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The Impact of Climate Change on the
Predictability of the Indian Monsoon
“ Weird things are happening.
Certainly monsoons are hitting in
the wrong places at the wrong times,
and officials aren’t ready for it. ”
– Devendra Fadnavis,
Indian Legislature Member from Nagpur
Ruthie King, Jennifer Mayer, Sabilah Eboo, and James Dawson
Take Away Concepts
For centuries, the culture of India has depended on the ability to
predict the monsoon. Now, global warming may begin to alter the
machinery that makes the monsoon predictable – which could
profoundly impact the social and political fabric of the Indian
subcontinent.
1). Understanding the Natural Monsoon Cycle
2). How ENSO Impacts India’s Monsoon
3). How the ENSO/Warming Relationship Damages Predictability
4). How Global Warming Itself Makes the Monsoon Less Predictable
5). Conclusions
6). Problems of Predictability
Natural Monsoon Cycle
The Natural Monsoon Process (Healy 2007):
•
Specific Heat of Water Higher Than Land
•
•
In Summer, Land Warms Faster than Ocean
•
Warm Air Rises, Causing Low Pressure
•
Low Pressure Pulls Wind Toward Land
Wind Carries Warm, Ocean Moisture to Land
http://images.google.com/imgres?imgurl=http://www.geo.arizona.edu/Antevs/ecol438/monsoon.gif
&imgrefurl=http://www.geo.arizona.edu/Antevs/ecol438/lect03a.html&h=428&w=402&sz=118&hl=
en&start=9&um=1&tbnid=52m1400nRohYJM:&tbnh=126&tbnw=118&prev=
In India, this “natural process is intensified” (Hahn and others 1975) because the
air is trapped by the Himalayas and forced to rise. As it rises, it cools and, due to
the adiabatic lapse rate, condenses to create more rain.
Hahn D, Manabe S. 1975. The Role of Mountains in the South Asian Monsoon Circulation. Journal of the Atmospheric Sciences 32: 1515-1540.
Healy, Mark. South Asia: Monsoons. World Regional Geography, Lecture: South Asia [Internet]. Fall 2007 [cited 30 October, 2007]; 5:00. Available
from: http://library.osu.edu/sites/guides/cbegd.php.
Natural ENSO/Monsoon Relationship
Global Conditions during El Nino Summers
http://images.google.com/imgres?imgurl=http://www.pmel.noaa.gov/tao/elnino/gif/winter.gif&imgrefurl=http://www.pmel.noaa.gov/tao/elnino/impacts.html&h=
302&w=533&sz=10&hl=en&start=13&um=1&tbnid=u6mf_pjLNuSLeM:&tbnh=75&tbnw=132&prev=
ENSO variability impacts temperatures in the Indian Ocean, which
impacts rainfall conditions in India. The Clausius-Clapeyron relation
states that warm air can hold more water. Thus, “the natural
ENSO/monsoon relationship” (Annamalai and others 2004) is:
El Nino conditions create drought, which weakens the monsoon
La Nina conditions create rain, which further intensifies the monsoon
Annamalai H, Xie SP, McCreary JP. 2004. Impact of Indian Ocean Sea Surface Temperature on
Developing El Nino. International Pacific Research Center at the University of Hawaii Honolulu.
Global Warming Will Lead to Less Predictability
in the ENSO/Global Warming Relationship
La Nina = Flooding
El Nino = Drought
Scientists are divided over how global warming will impact ENSO.
www.tropmet.res.in/~jsc/IITM-Brochure.pdf
One camp thinks that global warming will lead to near-constant El Nino conditions. They believe
that the ocean will warm uniformly, which will create an ocean-atmosphere coupling to sustain
El Nino. If this happens, the monsoon may occur less frequently and with less power.
Another thinks that global warming will lead to near-constant La Nina conditions. They believe
the western Pacific will warm most, which will strengthen the natural Walker Cell and sustain La
Nina. If this happens, the monsoon may occur for a longer amount of time with more power.
Pant, GB. 2003. Long-Term Climate Variability and Change Over Monsoon Asia. Indian Institute of Tropical Meteorology 7(3): 125-134.
