Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Asian monsoon much older than previously thought

15.09.2014

The Asian monsoon already existed 40 million years ago during a period of high atmospheric carbon dioxide and warmer temperatures, reports an international research team led by a University of Arizona geoscientist.

Scientists thought the climate pattern known as the Asian monsoon began 22-25 million years ago as a result of the uplift of the Tibetan Plateau and the Himalaya Mountains.


Mana Rugbumrung, a researcher at the Department of Mineral Resources in Bangkok, examines the freshly excavated skull of an anthracothere, a hippopotamus-like mammal that lived 40 million years ago in what is now Myanmar. Analyses of the teeth of these ancient mammals and others from the area revealed that the animals lived in a monsoon climate that had dry winters and very rainy summers.

Credit: Alexis Licht 2012

"It is surprising," said lead author Alexis Licht, now a research associate in the UA department of geosciences. "People thought the monsoon started much later."

The monsoon, the largest climate system in the world, governs the climate in much of mainland Asia, bringing torrential summer rains and dry winters.

Co-author Jay Quade, a UA professor of geosciences, said, "This research compellingly shows that a strong Asian monsoon system was in place at least by 35-40 million years ago."

The research by Licht and his colleagues shows the earlier start of the monsoon occurred at a time when atmospheric CO2 was three to four times greater than it is now. The monsoon then weakened 34 million years ago when atmospheric CO2 then decreased by 50 percent and an ice age occurred.

Licht said the study is the first to show the rise of the monsoon is as much a result of global climate as it is a result of topography. The team's paper is scheduled for early online publication in the journal Nature on Sept. 14.

This finding has major consequences for the ongoing global warming," he said. "It suggests increasing the atmospheric CO2 will increase the monsoonal precipitation significantly."

Unraveling the monsoon's origins required contributions from three different teams of scientists that were independently studying the environment of 40 million years ago.

All three investigations showed the monsoon climate pattern occurred 15 million years earlier than previously thought. Combining different lines of evidence from different places strengthened the group's confidence in the finding, Licht said. The climate modeling team also linked the development of the monsoon to the increased CO2 of the time.

Licht and his colleagues at Poitiers and Nancy universities in France examined snail and mammal fossils in Myanmar. The group led by G. Dupont-Nivet and colleagues at Utrecht University in the Netherlands studied lake deposits in Xining Basin in central China. J.-B. Ladant and Y. Donnadieu of the Laboratory of Sciences of the Climate and Environment (LSCE) in Gif-sur-Yvette, France, created climate simulations of the Asian climate 40 million years ago.

A complete list of authors of the group's publication, "Asian monsoons in a late Eocene greenhouse world," is at the bottom of this release, as is a list of funding sources.

Licht didn't set out to study the origin of the monsoon.

He chose his study site in Myanmar because the area was rich in mammal fossils, including some of the earliest ancestors of modern monkeys and apes. The research, part of his doctoral work at the University of Poitiers, focused on understanding the environments those early primates inhabited. Scientists thought those primates had a habitat like the current evergreen tropical rain forests of Borneo, which do not have pronounced differences between wet and dry seasons.

To learn about the past environment, Licht analyzed 40-million-year-old freshwater snail shells and teeth of mammals to see what types of oxygen they contained. The ratio of two different forms of oxygen, oxygen-18 and oxygen-16, shows whether the animal lived in a relatively wet climate or an arid one.

"One of the goals of the study was to document the pre-monsoonal conditions, but what we found were monsoonal conditions," he said.

To his surprise, the oxygen ratios told an unexpected story: The region had a seasonal pattern very much like the current monsoon – dry winters and very rainy summers.

"The early primates of Myanmar lived under intense seasonal stress – aridity and then monsoons," he said. "That was completely unexpected."

The team of researchers working in China found another line of evidence pointing to the existence of the monsoon about 40 million years ago. The monsoon climate pattern generates winter winds that blow dust from central Asia and deposits it in thick piles in China. The researchers found deposits of such dust dating back 41 million years ago, indicating the monsoon had occurred that long ago.

