Geoscience Reference
In-Depth Information
a comprehensive review of climate change impacts on livestock
and crops yields, including wheat, potatoes, barley and oats.
They emphasised the importance of elevated CO
2
concentration
and quantified potential yield responses to predicted rises. The
authors gave a detailed overview of the findings concerned with
crop growth, physiology and phenology. Bootsma et al. [1] used
linear regression analysis to examine the relationship between
barley yields (among others) and climate variables in Atlantic
Canada. They concluded that climate change is unlikely to have
a significant impact on barley yields, though a doubling of CO
2
could lead to a 10-15% increase. Nonhebel [12] examined the
effects of rising temperature and increases in CO
2
concentra-
tion on simulated wheat yields in Europe. She found that higher
temperatures caused faster crop growth, leading to a shorter
growing period and a decline in yield. CO
2
has the opposite
effect, with a doubling of atmospheric concentration leading to
a 40% rise in yields. Nonhebel also suggested that in general,
changes in the availability of water can have a greater impact
on yield than changes in temperature, but summarised that
where precipitation patterns remain largely constant, negative
effects of higher temperature are offset by positive effects of
CO
2
enrichment. Riha et al. [18] and Mearns et al. [9] stress
the importance of taking variability in temperature and pre-
cipitation into account when making crop yield predictions;
both studies demonstrate that increased inter-seasonal vari-
ability can reduce yields. Ozkan and Akcaoz [13] analysed the
impacts of annual and season variation of 27 climatic variables
on the yield of wheat, maize and cotton in the Cukurova region
of Turkey based on data from 1975 to 1999. They found that the
most significant climatic factors for wheat yields were maxi-
mum temperature during planting time and maximum rainfall
during flowering time. The wheat model could explain 46% of
the variation of yield.
Parry and Carter [16] provide an overview of higher-order
impacts of climate change on agriculture following first-order
impacts. They report the results of impact and adjustment
experiments conducted in five case studies (Iceland, Finland,
Japan, Saskatchewan in Canada and northern parts of the for-
mer USSR), employing farm simulations and input-output
models. They discuss the consequences of biophysical effects
for farm income and profitability, food production, regional
production costs and the wider economy. They then go on
to consider potential managerial, technological and policy
responses to these possible outcomes. Mendelsohn et al. [10] use
Ricardian analysis to examine the impact of global warming on
