Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Opposite Behaviors? Arctic Sea Ice Shrinks, Antarctic Grows

The steady and dramatic decline in the sea ice cover of the Arctic Ocean over the last three decades has become a focus of media and public attention. At the opposite end of the Earth, however, something more complex is happening.

A new NASA study shows that from 1978 to 2010 the total extent of sea ice surrounding Antarctica in the Southern Ocean grew by roughly 6,600 square miles every year, an area larger than the state of Connecticut. And previous research by the same authors indicates that this rate of increase has recently accelerated, up from an average rate of almost 4,300 square miles per year from 1978 to 2006.

September 2012 witnessed two opposite records concerning sea ice. Two weeks after the Arctic Ocean's ice cap experienced an all-time summertime low for the satellite era (left), Antarctic sea ice reached a record winter maximum extent (right). But sea ice in the Arctic has melted at a much faster rate than it has expanded in the Southern Ocean, as can be seen in this image by comparing the 2012 sea ice levels with the yellow outline, which in the Arctic image represents average sea ice minimum extent from 1979 through 2010 and in the Antarctic image shows the median sea ice extent in September from 1979 to 2000. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio and NASA Earth Observatory/ Jesse Allen

"There's been an overall increase in the sea ice cover in the Antarctic, which is the opposite of what is happening in the Arctic,” said lead author Claire Parkinson, a climate scientist with NASA's Goddard Space Flight Center, Greenbelt, Md. "However, this growth rate is not nearly as large as the decrease in the Arctic.”

The Earth’s poles have very different geographies. The Arctic Ocean is surrounded by North America, Greenland and Eurasia. These large landmasses trap most of the sea ice, which builds up and retreats with each yearly freeze-and-melt cycle. But a large fraction of the older, thicker Arctic sea ice has disappeared over the last three decades. The shrinking summer ice cover has exposed dark ocean water that absorbs sunlight and warms up, leading to more ice loss.

On the opposite side of the planet, Antarctica is a continent circled by open waters that let sea ice expand during the winter but also offer less shelter during the melt season. Most of the Southern Ocean’s frozen cover grows and retreats every year, leading to little perennial sea ice in Antarctica.

Using passive-microwave data from NASA's Nimbus 7 satellite and several Department of Defense meteorological satellites, Parkinson and colleague Don Cavalieri showed that sea ice changes were not uniform around Antarctica. Most of the growth from 1978 to 2010 occurred in the Ross Sea, which gained a little under 5,300 square miles of sea ice per year, with more modest increases in the Weddell Sea and Indian Ocean. At the same time, the region of the Bellingshausen and Amundsen Seas lost an average of about 3,200 square miles of ice every year.

Parkinson and Cavalieri said that the mixed pattern of ice growth and ice loss around the Southern Ocean could be due to changes in atmospheric circulation. Recent research points at the depleted ozone layer over Antarctica as a possible culprit. Ozone absorbs solar energy, so a lower concentration of this molecule can lead to a cooling of the stratosphere (the layer between six and 30 miles above the Earth's surface) over Antarctica. At the same time, the temperate latitudes have been warming, and the differential in temperatures has strengthened the circumpolar winds flowing over the Ross Ice Shelf.

"Winds off the Ross Ice Shelf are getting stronger and stronger, and that causes the sea ice to be pushed off the coast, which generates areas of open water, polynyas,” said Josefino Comiso, a senior scientist at NASA Goddard. "The larger the coastal polynya, the more ice it produces, because in polynyas the water is in direct contact with the very cold winter atmosphere and rapidly freezes.” As the wind keeps blowing, the ice expands further to the north.

This year's winter Antarctic sea ice maximum extent, reached two weeks after the Arctic Ocean's ice cap experienced an all-time summertime low, was a record high for the satellite era of 7.49 million square miles, about 193,000 square miles more than its average maximum extent for the last three decades.

The Antarctic minimum extents, which are reached in the midst of the Antarctic summer, in February, have also slightly increased to 1.33 million square miles in 2012, or around 251,000 square miles more than the average minimum extent since 1979.

The numbers for the southernmost ocean, however, pale in comparison with the rates at which the Arctic has been losing sea ice – the extent of the ice cover of the Arctic Ocean in September 2012 was 1.32 million square miles below the average September extent from 1979 to 2000. The lost ice area is equivalent to roughly two Alaskas.

Parkinson said that the fact that some areas of the Southern Ocean are cooling and producing more sea ice does not disprove a warming climate.

"Climate does not change uniformly: The Earth is very large and the expectation definitely would be that there would be different changes in different regions of the world,” Parkinson said. "That's true even if overall the system is warming.” Another recent NASA study showed that Antarctic sea ice slightly thinned from 2003 to 2008, but increases in the extent of the ice balanced the loss in thickness and led to an overall volume gain.

The new research, which used laser altimetry data from the Ice, Cloud, and land Elevation Satellite (ICESat), was the first to estimate sea ice thickness for the entire Southern Ocean from space.

Records of Antarctic sea ice thickness are much patchier than those of the Arctic, due to the logistical challenges of taking regular measurements in the fierce and frigid waters around Antarctica. The field data collection is mostly limited to research icebreakers that generally only travel there during spring and summer – so the sole means to get large-scale thickness measurements is from space.

"We have a good handle of the extent of the Antarctic sea ice, but the thickness has been the missing piece to monitor the sea ice mass balance,” said Thorsten Markus, one of the authors of the study and Project Scientist for ICESat-2, a satellite mission designed to replace the now defunct ICESat. ICESat-2 is scheduled to launch in 2016. "The extent can be greater, but if the sea ice gets thinner, the volume could stay the same."

Maria-José Viñas
NASA's Earth Science News Team

Maria-Jose Vinas | EurekAlert!
Further information:

More articles from Earth Sciences:

nachricht Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union

nachricht UM researchers study vast carbon residue of ocean life
19.10.2016 | University of Miami Rosenstiel School of Marine & Atmospheric Science

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>