RM during the whole
period has been observed the last two decades. Such comparative analysis of two
periods (1961-1990 and 1991-2009) leads to disappointing conclusions about the drastic
change in the nature of heat episode manifestations over the past 20 years. Taking into
account the hot summer climate of the country, the continuation of this tendency could
result in very negative consequences for all biological systems, primarily affecting the
most vulnerable components – agriculture and human health. A catastrophic drought
that occurred in 2007, led to disastrous consequences – 90% of country’s territory
and 80% of rural population depending of agriculture were affected by the diminished
harvest. The output of cereal crops declined by 63% compared to 2006 and the wheat
harvest reduced by 10 times. The total losses during this drought amounted $1 billion
USD [20]. The oppressive weather of that summer resulted in both direct and indirect
effects on human health, increased ambulance call-outs and the increase in total
mortality, especially from cardiovascular disease among the elderly population. As it
is shown in recent study, the direct heat effect during the 2007 hot summer in Chisinau
was responsible for about 200 excess deaths [4].
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