On the morning of January 7, 2010, a bright orange ship, squat and round-bellied, passed the northern tip of the Antarctic Peninsula. The Nathaniel B. Palmer, a 94-meter research icebreaker serving the U.S. National Science Foundation, had chugged southward for three days since leaving port in Punta Arenas, Chile, at the southern tip of South America. It had weathered a roller coaster of 8- to 12-meter sea swells, and winds over 100 kilometers per hour, as it crossed the Drake Passage between South America and Antarctica. The ship, with two dozen scientists on board, had come to investigate the effects of climate change on the thawing peninsula.

The Antarctic Peninsula has warmed by more than 2 degrees Celsius in recent decades—four times faster than other parts of the planet. This heating has triggered a dramatic series of glacial ice collapses: since 1980, over 5,000 square kilometers of floating glacial ice, 200 to 300 meters thick, has crumbled into the ocean. Those floating ice shelves had helped to stabilize glaciers behind them on land, slowing the glaciers’ flow into the sea. But with the ice shelves gone, the glaciers have accelerated into the ocean, speeding up by 2- to 9-fold.

» View the Antarctic Research Slide Show

The scientists on board the Palmer planned to investigate the mechanisms of those collapses. They also hoped to put the sudden, recent changes into a broader context, by reconstructing the history of ice shelves and glaciers in this part of Antarctica since the close of the last ice age, roughly 12,000 years ago.

As the Palmer sailed along the peninsula, multi-beam sonars on its underside fired chirps into the water—audible on every deck, in every cabin, every few seconds, day and night. Those pings painted a swath of orange-yellow-green across a computer monitor in a crowded laboratory on Deck 1—a topographic map of the ocean floor, with colors representing different depths. The swaths of color revealed undersea canyons that human eyes have never witnessed—deep grooves, 1,000 meters down, that glaciers had carved as they advanced outward from the Antarctic coast over the seafloor during the Ice Age.

Another set of sonars, operating at different frequencies that would penetrate the seafloor, returned images of the layers of sediment that have accumulated over the millennia in certain areas. Those layers held a record of glacial activity: coarse gravels deposited as a glacier 1,000 meters thick slithered over the ocean floor; finer muds laid down after the glacier retreated but the area was still shaded by a floating ice shelf 300 meters thick; and finally, layers of mud rich in ancient diatoms, microscopic organisms deposited after the ice shelf retreated and allowed sunlight to pierce cold, open water between the seasonal freezing of ice to about a meter thick.

In places where the sonar showed especially thick layers of sediment, the ship stopped. A crane swung over its rear deck, 1,000 meters of cable was spooled into the water and a core of that sediment was extracted from the ocean floor.

When a core was laid out on the laboratory on Deck 1, Eugene Domack, a marine geologist with Hamilton College, examined it, centimeter by centimeter with an eyepiece, to document its sequence of layers. Stefanie Brachfeld, a geologist from Montclair State University, analyzed the magnetic orientations of microscopic mineral grains in the sample. This sequence of changing orientations, which track movements in Earth's magnetic poles over thousands of years, would help to document the age of the sediment layers in places where organic carbon was too sparse to allow carbon 14 dating. A team of paleobiologists also sampled the microscopic shells of ancient organisms in the core for clues about the changing climate.

8 Comments

1. 1. R.Blakely 04:47 AM 6/23/12

   "Cold clues reveal how fast ice is disappearing, and therefore how quickly sea level could rise" is an interesting notion. But systems resist change, which means that disappearing Artic, and Antarctic ice, is due to global cooling not warming.
   Global cooling reduces snowfall in the Artic since less moisture is transported. Less snow means that glaciers are shrinking.
   When global warming does occur then we will enter another ice age, which is the more normal condition for Earth. Global warming will cause greater snowfall and thus glacier expansion.
   Measuring average temperature at the Earth's surface does not include a measure of cloud cover. An average rising surface temperature, and a shrinking cloud cover, is actually a condition of global cooling!
   

   Reply | Report Abuse | Link to this

2. 2. Eco_steve 07:54 AM 6/24/12

   Mr. Blakeley : Can you provide validated and refereed proof of your statements?

   Reply | Report Abuse | Link to this

3. 3. Steve Case 11:23 AM 6/25/12

   The head line says:
   
   "Cold clues reveal how fast ice is disappearing, and therefore how quickly sea level could rise"
   
   Sea level has had a negative acceleration over the last 20 years or so.
   
   Here's a screen shot:
   http://i39.tinypic.com/nr14bq.jpg
   From this Colorado University Presentation:
   Why has an acceleration of sea level rise not been observed during the altimeter era?
   Link:
   http://www.aviso.oceanobs.com/fileadmin/documents/OSTST/2011/oral/02_Thursday/Splinter%203%20SCI/04%20Nerem%20ostst_2011_nerem.pdf
   It shows that sea level has an acceleration of minus 0.06 MM/yr² since 1993.

   Reply | Report Abuse | Link to this

4. 4. R.Blakely in reply to Eco_steve 08:23 PM 6/25/12

   Global dimming has been measured over India. Dimming is a more significant effect than any change that CO2 concentration can cause. Global cooling is not evident from temperature measurement since cloud cover reacts, like most systems, to counter change. Reduced cloud cover increases surface heating since sunlight can heat the surface more.
   CO2 already blocks all 15-micron photons, and so more CO2 cannot cause any more warming.

   Reply | Report Abuse | Link to this

5. 5. Padgie in reply to R.Blakely 10:34 AM 7/1/12

   Thank you Mr Blakely. An average rising temperature is an indication of Global cooling? Global cooling not evident from temperature measurements? Cloud cover needs to be taken into account when measuring temperature. Certainly gives one an insight into the problems one faces when dealing with these issues.

   Reply | Report Abuse | Link to this

6. 6. Denny0789 12:34 PM 7/8/12

   NSIDC data shows the Antarctic is *gaining* sea ice, not losing it:
   http://nsidc.org/data/seaice_index/archives/index.html
   
   In the last decade (i.e. 120 months), there has been 1.4% more Antarctic sea ice than the decade before. In fact, for the most recent month (June), Antarctic sea ice is 9.6% higher than 10 years before. Over the NSIDC's total record, starting in Nov 1978, the linear trend of Antarctic sea ice implies a total increase of 4.2%, or 1.3% per decade.
   
   So why is Fox writing as if Antarctic sea ice is disappearing?

   Reply | Report Abuse | Link to this

7. 7. Denny0789 in reply to Steve Case 12:38 PM 7/8/12

   Your graph is out of date. AVISO now shows sea level back on its previous trend:
   http://www.aviso.oceanobs.com/en/news/ocean-indicators/mean-sea-level/index.html
   
   (It dipped because of the strong La Nina, which moved a lot of water from the oceans onto land. That water has not drained back to the oceans.)

   Reply | Report Abuse | Link to this

8. 8. V Pontchartrain 10:27 PM 7/10/12

   One interesting detail: On Google Maps most of the areas described in article as "Former Ice Shelves" seem to be PhotoShopped.

   Reply | Report Abuse | Link to this