Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Intensification and poleward shift of oceanic boundary currents

28.06.2016

Change means greater heat and more winter storms for Asia; Gulf Stream is the exception

Global warming results in fundamental changes to important ocean currents. As scientists from the Alfred-Wegener-Institute show in a new study, wind-driven subtropical boundary currents in the northern and southern hemisphere are not only going to increase in strength by the end of this century.


The oceans get heat from the tropical regions and release them to the mid-latitudes, especially over the routes of the subtropical western boundary currents.

Photo: F. Rödel / Alfred-Wegener-Institut

The Kuroshio Current, the Agulhas Current and other oceanic currents are shifting their paths towards the pole and thus carry higher temperatures and thus the risk of storms to temperate latitudes. For this study, researchers evaluated a wealth of independent observational data and climate simulations.

They showed the same pattern for all boundary currents, with the Gulf Stream as the only exception. According to the data, the latter will weaken over the next decades. The study has been published today in the Journal of Geophysical Research professional journal.

Along the eastern coasts of South Africa, Asia, Australasia, and South America, weather and climate will get significantly warmer over the next 100 years and thus presumably also significantly stormier on global average. The reason for this are changes to the western boundary currents that are already beginning to have a significant impact on weather events in these coastal regions.

These surface currents are driven by the wind; with flow speeds of up to nine kilometres per hour, they are amongst the fastest ocean currents in the world. They reach down to a depth of 1000 metres and move warm bodies of water from the tropics to the coastal regions of the temperate latitudes.

The best-known western boundary current in Europe is the Gulf Stream. Across the world, however, these also include the Kuroshio Current off the coast of Japan, the Brazil Current off the eastern coast of South America, the Eastern Australia Current as well as the Agulhas Current off the coast of South Africa.

Scientists from the Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research (AWI) have discovered these changes in a major comparative analysis of eleven independent climate data bases. On the one hand, the scientist evaluated oceanographic observational data as well as satellite data on the currents’ heat loss between 1958 and 2001.

On the other, they considered simulations for past and future climates as well as indicators for the flow speed of the currents, for water temperature and air pressure at the sea surface.

“Our analysis shows that the surface temperature of the boundary currents has increased two to three times faster than in other oceanic regions. In addition, the currents release 20 percent more heat than they did half a century ago, which leads to the conclusion that the temperature of the water has risen, its flow speed has increased and the currents thus transfer more water and also more heat from the tropics towards the pole. The cause of these changes were increasing winds in both hemispheres,” explains Hu Yang, AWI climate researcher and author of the study.

The greater the heat transfer from the sea, the higher possibly the probability of storms. “Over the next decades, Japan, China and Korea will need to expect higher air temperatures particularly in winter, because the Kuroshio Current will transport more heat and shift northward with the wind. This heat will change the atmospheric condition in such as way as to make storms more likely in this region. For the Eastern Australian Current, the Brazil Current and the Agulhas Current on the southern hemisphere, our analyses predict a southward shift, because there, too, the winds shift poleward,” explains Prof. Gerrit Lohman, climate modeller at the Alfred-Wegener-Institute and co-author of the study.

The Gulf Stream will become weaker

Warmer, stronger, poleward - according to the results, this pattern applies to all western subtropical boundary currents. The only exception is the Gulf Stream. “All of our results predict its long-term weakening. The reason for this is that the Gulf Stream is not only driven by the wind, but is also coupled with the thermohaline circulation. This is also often referred to as a global conveyor belt.

Our results indicate that the power of this conveyor belt will weaken in the long term - and in an order of magnitude that more than compensate for the plus of increasing winds. Without the influence of this circulation, the Gulf Stream would follow the same patterns as the other boundary currents,” outlines Gerrit Lohmann.

The climate scientists also fear far-reaching consequences for the fauna and flora of the coastal regions. “As these currents bring higher temperatures to these temperate latitudes, while advancing further north or south, many species will be forced to move to colder regions. But some of them won’t be able to face this challenge,” explains Gerrit Lohmann one of the possible consequences of the observed changes.


