Geoscience Reference
In-Depth Information
table 15.4
Estimated impact of heat wave on wheat yield
during 2004
Production loss
(million tonnes)
State
Yield loss (%)
Uttaranchal 8.60 0.066
Punjab 8.32 1.287
Haryana 7.62 0.704
Uttar Pradesh 6.75 1.720
Himachal Pradesh 5.79 0.033
Bihar 4.73 0.230
Rajasthan 3.87 0.213
Madhya Pradesh 1.11 0.084
Maharashtra 0.00 0.000
West Bengal 0.00 0.000
India 46.79 4.387
Source: ICAR, 2005. Annual Report, 2005, New Delhi.
in the temperature by 1°C, the precipitation will increase by at
least 100 mm and this increased precipitation will enhance 10%
yield of rice, wheat and maize. On the other hand, yield of cere-
als and other agricultural produce will come down heavily, par-
ticularly in warmer regions, as revealed in studies. Some studies
even predict severe drought in places in low latitudes. Whether
the effect of enhanced levels of GHGs will be beneficial or not,
as far as yield is concerned, is not clear even today.
15.6 Indirect effect
GHGs such as CO 2 , CH 4 and N 2 O are directly related with
agriculture. The global warming potential (GWP) of CH 4 is 20
times and that of N 2 O is 300 times more than that of CO 2 . These
GHGs are nearly transparent to the visible and near-infrared
wavelengths of sunlight, but they absorb and re-emit downward
a large fraction of the longer infrared radiation emitted by the
Earth. As a result of this heat trapping, the atmosphere radi-
ates large amounts of long-wavelength energy downward to the
Earth's surface and long-wavelength radiant energy received on
the Earth is increased.
It is certain that agriculture is a source of N 2 O. Nitrous oxide,
which is present in the atmosphere at about 310 ppbv, is slowly
increasing at a rate of about 25% annually. But despite its low
concentration and slow rise, N 2 O is becoming an important
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