|India's economy is largely dependent on agriculture and is already under stress due to its
increasing population, and the resulting increase in demand for energy, fresh water and food. This situation will worsen with the effects of global warming and Climate-related disasters. Climate Change will cause widespread misery and huge economic losses to India, adversely affecting public health, food security, agriculture, water resources and biodiversity. Although limited scientific research has been carried out on the impacts of climate change on India, some of the most obvious effects are listed below:
Scientists from the Indian Institute of Technology (IIT), New Delhi, already report that surface air
temperatures over India are going up at the rate of 0.4°C per hundred years, particularly during the postmonsoon
and winter season. Using models, they predict that mean winter temperatures will increase by
as much as 3.2°C by 2050 and 4.5°C by 2080, due to GHGs. They also predict that the summer
temperatures will increase by 2.2°C by 2050 and 3.2°C by 2080. However, studies show that the heating
up of India will not be uniform across the country. While the winters of north and northwest India may be
more than 2°C warmer by the middle of the next century, there could be a cooling of over 1°C in the
Northeast. Extreme temperatures and heat spells have already become common over Northern India, often causing
loss of human life and property. In 1998 alone, 650 deaths occurred in Orissa due to heat waves. There
could be even more intense cyclones, more intense rainstorms and more intense drought periods.
According to M B Lal of the Indian Institute of Technology, Delhi, preliminary results suggest more frequent
and heavy rainstorms over the Northeast which could mean even more flash floods in that region.
Effect on Monsoon
India is heavily dependent on the monsoon - to meet its
agricultural and water needs, and also for protecting and
propagating its rich biodiversity. Scientists of IIT, Delhi warn that
India will experience a decline in monsoon rainfall over the north
and central plains of India by 2050 because of the general
weakening of the monsoon. This is because there will be a
decrease in the land-sea thermal gradient. Since summer rainfall
accounts for almost 70 per cent of the total annual rainfall over
India and is crucial for Indian agriculture, this could have a
devastating effect on the Indian economy, and on food security. No
significant rainfall decrease is expected during the winter season. But the average annual levels and
monsoon season levels of soil moisture could decline significantly in the central plains. There will also be a
significant decline in surface runoff in these plains leading to less water in the rivers. However, it is
predicted that the semi-arid regions of western India are expected to receive higher than normal rainfall
as temperatures soar.
Effects on water resources
Relatively small climatic changes can cause large water resource problems, particularly in arid and semiarid
regions such as northwest India. This will have an impact on agriculture, drinking water, and on
generation of hydroelectric power, resulting in limited water supply and land degradation. Rainfall may
decline by 5 to 25 per cent during winters, causing droughts during dry summer months. The onset of the
summer monsoon over central India could vary in future. If rainfall decreases, water availability will
decrease across the country.
Apart from monsoon rain fed rivers, India depends mainly on the water supply from its perennial rivers,
which are continuously fed throughout the year by the glacial melt-waters from the Hindukush and
Himalayan ranges. But the Himalayan glaciers, which feed the major Indian rivers and keep them
perennial, are rapidly shrinking. The Pindari glacier is retreating at a rate of 13 metres a year while the
Gangotri glacier is receding at an annual rate of 30 metres. Glacial melting at this rate increases the risk of
The problem becomes all the more serious because the melting season coincides with the summer
monsoon season. Therefore, any intensification of the monsoon is likely to contribute to flood disasters in
the Himalayan catchment. Rising temperatures will also contribute to the raising of the snowline,
reducing the capacity of this natural reservoir, and increasing the risk of flash floods during the wet
season. Increase in temperatures can also lead to increased eutrophication in wetlands and fresh water
Effect on Agriculture
Increased temperatures will impact agricultural production.
Agricultural productivity can be affected in two ways: one,
directly, due to changes in temperature, precipitation or CO 2
levels and two, indirectly, through changes in soil, distribution
and frequency of infestation by pests, insects, diseases or weeds.
