NOAA joins with Princeton and other institutions in six-year study to help public better understand Southern Ocean

NOAA is one of 10 institutions working together on the Southern Ocean Carbon and Climate Observations and Modeling program, or SOCCOM, a six-year, $21 million initiative to improve our understanding of the importance and health of the Southern Ocean encircling Antarctica. (Image by Oscar Schofield, Rutgers University)

The Southern Ocean that encircles Antarctica lends a considerable hand in keeping Earth's temperature hospitable by soaking up half of the human-made carbon in the atmosphere and a majority of the planet's excess heat. Yet, the inner workings — and global importance — of this ocean that accounts for 30 percent of the world's ocean area remains relatively unknown to scientists, as observations remain hindered by dangerous seas.

NOAA is one of 10 institutions working together on the Southern Ocean Carbon and Climate Observations and Modeling program, or SOCCOM, a six-year, $21 million initiative to improve our understanding of the importance and health of the Southern Ocean encircling Antarctica. (Image by Oscar Schofield, Rutgers University)

Princeton University, NOAA and eight other partner institutions now seek to make the Southern Ocean better known scientifically and publicly through a $21 million program that will create a biogeochemical and physical portrait of the ocean using hundreds of robotic floats deployed around Antarctica and an expanded computational capacity. The Southern Ocean Carbon and Climate Observations and Modeling program, or SOCCOM, is a six-year initiative headquartered at Princeton and funded by the National Science Foundation’s Division of Polar Programs, with additional support from the NOAA and NASA. The U.S. Argo program, led by CPO's Steven Piotrowicz, will play a major role in the project. 

"The scarcity of observations in the Southern Ocean and inadequacy of earlier models, combined with its importance to the Earth's carbon and climate systems, means there is tremendous potential for groundbreaking research in this region," Sarmiento said.
Central to the program are roughly 200 floats outfitted with biogeochemical sensors that will provide almost continuous information related to the ocean's carbon, nutrient (nitrate, in particular) and oxygen content, both at and deep beneath the surface. The floats are augmented biogeochemical versions of the nearly 4,000 Argo floats deployed worldwide to measure ocean salinity and temperature. SOCCOM marks the first large-scale deployment of these biogeochemical floats.

"These floats are revolutionary and this major new observational initiative will give us unprecedented year-round coverage of biogeochemistry in the Southern Ocean," Sarmiento said.

The Southern Ocean research will involve using Argo type floats equipped with new sensors that measure pH, nitrates in addition to temperature and salinity. (NOAA)

The floats will increase the monthly data currently coming out of the Southern Ocean by 10 to 30 times, Sarmiento said. That data will be used to improve recently developed high-resolution earth-system models, which will allow for a better understanding of the Southern Ocean and for better projections of Earth’s climate and biogeochemical trajectory. In keeping with SOCCOM's knowledge sharing, or "broader impacts," component, all the information collected will be freely available to the public, researchers and industry.

SOCCOM will provide direct observations to further understand the importance of the Southern Ocean as suggested by models and ocean studies. Aside from carbon and heat uptake, models have indicated that the Southern Ocean delivers nutrients to lower-latitude surface waters that are critical to ocean ecosystems around the world. In addition, the impacts of ocean acidification as levels of carbon dioxide in atmosphere increase are projected to be most severe in the Southern Ocean.

Other than administering the project, Sarmiento and other Princeton researchers will co-lead the modeling and broader impacts components, as well as coordinated data management. Researchers from NOAA's Geophysical Fluid Dynamics Laboratory housed on Princeton's Forrestal Campus will carry out high-resolution earth-system simulations in support of the modeling effort, which is led by the University of Arizona and includes collaborators from the University of Miami.

The floats will be constructed at the University of Washington with sensors from the Monterey Bay Aquarium Research Institute; NOAA’s Climate Program Office will provide half of the basic Argo floats. Float deployment, observation analysis and data assimilation will be led by the Scripps Institution of Oceanography at the University of California-San Diego. Climate Central, a non-profit science and journalism organization based in Princeton, will oversee the broader-impacts component. Researchers from Oregon State University and NOAA will develop the floats’ carbon algorithms.

“The SOCCOM effort is the first systematic expansion of the US Argo program into biogeochemistry. The unique subsurface ocean observations from SOCCOM will contribute towards our efforts to observe the global oceans,” said David Legler, director of NOAA’s Climate Observations Division.

In addition, NASA will support a complementary project involving researchers at the University of Maine and Rutgers University that will equip the floats with bio-optical sensors intended to gather data about biological processes in the water column.

