Navigation Links
Volcanic eruptions affect rainfall over Asian monsoon region

Scientists have long known that large volcanic explosions can affect the weather by spewing particles that block solar energy and cool the air.

Some suspect that extended "volcanic winters" from gigantic eruptions helped kill off dinosaurs and Neanderthals.

In the summer following Indonesia's 1815 Tambora eruption, frost wrecked crops as far away as New England, and the 1991 blowout of the Philippines' Mount Pinatubo lowered average global temperatures by 0.7 degrees F--enough to mask the effects of greenhouse gases for a year or so.

Now, in research funded by the National Science Foundation (NSF)'s Division of Atmospheric and Geospace Sciences, scientists have discovered that eruptions also affect rainfall over the Asian monsoon region, where seasonal storms water crops for nearly half of Earth's population.

Tree-ring researchers at Columbia University's Lamont-Doherty Earth Observatory (LDEO) showed that big eruptions tend to dry up much of Central Asia, but bring more rain to southeast Asian countries including Vietnam, Laos, Cambodia, Thailand and Myanmar--the opposite of what many climate models predict.

A paper reporting their results appears in an advance online version of the American Geophysical Union (AGU) journal Geophysical Research Letters.

The growth rings of some tree species can be correlated with rainfall. LDEO's Tree Ring Lab used tree rings from some 300 sites across Asia to measure the effects of 54 volcanic eruptions going back about 800 years.

The data came from LDEO's new 1,000-year tree-ring atlas of Asian weather, which has produced evidence of long, devastating droughts.

"We might think of the solid Earth and the atmosphere as two different things, but everything in the system is interconnected," said Kevin Anchukaitis, the paper's lead author. "Volcanoes can be important players in climate over time."

Large explosive eruptions send up sulfur compounds that turn into tiny sulfate particles high in the atmosphere, where they deflect solar radiation.

The resulting cooling on Earth's surface can last for months or years.

Not all eruptions have that effect, however. For instance, the continuing eruption of Indonesia's Merapi this fall has killed dozens, but this latest episode is probably not big enough by itself to effect large-scale weather changes, scientists believe.

As for rainfall, in the simplest models, lowered temperatures decrease evaporation of water from the surface to the air. Less water vapor translates to less rain.

But matters are greatly complicated by atmospheric circulation patterns, cyclic changes in temperatures over the oceans, and the shapes of land masses.

Until now, most climate models incorporating changes in the sun and the atmosphere have predicted that volcanic explosions would disrupt the monsoon by bringing less rain to southeast Asia--but the researchers found the opposite.

They studied several eruptions, including one in 1258 from an unknown tropical site, thought to be the largest of the last millennium; the 1600-1601 eruption of Peru's Huaynaputina; Tambora in 1815; the 1883 explosion of Indonesia's Krakatau; Mexico's El Chichn in 1982; and Pinatubo.

Tree rings showed that huge swaths of southern China, Mongolia and surrounding areas consistently dried up in the year or two following big events, while mainland southeast Asia received increased rain.

The researchers believe there are many possible factors involved.

"The data only recently became available to test the models," said Rosanne D'Arrigo, one of the paper's co-authors. "There's a lot of work to be done to understand how all these different forces interact."

In some episodes pinpointed by the study, it appears that strong cycles of the El Nio-Southern Oscillation, which drives temperatures over the Pacific and Indian Oceans and is thought to strongly affect the Asian monsoon, might have counteracted eruptions, lessening their drying or moistening effects. p>

But it could work the other way, too, said Anchukaitis; if atmospheric dynamics and volcanic eruptions come together with the right timing, they could reinforce one another--with drastic results.

"Then you get flooding or drought, and neither flooding nor drought is good for the people living in those regions," he said.

Ultimately, said Anchukaitis, such studies should help scientists refine models of how natural and man-made forces might act together to shift weather patterns--a vital question for all areas of the world.


Contact: Cheryl Dybas
National Science Foundation

Related biology news :

1. LSU professor uses volcanic emissions to study Earths atmospheric past
2. Envisat captures renewed volcanic activity
3. Scientists to measure impact of volcanic ash on ocean biology
4. Volcanic ash research shows how plumes end up in the jet stream
5. New satellite image of volcanic ash cloud
6. British scientific expedition discovers worlds deepest known undersea volcanic vents
7. Volcanic hazard map produced for island of Gran Canaria
8. Earths highest known microbial systems fueled by volcanic gases
9. Research proves gender-bending chemicals affect reproduction
10. Shifting forms: Penn study shows how variations of same protein affect immune response
11. Insights into environmental conditions that affect highly pathogenic bird flu virus survival
Post Your Comments:
Related Image:
Volcanic eruptions affect rainfall over Asian monsoon region
(Date:10/29/2015)... ANN ARBOR, Mich. , Oct. 29, 2015 ... with Eurofins Genomics for U.S. distribution of its ... DNA-seq kit and Rubicon,s new ThruPLEX Plasma-seq ... DNA to enable the preparation of NGS libraries ... in plasma for diagnostic and prognostic applications in ...
(Date:10/27/2015)... NEW YORK , Oct. 27, 2015 ... the major issues of concern for various industry verticals ... This is due to the growing demand for secure ... practices in various ,sectors, such as hacking of bank ... concerns for electronic equipment such as PC,s, laptops, and ...
(Date:10/26/2015)... PALO ALTO, Calif. and LAS ... – Nok Nok Labs , an innovator in ... FIDO Alliance , today announced the launch of its ... the first unified platform enabling organizations to use standards-based ... authentication. The Nok Nok S3 Authentication Suite is ideal ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... 2015 --> ... - 2020 report analyzes that automating biobanking workflow ... in long-term samples, minimizing manual errors, improving the ... manual errors such as mislabeling or inaccurate sample ... plays a vital role in blood fractionation, DNA ...
(Date:11/25/2015)... 2015 Studies reveal the differences ... and pave the way for more effective treatment for one ...   --> --> ... problems in cats, yet relatively little was understood about the ... have been conducted by researchers from the WALTHAM Centre for ...
(Date:11/25/2015)... 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ:  AEZS; TSX: ... prospects remain fundamentally strong and highlights the following ... received DSMB recommendation to continue the ZoptEC Phase ... the final interim efficacy and safety data ... men with heavily pretreated castration- and Taxane-resistant prostate ...
(Date:11/25/2015)... November 25, 2015 The ... is a professional and in-depth study on the ...      (Logo: ) , ... industry including definitions, classifications, applications and industry chain ... the international markets including development trends, competitive landscape ...
Breaking Biology Technology: