Polar bears are the poster children for the rapid loss of sea ice in the Arctic. ©Henry H. Holdsworth
Cute, adorable animals are often used to garner support for environmental causes in places that are remote. After all, it’s hard to have concern for an area that is at the opposite end of the Earth from where you live and for which you have no plans to ever see. It’s why polar bears, for example, have been used as the poster children for the rapid loss of sea ice in the Arctic ever since “global warming” became a household phrase decades ago.
Today, scientists largely agree that humans have been major players in that loss. Recently, in fact, researchers have found that neither natural climate fluctuations nor self-acceleration can explain the observed Arctic sea-ice retreat. Instead, they’ve found a strong, plausible correlation with increasing greenhouse gas concentrations—increasing as a result of human activities.
What is surprising, though, is that at the opposite end of the Earth, no such link between greenhouse gas concentrations and retreating sea ice has been found. In truth, Antarctic sea ice is actually gaining ground.
Scientists have found a strong, plausible correlation between the rapid loss of sea ice in the Arctic and increasing greenhouse gas concentrations due to human activities.
So, if we’re losing ice at one end of the planet, but gaining at the other, is there cause for concern?
In the Arctic
When trying to assess the cause of weather patterns, scientists usually employ complex climate models. But recently, at Germany’s Max Planck Institute for Meteorology, researchers attempting to identify what could be causing the observed sea-ice loss in the Arctic tried a different strategy. Instead of using standard climate models, they used historical records that described the natural variations of sea-ice extent between the early 1950s and late 1970s. These natural fluctuations were then compared to the magnitude of fluctuations of the Arctic sea-ice cover—as measured from satellites—since the late 1970s.
From such a comparison, the scientists found only a minute possibility that the recently observed lack of sea ice in the Arctic simply happened by chance. They also found that whenever there was a strong sea-ice loss from one year to the next, the extent of the ice always recovered somewhat in the following year. This would not be the case if the sea-ice retreat were self-accelerating.
Unlike the Arctic, Antarctica is an icy continent surrounded by water. ©Colin McNulty
Having excluded natural fluctuations and self-acceleration as the main drivers for the sea-ice retreat, the scientists then examined other possible factors, such as solar radiation, prevailing wind patterns, volcanic eruptions, oceanic heat transport and cosmic rays. No plausible link to any of them could be established.
In the Antarctic
In the Antarctic, however, the situation is different. Here, the sea-ice cover is slightly increasing—all the while the sea-surface temperature around Antarctica has risen.
Obviously, greenhouse gases are not having the same effect in the South as they are in the North. So veteran climate researchers—looking beyond the usual climate models again—analyzed Southern Ocean temperature records and simulations of sea-surface temperatures. They found that higher sea-surface temperatures during the last half of the 20th century probably sparked the hydrological cycle above the Southern Ocean, creating a scenario in which more sea ice can grow. Higher sea-surface temperatures increase evaporation in more temperate zones, which increases snowfall closer to Antarctica. And that extra precipitation adds another factor that helps to grow sea ice: it lowers the salinity of the surface water, slowing the melting of sea ice.
In the future, if more of the snowfall in Antarctica turns into rainfall, the sea ice around the continent will begin to melt much more rapidly.
It now appears that the major reason for the discrepancy in sea-ice loss and gain at the two poles lies in the different landmass distributions in the two places. In the Arctic Ocean, the ice is virtually landlocked, and its melting and freezing determines its extent. Therefore, greenhouse gases play an important role in the North.
But in Antarctica, the sea ice is free to drift around in the open Southern Ocean. The prevailing winds and ocean currents govern the extent of the ice there. So, in one case, there is an icy ocean surrounded by land. In the other, there is an icy continent surrounded by icy water. It makes all the difference.
It could soon be the same animal
The Antarctic sea ice’s apparent immunity to global warming, however, could be temporary. If the sea and air warm even more in the 21st century as projected, much of the extra snowfall in the Antarctic could turn into rainfall, which would rapidly melt ice all around the southernmost continent.
Traveling to one of the poles is not within reach for everyone. But caring about places you may never see in person is important for the future of the planet. ©Colby J Brokvist
For most of us, traveling to the Arctic or Antarctica would be just about the most far-flung adventures we could have—and therefore out of reach. So should the probability of future sea-ice loss in Antarctica concern us, especially in light of all the other environmental causes that need our attention? It’s hard to drum up concern for a place actually gaining ice.
The Sierra Club reports that satellite measurements taken from 2003 to 2010 indicate that the Earth lost 1,000 cubic miles of ice—enough to cover the United States in a foot and a half of water. And in the U.S., the winter of 2011-2012 proved to be the fourth warmest in recorded history—a phenomenon that could be linked to the loss of summer sea ice in the Arctic.
If the same thing happens in Antarctica that is occurring in the Arctic, we all may be in over our heads soon.
Here’s to finding your true places and natural habitats,
Candy
I think something unusual is happening looking at what is taking place at the two ends. There should be great concern for the scenarios that are arising. In one way or the other, this will affect the flora and fauna communities of the two regions. The end result of it all will have both direct and indirect effect to mankind. So better find out what is the cause and if possible find solution(s) before is too late.
Losing the sea ice in Antarctica may have a serious consequence. It is thought by some that the sea ice serves as a sort of wall or block which prevents the much larger continental ice mass from slipping from the land into the sea. Without sea ice, the continental ice mass would flow more swiftly into the ocean, the sea level increase would be much greater, much faster–Similar to the effect of Greenland’s land based glaciers sliding to the sea.
Interesting. Good example of why the terminology “global warming” was phased out in favor of “climate change,” although the research data still seems to paint a pretty damning picture for Antarctica’s future if the trend continues. I always prefer to see the primary data with regards to arguments like this, though. This article makes it sound like we’re seeing a small and short-lived increase in Antarctic ice cover, in the period before we’re headed for a precipitous crash.
Anthropogenic climate change seems well-supported at this point, but the whole debate around it is also a good example of why I tend to loathe the introduction of politics into science. Too often, two opposing positions on a matter that should be decided by the data get staked out by our two political parties, and each “team” hunkers down around their chosen side and lets it become a matter of faith instead of reason.
Interesting article candice.
Thanks, Candice, for bringing this to our attention.
Frederic,
Thanks for reading and replying.
According to the National Snow and Ice Data Center at the University of Colorado in Boulder, “Overall, Antarctic sea ice has grown slightly over the past thirty years of the satellite record, but the trends are very small, and the ice extent varies a lot from year to year. In Southern Hemisphere winter months, ice extent has increased by around one percent per decade. In the summer, ice has increased by two to three percent per decade, but the variation is larger than the trend.”
So although Antarctic sea ice is increasing overall, certain regions around Antarctica are losing ice at a rapid pace. I think we are more in agreement than we are at odds.
For your reference, see: https://nsidc.org/icelights/2012/01/11/sea-ice-down-under-antarctic-ice-and-climate/
Thanks again for commenting.
C.G.A.
You would do well to more carefully research what is happening with the Antarctica ice. Contrary to what you state, ice buildup in Antarctica is barely holding its own. The underlying temperatures of the surrounding seawater have being going up, resulting in an acceleration of ice breaking off from the various shelves, to melt at sea.
For example, a large section of the Ross Ice shelf – an area greater than the country of Belgium – calved off in 2000. Nasa satellite imagery has revealed more large fissures developing in many of Antarctica’s ice shelves. When these massive plates break off, the glaciers that feed them, accelerate in their descent to sea.
As global temperatures rise, and ocean currents shift due to warmer waters, the results in the long term could be catastrophic. Unless mankind makes a radical change in our lifestyle, and use of fossil fuels, especially in the Northern Hemisphere, the results for our children and their children… could be dire.
Further reading here: https://en.wikipedia.org/wiki/Ross_Ice_Shelf
(check the last paragraph under Composition and Movement)
Regards,
Frederic in Montréal