Climate swings contribute more to increased monsoon rainfall
Washington: Natural swings in the climate have significantly intensified Northern Hemisphere monsoon rainfall, indicating that they must be taken into account for climate predictions in the coming decades.
Monsoon rainfall in the Northern Hemisphere impacts about 60 percent of the World population in Southeast Asia, West Africa and North America.
Given the possible impacts of global warming, solid predictions of monsoon rainfall for the next decades are important for infrastructure planning and sustainable economic development.
Such predictions, however, are very complex because they require not only pinning down how manmade greenhouse gas emissions will impact the monsoons and monsoon rainfall, but also a knowledge of natural long-term climate swings, about which little is known so far.
To tackle this problem an international team of scientists around Meteorology Professor Bin Wang at the International Pacific Research Center, University of Hawaii at Manoa, examined climate data to see what happened in the Northern Hemisphere during the last three decades, a time during which the global-mean surface-air temperature rose by about 0.4C.
Current theory predicts that the Northern Hemisphere summer monsoon circulation should weaken under anthropogenic global warming.
Wang and his colleagues, however, found that over the past 30 years, the summer monsoon circulation, as well as the Hadley and Walker circulations, have all substantially intensified.
This intensification has resulted in significantly greater global summer monsoon rainfall in the Northern Hemisphere than predicted from greenhouse-gas-induced warming alone - namely a 9.5 percent increase, compared to the anthropogenic predicted contribution of 2.6 percent per degree of global warming.
Most of the recent intensification is attributable to a cooling of the eastern Pacific that began in 1998.
This cooling is the result of natural long-term swings in ocean surface temperatures, particularly swings in the Interdecadal Pacific Oscillation or mega-El Nino-Southern Oscillation, which has lately been in a mega-La Nina or cool phase.
Another natural climate swing, called the Atlantic Multidecadal Oscillation, also contributes to the intensification of monsoon rainfall.
"These natural swings in the climate system must be understood in order to make realistic predictions of monsoon rainfall and of other climate features in the coming decades," Wang said.
The findings are published in the online publication of the Proceedings of the National Academy of Sciences.
More from India
More from World
More from Sports
More from Entertaiment
- CM Kejriwal shortlists 39 'unwanted' IAS officers in Delhi
- Rajasthan: Gujjars revive reservation agitation, block rail track
- J Jayalalithaa sworn-in as Chief Minister of Tamil Nadu
- Dr Subhash Chandra Show: Aspiring for more than what you have!
- ISIS to buy first nuclear weapon from Pak?
- Mumbai: CCTV captures assailant with gun at Film City
- Mathura SSP receives death threat letter, message for PM Modi
- BJP now central pole of Indian politics: Arun Jaitley
- Maharashtra FDA sends Maggi noodles for lab testing
- Watch: Fast N Facts @ 7:30pm
- Haridwar: Hotel Radisson Blu sealed for polluting Ganga
- Delhi: Two killed in road accident in New Ashok Nagar
- Girl in Punjab's Pathankot quit studies for fear of eve-teasing
- Fiji: Floating island restaurant in middle of ocean
- Special: Furious over rising water crisis, people take to the streets
- Goa Board SSC Exam Results 2015 announced
- Rahul Gandhi to pressurise govt to act on one-rank-one-pension issue
- ISIS close to buying nuclear weapon from Pakistan?
- Manohar Parrikar visits forward areas along LoC, reviews security situation
- There will be no delay in appointing CIC, CVC: Jitendra Singh
- Credibility of Prime Minister's Office restored by BJP, says Arun Jaitley
- ISIS justifies raping slave girls, says Michelle Obama is 'worth $40'
- Arvind Kejriwal to highlight AAP govt's 100 days work on Monday
- 'Unhappy' Celina Jaitley asks Sunny Leone to move out?
- BJP's plan for one-year celebration: 200 big rallies, 5,000 public meetings
- IPL 2015 Final: Mumbai Indians vs Chennai Super Kings - Preview
- Heatwave leaves 153 dead in Telangana, Andhra Pradesh
- CBSE Results 2015: 10th board exam results to be declared on May 27
- IPL 8 Final: We need to be at our best against Mumbai, says Michael Hussey
- Jayalalithaa returns as Tamil Nadu CM: As it happened