1. Climate Change & India’s Monsoons
Katie Boyer
May 6, 2008

2. Why India?
1.13 billion people – 2nd most populous country in the world – 1/6th the world’s population
Over 200 million citizens of India are undernourished
Agriculture employs 70% of people and produces 25% of the nation’s GDP
1/4th of exports are agricultural goods
Country depends on rain!
Most of the annual 975 mm of rain comes in form of annual tropical monsoon
Water fills tributaries used for drinking water
Rice = staple food of 65% of the population = 55% of India’s rice is rain fed

3. India’s Monsoons
Stems from the differences in temperature & pressure between the land and the ocean
2 components in control:
Land component = Eurasian (Himalayan) snow cover
Ocean component = ENSO
Results
Northwestern India – little rainy period
Southern & Northeastern India – more rain & longer season
Highly susceptible to variation in rains and even failure

4. El Nino/ Southern Oscillation
Positive Feedback Loop:
Weakening winds 
Decreased upwelling in SA 
Lowering thermocline 
Warmer ocean temperatures 
Weakening winds

5. Himalayan Snow Cover
Extent of rainfall negatively correlated with extent of Eurasian snowfall
Less winter precipitation  less cooling of continental land mass & lower albedo  higher rainfall (non-ENSO)
Relationship diminishes during El Nino years

6. ENSO Years & Monsoon Global warming seems to weaken relationship
Causes warming oceans & displacement of Walker circulation  displaces rainfall producing systems
132 year record of India’s rain = every drought was accompanied by El Nino year (but not vice versa)
Followed by La Nina, which causes floods

7. Forecasting
Early methods used snow cover as only factor in predicting monsoon
Important for disaster mitigation, crop planning, and power generation
Global dimming
Pollutants are blowing offshore, blocking sunlight, and shifting heating patterns that drive the monsoon
Reduction of particulate matter may increase difference between land & sea temps

8. El Nino-like State
A study of 79 coupled ocean-atmosphere simulations from 12 different climate models based on 6 different IPCC scenarios (Paeth et al.)
All scenarios = substantial warming in eastern tropical Pacific amounting to 5°C until 2100
Results  failed monsoon, drought, dried out soils, decreased land fertility, famine

9. La Nina-like State 12 simulations (Doherty and Hulme)
4 = inconclusive
2 = El Nino-like state
Results  shifting rains, intensification of the monsoon, flooding, reversal of the ENSO system

10. Personal Conclusion
Higher ocean temperatures during more frequent ENSO years may create more fuel for future ENSO years  move into a permanent El Nino-like state
Droughts in areas that are normally wet and floods in areas that are normally dry – 2007 produced massive flooding across India
More models are necessary
Ethics  Who’s to blame? Who needs to act?

11. Affects on India
Floods, drought, tornadoes, plant diseases, insect pests
Dried up major river basins
Famine
Northern India expected to experience the greatest warming trend
Water shortage
Dry areas get drier while wet areas get wetter
Shift in biodiversity
10% increase in area prone to malaria by 2080
Sea level rise of 1 meter could displace 7 million people