Science Current Events | Science News | Brightsurf.com
 
Email a Friend Send to a friend
Printer Friendly Print Sedimentary records link Himalayan erosion rates and monsoon intensity through time
Slashdot It! Slashdot Sedimentary records link Himalayan erosion rates and monsoon intensity through time
Submit to Reddit Submit Sedimentary records link Himalayan erosion rates and monsoon intensity through time to Reddit
Reading: Sedimentary records link Himalayan erosion rates and monsoon intensity through timeTwitter This Reading: Sedimentary records link Himalayan erosion rates and monsoon intensity through timeTwitter Sedimentary records link Himalayan erosion rates and monsoon intensity through time
Add to Facebook Add Sedimentary records link Himalayan erosion rates and monsoon intensity through time to Facebook

Sedimentary records link Himalayan erosion rates and monsoon intensity through time

November 10, 2008

TEMPE, Ariz. - Throughout history, the changing fortunes of human societies in Asia have been linked to variations in the precipitation resulting from seasonal monsoons. A new paper published in the British journal Nature Geoscience suggests that variations in monsoon climate over longer time scales also influenced the evolution of the world's highest mountain chain, the Himalaya.

The climate over much of Asia is dominated by seasonal winds that carry moist air over the Pacific Ocean into East Asia and over the Indian Ocean into South Asia. The East and South Asian monsoons are responsible for most of the rainfall in these regions. Although the time when these monsoon patterns were first established is unknown, many lines of evidence suggest that they first came about at least 24 million years ago.




The new study uses geochemical data from an Ocean Drilling Project sediment core extracted from the seafloor of the South China Sea to establish a record of the East Asian monsoon climate over that time interval.

"Sediments in this core were eroded from the drainage area of the Pearl River system in China, and their chemistry records the relative intensity through time of chemical weathering in an area that received the bulk of its precipitation from East Asian monsoon storms," explains Peter Clift, lead author of the study and a professor of geology and petroleum geology at the University of Aberdeen in Scotland.

Many researchers believe that a geologically "abrupt" uplift of the Tibetan Plateau - the largest high-altitude region on Earth, with an average elevation of more than 4,000 meters (13,000 feet) - at 8 to10 million years ago caused a major intensification in the monsoon climate.

"South China Sea data do not support that interpretation," says Kip Hodges, a co-author of the paper and director of the School of Earth and Space Exploration in the College of Liberal Arts and Sciences at Arizona State University. "Other than a brief drop between about 17 and 15 million years ago, the pattern in the core suggests a steady increase in East Asian monsoon intensity from 23 to 10 million years ago, followed by a steady weakening until about 4 million years ago. After that, the intensity began to increase once more. The implication is that either the development of the plateau was not as abrupt as we might have thought, or that an abrupt uplift of the plateau at 8 to 10 million years caused a change in precipitation patterns that was not recorded in East Asia."

Another controversy surrounds the degree of coupling between the South and East Asian monsoons. Could one have varied in intensity differently from the other?

The team compared the South China Sea record with less-complete sedimentary records from the Arabian Sea and Bay of Bengal - which contain sediments that were eroded from the Himalaya, where the principal rainfall comes from South Asian monsoon storms - to argue for a linkage between the two monsoon systems over most of the past 23 million years.

"The really exciting moment in this research came when we began to compare patterns from one record to another and found broad agreement," says Clift.

The most interesting correlation was found when the team compared the sedimentary records to cooling age patterns in the Himalaya. Hodges and his students have spent years using isotopic dating techniques to determine the cooling ages of thousands of bedrock and sediment samples from all over the Himalaya.

"Most people are familiar with the use of such techniques to determine the crystallization ages of minerals and rocks," says Hodges. "They also can be used to determine when a mineral cooled through a certain temperature. The principal mechanism by which samples cool in mountainous regions is erosion, so a high frequency of minerals with the same cooling age generally means a high rate of erosion at that time."

Compilations of the cooling ages obtained by Hodges' group and other researchers show that the periods of high East Asian monsoon intensity matched well with high frequencies of cooling ages, implying a relationship between monsoon intensity and erosion in the Himalaya.

"While it makes sense intuitively that heavy rainfall should be correlated with more aggressive erosion, it is important to see such direct evidence of the coupling between the processes that define the evolution of mountain ranges and climatic processes," Hodges explains. "It implies, once again, that Earth is a complex system, and we cannot begin to fully understand mountain building without appreciating the roles of the hydrosphere and atmosphere in the evolution of mountain ranges."

But Hodges cautions that the results of this study are suggestive.

"It is important to confirm our interpretations by generating a more comprehensive cooling age dataset from regions of the Himalaya that have not yet been studied because of logistical constraints or political instability."

Adds Clift, "We really need more complete offshore sedimentary records from the Arabian Sea and Bengal Fan to make a solid case for linkages between the South and East Asian monsoon systems."

Arizona State University





Science News and Science Current Events Tag Cloud
This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size.
New Species   Big Bang   Blindness   Cell Division   Pneumonia   Preeclampsia   Cochlear Implant   Cerebral Malaria   Water Purification   Emotions   Vitamin   Heart Disease   Immune Response   Menopause   Twins   Hurricane   Ischemic Stroke   Estrogen Receptor   Growth Hormone   Folic Acid   Physical Activity   Medication   Mass Extinction   Iron Deficiency   Neurodegeneration  
Related Asian Monsoon Current Events and Asian Monsoon News Articles Asian Monsoon Current Events and Asian Monsoon News RSS Asian Monsoon Current Events and Asian Monsoon News RSS
World's largest aerosol sensing network has leafy origins
Twenty years ago, Brent Holben was part of a NASA team studying vegetation from space. In an unlikely career twist, his research morphed into the study of a critical, if overlooked, subplot in the story of climate change.

Sedimentary records link Himalayan erosion rates and monsoon intensity through time
Throughout history, the changing fortunes of human societies in Asia have been linked to variations in the precipitation resulting from seasonal monsoons.

Climate change may affect East Asia differently to North Atlantic nations, study suggests
The extreme effects of climate change on the world depicted in the US blockbuster movie The Day After Tomorrow may not be quite true where East Asia is concerned.

Tibet Provides Passage for Chemicals to Reach the Stratosphere
NASA and university researchers have found that thunderstorms over Tibet provide a main pathway for water vapor and chemicals to travel from the lower atmosphere, where human activity directly affects atmospheric composition, into the stratosphere, where the protective ozone layer resides.

Dr A.H. Heineken Prize for Environmental Sciences 2002 for Lonnie G. Thompson
The Royal Netherlands Academy of Arts and Sciences has awarded the Dr A.H. Heineken Prize for Environmental Sciences 2002 (USD 150,000) to Professor Lonnie G. Thompson Byrd Polar Research Center, Ohio State University, United States ‘for his pioneering work in research into ice cores in the polar regions and the tropics’. The subject Lonnie Thompson is convinced that ice forms the best archive of the earth’s climate. And that frozen history is located not only at the North and South Poles, but also in the tropics – for example at the peaks of Mt. Kilimanjaro, where the ice caps are in fact melting rapidly. Thompson was one of the first to realise that global warmi

Nature press release for 31 January issue
[415512] CLIMATE: FLOOD WARNING (pp512-514; 514-517; N&V) Very wet winters will be up to five times more likely than today for much of central and northern Europe over the next century. The probability of very wet summers in the Asian monsoon region will rise by a similar amount, increasing the risk of flooding. So say Tim Palmer of the European Centre for Medium-Range Weather Forecast in Reading, UK, and Jouni R'¤is'¤nen of the Swedish Meteorological and Hydrological Institute in Norrköping, Sweden, in this week`s Nature. The duo have analysed the output of 19 climate models. In the same issue, Christopher Milly of the US Geological Survey, Princeton, New Jersey, and co-workers present evi
More Asian Monsoon Current Events and Asian Monsoon News Articles
Monsoon Sunday 1:

Monsoon Sunday 1:
by Maharaja Entertainments (Pvt.) Ltd.



The Asian Monsoon: Causes, History and Effects

The Asian Monsoon: Causes, History and Effects
by Peter D. Clift (Author), R. Alan Plumb (Author)

The Asian monsoon is one of the most dramatic climatic phenomena on Earth, with far reaching environmental and societal effects. Almost two thirds of humanity lives within regions influenced by the monsoon. With the emerging Asian economies, the importance of the region to the global economy has never been more marked. The Asian Monsoon describes the evolution of the monsoon, and proposes a connection between the tectonic evolution of the solid Earth and monsoon intensity. The authors explain how the monsoon has been linked to orbital processes and thus to other parts of the global climate system, especially glaciation. Finally, they summarize how monsoon evolution since the last Ice Age has impacted human societies, as well as commenting on the potential impact of future climate change....

