The region has dumped the equivalent of 72 cubic miles of water—enough to fill , Empire State Buildings—into the ocean since then, researchers report today in Science. It shows that the ice sheet can react very rapidly to changes in its environment. Ice shelves line the coast and usually keep the glaciers and ice sheets that sit atop Antarctica in place. But the waters in the Bellingshausen and nearby Amundsen seas have warmed by about 1 degree Fahrenheit in the past 30 years because of changing winds.
A layer of ocean called the Circumpolar Deep Water, typically kept far offshore by those winds, has infiltrated coastal areas, warming them up and eating away at the protective shelves.
There is enough ice on Antarctica that, if it all melted, sea level would increase by some feet. Even without such a major event, the IPCC projected in its report that sea level will rise anywhere between 4 and 35 inches 10 and 89 centimeters by the end of the century.
The high end of that projection—nearly three feet a meter —would be "an unmitigated disaster," according to Douglas. Down on the bayou, all of those predictions make Windell Curole shudder.
Rising sea level is not the only change Earth's oceans are undergoing. The ten-year-long World Ocean Circulation Experiment , launched in , has helped researchers to better understand what is now called the ocean conveyor belt. Oceans, in effect, mimic some functions of the human circulatory system. Just as arteries carry oxygenated blood from the heart to the extremities, and veins return blood to be replenished with oxygen, oceans provide life-sustaining circulation to the planet.
Propelled mainly by prevailing winds and differences in water density, which changes with the temperature and salinity of the seawater, ocean currents are critical in cooling, warming, and watering the planet's terrestrial surfaces—and in transferring heat from the Equator to the Poles. The engine running the conveyor belt is the density-driven thermohaline circulation "thermo" for heat and "haline" for salt. Warm, salty water flows from the tropical Atlantic north toward the Pole in surface currents like the Gulf Stream.
This saline water loses heat to the air as it is carried to the far reaches of the North Atlantic. The coldness and high salinity together make the water more dense, and it sinks deep into the ocean.
Surface water moves in to replace it. The deep, cold water flows into the South Atlantic, Indian, and Pacific Oceans, eventually mixing again with warm water and rising back to the surface. Changes in water temperature and salinity, depending on how drastic they are, might have considerable effects on the ocean conveyor belt. Ocean temperatures are rising in all ocean basins and at much deeper depths than previously thought, say scientists at the National Oceanic and Atmospheric Administration NOAA.
Arguably, the largest oceanic change ever measured in the era of modern instruments is in the declining salinity of the subpolar seas bordering the North Atlantic.
Robert Gagosian, president and director of the Woods Hole Oceanographic Institution, believes that oceans hold the key to potential dramatic shifts in the Earth's climate. He warns that too much change in ocean temperature and salinity could disrupt the North Atlantic thermohaline circulation enough to slow down or possibly halt the conveyor belt—causing drastic climate changes in time spans as short as a decade. The future breakdown of the thermohaline circulation remains a disturbing, if remote, possibility.
But the link between changing atmospheric chemistry and the changing oceans is indisputable, says Nicholas Bates, a principal investigator for the Bermuda Atlantic Time-series Study station, which monitors the temperature, chemical composition, and salinity of deep-ocean water in the Sargasso Sea southeast of the Bermuda Triangle.
Oceans are important sinks, or absorption centers, for carbon dioxide, and take up about a third of human-generated CO2. Data from the Bermuda monitoring programs show that CO2 levels at the ocean surface are rising at about the same rate as atmospheric CO2. But it is in the deeper levels where Bates has observed even greater change.
In the waters between and 1, feet and meters deep, CO2 levels are rising at nearly twice the rate as in the surface waters. While scientists like Bates monitor changes in the oceans, others evaluate CO2 levels in the atmosphere.
