Nav: Home

Warm summers could weaken ocean circulation

March 13, 2018

The temperature and salinity of seawater are key drivers for the global ocean circulation system. Warm and saline water transported poleward cools at the surface when it reaches high latitudes and becomes denser and subsequently sinks into the deep ocean. This process is called convection. At depth, the water is circulated back towards the equator drawing new water masses behind it. Deep convection occurs only in a few regions around the globe, including the Irminger Sea and the Labrador Sea near Greenland. But what happens if additional freshwater, for example from melting glaciers, enters this system? Model calculations predict a possible weakening of deep convection, but so far this could not be confirmed by direct observations.

By using long-term observations, scientists from the GEOMAR Helmholtz Centre for Ocean Research Kiel have now shown that freshwater has already impacted convection in the last decade. The results have been published in the international journal Nature Climate Change.

The study is based on the analysis of data obtained from moored observatories in the Labrador Sea and the Irminger See and from oceanographic floats. In addition, satellite observations of the ocean surface and atmospheric data were included. "For various periods over the last 60 years, we have been able to combine important processes: atmospheric variability, such as the North Atlantic Oscillation, water and air temperatures, the occurrence of fresh surface water, and the duration of convection," explains Dr. Marilena Oltmanns from GEOMAR, lead author of the study.

The evaluation of the data show a clear correlation between the sea surface temperatures in the Irminger Sea in summer, the amount of surface freshwater in this region and the atmospheric conditions and onset of convection in the following winter. "In case that warm summers with increased surface freshwater occur within extended warm periods, the ocean loses less heat in the following winter. As a result, the fresh surface layer that formed in summer remains stable for a longer time resulting in a delayed onset of convection", says Dr. Oltmanns.

Typically, freshwater is mixed down by convection each winter. If convection sets in later, a higher proportion of freshwater remains near the surface and combines with freshwater from the following spring. "This effect could add up in future warm periods and thus weaken the convection - especially with regard to the rising temperatures and increased melting", the oceanographer concludes.

The study reveals the importance of long-term observations at key locations of the global ocean circulation. Dr. Johannes Karstensen, co-author of the study, emphasizes: "Only through long-term measurement programmes the connection between the complex oceanic and atmospheric processes can be identified. Thus, the continuous funding of personnel, ships and material is important--which in this case was provided through the support of individual projects of the German Science Foundation DFG, the German Federal Ministry of Education and Research."
-end-


Helmholtz Centre for Ocean Research Kiel (GEOMAR)

Related Science Articles:

PETA science group promotes animal-free science at society of toxicology conference
The PETA International Science Consortium Ltd. is presenting two posters on animal-free methods for testing inhalation toxicity at the 56th annual Society of Toxicology (SOT) meeting March 12 to 16, 2017, in Baltimore, Maryland.
AAAS and March for Science partner to uphold science
AAAS, the world's largest general scientific organization, announced Thursday that it will partner with the March for Science, a nonpartisan set of activities that aim to promote science education and the use of scientific evidence to inform policy.
Citizen Science in the Digital Age: Rhetoric, Science and Public Engagement
James Wynn's timely investigation highlights scientific studies grounded in publicly gathered data and probes the rhetoric these studies employ.
Science/Science Careers' survey ranks top biotech, pharma, and biopharma employers
The Science and Science Careers' 2016 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.
Three natural science professors win TJ Park Science Fellowship
Professor Jung-Min Kee (Department of Chemistry, UNIST), Professor Kyudong Choi (Department of Mathematical Sciences, UNIST), and Professor Kwanpyo Kim (Department of Physics, UNIST) are the recipients of the Cheong-Am (TJ Park) Science Fellowship of the year 2016.
Danforth Plant Science Center & Valent BioSciences collaborate in root science initiative
A Master Agreement will focus on improving agriculture with non-destructive imaging technology for root growth dynamics.
2016 Cool Science Image contest: Amazing pictures tell tales of science, nature
Ten images and two videos by University of Wisconsin-Madison students, faculty and staff have been named winners of the 2016 Cool Science Image contest.
National Science Foundation and Popular Science announce 2016 Vizzies winners
The National Science Foundation (NSF) and Popular Science magazine today announced the winners of the 2016 Vizzies, awards that celebrate the use of visual media to clearly and accessibly communicate scientific data and research.
Over 900 science leaders from over 100 countries gather at the World Science Forum 2015 Budapest calling for a more responsible and ethical use of science to address pressing global challenges in environment and health
At the Opening Ceremony of World Science Forum 2015 under the theme of 'The Enabling Power of Science' a panel of global thought-leaders declared renewed intent to fight poverty and promote just, equitable and inclusive social development based on the restoration, protection and sustainable use of natural resources and ecosystems.
AAAS to expand the Science family of journals by launching 2 new journals -- Science Robotics and Science Immunology
In keeping with its mission to advance scientific progress and innovation, the world's largest general scientific organization -- the American Association for the Advancement of Science -- today announced plans for two new peer-reviewed journals, Science Robotics and Science Immunology.

Related Science Reading:

Women in Science: 50 Fearless Pioneers Who Changed the World
by Rachel Ignotofsky (Author)

The Everything Kids' Science Experiments Book: Boil Ice, Float Water, Measure Gravity-Challenge the World Around You!
by Tom Robinson (Author)

Klutz LEGO Chain Reactions Craft Kit
by Klutz Press

Awesome Science Experiments for Kids: 100+ Fun STEM / STEAM Projects and Why They Work
by Crystal Chatterton (Author)

The Science Book: Everything You Need to Know About the World and How It Works
by National Geographic (Author), Marshall Brain (Foreword)

Science Encyclopedia: Atom Smashing, Food Chemistry, Animals, Space, and More!
by National Geographic Kids (Author)

The Science of Good Cooking: Master 50 Simple Concepts to Enjoy a Lifetime of Success in the Kitchen (Cook's Illustrated Cookbooks)
by The Editors of America's Test Kitchen and Guy Crosby Ph.D (Author)

Everything You Need to Ace Science in One Big Fat Notebook: The Complete Middle School Study Guide (Big Fat Notebooks)
by Workman Publishing (Author), Sharon Madanes (Author), Michael Geisen (Editor), Editors of Brain Quest (Editor)

The Food Lab: Better Home Cooking Through Science
by J. Kenji López-Alt (Author)

Indescribable: 100 Devotions for Kids About God and Science
by Louie Giglio (Author)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Circular
We're told if the economy is growing, and if we keep producing, that's a good thing. But at what cost? This hour, TED speakers explore circular systems that regenerate and re-use what we already have. Guests include economist Kate Raworth, environmental activist Tristram Stuart, landscape architect Kate Orff, entrepreneur David Katz, and graphic designer Jessi Arrington.
Now Playing: Science for the People

#504 The Art of Logic
How can mathematics help us have better arguments? This week we spend the hour with "The Art of Logic in an Illogical World" author, mathematician Eugenia Cheng, as she makes her case that the logic of mathematics can combine with emotional resonance to allow us to have better debates and arguments. Along the way we learn a lot about rigorous logic using arguments you're probably having every day, while also learning a lot about our own underlying beliefs and assumptions.