models, are tabulated in Table 1.2. Figure 1.6 summarizes
the temporal variations in the observed and projected
future changes by the IITM-ESM in some key regional climate variables during the twentieth and twenty-first
centuries.
1.2.4 Synthesis of Regional Climate Change
The surface air temperature over India has risen by about
0.7 °C during 1901–2018. There are clear signatures of
human-induced changes in climate over the Indian region in
recent decades, as evidenced by observations, reanalysis
datasets and climate model simulations. These changes are
on account of anthropogenic GHG and aerosol forcings, and
changes in land use and land cover (e.g. Krishnan and
Ramanathan 2002; Dileepkumar et al. 2018).
Future projections of regional climate, under different
climate change scenarios, indicate robust changes in the
mean, variability and extremes of several key climatic
parameters over the Indian subcontinent and adjoining areas,
e.g. land temperature and precipitation, monsoons, Indian
Ocean temperature and sea level, tropical cyclones, Himalayan cryosphere, etc.
A synthesis of the assessed past and projected changes in
key climate variables pertinent to the Indian region is
160
120
80
40
Fig. 1.6 Temporal variation of selected climate variables from
observations (panels on the left) and IITM-ESM projections (panels
on the right) : Near surface air temperature (°C) over India in (a) and
(f); Summer monsoon precipitation (mm/day) over Indian land region
in (b) and (g); Sea surface temperature of the north Indian Ocean
(NIO; °C) in (c) and (h); Thermosteric sea level (m) in the north Indian
Ocean in (d) and (i); and Himalayan snow cover extent (x 10000 km
2
)
in (e) and (j). Note that the time-series of all variables, except
Himalayan snow cover extent, are shown as anomalies w.r.t. a
specified baseline. Absolute values of the Himalayan snow cover
extent are shown in (e) and (j). The IITM-ESM projections cover the
period from 1850 to 2100, with the future projections based on the
SSP2-4.5 scenario. All anomalies in the IITM-ESM projections are
computed w.r.t. the pre-industrial baseline (1850–1900) and anomalies
in observed changes (left panels) are w.r.t. the recent period
(1976–2005)
14
R. Krishnan et al.
the temporal variations in the observed and projected
future changes by the IITM-ESM in some key regional climate variables during the twentieth and twenty-first
centuries.
1.2.4 Synthesis of Regional Climate Change
The surface air temperature over India has risen by about
0.7 °C during 1901–2018. There are clear signatures of
human-induced changes in climate over the Indian region in
recent decades, as evidenced by observations, reanalysis
datasets and climate model simulations. These changes are
on account of anthropogenic GHG and aerosol forcings, and
changes in land use and land cover (e.g. Krishnan and
Ramanathan 2002; Dileepkumar et al. 2018).
Future projections of regional climate, under different
climate change scenarios, indicate robust changes in the
mean, variability and extremes of several key climatic
parameters over the Indian subcontinent and adjoining areas,
e.g. land temperature and precipitation, monsoons, Indian
Ocean temperature and sea level, tropical cyclones, Himalayan cryosphere, etc.
A synthesis of the assessed past and projected changes in
key climate variables pertinent to the Indian region is
160
120
80
40
Fig. 1.6 Temporal variation of selected climate variables from
observations (panels on the left) and IITM-ESM projections (panels
on the right) : Near surface air temperature (°C) over India in (a) and
(f); Summer monsoon precipitation (mm/day) over Indian land region
in (b) and (g); Sea surface temperature of the north Indian Ocean
(NIO; °C) in (c) and (h); Thermosteric sea level (m) in the north Indian
Ocean in (d) and (i); and Himalayan snow cover extent (x 10000 km
2
)
in (e) and (j). Note that the time-series of all variables, except
Himalayan snow cover extent, are shown as anomalies w.r.t. a
specified baseline. Absolute values of the Himalayan snow cover
extent are shown in (e) and (j). The IITM-ESM projections cover the
period from 1850 to 2100, with the future projections based on the
SSP2-4.5 scenario. All anomalies in the IITM-ESM projections are
computed w.r.t. the pre-industrial baseline (1850–1900) and anomalies
in observed changes (left panels) are w.r.t. the recent period
(1976–2005)
14
R. Krishnan et al.