Geoscience Reference
In-Depth Information
between −22% and 18% under different climate scenarios con-
sidering ±2°C and ±4°C change in temperature, ±20 and ±40%
change in precipitation.
Some estimations say that there is a decrease in rice yields
at the rate of 0.71 tonne/ha with an increase in minimum tem-
perature from 18°C to 19°C and a decrease of 0.41 ton/ha with
a temperature increase from 22°C to 23°C. Whereas other esti-
mations suggest that a 2°C increase in mean air temperature
could decrease rice yield by about 0.75 ton/ha in the high yield
areas and by about 0.06 ton/ha in the low yield coastal regions.
Further, a 0.5°C increase in winter temperature would reduce
wheat crop duration by 7 days and reduce yield by 0.45 ton/ha.
An increase in winter temperature of 0.5°C would thereby trans-
late into a 10% reduction in wheat production in the high yield
states of Punjab, Haryana and Uttar Pradesh. Hence, a potential
rise in temperature will have disastrous consequences on wheat
production in India. The study showed that with rice increasing
mean daily temperature decreases the period from transplanta-
tion to maturity. Such reduction in duration is often accompa-
nied by decreasing crop fields. There are, however, genotypic
differences per day yield potential. A breeder can consciously
select strains with high per day productivity. Increased levels
of CO
2
increase the photosynthetic rate and, hence, dry matter
production, but an increase in temperature reduces crop dura-
tion and thereby an increase in the yields. In Pantnagar dis-
trict the irrigated yield was stimulated under doubled CO
2
and
increased temperature. This study concluded that the impact on
rice production would be positive in the absence of nutrient and
water limitations. Another crop simulation study estimated that
under elevated CO
2
condition, the wheat yields could decrease
by 28-68% without considering the CO
2
fertilisation effects.
Researchers suggest that in North India, a 1°C rise in mean tem-
perature would have no significant effect on wheat yields, while
a 2°C increase would reduce yields in most places. Recent
studies have examined the adaptation options while estimat-
ing the agricultural impacts. The study showed that even with
adaptation by farmers of their cropping patterns and inputs, in
response to climate change, the losses would remain significant.
The loss in farm-level net revenue is estimated to range between
9% and 25% for a temperature rise of 2-3.5°C.
Estimations are there that India's climate could become
warmer under conditions of increased atmospheric CO
2
. The
average temperature range is predicted to be 2.33-4.78°C with a
doubling in CO
2
concentrations. It is also likely that there will be
an increase in the frequency of heavy rainfall events in South and
