RCP8.5 simulations, at least 65% of seasons are projected to be extremely hot over
all land areas, with severe implications for human health and natural systems.
Sippel and Otto (2014) described how the risk of hydrometeorological extreme
events has changed with a warming climate. For Southeast Europe, these authors
focused on the very hot and dry summer of 2012, which in combination with
heatwaves reaching 40 °C affected the entire region. It was the hottest and the third
driest season recorded in Serbia, due to the prevalence of high-pressure divergences
and lead to an economic loss of about one billion Euros.
These authors explored the tendencies in inter-decadal changes obtained from
the probabilistic analysis that can be used to evaluate a meteorological risk of
extreme weather. The decade-long simulations smooth out the influence of natural
climatic variability, allowing also evaluating the return times of meteorological
events. Indexes for obtaining proxies for impact-relevant meteorological conditions
were derived for combinations of climate variables. Such an index for
seasonal/monthly precipitation deficit makes it possible to estimate probabilities for
summer dryness. The likelihood of changes in heat and dryness in Southeast Europe
using two-decade data series was also determined.
Seasonal temperature anomalies ranging from 2 to 5 °C, compared to those of
the period of 1961–1990, showed that very low precipitation has occurred
throughout South and Eastern Europe. Within this climatic scenario, there were
multi-day heatwaves reflecting turbulent phenomena of higher frequency. During
two heatwaves in August 2010, daily minimum and maximum temperatures ranged
from values as high as 25–40 °C. The multi-day temperature events are relevant
when compared with the full-year temperature increases.
For the evaluation of temperature impact events, a 5-day sampling period can be
more important than, for example, monthly mean temperatures, for exampl, as a
proxy for short-term heat stress during a summer heatwave. Sippel and Otto (2014)
also showed that a 5-day mean wet-bulb global temperature in the summer works as
a proxy for short-term heat stress for human health. When temperatures rise,
evapotranspiration also increases causing an increase in water demand for agricultural crops, within monthly and seasonal time scales.
Sippel and Otto (2014) assumed thereby that general dryness increased in the
given region, independently of the absence of pronounced changes in the precipitation regime. They showed also that a hypothetical water balance, defined as the
difference precipitation and potential evapotranspiration (P-PET), could be used as
a proxy for local dryness, with PET computed according to the Thornthwaite
method:
PET ¼ 16Kð10T=IÞ
m
ð8:2Þ
where K is a function of days in a given month and latitude, reflecting the average
number of daytime hours in that month, T is the mean monthly air temperature (in °
C), and I is a location heat index based on monthly-mean temperatures defined as
8.4 Occurrence of Extreme Events
289
all land areas, with severe implications for human health and natural systems.
Sippel and Otto (2014) described how the risk of hydrometeorological extreme
events has changed with a warming climate. For Southeast Europe, these authors
focused on the very hot and dry summer of 2012, which in combination with
heatwaves reaching 40 °C affected the entire region. It was the hottest and the third
driest season recorded in Serbia, due to the prevalence of high-pressure divergences
and lead to an economic loss of about one billion Euros.
These authors explored the tendencies in inter-decadal changes obtained from
the probabilistic analysis that can be used to evaluate a meteorological risk of
extreme weather. The decade-long simulations smooth out the influence of natural
climatic variability, allowing also evaluating the return times of meteorological
events. Indexes for obtaining proxies for impact-relevant meteorological conditions
were derived for combinations of climate variables. Such an index for
seasonal/monthly precipitation deficit makes it possible to estimate probabilities for
summer dryness. The likelihood of changes in heat and dryness in Southeast Europe
using two-decade data series was also determined.
Seasonal temperature anomalies ranging from 2 to 5 °C, compared to those of
the period of 1961–1990, showed that very low precipitation has occurred
throughout South and Eastern Europe. Within this climatic scenario, there were
multi-day heatwaves reflecting turbulent phenomena of higher frequency. During
two heatwaves in August 2010, daily minimum and maximum temperatures ranged
from values as high as 25–40 °C. The multi-day temperature events are relevant
when compared with the full-year temperature increases.
For the evaluation of temperature impact events, a 5-day sampling period can be
more important than, for example, monthly mean temperatures, for exampl, as a
proxy for short-term heat stress during a summer heatwave. Sippel and Otto (2014)
also showed that a 5-day mean wet-bulb global temperature in the summer works as
a proxy for short-term heat stress for human health. When temperatures rise,
evapotranspiration also increases causing an increase in water demand for agricultural crops, within monthly and seasonal time scales.
Sippel and Otto (2014) assumed thereby that general dryness increased in the
given region, independently of the absence of pronounced changes in the precipitation regime. They showed also that a hypothetical water balance, defined as the
difference precipitation and potential evapotranspiration (P-PET), could be used as
a proxy for local dryness, with PET computed according to the Thornthwaite
method:
PET ¼ 16Kð10T=IÞ
m
ð8:2Þ
where K is a function of days in a given month and latitude, reflecting the average
number of daytime hours in that month, T is the mean monthly air temperature (in °
C), and I is a location heat index based on monthly-mean temperatures defined as
8.4 Occurrence of Extreme Events
289