This web story was written by Morgan Kelly, science writer for Princeton University, and includes an additional quote from NOAA's David Legler

Source: NOAA

Atmospheric warming heats the bottom of ice sheets, as well as the top

A 70-meter-deep basin formed near the summit of Greenland’s Flade Isblink Ice Cap in the fall of 2012 when a lake 540 meters beneath the ice surface suddenly emptied. Summer meltwater streams on the ice cap surface (blue) enter crevasses near the bottom of the image. Photo Credit: WorldView-2 Imagery (c) 2014, DigitalGlobe, Inc.

University of Minnesota researchers are part of a national team of scientists that has published a new paper showing for the first time that meltwater from the surface of an ice cap in northeastern Greenland can make its way beneath the ice and become trapped, refilling a subglacial lake. This meltwater provides heat to the bottom of the ice sheet.

These groundbreaking findings provide new information about atmospheric warming and its affect on the critical zone at the base of the ice. The warmth provided by the water could make the ice sheet move faster and alter how it responds to the changing climate.

The research is detailed in a new paper published today online by the journal Nature. The research was led by Cornell University Earth and Atmospheric Sciences researcher Michael Willis, who is also an adjunct faculty member in the geological sciences department at UNC-Chapel Hill's College of Arts and Sciences. The research study’s co-authors are Bradley Herried, University of Minnesota School of Earth Science’s Polar Geospatial Center; Michael Bevis, Ohio State University School of Earth Sciences; and Robin Bell, Columbia University Lamont Doherty Earth Observatory.

“We’re seeing surface meltwater make its way to the base of the ice where it can get trapped and stored at the boundary between the bedrock beneath the ice sheet and the ice itself,” Willis said. “As the lake beneath the ice fills with surface meltwater, the heat released by this trapped meltwater can soften surrounding ice, which may eventually cause an increase in ice flow.”

The researchers were able to pinpoint when the subglacial lake refilled using data collected from high-resolution satellite images from the University of Minnesota’s Polar Geospatial Center, as well as data from NASA’s operation IceBridge for calibration and verification.

The direct link between the surface meltwater and the filling of a lake at the base of the ice has never been seen before. Over the last few years the number of lakes on the surface of the Greenland ice sheet has greatly increased. Surface lakes are also occurring much farther inland at higher altitudes than in the past. If this mechanism of transferring water and warmth from the surface lakes to the bottom of the ice sheet is common then the Greenland Ice Sheet is likely to respond more rapidly to climate change than is currently predicted.

The Greenland ice sheet comprises about 80 percent of the land mass of Greenland and previous studies have documented that the ice sheet is melting at a faster rate due to climate change. The movement of meltwater beneath the ice sheet, from the interior to the ocean, is the topic of many investigations as it can control the speed at which the ice sheet moves. This is the first study to document that surface water can penetrate to the bottom of an ice cap and be trapped in place. Researchers say this process could also occur at other large bodies of ice.

The study was sparked in 2012 when Willis was mapping ice changes around the edge of the Greenland Ice Sheet as part of a study funded by U.S. National Science Foundation (NSF) to understand how much of the accelerating ice loss in Greenland is caused by melting and how much is caused by the increase of ice moving into the ocean.

During his research, Willis spotted a 70-meter-deep hole (the equivalent of a 10-story building) that had formed when a subglacial lake, far beneath the ice surface, emptied in the late fall of 2011. Subglacial lakes are rare in Greenland, and the presence of such a lake in the far northeast came as a surprise. The ice in this region is much too slow, too cold and too thin to allow melting beneath the ice cap, which is how a subglacial lake usually forms. 

Between 2012 and 2014, Willis watched as summer meltwater on the surface of the ice made its way down cracks around the hole and refilled the empty lake basin at the base of the ice cap. When water was flowing on the surface, the subglacial lake filled. When water stopped flowing on the surface, the subglacial lake stopped refilling.

Each summer scientists see bright blue streams form on the surface of Greenland as warm air melts the ice sheet. What happens to this water when it disappears into cracks in the ice has remained a mystery.

“This discovery that water can be stored in lakes beneath the ice shows how the plumbing on the surface is linked to the plumbing at the base," said co-author Bell.

The Cornell-led team calculated that the lake beneath the ice has filled about half way since its 2011 blowout that originally drove water from the lake at a volume of 215 cubic meters per second (nearly 57,000 gallons—close to the volume of a 30-foot-by-50-foot backyard swimming pool every second.)  As the lake refills, the surface meltwater carries stored heat, called latent heat, along with it from the relatively warm atmosphere to the icy depths. This latent heat reduces the stiffness of the surrounding ice and makes the ice more likely to flow out to sea.

Even though researchers have long known of the existence of subglacial lakes, never before have they witnessed any refilling from the surface. The refilling signals to researchers that Greenland’s ice loss has likely reached a milestone.

"We can actually see the meltwater pour down into these holes and then watch these subglacial lakes drain out and fill up again in real time,” said study co-author Bevis. “With melting like that, even the deep interior of the ice sheet is going to change. If enough water is pouring down into the Greenland Ice Sheet for us to see the same subglacial lake empty and refill itself over and over, then there must be so much latent heat being released under the ice that we’d have to expect it to change the large-scale behavior of the ice sheet.”

Source: University of Minnesota

NASA: Subglacial Lakes Seen Refilling in Greenland

Refrozen meltwater ponds in northeast Greenland seen during an April 2013 IceBridge flight. Image Credit: NASA/Michael Studinger

Scientists using satellite images and data from NASA’s Operation IceBridge have found evidence of a drained and refilled subglacial lake beneath northeastern Greenland’s Flade Ice Cap. This sub-ice body of water is only one of a handful that have been detected in Greenland and its presence sheds new light on how the Greenland Ice Sheet reacts to warming temperatures.

Subglacial lakes are relatively common in Antarctica, and although recent studies have mathematically predicted possible locations for hundreds of such features in Greenland, few have actually been found. Bodies of water beneath the ice are normally detected either with ice-penetrating radar or by observing rapid changes in ice surface elevation such as bulges or basins.

In a new study funded by the National Science Foundation and published in the Jan. 21 issue of the journal Nature, a research team led by Michael Willis, a glaciologist at Cornell University in Ithaca, New York, found a large basin that formed over a 21-day period in the summer of 2011 using satellite images. The size and rapid formation of this basin was consistent with a drained subglacial lake, but its location raised a question. Where did the water in the lake come from?

Subglacial lakes typically form at the base of an ice sheet or glacier because of either friction or trapped heat from bedrock below. In order for this to happen, ice needs to move quickly or be thick enough to protect the ice sheet base from cold air at the surface and trap heat coming from the bedrock below. But something else had to be at work here. The research team used weather data and ice thickness measurements from IceBridge flights to calculate the temperature beneath the ice and found that it was well below what’s needed for normal basal melt.

Continued observation showed that the basin floor rose significantly during the next summer at the same time that nearby surface meltwater drained into cracks along the basin’s edge. This led the team to hypothesize that water from surface melting was refilling a lake beneath the ice. Snow accumulation and ice movement accounted for a portion of the basin’s rise, with meltwater runoff estimates filling in the rest of the increase, supporting the hypothesis.

This finding points to the possibility of similar meltwater-filled subglacial lakes in other parts of Greenland. Existing research has shown an extensive network of sub-ice drainage channels in Greenland that are thought to quickly move surface melt along the bed and to the ocean. The presence of subglacial lakes in Greenland could affect how parts of the ice sheet move by adding heat to ice at the base and softening. Further research on subglacial lakes in Greenland will likely help researchers improve projections of how the ice sheet will change in response to future warming.

Source: Nasa

Emergence of modern sea ice in Arctic Ocean, 2.6 million years ago

Field Work in the Arctic sea ice. Credit: Thomas A. Brown and Simon T. Belt

"We have not seen an ice free period in the Arctic Ocean for 2,6 million years. However, we may see it in our lifetime." says marine geologist Jochen Knies. In an international collaborative project, Knies has studied the historic emergence of the ice in the Arctic Ocean. The results are published in Nature Communications.

The extent of sea ice cover in Arctic was much less than it is today between four and five million years ago. The maximum winter extent did not reaching its current location until around 2.6 million years ago. This new knowledge can now be used to improve future climate models.

"We have not seen an ice free period in the Arctic Ocean for 2,6 million years. However, we may see it in our lifetime. The new IPCC report shows that the expanse of the Arctic ice cover has been quickly shrinking since the 70-ies, with 2012 being the year of the sea ice minimum," Jochen Knies.

He is marine geologist at the Geological Survey of Norway (NGU) and Centre for Arctic Gas Hydrate, Climate and Environment, UiT The Arctic Univeristy of Norway.

In an international collaborative project, Jochen Knies has studied the trend in the sea ice extent in the Arctic Ocean from 5.3 to 2.6 million years ago. That was the last time Earth experienced a long period with a climate that, on average, was warm before cold ice ages began to alternate with mild interglacials.

Fossils reveal past sea ice extent

"When we studied molecules from certain plant fossils preserved in sediments at the bottom of the ocean, we found that large expanses of the Arctic Ocean were free of sea ice until four million years ago," Knies tells us.

"Later, the sea ice gradually expanded from the very high Arctic before reaching, for the first time, what we now see as the boundary of the winter ice around 2.6 million years ago ," says Jochen Knies, who is also attached to CAGE, the Centre for Arctic Gas Hydrate, 

Environment and Climate at the University of Tromsø, the Arctic University of Norway.

Arctic Ocean likely to be completely free of sea ice

The research is of great interest on the international stage because present-day global warming is strongly tied to a shrinking ice cover in the Arctic Ocean. By the end of the present century, the Arctic Ocean seems likely to be completely free of sea ice, especially in summer.

This may have major significance for the entire planet 's climate system. Polar oceans , their temperature and salinity, are important drivers for world ocean circulation that distributes heat in the oceans. It also affects the heat distribution in the atmosphere. Trying to anticipate future changes in this finely tuned system, is a priority for climate researchers. For that they use climate modeling , which relies on good data.

"Our results can be used as a tool in climate modelling to show us what kind of climate we can expect at the turn of the next century. There is no doubt that this will be one of many tools the UN Climate Panel will make use of, too. The extent of the ice in the Arctic has always been very uncertain but, through this work, we show how the sea ice in the Arctic Ocean developed before all the land-based ice masses in the Northern Hemisphere were established," Jochen Knies explains.

Seabed samples from Spitsbergen

A deep well into the ocean floor northwest of Spitsbergen was the basis for this research. It was drilled as part of the International Ocean Drilling Programme, (IODP), to determine the age of the ocean-floor sediments in the area. Then, by analysing the sediments for chemical fossils made by certain microscopic plants that live in sea ice and the surrounding oceans, Knies and his co-workers were able to fingerprint the environmental conditions as they changed through time.

"One thing these layers of sediment enable us to do is to "read" when the sea ice reached that precise point," Jochen Knies tells us.

The scientists believe that the growth of sea ice until 2.6 million years ago was partly due to the considerable exhumation of the land masses in the circum-Arctic that occurred during this period. "Significant changes in altitudes above sea level in several parts of the Arctic, including Svalbard and Greenland, with build-up of ice on land, stimulated the distribution of the sea ice," Jochen Knies says.

"In addition, the opening of the Bering Strait between America and Russia and the closure of the Panama Cannel in central America at the same time resulted in a huge supply of fresh water to the Arctic, which also led to the formation of more sea ice in the Arctic Ocean," Jochen Knies adds.

All the large ice sheets in the Northern Hemisphere existed around 2.6 million years ago.

Scientists at Norwegian Geological Survey (NGU), CAGE, UiT The Arctic University of Norway,University of Plymouth, Universitat Autònoma de Barcelona, Stellenbosch University in South Africa and Institució Catalana de Recerca i Estudis Avançats in Barcelona have collaborated in this work.

Source:  University of Tromso (Universitetet i Tromsø - UiT)

Is Sahara Desert several million years older than previously thought?

Sahara desert. Credit: © mrks_v / Fotolia

A team of scientists from Norway, France and China have revised the view that the Sahara desert has existed for only the last 2 to 3 million years.

The Sahara is the world's largest subtropical desert. During the last decades, numerous scientific studies have probed its geological and archeological archives seeking to reveal its history. Despite some important breakthroughs, there are still basic questions that lack satisfactory answers.

For example, how old is the Sahara desert? It is widely believed that Sahara desert first appeared during the last 2 to 3 million years, but recent discoveries such as ancient sand dunes and dust records in marine cores push the possible onset of Saharan aridity back in time by several million years. Until now, however, there have been no good explanations for such an early Sahara onset.

This study pinpoints the Tortonian stage (~7-11 million years ago) as a pivotal period for triggering North African aridity and creating the Sahara desert. Using snapshot simulations with the Norwegian Earth System Model (NorESM) model suite, the international team explored the climate evolution of North Africa through major tectonic shifts over the last 30 million years. They found that the region undergoes aridification with the shrinkage of the Tethys -- a giant ocean that was the origin of the modern Mediterranean, Black and Caspian Seas -- during the Tortonian.

The simulations are the first to show that the Tethys shrinkage has two main consequences for North African climate. First, it weakens the African summer monsoon circulations and dries out North Africa. Second, it enhances the sensitivity of the African summer monsoon and its associated rainfall to orbital forcing. The Tortonian stage thus marks the time when North Africa shifted from a permanently lush, vegetated landscape to a landscape experiencing arid/humid cycles on orbital time scales.

Interestingly, these major changes in North African climate and environment are coincident with an important time period for the emergence of early hominids.

Source: Uni Research