recent past, as well as changes anticipated over the
twenty-first century based on simulations by state-of-the-art
global climate models.
The SST of the TIO has warmed by about 1 °C over the
period 1951–2015, which is much higher than the global
average SST rise of about 0.7 °C over the same period. Most
of this temperature rise is attributed to anthropogenic emissions. Heat content in the upper Indian Ocean (OHC700) has
also exhibited an increasing trend since the 1950s, with a
notably abrupt rise after the year 2000. Observed declining
trends in phytoplankton and oxygen concentrations in the
TIO, attributed to SST warming, and the increasing acidification of the Indian Ocean due to excess CO 2 uptake, have
also likely impacted marine ecosystems in the western
Indian Ocean.
Climate models project a rise in surface temperatures of
the TIO by 1.2–1.6 °C and 1.6–2.7 °C in the near and far
futures across GHG emissions scenarios (RCP4.5 and
RCP8.5) relative to the reference period 1976–2005. Trends
in other observed changes are also projected to continue with
global warming.
Lack of sufficient observations in the western Indian
Ocean and the Indonesian Through flow has hampered the
understanding of changes in the heat budget of the Indian
Ocean. Increasing the skill of Indian Ocean forecasts
requires coordinated efforts in monitoring changes in the
Indian Ocean at different time scales and at different depths.
Efforts in these directions are already underway.
The central role of the Indian Ocean in modulating the
regional climate implies that changes in this basin have
serious implications for both the densely populated coastal
regions around this basin, and for marine ecosystems.
Hence, efforts towards detailed and continuous monitoring
of ongoing changes and improving climate models are
essential for developing effective adaptation and mitigation
strategies to reduce risk due to climate change.
References
Allison LC, Roberts CD, Palmer MD, Hermanson L, Killick RE,
Rayner NA, Smith DM, Andrews MB (2019) Towards quantifying
uncertainty in ocean heat content changes using synthetic profiles.
Environ Res Lett 14(8):084037
Ashok K, Behera SK, Rao SA, Weng H, Yamagata T (2007) El Niño
Modoki and its possible teleconnection. J Geophys Res Oceans 112:
C11007. https://doi.org/10.1029/2006JC003798
Anandh TS, Das BK, Kumar B, Kuttippurath J, Chakraborty A (2018)
Analyses of the oceanic heat content during 1980–2014 and
satellite-era cyclones over Bay of Bengal. Int J Climatol 38:5619–
5632. https://doi.org/10.1002/joc.5767
Barnett TP, Pierce DW, Schnur R (2001) Detection of anthropogenic
climate change in the world’s oceans. Science 292:270–274. https://
doi.org/10.1126/science.1058304
Barnett TP, Pierce DW, AchutaRao KM, Gleckler PJ, Santer BD,
Gregory JM, Washington WM (2005) Penetration of
human-induced warming into the world’s oceans. Science
309:284–287. https://doi.org/10.1126/science.1112418
Beal LM, Vialard J, Roxy MK et al (2019) IndOOS-2: a roadmap to
sustained observations of the Indian Ocean for 2020–2030.
CLIVAR-4/2019. https://doi.org/10.36071/clivar.rp.4-1.2019
Bopp L, Resplandy L, Orr JC, Doney SC, Dunne JP, Gehlen M,
Vichi M (2013) Multiple stressors of ocean ecosystems in the 21st
century: projections with CMIP5 models. Biogeosciences 10
(10):6225–6245. https://doi.org/10.5194/bg-10-6225-2013
Cai W, Santoso A, Wang G et al (2014) Increased frequency of extreme
Indian Ocean Dipole events due to greenhouse warming. Nature
510:254–258. https://doi.org/10.1038/nature13327
Cai W, Zheng X-T, Weller E et al (2013) Projected response of the
Indian Ocean Dipole to greenhouse warming. Nat Geosci 6:999–
1007. https://doi.org/10.1038/ngeo2009
Canadell JG et al (2007) Contributions to accelerating atmospheric CO 2
growth from economic activity, carbon intensity, and efficiency of
natural sinks. Proc Natl Acad Sci USA 104:18866–18870
Chakravorty S, Gnanaseelan C, Pillai PA (2016) Combined influence of
remote and local SST forcing on Indian Summer Monsoon Rainfall
variability. Clim Dyn 47(9–10):2817–2831
Cheng LJ, Zhu J, Abraham J (2015) Global upper ocean heat content
estimation: recent progress and the remaining challenges. Atmos
Oceanic
Sci
Lett
8:333–338.
https://doi.org/10.3878/
AOSL20150031
Cheng L, Trenberth KE, Palmer MD, Zhu J, Abraham JP (2016)
Observed and simulated full-depth ocean heat-content changes for
1970–2005. Ocean Sci 12(4):925–935. https://doi.org/10.5194/os12-925-2016
Cheng L, Trenberth K, Fasullo J, Boyer T, Abraham J, Zhu J (2017)
Improved estimates of ocean heat content from 1960 to 2015. Sci
Adv 3:e1601545. https://doi.org/10.1126/sciadv.1601545
Cherchi A (2019) Connecting AMOC changes. Nat Clim Chang 9:729–
730
Chowdary JS, Gnanaseelan C (2007) Basin-wide warming of the Indian
Ocean during El Nino and Indian Ocean dipole years. Int J Climatol
27:1421–1438
Chowdary JS, John N, Gnanaseelan C (2014) Interannual variability of
surface air-temperature over India: impact of ENSO and Indian
Ocean Sea surface temperature. Int J Climatol 34(2):416–429
Chowdary JS, Xie SP, Tokinaga H, Okumura YM, Kubota H,
Johnson N, Zheng XT (2012) Interdecadal variations in ENSO
teleconnection to the Indo–western Pacific for 1870–2007. J Clim
25(5):1722–1744. https://doi.org/10.1175/JCLI-D-11-00070.1
Collins M, Knutti R, Arblaster J, Dufresne JL, Fichefet T, Friedlingstein P, Gao X, Gutowski WJ, Johns T, Krinner G, Shongwe M,
Tebaldi C, Weaver AJ, Wehner M (2013) Long-term climate
change: projections, commitments and irreversibility. In:
Stocker TF, Qin D, Plattner GK, Tignor M, Allen SK,
Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate
change 2013: the physical science basis. Contribution of working
group I to the fifth assessment report of the intergovernmental panel
on climate change. Cambridge University Press, Cambridge
Collins M, Sutherland M, Bouwer L, Cheong SM, Frölicher T, Jacot
Des Combes H, Roxy MK, Losada I, McInnes K, Ratter B,
Rivera-Arriga E, Susanto RD, Swingedouw D, Tibig L (2019)
Extremes, abrupt changes and managing risks. In: Portner et al
(eds) IPCC special report on oceans and cryosphere in a changing
climate. Cambridge University Press, Cambridge
Deepa JS, Gnanaseelan C, Mohapatra S, Chowdary JS, Karmakar A,
Kakatkar R, Parekh A (2019) The tropical Indian Ocean decadal sea
level response to the Pacific decadal oscillation forcing. Clim Dyn
52:5045–5058. https://doi.org/10.1007/s00382-018-4431-9
10 Indian Ocean Warming
203
twenty-first century based on simulations by state-of-the-art
global climate models.
The SST of the TIO has warmed by about 1 °C over the
period 1951–2015, which is much higher than the global
average SST rise of about 0.7 °C over the same period. Most
of this temperature rise is attributed to anthropogenic emissions. Heat content in the upper Indian Ocean (OHC700) has
also exhibited an increasing trend since the 1950s, with a
notably abrupt rise after the year 2000. Observed declining
trends in phytoplankton and oxygen concentrations in the
TIO, attributed to SST warming, and the increasing acidification of the Indian Ocean due to excess CO 2 uptake, have
also likely impacted marine ecosystems in the western
Indian Ocean.
Climate models project a rise in surface temperatures of
the TIO by 1.2–1.6 °C and 1.6–2.7 °C in the near and far
futures across GHG emissions scenarios (RCP4.5 and
RCP8.5) relative to the reference period 1976–2005. Trends
in other observed changes are also projected to continue with
global warming.
Lack of sufficient observations in the western Indian
Ocean and the Indonesian Through flow has hampered the
understanding of changes in the heat budget of the Indian
Ocean. Increasing the skill of Indian Ocean forecasts
requires coordinated efforts in monitoring changes in the
Indian Ocean at different time scales and at different depths.
Efforts in these directions are already underway.
The central role of the Indian Ocean in modulating the
regional climate implies that changes in this basin have
serious implications for both the densely populated coastal
regions around this basin, and for marine ecosystems.
Hence, efforts towards detailed and continuous monitoring
of ongoing changes and improving climate models are
essential for developing effective adaptation and mitigation
strategies to reduce risk due to climate change.
References
Allison LC, Roberts CD, Palmer MD, Hermanson L, Killick RE,
Rayner NA, Smith DM, Andrews MB (2019) Towards quantifying
uncertainty in ocean heat content changes using synthetic profiles.
