Climate
and Climate
Change in India
India is a tropical country, with three main climatic classifications. The humid and semi-humid areas are the west coast, the
Himalayas, and the north-eastern region around Bangladesh. These areas receive a lot of rain from the southwest monsoon.
The sub-humid areas include the states of West Bengal, Orissa, Madhya
Pradesh, and the northern parts of Andhra Pradesh, Punjab, and Uttar Pradesh,
and a narrow coastal strip of Tamil Nadu. The
arid and semi-arid regions include Gujarat, Rajasthan, parts of the Himalayas,
and the center of the country (Takahashi and Arakawa, 1981). *link in a map here
India’s seasons are determined by the southwest monsoon which delivers
so much rain that yearly precipitation totals differ very little from that of
the monsoon season. The southwest
monsoon arrives between June and September, depending on the part of the
country. Although called the southwest monsoon, it arrives from the
southeast and travels towards the northwest of India and then retreats back on
the same path. Typically the
hottest month is May, but then the monsoon arrives bringing cooler temperatures.
Cyclones occur in October and November after the monsoon (Takahashi and
Arakawa, 1981).
Climate Change in India
The mean surface temperature in Tropical Asia has
increased 0.3-0.8°C over the past 100 years, although there has been no trend
in mean rainfall for the past thirty years in the area. There is also no discernible change in the number, frequency,
or intensity of the tropical cyclones over the past 100 years, although some
decadal patterns do exist (McLean et al.,
1998). Temperature predictions for India due to anthropogenically-caused climate
change for the year 2040 versus 1980 are for a 0.7°C and 1.0°C increase for
maximum and minimum surface air temperatures, respectively.
However, this warming will be less prominent during the monsoon season.
Winter diurnal temperature range is predicted to decrease (McLean et al., 1998). With a
doubling of pre-industrial levels of CO2 in the atmosphere, the
United Kingdom Meteorological Office (UKMO) GCM predicts a temperature increase
for India of 16.2%, the Goddard Institute for Space Studies (GISS) GCM predicts
an increase of 10%, and the Geophysical Fluid Dynamics Laboratory (GFDL) GCM
predicts an increase of 23.5%. Some
recent studies, however, have indicated that the GCMs temperature predictions
are too high (Dinar et al., 1998).
Each of these three models predicts an increase in precipitation with a
doubling of CO2 levels from pre-industrial levels, but they predict
differing magnitudes of increase at different times of the year (Dinar et al., 1998). The IPCC
predicts that there will be an increase in the magnitude and frequency of
extreme rainfall events in tropical Asia, but that due to the effect of sulfate
aerosols, the mean summer monsoon rainfall in India will decrease by 0.5 mm/day.
There is some uncertainty as to how much anthropogenic aerosols are being
emitted, thus limiting the confidence of these predictions (McLean et
al., 1998).
Soil moisture is also supposed to be altered due to changes in
precipitation, runoff, percolation, evaporation and rainfall distribution.
However, soil moisture is very hard to predict due to the many factors
involved and the uncertainty associated in making any climate change prediction
(Dinar et al., 1998).
The distribution of
malaria is expected to change in India due to climate change.
The changes in distribution are likely to happen in areas that currently
experience seasonal malaria, or in fringe populations where non-immune residents
will more readily suffer from malaria once infected (McLean et
al., 1998).
