Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



ICE WORLD
New findings on the past and future of sea ice cover in the Arctic
by Staff Writers
Bremerhaven, Germany (SPX) Aug 30, 2017


This is the Kasten corer on board the German RV Polarstern.

Temperatures in the Arctic are currently climbing two to three times faster than the global average. The result - and, thanks to feedback effects, also the cause - is dwindling sea ice. In a study published in the actual volume of Nature Communications, geo- and climate researchers at the Alfred-Wegener Institute, Helmholtz Centre for Polar- and Marine Research (AWI) show that, in the course of our planet's history, summertime sea ice was to be found in the central Arctic in periods characterised by higher global temperatures - but less CO2 - than today.

Prognoses for the future of the Arctic can only be as reliable as the models and data they're based on. The scenarios projected by climate modellers vary greatly, and it remains unclear when we can expect to see the Arctic Ocean free of ice in the summer. At the same time, there is considerable public interest in dependable predictions concerning Arctic sea ice development over the next few decades, so as to have a basis for long-term strategic planning.

Researchers at the Alfred Wegener Institute have now more closely analysed the glacial history of the central Arctic with the help of sediment core data and climate simulations. Their findings indicate that the region was home to sea ice during the last interglacial, between 115,000 and 130,000 years ago.

"Thanks to the sediment core data, we have clear evidence that, during the last interglacial roughly 125,000 years ago, the central Arctic Ocean was still covered with sea ice during the summer. In contrast, in an area to the northeast of Spitsbergen, the summertime sea ice virtually disappeared," explains Prof Rudiger Stein, a geologist at the Alfred Wegener Institute and first author of the Nature Communications study, adding, "This is also confirmed by the climate simulations run by AWI modellers involved in the study."

However, comparing the results of the climate simulations for the most recent interglacial with scenario calculations for the future reveals substantial differences: thanks to the more intense solar radiation, back then the air temperatures at higher latitudes were also a few degrees higher than at present.

However, the carbon dioxide concentration in the atmosphere - roughly 290 ppm (parts per million) - was ca. 110 ppm lower than the current level, as ice core data from the Antarctic shows. For their scenario calculations, the AWI modellers plugged in atmospheric CO2 concentrations in excess of 500 ppm, a level in keeping with the forecasts released by the Intergovernmental Panel on Climate Change (IPCC).

Under these conditions, a disproportionately rapid retreat of summertime sea ice in the central Arctic Ocean over the course of the next few decades, followed by its complete disappearance - depending on how quickly CO2 levels rise - roughly 250 years from now, is to be expected.

The outcomes of the study reveal the complexity of the processes shaping climate change in the Arctic and point to significant spatial and chronological variances in sea ice cover. To slow the warming of the Arctic and the permanent loss of sea ice, reducing the level of anthropogenic CO2 emissions in the atmosphere is vital.

For the purposes of their study, the researchers used what is referred to as "proxies" - indicators that contain information on past environmental conditions. They concentrated on organic proxies, also known as biomarkers. Some of these biomarkers are produced by certain species of algae, among which one group can only be found in open surface water, while the members of another group only live in sea ice (or did so in the Earth's distant past).

"When we confirm the presence of these algal biomarkers in our sediment layers, it allows us to draw conclusions on the depositional environment and the environmental conditions at the respective time," says Stein.

Since the biomarker groups they investigated are based on algae - i.e., on plants that require light for photosynthesis - the absence of both groups is an important indicator of a very thick and largely contiguous ice cover. Such conditions would make photosynthesis impossible, both for the algae in the surface water directly under the ice and those dwelling deeper in the ice close to the ice-water interface.

In addition to these valuable new insights into sea ice distribution during the last interglacial, the study also produced another exciting finding, one concerning the extent of circum-Arctic ice sheets during the Saale glaciation.

As Stein relates, "Towards the end of the Saale glaciation (roughly 140,000 to 150,000 years ago), the glaciers most likely extended beyond the outer shelf. They produced masses of cold air that blew out to sea as powerful fall winds (katabatic winds) and created large expanses of open water (polynyas) - a process still frequently observed around the Antarctic continent."

These conditions would seem to contradict the hypotheses put forward by international researchers (Jakobsson et al., 2016), who postulated in 2016 that the glaciers in North America and Eurasia expanded beyond the continental shelf during the Saale glaciation and into open water, covering the entire Arctic Ocean with a nearly kilometre-thick layer of solid ice.

"Yet our biomarker data show acceptable living conditions for phytoplankton and sea ice algae, namely open waters and seasonal ice cover - a wide difference to kilometre-thick ice," says Rudiger Stein.

However, the geologist goes on to explain, "That being said, a chronological sequence of extremely extended thick ice sheets (similar to what Jakobsson et al. have postulated) followed by sea ice formation with polynyas seems to be possible, as the initial results of our own investigations on the southern Lomonosov Ridge have shown. To finally approve this, however, further detailed investigations, especially of well dated sediment cores, are needed."

Ruediger Stein, Kirsten Fahl, Paul Gierz, Frank Niessen and Gerrit Lohmann: Arctic Ocean sea ice cover during the penultimate glacial and the last interglacial. Nature Communications. doi: 10.1038/s41467-017-00552-1.

ICE WORLD
Methane hydrate is not a smoking gun in the Arctic Ocean
Oslo, Norway (SPX) Aug 23, 2017
Clathrate (hydrate) gun hypothesis stirred quite the controversy when it was posed in 2003. It stated that methane hydrates - frozen water cages containing methane gas found below the ocean floor - can melt due to increasing ocean temperatures. According to the hypothesis this melt can happen in a time span of a human life, dissociating vast amounts of hydrate and releasing methane into th ... read more

Related Links
Helmholtz Centre for Polar and Marine Research
Beyond the Ice Age


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

ICE 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

ICE 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

ICE 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

ICE 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

ICE 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

ICE 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

ICE 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

ICE 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




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