Geoscience Reference
In-Depth Information
Extreme weather conditions, such as floods, droughts, heat and
cold waves, flashfloods, cyclones and hailstorms are direct haz-
ards to crops. More subtle fluctuations in weather during critical
phases of crop development can also have a substantial impact
on yields. Cultivated areas are subject to a broader range of influ-
ences, including changes in commodity prices, costs of inputs
and availability of irrigation water. Climate may have indirect
and possibly lagged influences on harvested areas.
10.6
projected climate change scenarios over the
Indian subcontinent
Climate change is no longer a distant scientific prognosis but is
becoming a reality. The anthropogenic increases in emissions
of greenhouse gases and aerosols in the atmosphere result in a
change in the radiative forcing and a rise in the Earth's tempera-
ture. The bottom-line conclusion of the Third Assessment Report
of the Intergovernmental Panel on Climate Change (IPCC, 2001)
is that the average global surface temperature will increase
between 1.4°C and 3°C above 1990 levels by 2100 for low emis-
sion scenarios and between 2.5°C and 5.8°C for higher emission
scenarios of greenhouse gases and aerosols in the atmosphere.
10.7
Vulnerability of crop production
Estimating the effect of a changing climate on crop produc-
tion in India is difficult due to the variety of cropping systems
and levels of technology used. However, the use of crop growth
models is one way in which these effects can be studied, and
probably represents the best method we have at present for
doing so. Although a large number of simplifying assumptions
must necessarily be made, these models allow the complex
interaction between the main environmental variables influenc-
ing crop yields to be understood.
10.8
Uncertainties due to scenarios and crop models
on impact assessment
Estimates of the impact of climate change on crop production
could be biased depending upon the uncertainties in climate
change scenarios, region of study, crop models used for impact
assessment and the level of management. So it is very important