Notes for Editors:
The study has been published with the following title in the Journal of Geophysical Research:
Hu Yang, Gerrit Lohmann, Wei Wei, Mihai Dima, Monica Ionita, Jiping Liu: Intensification and Poleward Shift of Subtropical Western Boundary Currents in a warming climate, Journal of Geophysical Research, DOI: 10.1002/2015JC011513 , http://onlinelibrary.wiley.com/doi/10.1002/2015JC011513/abstract

Printable photographs can be found in the online version of this press release at: http://www.awi.de/nc/en/about-us/service/press.html

Your scientific contacts at the Alfred Wegener Institute:
• Hu Yang – for interviews in English and Mandarin (tel: +49(471)4831-1051; e-mail: hu.yang(at)awi.de)
• Prof. Dr. Gerrit Lohmann (tel.: +49(471)4831-1758; e-mail: Gerrit.Lohmann(at)awi.de)

Your contact in the Communications and Media Department is Sina Löschke (Tel.: +49 (0)471 4831 - 2008; e-mail: medien(at)awi.de).

The Alfred Wegener Institute conducts research in the Arctic, the Antarctic and in mid- to high-latitude oceans. It coordinates polar research in Germany and provides important infrastructure such as the research icebreaker “Polarstern” and stations in the Arctic and Antarctic for the international science community. The Alfred Wegener Institute is one of the 18 research centres belonging to the Helmholtz Association, Germany's largest scientific organisation.

Ralf Röchert | idw - Informationsdienst Wissenschaft
Further information:
http://www.awi.de/

More articles from Earth Sciences:

nachricht New study offers roadmap for detecting changes in the ocean due to climate change
20.08.2019 | Princeton University

nachricht New insight into glaciers regulating global silicon cycling
14.08.2019 | University of Bristol

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Towards an 'orrery' for quantum gauge theory

Experimental progress towards engineering quantized gauge fields coupled to ultracold matter promises a versatile platform to tackle problems ranging from condensed-matter to high-energy physics

The interaction between fields and matter is a recurring theme throughout physics. Classical cases such as the trajectories of one celestial body moving in the...

Im Focus: A miniature stretchable pump for the next generation of soft robots

Soft robots have a distinct advantage over their rigid forebears: they can adapt to complex environments, handle fragile objects and interact safely with humans. Made from silicone, rubber or other stretchable polymers, they are ideal for use in rehabilitation exoskeletons and robotic clothing. Soft bio-inspired robots could one day be deployed to explore remote or dangerous environments.

Most soft robots are actuated by rigid, noisy pumps that push fluids into the machines' moving parts. Because they are connected to these bulky pumps by tubes,...

Im Focus: Vehicle Emissions: New sensor technology to improve air quality in cities

Researchers at TU Graz are working together with European partners on new possibilities of measuring vehicle emissions.

Today, air pollution is one of the biggest challenges facing European cities. As part of the Horizon 2020 research project CARES (City Air Remote Emission...

Im Focus: Self healing robots that "feel pain"

Over the next three years, researchers from the Vrije Universiteit Brussel, University of Cambridge, École Supérieure de Physique et de Chimie Industrielles de la ville de Paris (ESPCI-Paris) and Empa will be working together with the Dutch Polymer manufacturer SupraPolix on the next generation of robots: (soft) robots that ‘feel pain’ and heal themselves. The partners can count on 3 million Euro in support from the European Commission.

Soon robots will not only be found in factories and laboratories, but will be assisting us in our immediate environment. They will help us in the household, to...

Im Focus: Scientists create the world's thinnest gold

Scientists at the University of Leeds have created a new form of gold which is just two atoms thick - the thinnest unsupported gold ever created.

The researchers measured the thickness of the gold to be 0.47 nanometres - that is one million times thinner than a human finger nail. The material is regarded...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The power of thought – the key to success: CYBATHLON BCI Series 2019

16.08.2019 | Event News

4th Hybrid Materials and Structures 2020 28 - 29 April 2020, Karlsruhe, Germany

14.08.2019 | Event News

What will the digital city of the future look like? City Science Summit on 1st and 2nd October 2019 in Hamburg

12.08.2019 | Event News

 
Latest News

All-in-one: New microbe degrades oil to gas

20.08.2019 | Life Sciences

Spinning lightwaves on a one-way street

20.08.2019 | Physics and Astronomy

Materials that can revolutionize how light is harnessed for solar energy

20.08.2019 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>