In Vestmannaeyjar, Iceland, a lighthouse attendant opens a large silver suitcase that looks like something out of a James Bond movie, telescopes out an attached foot 4. Two two-and-a-half liter about 26 quarts flasks in the suitcase fill with ambient air. In North Africa, an Algerian monk at Assekrem does the same. Around the world, collectors like these are monitoring the cocoon of gases that compose our atmosphere and permit life as we know it to persist.
When the weekly collection is done, all the flasks are sent to Boulder, Colorado. There, Pieter Tans, a Dutch-born atmospheric scientist with NOAA's Climate Monitoring and Diagnostics Laboratory, oversees a slew of sensitive instruments that test the air in the flasks for its chemical composition. In this way Tans helps assess the state of the world's atmosphere. Walking through the various labs filled with cylinders of standardized gas mixtures, absolute manometers, and gas chromatographs, Tans offers up a short history of atmospheric monitoring.
In the late s a researcher named Charles Keeling began measuring CO2 in the atmosphere above Hawaii's 13,foot 4,meter Mauna Loa. The first thing that caught Keeling's eye was how CO2 level rose and fell seasonally. That made sense since, during spring and summer, plants take in CO2 during photosynthesis and produce oxygen in the atmosphere.
In the fall and winter, when plants decay, they release greater quantities of CO2 through respiration and decay. Keeling's vacillating seasonal curve became famous as a visual representation of the Earth "breathing. It has been really cool to see something that is almost definitively associated with the hands of women. These locations have resources that would be amenable to use by groups, so not just hunters, but also family.
Doyle says that, from a Native American perspective, it was no surprise to find evidence of community living and gender cooperation in these areas. It was a beautiful thing to see that proven. The icy mountains of Norway have proven rich, latterday hunting grounds for glacial archaeologists and it was here in that some of the most important finds were made.
Solli points out that until scientists began to find these objects and document indigenous use of the mountains in antiquity, many Norwegians knew little about this part of their own history. That year, archaeologists were working on the Lendbreen glacier in Oppland County, when they found what appeared to be a crumpled up piece of fabric. The tunic was woven from sheep wool in a diamond twill design between AD and and had been well worn, repaired and patched. Only a handful of garments from this period have ever been found in Europe.
With a simple cut — it was pulled over the head like a jumper — it was probably worn by a slender man around 5ft 6in tall, Vedeler reported. Bronze Age leather shoes from 1,BC and a ski with strapping from AD have also melted free in Norway in recent years. Last year, snowshoes for horses and other items relating to the hunting and domestication of animals were uncovered in the same area. He points out that, remarkably, scientists in both Mongolia and Norway have discovered that identical, yet innovative hunting methods were used.
The poles were used to corral the herds into position for hunters, says Pilo. The poles, topped with flags, were planted into the ice and used to alarm the animals, who instinctively fear any sign of motion on the featureless landscapes. The flocks would head away from the fluttering flags, towards the waiting hunters. Pilo says he particularly enjoys finding objects with a human feel and connection to them, such as clothing. Once in , he found a small arrow that seemed a little different from others he had encountered.
In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Fifty years ago, many scientists were looking up. But in Antarctica, John Mercer was looking down — and he was concerned about what he saw.
That year, the late Mercer, a glaciologist at Ohio State University in Columbus, first warned about the potential for rapid sea-level rise from melting ice caps. Mercer Int. Geological evidence from a former lake, located at an altitude of 1, metres in the Transantarctic Mountains, suggested that the area was once awash with open water and floating icebergs.
Mercer took that as evidence that the entire West Antarctic Ice Sheet had once melted away. The paper was an intriguing synthesis of the science of the times. Using multiple lines of evidence, Mercer sought to explain how sea levels could have risen by 6 metres in the previous interglacial period, around , years ago. The melting of Greenland or the East Antarctic Ice Sheet could not explain it, because both are located on solid earth and would respond relatively slowly to warming.
By contrast, much of the West Antarctic Ice Sheet is grounded well below sea level. Many credit a paper by Johannes Weertman, a geophysicist at Northwestern University in Evanston, Illinois, with providing a technical explanation for how such a massive ice sheet could disintegrate J.
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