Impacts of Climate Change on Agriculture - Climate Resilient Agriculture for Ensuring Food Security - page 45

Table 4.2 (continued )

Potential impacts on agricultural
production

Climate and related
physical factors

Confi dence level of
the potential impact

Expected direction of change

Precipitation
intensity

Intensifi ed hydrological cycle,
but with regional variations.
Seasonal changes by ±10 %

Changed patterns of erosion and
accretion. Changed storm impacts

High

Changed occurrence of storm
fl ooding and storm damage.
Increased water logging. Increased
pest damage

Temperature Increase by 1-2 °C. Winters

warming more than summers.
Increased frequency of heat
waves

Faster, shorter, earlier growing
seasons. Range moving north and
to higher altitudes. Modifi cations
in crop suitability and productivity.
Heat stress risk. Increased
evapotranspiration

High

Changes in weeds, crop pests,
and diseases. Changes in water
requirements. Changes in crop
quality

Differences in day-night
temperature

Modifi cations in crop productivity
and quality

Medium

Heat stress Increases in heat waves Damage to grain formation,

increase in some pests

High

Variability Increases across most climatic

variables. Predictions uncertain

Changing risk of damaging events
(heat waves, frost, droughts, fl oods)
which affect crops and timing of
farm operations

Very low

4.1 Projections

It is frequently assumed that global change
will bring higher temperatures, altered precipita-
tion, and higher levels of atmospheric CO 2 (IPCC
1990 ). What might these changes mean for the
biophysical response of agricultural crops?
The IPCC Third Assessment Report, pub-
lished in 2001, concluded that the poorest coun-
tries would be hardest hit, with reductions in crop
yields in most tropical and subtropical regions
due to decreased water availability and new or
changed insect pest incidence. In Africa and
Latin America, many rainfed crops are near their
maximum temperature tolerance, so that yields
are likely to fall sharply for even small climate
changes; falls in agricultural productivity of up to
30 % over the twenty-fi rst century are projected.
Marine life and the fi shing industry will also be
severely affected in some places.
Climate change induced by increasing green-
house gases is likely to affect average crop yield
to drop down to 50 % in Pakistan according to the
UKMO scenario, whereas corn production in

• The positive effect of increased CO 2 on crop
growth plays a very critical role.
• A further increase of phytotoxic surface ozone
(O 3 ) until the end of the century which may
lead to considerable crop losses at least until
2030, especially in China (Van Deningen et al.
2009 ).
• The rise in sea levels and tropical cyclones are
major threats to rice production in the Asian
mega deltas especially in Vietnam, Bangladesh,
and Myanmar.
• Agriculture contributes to approximately
30 % to the global GHG emissions (IPCC
2007 ; Bellarby et al. 2008 ) - a linear progres-
sion of industrial agriculture and its extension
to all developing countries is a contradiction
to climate protection.
• Looking at crop yields alone might be too
narrow - the nutritional value of the future
crops might counteract some of the yield gains.