Environ Res Lett 14(8):084037
Ashok K, Behera SK, Rao SA, Weng H, Yamagata T (2007) El Niño
Modoki and its possible teleconnection. J Geophys Res Oceans 112:
C11007. https://doi.org/10.1029/2006JC003798
Anandh TS, Das BK, Kumar B, Kuttippurath J, Chakraborty A (2018)
Analyses of the oceanic heat content during 1980–2014 and
satellite-era cyclones over Bay of Bengal. Int J Climatol 38:5619–
5632. https://doi.org/10.1002/joc.5767
Barnett TP, Pierce DW, Schnur R (2001) Detection of anthropogenic
climate change in the world’s oceans. Science 292:270–274. https://
doi.org/10.1126/science.1058304
Barnett TP, Pierce DW, AchutaRao KM, Gleckler PJ, Santer BD,
Gregory JM, Washington WM (2005) Penetration of
human-induced warming into the world’s oceans. Science
309:284–287. https://doi.org/10.1126/science.1112418
Beal LM, Vialard J, Roxy MK et al (2019) IndOOS-2: a roadmap to
sustained observations of the Indian Ocean for 2020–2030.
CLIVAR-4/2019. https://doi.org/10.36071/clivar.rp.4-1.2019
Bopp L, Resplandy L, Orr JC, Doney SC, Dunne JP, Gehlen M,
Vichi M (2013) Multiple stressors of ocean ecosystems in the 21st
century: projections with CMIP5 models. Biogeosciences 10
(10):6225–6245. https://doi.org/10.5194/bg-10-6225-2013
Cai W, Santoso A, Wang G et al (2014) Increased frequency of extreme
Indian Ocean Dipole events due to greenhouse warming. Nature
510:254–258. https://doi.org/10.1038/nature13327
Cai W, Zheng X-T, Weller E et al (2013) Projected response of the
Indian Ocean Dipole to greenhouse warming. Nat Geosci 6:999–
1007. https://doi.org/10.1038/ngeo2009
Canadell JG et al (2007) Contributions to accelerating atmospheric CO 2
growth from economic activity, carbon intensity, and efficiency of
natural sinks. Proc Natl Acad Sci USA 104:18866–18870
Chakravorty S, Gnanaseelan C, Pillai PA (2016) Combined influence of
remote and local SST forcing on Indian Summer Monsoon Rainfall
variability. Clim Dyn 47(9–10):2817–2831
Cheng LJ, Zhu J, Abraham J (2015) Global upper ocean heat content
estimation: recent progress and the remaining challenges. Atmos
Oceanic
Sci
Lett
8:333–338.
https://doi.org/10.3878/
AOSL20150031
Cheng L, Trenberth KE, Palmer MD, Zhu J, Abraham JP (2016)
Observed and simulated full-depth ocean heat-content changes for
1970–2005. Ocean Sci 12(4):925–935. https://doi.org/10.5194/os12-925-2016
Cheng L, Trenberth K, Fasullo J, Boyer T, Abraham J, Zhu J (2017)
Improved estimates of ocean heat content from 1960 to 2015. Sci
Adv 3:e1601545. https://doi.org/10.1126/sciadv.1601545
Cherchi A (2019) Connecting AMOC changes. Nat Clim Chang 9:729–
730
Chowdary JS, Gnanaseelan C (2007) Basin-wide warming of the Indian
Ocean during El Nino and Indian Ocean dipole years. Int J Climatol
27:1421–1438
Chowdary JS, John N, Gnanaseelan C (2014) Interannual variability of
surface air-temperature over India: impact of ENSO and Indian
Ocean Sea surface temperature. Int J Climatol 34(2):416–429
Chowdary JS, Xie SP, Tokinaga H, Okumura YM, Kubota H,
Johnson N, Zheng XT (2012) Interdecadal variations in ENSO
teleconnection to the Indo–western Pacific for 1870–2007. J Clim
25(5):1722–1744. https://doi.org/10.1175/JCLI-D-11-00070.1
Collins M, Knutti R, Arblaster J, Dufresne JL, Fichefet T, Friedlingstein P, Gao X, Gutowski WJ, Johns T, Krinner G, Shongwe M,
Tebaldi C, Weaver AJ, Wehner M (2013) Long-term climate
change: projections, commitments and irreversibility. In:
Stocker TF, Qin D, Plattner GK, Tignor M, Allen SK,
Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate
change 2013: the physical science basis. Contribution of working
group I to the fifth assessment report of the intergovernmental panel
on climate change. Cambridge University Press, Cambridge
Collins M, Sutherland M, Bouwer L, Cheong SM, Frölicher T, Jacot
Des Combes H, Roxy MK, Losada I, McInnes K, Ratter B,
Rivera-Arriga E, Susanto RD, Swingedouw D, Tibig L (2019)
Extremes, abrupt changes and managing risks. In: Portner et al
(eds) IPCC special report on oceans and cryosphere in a changing
climate. Cambridge University Press, Cambridge
Deepa JS, Gnanaseelan C, Mohapatra S, Chowdary JS, Karmakar A,
Kakatkar R, Parekh A (2019) The tropical Indian Ocean decadal sea
level response to the Pacific decadal oscillation forcing. Clim Dyn
52:5045–5058. https://doi.org/10.1007/s00382-018-4431-9
10 Indian Ocean Warming
203