Subscribe to our free daily newsletters
. Earth Science News .




Subscribe to our free daily newsletters



WATER WORLD
Researchers untangle causes of differences in East Coast sea level rise
by Staff Writers
New York NY (SPX) May 28, 2017


US East Coast sea-level rise acceleration, post-1990. Credit Davis and Vinogradova, Geophysical Research Letters, 2017

For years, scientists have been warning of a so-called "hot spot" of accelerated sea-level rise along the northeastern U.S. coast. But accurately modeling this acceleration as well as variations in sea-level rise from one region to another has proven challenging.

Now an upcoming paper in Geophysical Research Letters offers the first comprehensive model for understanding differences in sea level rise along North America's East Coast. That model incorporates data not just from atmospheric pressure and ocean dynamics - changing currents, rising ocean temperatures and salinity all influence sea level - but also, for the first time, ice mass change in Greenland and Antarctica. The researchers say their model supports a growing consensus that sea level rise began accelerating in 1990 and that what they found will improve estimates of future sea level rise at a local level.

"A lot of people have been looking for sea level acceleration and have been having trouble finding it," said James Davis, co-author on the paper and a professor and researcher at the Lamont-Doherty Earth Observatory. "The fact that we could model this well seems to indicate that what we are measuring is correct."

Davis worked together with oceanographer Nadya Vinogradova, founder of Cambridge Climate Institute in Massachusetts, on the sea level rise modeling project. Their model, which incorporated assumptions that acceleration of sea level rise began in the 1990s and not before that, accurately predicted variations in sea level rise along North America's East Coast that have been observed in tide-gauge data for over a half century.

Recent research indicates that global mean sea level, or the average height of the world's oceans, has been increasing by 3 millimeters (.1 inches) per year on average since 1993, when satellites first started measuring it. But along the U.S. East Coast north of Cape Hatteras, rates of sea level rise were found to be some three to four times higher than the global average over certain periods.

Essential to the model Davis and Vinogradova built was research published in 2014 that for the first time measured acceleration in glacial melt in Greenland and Antarctica using data from NASA satellite GRACE.

Another critical element was their addition of ocean dynamic modeling from University of Hamburg's GECCO2 that, although low resolution compared to more current models, allowed them to look at a timeline going back to 1948. Newer, higher resolution models don't reach back any further than 1990.

The researchers combined the GRACE and GECCO2 models with atmospheric pressure data and compared these against East Coast tide-gauge records, which measure actual sea levels at the shoreline and are plentiful and high quality for much of the 20th and early 21st centuries.

Davis and Vinogradova found that contributions to the ocean from melting of the Greenland ice sheet actually tend to accelerate sea level rise along the southern part of the U.S. East Coast, south of latitude 35?, in part due to a force called gravitational self-attraction and elastic loading.

Though the melted ice adds volume to the oceans, it also causes sea levels closest to a melted glacier to fall due to a decline in gravitational pull from mass loss, called gravitational self-attraction. The loss of ice mass also causes the land that was underneath that ice to rise, and depresses the floor of surrounding ocean basin, which is called elastic loading.

In contrast, changing ocean dynamics are responsible for accelerated sea level rise along the northern part of the coast, north of latitude 40?. For instance, an influx of freshwater from Greenland glacial melt to the nearby northern Atlantic, as well as rising ocean temperatures in the northern Atlantic, are weakening an established current system called the Atlantic Meridional Overturning Circulation, which drives the Gulf Stream.

Typically the Gulf Stream depresses sea level right along the coast, so as this current weakens, sea levels bounce back. Meanwhile, higher ocean temperatures kick up sea level by expanding the water column.

Davis and Vinogradova chose to focus on the acceleration of sea level rise specifically to avoid the problem of accurately measuring what is known as post-glacial rebound. Post-glacial rebound is the ongoing shape-shifting of the earth's surface that occurs after it is released from the burden of mountains of glacial ice, a process that began in North America at the end of its last ice age 16,000 years ago. (These changes occur very slowly over long time periods, unlike elastic loading, which is near-instantaneous and "elastic.")

As with elastic loading, post-glacial rebound can causes the land or sea floor to bulge in some places and to sink in others, which can change the relationship between sea level and the land. Post-glacial rebound was the primary contributor to sea-level change over much of the 20th century along some parts of the East Coast - from Chesapeake Bay to New York as well as north of Maine. But short-term accelerations tend to be less sensitive to changes like post-glacial rebound that occur on time scales of thousands of years, said Davis.

Davis said that even though the results of their modeling do support the notion that sea level rise has been accelerating over the past 25 years, that doesn't mean it will continue.

"What we're seeing is big," said Davis. "But there's nothing in this paper that says, 'Oh, I've discovered acceleration and we're all going to drown now.' You can't predict forward." There are many sources of feedback in the system that scientists still don't understand, he said.

Still, Davis suggested the findings might serve as a tool for local governments. "Suppose you're a mayor in Miami and you hear that the projections for Greenland ice melt are wrong, and they're going to be much greater in the next century. You have to worry much more than if you're a mayor in Nova Scotia. But then if you're talking about ocean currents, it's flipped," said Davis.

"Wherever you live, you can't just go by these [Intergovernmental Panel on Climate Change] reports that say global sea level rise is one number."

WATER WORLD
Sequestering blue carbon through better management of coastal ecosystems
Logan UT (SPX) May 28, 2017
Focusing on the management of carbon stores within vegetated coastal habitats provides an opportunity to mitigate some aspects of global warming. Trisha Atwood from Utah State University's Watershed Sciences Department of the Quinney College of Natural Resources and the Ecology Center has collaborated with several co-authors from Australia, including lead author Peter Macreadie from Deakin Unive ... read more

Related Links
The Earth Institute at Columbia University
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
Targeted conservation could protect more of Earth's biodiversity

Study finds Congo's miners often resort to hunting wildlife for food

Nuclear spent fuel fire could force millions of people to relocate

UN braces for up to 200,000 Iraqis to flee Mosul

WATER WORLD
Neutron lifetime measurements take new shape for in situ detection

One-dimensional crystals for low-temperature thermoelectric cooling

New theory predicts wetted area of droplets colliding with flat surface

Breaking glass in infinite dimensions

WATER WORLD
Researchers untangle causes of differences in East Coast sea level rise

LA lawns use 70 billion gallons of water a year

Great Barrier Reef bleaching worse than first thought

How X-rays helped to solve mystery of floating rocks

WATER WORLD
Methane seeping from Arctic seabed may have an upside

NASA's Arctic Ecosystem Science Flights Begin

Elevation could help explain why Antarctica is warming slower than Arctic

China says no mining planned in Antarctica

WATER WORLD
In China, maggots finish plates, and food waste

Bordeaux pins hopes for ravaged vineyards on June bloom

Bordeaux pins hopes for ravaged vineyards on June bloom

Helping plants pump iron

WATER WORLD
Sri Lanka appeals for help as floods foul water supply

Sri Lanka deploys thousands of troops as flood toll climbs to 169

Sri Lanka deploys more troops as flood toll climbs to 180

Study explains severity of 9.2 magnitude Sumatra earthquake

WATER WORLD
Biafra's military veterans: no regrets, 50 years on

Rwanda to control presidential candidates' social media use

Africa, so close yet so far from G7 summit

Nigeria seizes illegal arms shipment

WATER WORLD
Fossil skeleton confirms earliest primates were tree dwellers

Springs were critical water sources for early humans in East Africa, Rutgers study finds

New hypothesis about the origin of humankind suggests oldest hominin lived in Europe

Portions of human skeletal structure were established millions of years earlier than previously thought,




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - 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. Privacy Statement