. 24/7 Space News .
WATER WORLD
Caspian Sea evaporating as temperatures rise
by Staff Writers
Washington DC (SPX) Aug 30, 2017


The Caspian Sea as seen from the International Space Station in 2015. A new study finds water levels in the Caspian Sea dropped nearly 7 centimeters (3 inches) per year from 1996 to 2015. The current Caspian Sea level is only about 1 meter (3 feet) above the historic low level it reached in the late 1970s. Credit: Scott Kelly/NASA-JSC.

Earth's largest inland body of water has been slowly evaporating for the past two decades due to rising temperatures associated with climate change, a new study finds.

Water levels in the Caspian Sea dropped nearly 7 centimeters (3 inches) per year from 1996 to 2015, or nearly 1.5 meters (5 feet) total, according to the new study. The current Caspian Sea level is only about 1 meter (3 feet) above the historic low level it reached in the late 1970s.

Increased evaporation over the Caspian Sea has been linked to increased surface air temperatures. According to the data from the study, the average yearly surface temperature over the Caspian Sea rose by about 1 degree Celsius (1.8 degrees Fahrenheit) between the two timeframes studied, 1979-1995 and 1996-2015. These rising temperatures are likely a result of climate change, according to the study's authors.

Evaporation brought about by warming temperatures appears to be the primary cause of the current drop in sea level and the decline will likely continue as the planet warms, according to the study's authors.

"From our point of view as geoscientists, it's an interesting place because it's possible to construct a sort of budget for the total amount of water that's there," said Clark Wilson, a geophysicist with the Jackson School of Geosciences at the University of Texas at Austin, and co-author of the new study published in Geophysical Research Letters, a journal of the American Geophysical Union. "The real control that causes it to go up and down over long periods of time is really most likely the evaporation, which is almost completely dominated by temperature."

The Caspian Sea, located between Europe and Asia, is roughly the size of Montana at 371,000 square kilometers (143,244 square miles). It has experienced substantial changes in its water level over the past several hundred years, but previous studies were unable to nail down the exact causes of the sea level changes.

The Caspian Sea is bordered by five countries and contains an abundance of natural resources and diverse wildlife. The sea also contains oil and natural gas reserves, and is an important resource for fisheries in the surrounding countries.

The new study began after Wilson and Jianli Chen, the study's lead author from the Center for Space Research at the University of Texas at Austin, along with other researchers, used the Caspian Sea to calibrate data from the twin satellites of the GRACE mission launched in 2002. By comparing measurements of the Caspian Sea from GRACE data and Earth-based measurements, the researchers helped improve the satellite data's accuracy. In doing so, they noticed the Caspian Sea's water levels were undergoing significant changes.

"Once we got through with [the calibration], Jianli Chen said, 'Well, you know, this is very curious. Why is this changing so much?'" Wilson said. "That got us going on the current question, which is trying to understand what the reason is for these multimeter variations in the sea level. It's an interesting place, and it's been studied for a long time, but it wasn't really clear."

The researchers looked at the three primary influences on Caspian Sea water levels: water from rivers that drain into the sea, precipitation and evaporation.

They compiled information about water level changes observed by satellites, records of precipitation and drainage into the sea from rivers, and estimations of precipitation and evaporation from climate models. The researchers then assembled a record of how much each of these factors contributed to observed changes in the Caspian Sea level from 1979 to 2015.

They found Caspian Sea levels increased by about 12 centimeters (5 inches) per year from 1979-1995. But in 1996, sea levels began to drop, and declined by an average of nearly 7 centimeters (3 inches) per year through 2015. From 1996-2015, the Caspian Sea level dropped nearly 1.4 meters (4.5 feet), according to sea level records used in the study.

Evaporation contributed to about half of that decline, while the combined effects of precipitation and river discharge changes contributed to the other half. According to the study, the observed evaporation rates are associated with increased surface air temperature and other climate factors such as surface humidity and wind.

The new study provides the first convincing evidence that increased evaporation over the Caspian Sea is a more important driving force of Caspian sea level change than river discharge or precipitation, said Anny Cazenave, a CNES space geodesist at the Laboratoire d'Etudes en Geophysique et Oceanographie Spatiales (LEGOS) at Observatoire Midi-Pyrenees in Toulouse, France, who was not involved in the new study.

"An interesting finding from the study is that over the last two decades, climate-model predicted water loss ... apparently cannot be balanced by water gain from discharge, and increased evaporation is a major factor leading to this imbalance," Cazenave said.