Conclusions from Part 1:
India relies in part on the natural cycle
of ENSO variability in order to predict the
timing and severity of the monsoon. As
global warming changes ENSO, these
predictions will become less accurate.
The ultimate result will be more
surprising and damaging monsoons.
Global Warming and the Monsoon
In 2001, the Japanese Centre for Climate System
Research and the National Institute for Environmental
Studies ran a model which coupled atmosphere-ocean
general circulation around India to simulate India's
monsoon as closely as possible in order to project
climate change onto it. They projected A1, A2, B1 and B2.
The summed average of the models “suggests an
annual mean area-averaged surface warming over the
Indian subcontinent to range between 3.5 and 5.5°C
over the region during 2080s." (Murari and others 2001)
http://144.16.79.155/currsci/nov102001/1196.pdf
http://144.16.79.155/currsci/nov102001/1196.pdf
Climate change will have a greater impact on India's winter, with a "5 to 25%
decline in rainfall," thus increasing the extreme anti-monsoon drought which
already occurs during the winter months. (Murari and others 2001)
The climate change during summer will increase land temperatures and increase
the pressure gradient between the land and ocean. This will intensify the
monsoon and increase rainfall "10 - 15%... over India” (Murari and others 2001)
The model indicates intensifying seasons, but it also shows an increased volatility
and unpredictability of the cycle. India relies on knowing when the floods and
droughts will occur, but with climate change, "the date of onset monsoons over
central India could become more variable" (Murari and others 2001).
Conclusions from Part 2:
A2: 2071-2100; www.defra.gov.uk/ENVIRONMENT/climatechange/internat/devcountry/pdf/india-climate-2-climate.pdf
India relies on predictable pressure gradients and
temperatures to predict when the monsoon will come
and how severe it will be.
As global warming continues, these temperatures and
pressures will become less predictable. The monsoon
will thus become more volatile and its arrival will
become less foreseeable.
On the whole, we have to take long-term monsoon
predictions with a grain of salt.
But, according to Kurzweil’s “Singularity Law of
Accelerating Returns” (as explained by Peter
Eisenberger), knowledge is like a puzzle; we open new
doors with each new piece.
In this sense, the research that climatologists are
currently doing on ENSO / global warming linkages is
promising. Although the exact semantics of the
interaction is unclear, new research will yield new
ideas to be researched until, ultimately,
the problem is understood.
Bibliography:
Hahn D, Manabe S. 1975. The Role of Mountains in the South Asian Monsoon Circulation. Journal of the Atmospheric
Sciences 32: 1515-1540.
Healy, Mark. South Asia: Monsoons. World Regional Geography, Lecture: South Asia [Internet]. Fall 2007 [cited 30 October,
2007]; 5:00. Available from: http://library.osu.edu/sites/guides/cbegd.php.
Annamalai H, Xie SP, McCreary JP. 2004. Impact of Indian Ocean Sea Surface Temperature on Developing El Nino.
International Pacific Research Center at the University of Hawaii Honolulu.
Pant, GB. 2003. Long-Term Climate Variability and Change Over Monsoon Asia. Indian Institute of Tropical Meteorology
7(3): 125-134.
Battisti D, Sarachik E. Impacts of El Niño and benefits of El Niño prediction. National Oceanic and Atmospheric
Administration [Internet]. 2007 [cited 2007 Nov 8]; 1-4. Available from:
http://www.pmel.noaa.gov/tao/elnino/impacts.html.
Kumar K, Kumar R, Soman M. Seasonal Forecasting of Indian Summer Monsoon Rainfall: A Review. Indian Institute of
Tropical Meteorology [Internet]. 2007 [cited 2007 Nov 8]; 1-8. Available
from: http://www.tropmet.res.in/%7Ekolli/MOL/Forecasting/frameindex.html.
Meise CJ, Johnson DL, Stehlik LL, Manderson J, Shaheen P. 2003. Growth rates of juvenile Winter Flounder under varying
environmental conditions. Trans Am Fish Soc 132(2):225-345.
Murari L, Nazawa T, Namori S, Harasawa H, Takahashi K, Kimoto M, Abe-Ouchi A, Nakajima T, Takemura T, Numaguti A. 2001.
Future Climate Change: Implications for Indian Summer Monsoon and its Variability. Current Science 81(9): 1197-1207.