Featured Research

from universities, journals, and other organizations

Natural climate swings contribute more to increased monsoon rainfall than global warming

Date:
March 20, 2013
Source:
University of Hawaii ‑ SOEST
Summary:
Natural swings in the climate have significantly intensified Northern Hemisphere monsoon rainfall, showing that these swings must be taken into account for climate predictions in the coming decades.

This is a three-layered cloud structure in a developing Madden-Julian Oscillation during the Indian Ocean DYNAMO field experiments (November 2011). The photo won first place in the DYNAMO photo contest.
Credit: Owen Shieh, University of Hawaii

Natural swings in the climate have significantly intensified Northern Hemisphere monsoon rainfall, showing that these swings must be taken into account for climate predictions in the coming decades, a new study finds.

The findings are published in the March 18 online publication of the Proceedings of the National Academy of Sciences.

Monsoon rainfall in the Northern Hemisphere impacts about 60% 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 humanmade 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 0.4°C. 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% increase, compared to the anthropogenic predicted contribution of 2.6% 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 Niño-Southern Oscillation, which has lately been in a mega-La Niña 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," says Wang. "We must be able to determine the relative contributions of greenhouse-gas emissions and of long-term natural swings to future climate change."


Story Source:

The above story is based on materials provided by University of Hawaii ‑ SOEST. Note: Materials may be edited for content and length.


Journal Reference:

  1. B. Wang, J. Liu, H.-J. Kim, P. J. Webster, S.-Y. Yim, B. Xiang. Northern Hemisphere summer monsoon intensified by mega-El Nino/southern oscillation and Atlantic multidecadal oscillation. Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1219405110

Cite This Page:

University of Hawaii ‑ SOEST. "Natural climate swings contribute more to increased monsoon rainfall than global warming." ScienceDaily. ScienceDaily, 20 March 2013. <www.sciencedaily.com/releases/2013/03/130320155251.htm>.
University of Hawaii ‑ SOEST. (2013, March 20). Natural climate swings contribute more to increased monsoon rainfall than global warming. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2013/03/130320155251.htm
University of Hawaii ‑ SOEST. "Natural climate swings contribute more to increased monsoon rainfall than global warming." ScienceDaily. www.sciencedaily.com/releases/2013/03/130320155251.htm (accessed July 31, 2014).

Share This




More Earth & Climate News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) — Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Florida Panther Rebound Upsets Ranchers

Florida Panther Rebound Upsets Ranchers

AP (July 31, 2014) — With Florida's panther population rebounding, some ranchers complain the protected predators are once again killing their calves. (July 31) Video provided by AP
Powered by NewsLook.com
Big Waves In Arctic Ocean Threaten Polar Ice

Big Waves In Arctic Ocean Threaten Polar Ice

Newsy (July 30, 2014) — Big waves in parts of the Arctic Ocean are unprecedented, mainly because they used to be covered in ice. Video provided by Newsy
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) — Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



    Save/Print:
    Share:  

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile iPhone Android Web
    Follow Facebook Twitter Google+
    Subscribe RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins