| Extreme weather events such as late frosts, droughts, heat waves and rain storms can have
devastating effects on cropping systems. Damages due to extreme events are strongly
dependent on crop type, crop stage, soil type and soil conditions. The perspective of rising
risk-exposure is exacerbated further by limited aid received for agricultural damage, an
overall reduction of direct income support to farmers and projected intensification of weather
extremes with climate change. According to both the agriculture and finance sectors, a risk
assessment of extreme weather events and their impact on cropping systems is
needed.
The impact of extreme weather events particularly during the sensitive periods of the
farming calendar requires a modelling approach to capture the mixture of non-linear
interactions between the crop, its environment and the occurrence of the meteorological
event. The risk of soil moisture deficit increases towards harvesting, such that drought stress
occurs in spring and summer. Conversely, waterlogging occurs mostly during early spring
and autumn. Risks of temperature stress appear during winter and spring for chilling and
during summer for heat. Since crop development is driven by thermal time and photoperiod,
the regional crop model REGCROP (Gobin, 2010) enabled to examine the likely frequency,
magnitude and impacts of frost, drought, heat stress and waterlogging in relation to the
cropping season and crop sensitive stages. The risk profiles were subsequently
confronted with yields, yield losses and insurance claims for different crops. Physically
based crop models such as REGCROP assist in understanding the links between
different factors causing crop damage as demonstrated for cropping systems in
Belgium.
Extreme weather events have already precipitated contraction of insurance coverage in
some markets (e.g. hail insurance), and the process can be expected to continue if the losses
or damages from such events increase in the future. Climate change will stress this further
and impacts on crop growth are expected to be twofold, owing to the sensitive stages
occurring earlier during the growing season and to the changes in return period of extreme
weather events. Though average yields have risen continuously due to technological
advances, there is no evidence that relative tolerance to adverse weather events has
improved.
The research is funded by the Belgian Science Policy Organisation (Belspo) under
contract nr SD/RI/03A. |