Geoscience Reference
In-Depth Information
improved varieties, genetically modified organisms and irriga-
tion systems, weather is still a key factor in agricultural produc-
tivity, as well as soil properties and natural communities (Curry
et al., 1990; Curtis and Wang, 1998). The effect of climate on
agriculture is related to variabilities in local climates rather
than in global climate patterns (Kaufmann and Snell, 1997;
Freckleton et al., 1999; Gadgil et al., 1999; Tan and Shibasaki,
2006). The international aspect of trade and security in terms
of food implies the need to also consider the effects of climate
change on a global scale. The poorest countries would be hard-
est hit with reductions in crop yields mostly in tropical and sub-
tropical regions due to decreased water availability and new
or changed insect pest incidence (Anonymous, 2001a,b; Cline,
2007, 2008). Marine life and the fishing industry will also
be severely affected in some places. Climate change induced
by increasing GHGs is likely to affect crops differently from
region to region. A decrease in potential yields is likely to be
caused by the shortening growth period, decreases in water
availability and poor vernalisation. Climatic change would
affect agriculture in several ways as
•
Productivity, in terms of quantity and quality of crops
•
Agricultural practices through changes of water use (irri-
gation) and agricultural inputs such as herbicides, insec-
ticides and fertilisers
•
Environmental effects relating to frequency and intensity
of soil drainage (leading to nitrogen leaching), soil ero-
sion, reduction of crop diversity
•
Rural space through the loss and gain of cultivated
lands, land speculation, land renunciation and hydraulic
amenities
•
Adaptation, that is, organisms may become more or less
competitive, as well as humans' urgency to develop more
competitive organisms, such as flood-resistant or salt-
resistant varieties of rice.
The possible changes to climate and atmosphere in the com-
ing decades may influence GHG emissions from agriculture and
the effectiveness of practices adopted to minimise those (Smith
et al., 2007a). The concentration of CO
2
is projected to double
within the next century. This will influence the plant growth
rates, plant litter composition, drought tolerance and nitrogen
demands (Torbert et al., 2000; Norby et al., 2001; Jensen and
Christensen, 2004; Henry et al., 2005; Van Groenigen et al.,
2005; Long et al., 2006). Increasing temperatures may not
