Geoscience Reference
In-Depth Information
However, CO 2 is essential for plant growth. The rise of CO 2
will promote plant growth through intensified photosynthesis.
Some reports indicate that a rise in the levels of CO 2 would
actually benefit plants, rather than harm them. The growth
rates of C3 plants increase in response to elevated concen-
trations of CO 2 . Thus, global warming might increase plant
growth, because of higher temperatures and higher levels of
atmospheric CO 2 . High atmospheric temperatures caused by
elevated concentrations of CO 2 will induce heat injury and
physiological disorders in some crops, which will decrease the
income of farmers and agricultural countries. Photosynthesis
is one of the most sensitive physiological processes to high-
temperature stress. Reproductive development is more sensi-
tive than vegetative development to high temperatures, and
heat sensitivity differs among crops. Thus, global warming
can have opposite effects on plant growth. From a long-term
viewpoint, however, high atmospheric temperatures will drive
the main sites of crop production. Water shortages caused by
global warming will be the greatest problem for crop produc-
tion. Plants fundamentally rely on adequate fresh water, and
agricultural water accounts for 70% of water use worldwide. As
higher temperatures increase evaporation from water sources
and decrease precipitation, arid regions will become further
desolated. Overall, the entire crop production will be affected
by global warming, resulting in worldwide food shortages.
15.2 predictions of climate change models
To estimate the impact of long-term global climate changes
on agriculture, we should understand the direction and mag-
nitude of climate changes. Climate change projections rely
on large, complex computer models, known as global circu-
lation models (GCMs) that have been successful in depicting
the gross features of the observed large-scale climatological
features. However, there is great uncertainty associated with
these projections on a regional scale, since GCMs are yet to
realistically reproduce the observed features at a regional
scale, particularly over the monsoon region. The most com-
monly used GCMs are GISS (Goddard Institute for Space
Studies, National Aeronautics and Space Administration),
GFDL (Geophysical Fluid Dynamics Laboratory, National
Oceanic and Atmospheric administration) and UKMO
(United Kingdom Meteorological Office). There are inherent
Search WWH ::




Custom Search