northern India (0.01
C–0.07
C per year). All other states have no noticeable
trend.
3. A significant increasing trend (0.01
C–0.07
C per year) of annual mean
temperature is observed in most of the states of India, especially over the western,
central, southern, and eastern coastal parts of India. Moreover, increasing trends
have also been observed in most of the northeastern provinces. A significant
decreasing trend (0.01
C per year) of annual mean temperature is noticed in
northern India. No trend has been noted in the other six states of the country.
4. An increasing trend (0.04 mm/year–14.68 mm/year) of annual average rainfall is
observed mostly in the southeastern, eastern, northwestern, and the riverine plain
region of the northeastern states of India. A decreasing trend (0.05 mm/year–
7.77 mm/year) of annual average rainfall is observed in the central as well as
along the western coastal part of the country. A remarkable decreasing trend is
also noticed along the Himalayan foothill region of northeast India (14.68 mm/
year) and in the Andaman and Nicobar Islands (7.77 mm/year), respectively.
IPCC (2014), in its fifth assessment report, identified an increase in the number of
monsoon break days and a decrease in the number of monsoon depressions over
India, which has resulted in an overall decline in mean rainfall of the monsoon
season. Increase in extreme rainfall events over central India and in many other parts
of the country has also been observed. According to this report, the frequency of
heavy precipitation events is increasing in South Asia whereas light rain events are
decreasing.
Projected Trend of Climate Change
IPCC (2013) opines that “future climate will depend on committed warming caused
by past anthropogenic emissions and natural climate variability” (Christensen et al.
2013). Continuous emission of greenhouse gas will lead to increased temperatures,
resulting in changes in interrelated components of the climatic system. Based on
different possible time series scenarios of emissions and concentrations of greenhouse gases, aerosols, and chemically active gases, known as representative concentration pathways (RCPs), IPCC has projected changes in mean surface
temperature and other climatic parameters for different periods of the twenty-first
century relative to the 1986–2005 period. According to this report, by the end of the
twenty-first century (2081–2100), global mean surface temperature will rise in the
range 0.3
C–1.7
C under RCP 2.6, 1.1
C–2.6
C under RCP 4.5, 1.4
C–3.1
C
under RCP 6.0, and 2.6
C–4.8
C under RCP 8.5.
In a similar global trend, IPCC has projected a clear increase in temperature over
India, especially in winter (Christensen et al. 2013). As per the RCP 4.5 scenario
based on the CMIP5 model, annual mean surface temperature of South Asia will
increase in the range of 0.2
C–1.3
C by 2035, relative to the 1986–2005 period. By
2065, the rise of annual mean surface temperature of South Asia will be in the range
6 Impact of Climate Change on Groundwater Resource of India: A Geographical. . .
131
C–0.07
C per year). All other states have no noticeable
trend.
3. A significant increasing trend (0.01
C–0.07
C per year) of annual mean
temperature is observed in most of the states of India, especially over the western,
central, southern, and eastern coastal parts of India. Moreover, increasing trends
have also been observed in most of the northeastern provinces. A significant
decreasing trend (0.01
C per year) of annual mean temperature is noticed in
northern India. No trend has been noted in the other six states of the country.
4. An increasing trend (0.04 mm/year–14.68 mm/year) of annual average rainfall is
observed mostly in the southeastern, eastern, northwestern, and the riverine plain
region of the northeastern states of India. A decreasing trend (0.05 mm/year–
7.77 mm/year) of annual average rainfall is observed in the central as well as
along the western coastal part of the country. A remarkable decreasing trend is
also noticed along the Himalayan foothill region of northeast India (14.68 mm/
year) and in the Andaman and Nicobar Islands (7.77 mm/year), respectively.
IPCC (2014), in its fifth assessment report, identified an increase in the number of
monsoon break days and a decrease in the number of monsoon depressions over
India, which has resulted in an overall decline in mean rainfall of the monsoon
season. Increase in extreme rainfall events over central India and in many other parts
of the country has also been observed. According to this report, the frequency of
heavy precipitation events is increasing in South Asia whereas light rain events are
decreasing.
Projected Trend of Climate Change
IPCC (2013) opines that “future climate will depend on committed warming caused
by past anthropogenic emissions and natural climate variability” (Christensen et al.
2013). Continuous emission of greenhouse gas will lead to increased temperatures,
resulting in changes in interrelated components of the climatic system. Based on
different possible time series scenarios of emissions and concentrations of greenhouse gases, aerosols, and chemically active gases, known as representative concentration pathways (RCPs), IPCC has projected changes in mean surface
temperature and other climatic parameters for different periods of the twenty-first
century relative to the 1986–2005 period. According to this report, by the end of the
twenty-first century (2081–2100), global mean surface temperature will rise in the
range 0.3
C–1.7
C under RCP 2.6, 1.1
C–2.6
C under RCP 4.5, 1.4
C–3.1
C
under RCP 6.0, and 2.6
C–4.8
C under RCP 8.5.
In a similar global trend, IPCC has projected a clear increase in temperature over
India, especially in winter (Christensen et al. 2013). As per the RCP 4.5 scenario
based on the CMIP5 model, annual mean surface temperature of South Asia will
increase in the range of 0.2
C–1.3
C by 2035, relative to the 1986–2005 period. By
2065, the rise of annual mean surface temperature of South Asia will be in the range
6 Impact of Climate Change on Groundwater Resource of India: A Geographical. . .
131