Higher mean temperatures increased evaporation and
transpiration rates. Even a small increase of 1°C could increase
the rate of evaporation/ transpiration by 5-15 per cent. With no
rainfall to compensate, yields will be reduced. In north India, for
instance, a temperature rise of 0.5°C could reduce wheat yields
due to heat stress by about 10 percent if rainfall does not increase. Scientists from IIT Delhi predict that a
temperature increase of 3°C will result in a 15-20 percent decrease in wheat yields, and also a decrease in
rice yields. In northwest India, though higher yields are projected for rice and wheat if carbon dioxide
levels in the atmosphere increase. A 3°C and 2°C rise in temperature (for wheat and rice respectively)
nearly cancels out this positive effect. Production will go down if water shortage is taken into account.
Similarly, models suggest that soybean production in the country will go up by 50 per cent if atmospheric
carbon dioxide concentrations double. But if rainfall decreases significantly and temperature increases,
production could go down by 6 per cent. This will severely affect a state like Madhya Pradesh, which
produces 72 per cent of soybean grown in India.
Agriculture will be adversely affected not only by an increase or decrease in the overall amounts of
rainfall, but also by shifts in the timing of the rainfall. For instance, over the last few years, the
Chattisgarh region has received less than its share of pre-monsoon showers in May and June. These
showers are important to ensure adequate moisture in fields being prepared for rice crops
Agriculture will be worst affected in the coastal regions of Gujarat and Maharashtra, where agriculturally
fertile areas are vulnerable to inundation and salinization. Standing crop in these regions is also more
likely to be damaged due to cyclonic activity. In Rajasthan, a 2°C rise in temperature was estimated to
reduce production of pearl millet by 10-15 per cent.
Rise in surface temperature will create more conducive conditions for pest infection, which is already a
major constraint in achieving higher crop production in India, and hence negatively affecting agriculture.
Impact on Human Health
Climate change simulation models suggest that a rise in temperature and change in humidity will
adversely affect human health in India. A warmer and wetter India will see a rise in heat-related and
infectious diseases. More people will die due to heat waves. Heat stress could result in heat cramps, heat
exhaustion, heat stroke, and damage physiological functions, metabolic processes and immune systems.
Increased temperatures can increase the range of vector borne diseases such as malaria, dengue fever,
yellow fever and several types of encephalitis, particularly in regions where minimum temperatures
currently limit pathogen and vector development. An apt example to prove this point is the summer of
1994, when western India experienced temperatures as high as 50°C, providing favourable conditions for
disease-carrying vectors to breed. Not surprisingly, 1994 was also the year that the town of Surat in
Gujarat was hit by an epidemic of pneumonic plague, resulting in 59 deaths. In the same year, as summer
gave way to the monsoon and western India was flooded with rains for three months, Surat was hit by a
malaria epidemic. The cause could be the numerous unattended puddles (resulting from heavy rainfall),
which provides good breeding conditions for mosquitoes.
Water borne diseases, natural disasters, environmental migration, nutritional deficiency could be other
major risk factors. Waterborne diseases including cholera and diarrhoeal diseases will increase as rainfall
patterns change, restricting human access to water supplies and sanitation. Global warming will increase
the incidence of respiratory and cardiovascular diseases in arid and semi-arid parts of India. Cyclones and
floods will also cause rise in illnesses, diseases, injuries and loss of life.
Effect on Ecosystems and Biodiversity
As temperatures rise, species which cannot adapt will go extinct,
while others will migrate to new locations under changing
climatic conditions. Increase in temperatures will result in shifts
of lower altitude tropical and subtropical forests to higher
altitude temperate forest regions, resulting in the extinction of
some temperate vegetation types. One tenth of the world's
known species of higher altitude plants and animals occur in the
Himalayas. Increased dry spells could also place dry and moist deciduous
forests at increased risk from forest fires. Decrease in rainfall and
the resultant soil moisture stress could result in drier teak dominated forests replacing Sal trees in central
India. “In any case an increased turnover of forest species is indicated,” says M Lal from IIT Delhi. This
could potentially result in species extinction and decline in biodiversity.
The state of Gujarat has the largest area of mangrove forests after West Bengal. The mangroves are
threatened by the rise in temperature, which causes decreased tree height and leaf size. Besides
temperature stress, the mangroves in the Gulf towards Jamnagar and the Kutch coasts are also threatened
by sea level rise and drought. The district of Kutch in Gujarat has large areas of marine wetlands, which play an important role in
maintaining the coastal environment, and in providing sustenance to coastal communities. These could be
adversely impacted due to elevation of water temperature and sea level rise. The Rann of Kutch supports
large Greater Flamingo colonies. With sea level rise, these salt marshes and mudflats will submerge,
decreasing their habitat, and that of lesser floricans. About 2000 Indian wild asses in the Rann of Kutch
could lose their only habitat. Severe coral bleaching will occur all along the Indian coast as a result of seawater warming. Coral reefs are threatened by changes in temperature, rising sea levels and increased concentrations of carbon dioxide in
the atmosphere. Already, nearly 30 per cent of the coral reefs in the Gulf of Kutch are 'bleached' as they
loose the colourful algae that live on them - an occurrence associated with seawater warming. In future,
the entire belt of coral reefs along the south Gujarat coast is in danger of getting bleached.
Effect of Sea Level Rise on Coastal Low Lands and Deltas
A trend of sea level rise due to thermal expansion of seawater in the Indian Ocean is expected to inundate
low lying areas, drown coastal marshes and wetlands, erode beaches, exacerbate flooding and increase
the salinity of rivers, bays and aquifers.
Deltas will be threatened by flooding, erosion and salt intrusion. The major delta area of the Ganga,
Brahmaputra, and Indus rivers, which have large populations reliant on riverine resources, will be
affected by changes in water regimes, salt-water intrusion and land loss. Many large Indian cities are
situated on the coast, flood plains and river deltas. A one-metre sea level rise will displace approximately
7.1 million people in India and about 5764 square kilometres (km) of land area will be lost, along with 4200
km of roads.
The coastal states of Maharashtra, Goa and Gujarat face a grave risk from sea level rise, which could flood
land (including agricultural land), and cause damage to coastal infrastructure and other property. Goa will
be the worst hit, losing a large percentage of its total land area, including many of its famous beaches and
tourist infrastructure. A one metre rise in sea level will adversely affect 7 per cent of the population in
Goa, and cause damages to the tune of Rs 8,100 crore.
In the state of Maharashtra, over 13 lakh people are at risk. The cost of damages for Mumbai, the business
capital of India, is estimated to be Rs 2,28,700 crore. Mumbai's northern suburbs like Versova Beach and
other populated areas along tidal mud flats and creeks are vulnerable to land loss and increased flooding
due to sea level rise.
Beyond actual inundation, rising sea levels will also put millions of people at greater risk of flooding and
displace a large number of people. Increased seawater percolation may further reduce freshwater
supplies. Coastal erosion will increase substantially. Loss of coastal mangroves will have an impact on
fisheries and coastal fishing communities will be severely affected.
The Andaman and Nicobar Islands and the coral reef of the Lakshadweep archipelago are most vulnerable.
Orissa, West Bengal and Maharashtra face real danger, as also the Lakshadweep group of islands where the
entire population is at risk. Most of the areas likely to be lost in West Bengal include the Sunderban
mangrove swamps, already variously degraded, and reserved forests. Andhra Pradesh & Tamil Nadu, two
coastal states with long and heavily populated coastlines will also face the risk of coastal erosion and
displacement. Mangroves in the Krishna - Godavari & Kaveri deltas will be gravely affected, as will
Important Bird Areas such as Pulicat, Point Calimere & Neelapattu wetlands. Intensive food grain
production practiced in these states will be negatively affected by salt water intrusion.