"If the temperature in the Caspian Sea region continues to increase, the evaporation rate is also expected to increase. Unless river discharge increases accordingly or precipitation in the Caspian drainage basin increases accordingly, the imbalance is likely to continue."

The Caspian reached a historic low of 29 meters (95 feet) below mean sea level in the late 1970s before water levels increased in 1978. If current evaporation rates continue, the results suggest the sea could approach the historic low again, according to the study's authors.

Evaporation will have the biggest impact on the northern portion of the Caspian Sea because much of the water in that area is less than 5 meters (16 feet) deep, Wilson said. If the current trend of a 7-centimeter decrease per year continues at a steady rate, it would take around 75 years for the northern part of the sea to disappear, according to the new study.

The Caspian Sea supports many unique and ancient species remaining from when the sea was a part of the Tethys Ocean during the Mesozoic era, approximately 300 million years ago.

Although most of these species live in the southern and middle regions of the Caspian, some use the shallow northern area as spawning grounds, including 90 percent of the world's sturgeons. Dropping sea levels would also impact the Kara-Bogaz-Gol Bay on the eastern side of the sea, which is less than 5 meters (16 feet) deep and contains one of the world's largest natural deposit of sea salts, according to the study's authors.

Wilson said the next step in this research is to project future changes in Caspian Sea level using climate models. Although this study identified the trends in sea level and their causes, the researchers did not project specific estimates of how these levels might change in the future.

"If you're going to take this to the next step, it would be to take a suite of climate models or look at some sort of ensemble predictions of future temperatures to get some idea of what those scenarios might be for the Caspian Sea," Wilson said. "You can imagine if you had a continued decline in sea level that led to several meters of loss, you've considerably diminished the size of the sea."

Research paper

WATER WORLD
Ecuador prison for Chinese fishers caught in Galapagos
Quito (AFP) Aug 28, 2017
A court in Ecuador sentenced the crew of a Chinese ship caught fishing endangered sharks in the Galapagos marine reserve to prison terms on Sunday. The Chinese-flagged Fu Yuan Yu Leng 999 was caught within the protected zone on August 13 with 300 tonnes of fish - including some 6,000 sharks, mostly protected species such as the hammerhead and the bigeye thresher. The court announced on ... read more

Related Links
American Geophysical Union
Water News - Science, Technology and Politics


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

WATER WORLD
'Gifted' high-tech takes spotlight at Berlin's IFA fair

NASA Offers Space Station as Catalyst for Discovery in Washington

Forty years on, Voyager still hurtles through space

ISS Orbit Increases Almost 2,000 Feet After Adjustment Maneuver - Control Center

WATER WORLD
ISRO Develops Ship-Based Antenna System to Track Satellite Launches

Falcon 9 launches from Vandenberg

SpaceX launches Taiwan's first home-built satellite

Indian Space Agency, Israeli counterpart to formalize strategic collaborations

WATER WORLD
For Moratorium on Sending Commands to Mars, Blame the Sun

Tributes to wetter times on Mars

Opportunity will spend three weeks at current location due to Solar Conjunction

Curiosity Mars Rover Begins Study of Ridge Destination

WATER WORLD
ESA and Chinese astronauts train together

To boldly go where no startup has gone before

China's satellite sends unbreakable cipher from space

Xian Satellite Control Center resolves over 10 major satellite faults in 50 years

WATER WORLD
ASTROSCALE Raises a Total of $25 Million in Series C Led by Private Companies

LISA Pathfinder: bake, rattle and roll

Bids for government funding prove strong interest in LaunchUK

Blue Sky Network Reaffirms Commitment to Brazilian Market

WATER WORLD
Clamping down on causality by probing laser cavities

Rare-metals in the Himalayas: The potential world-class treasure

Why does rubbing a balloon on your hair make it stick?

Making 3-D printing safer

WATER WORLD
A New Search for Extrasolar Planets from the Arecibo Observatory

Gulf of Mexico tube worm is one of the longest-living animals in the world

Molecular Outflow Launched Beyond Disk Around Young Star

Scientists take first snapshots of a molecular propeller that runs at 100 degrees Celsius

WATER WORLD
New Horizons Video Soars over Pluto's Majestic Mountains and Icy Plains

Juno spots Jupiter's Great Red Spot

New evidence in support of the Planet Nine hypothesis

Scientists probe Neptune's depths to reveal secrets of icy planets









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.