Monsoon Clouds Over the Houses of Gyantse, Tibet Photographic Poster Print, 24x32

Monsoon Clouds Over the Houses of Gyantse, Tibet Photographic Poster Print, 24x32
by Art.com

Art.com is the world's largest retailer of art prints, posters, photographs, and framed artwork. With our huge selection of over 400,000 prints, you'll easily find the perfect piece for your home, office, or classroom. Our art is printed on quality paper. When you order framed artwork, the piece is built by our team of in-house professionals. Visit our Amazon store today at www.amazon.com/artdotcom to find Special Offers and search for products based on 'Artist Name' and 'Subject Categories' such as Movie, Music, Vintage, TV, Children, Travel, Kitchen, Museum Art, Animals, Floral, Motivational, and Sports. Art.com is dedicated to providing you with high quality products and service by offering you 100% satisfaction guaranteed. We ship internationally to over 80 countries. Decorate your...

The Asian Monsoon

The Asian Monsoon
by Cambridge University Press

The Asian monsoon is one of the most dramatic climatic phenomena on Earth, with far reaching environmental and societal effects. Almost two thirds of humanity lives within regions influenced by the monsoon. With the emerging Asian economies, the importance of the region to the global economy has never been more marked. The Asian Monsoon describes the evolution of the monsoon, and proposes a connection between the tectonic evolution of the solid Earth and monsoon intensity. The authors explain how the monsoon has been linked to orbital processes and thus to other parts of the global climate system, especially glaciation. Finally, they summarize how monsoon evolution since the last Ice Age has impacted human societies, as well as commenting on the potential impact of future climate change....

Ever So Lonely / Sunset Over The Ganges [ 7 inch VINYL single. 45 rpm ] { U.K. Picture Sleeve}

Ever So Lonely / Sunset Over The Ganges [ 7 inch VINYL single. 45 rpm ] { U.K. Picture Sleeve}

7 inch Vinyl single. 45 RPM. U.K. import.

Monsoon of Perfume

Monsoon of Perfume
by M80



The Asian Monsoon  (Springer Praxis Books / Environmental Sciences)

The Asian Monsoon (Springer Praxis Books / Environmental Sciences)
by Bin Wang (Author)

Satellite observations and computing technology have advanced our understanding of the monsoon climate enormously in the last two decades. The author provides an update of the knowledge gained over this period, presenting the modern morphology and the physical principles of monsoon climate variation on all time scales ranging from intraseasonal to tectonic time scales. He brings new ideas that can be expected to markedly improve the prediction of monsoon climate, and includes contributions by experts who expand our understanding of the monsoon environment by their study of paleoclimate records, who present evidence of human influences on monsoon climate, and who describe the links of the monsoon to the economy and to human health.

This is a comprehensive interdisciplinary text book...

Monsoon Magic

Monsoon Magic
by Music Today



Development of the East Asian monsoon and Northern Hemisphere glaciation: oxygen isotope records from the South China Sea [An article from: Quaternary Science Reviews]

Development of the East Asian monsoon and Northern Hemisphere glaciation: oxygen isotope records from the South China Sea [An article from: Quaternary Science Reviews]
by J. Tian (Author), P. Wang (Author), X. Cheng (Author)

This digital document is a journal article from Quaternary Science Reviews, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Oxygen isotope records of the surface-dwelling foraminifer Globigerinoides ruber from ODP Site 1143 in the southern South China Sea (SCS) are presented for the last 5Ma. The G. ruber @d^1^8O of Site 1143 for the past 500ka is lighter by 0.5-1.0%% in interglacial, and by 0.1-0.5%% in glacial periods, than the Site 806B record from the Ontong Java Plateau. We infer the light glacial/interglacial G. ruber @d^1^8O at Site 1143, compared with the open western Pacific, to have been caused by stronger...

Monsoon

Monsoon
by Juso Record



© 2009 BrightSurf.com