The third team's climate simulations indicated strong Asian monsoons 40 million years ago. The simulations showed the level of atmospheric CO2 was connected to the strength of the monsoon, which was stronger 40 million years ago when CO2 levels were higher and weakened 34 million years ago when CO2 levels dropped.

Licht's next step is to investigate how geologically short-term increases of atmospheric CO2 known as hyperthermals affected the monsoon's behavior 40 million years ago.

"The response of the monsoon to those hyperthermals could provide interesting analogs to the ongoing global warming," he said.

###

Researcher contact information:

Alexis Licht
University of Arizona
alicht@email.arizona.edu
Languages spoken: French and English

Jay Quade
University of Arizona
quadej@email.arizona.edu
(520) 626-1847

Jean-Jacques Jaeger
University of Poitiers (France)
+33549453758
jean-jacques.jaeger@univ-poitiers.fr

Guillaume Dupont-Nivet
University of Rennes (France)
+493319775784 (currently in Potsdam, Germany)
guillaume.dupont-nivet@univ-rennes1.fr

Yannick Donnadieu
+33169088666
Laboratory of Sciences of the Climate and Environment (France)
Yannick.Donnadieu@lsce.ipsl.fr

Related Web sites:

Alexis Licht: http://www.ipgp.fr/~licht/index.html

Jay Quade: http://www.geo.arizona.edu/Quade

UA Geosciences: http://www.geo.arizona.edu/

Complete list of authors and their affiliations:

A. Licht (University of Arizona, Tucson; University of Poitiers, France; and Centre of Petrographic and Geochemical Research (CRPG), Vandoeuvre les Nancy, France); M. van Cappelle (Utrecht University, Netherlands and Imperial College, London); H. A. Abels (Utrecht University, Netherlands and University of Leuven, Belgium); J.-B. Ladant (Laboratory of Sciences of the Climate and Environment (LSCE), Gif-sur-Yvette, France); J. Trabucho-Alexandre (Durham University, U.K); C. France-Lanord (CRPG, Vandoeuvre les Nancy, France); Y. Donnadieu (LSCE, Gif-sur-Yvette, France); J. Vandenberghe (Vrije University, Amsterdam): T. Rigaudier (CRPG, Vandoeuvre les Nancy, France); C. Lécuyer (University of Lyon, France); D. Terry Jr. (Temple University, Philadelphia); R. Adriaens (University of Leuven, Belgium); A. Boura (Pierre and Marie Curie University and National Museum of Natural History, Paris); Z. Guo (Peking University, Beijing); Aung Naing Soe (Defence Services Academy, Pyin Oo Lwin, Myanmar); J. Quade (University of Arizona, Tucson); G. Dupont-Nivet (University of Leuven, Belgium; Peking University, Beijing; University of Rennes, France; University of Potsdam, Germany); J.-J. Jaeger (University of Poitiers, France).

The research was supported by the following organizations: 09-BLAN-0238-02 Program of the French National Research Agency (ANR); the Universities of Poitiers and Nancy; the Netherlands Organisation for Scientific Research (NWO-ALW); the Marie Curie Career Integration Grant (CIG) 294282; the Ministry of Culture of the Republic of the Union of Myanmar; the French Ministries of Foreign Affairs and of Higher Education and Research; the Alexander von Humboldt Foundation; the Chinese Ministry of Education; the National Natural Science Foundation of China; and the Fyssen Foundation.

Mari N. Jensen | Eurek Alert!

Further reports about: Arizona Asian CO2 Climate Environment Foundation Gif-sur-Yvette Myanmar deposits monsoon monsoons primates

More articles from Earth Sciences:

nachricht New plate adds plot twist to ancient tectonic tale
15.08.2017 | Rice University

nachricht Global warming will leave different fingerprints on global subtropical anticyclones
14.08.2017 | Institute of Atmospheric Physics, Chinese Academy of Sciences

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>