28 February 2012

Antarctica in the heart of the story

(Photo : INACH)
Expedition Criosfera. No, this is not the title of the next movie by James Cameron! It is the name of an international expedition that took place in Antarctica, during last December and January. The team was composed of Brazilian and Chilean scientists and was based near the glacier Union, in the middle of the Antarctic Peninsula… latitude 84° South, only 1 000km far from the South Pole.

Antarctica tells the story

Antarctic Peninsula and 
the south coasts of Chile.
Enlarge (Google Maps)
We met Dr. Ricardo Jaña few days after he came back from the expedition. Ricardo works as glaciologist at the Instituto Antártico Chileno (INACH, Chilean Institute for Antarctica) and he was the only Chilean scientist of the team.

Ricardo explains: “The first objective of the expedition was to install an atmospheric module to measure environmental parameters, transmitted live to Brazil”. The team also extracted a 100m long sample of ice, called ice core. Such long samples provide data for a very long period. The analysis of the air bubbles trapped in the ice cores allows the scientists to know what the atmosphere was composed of several centuries ago. Compiled with additional data, characteristics of the climate are reconstructed. We know for instance that the temperatures are connected to the global atmospheric concentration of carbon dioxide. Ricardo adds : “Doing this we try to know the past in order to predict the future”. Knowing how the climate behaved in the past according to numerous parameters, the scientists intend to anticipate how the planet should react in the future. The ices of Antarctica tell the story of the climate!

Atmospheric concentrations of CO2 over the last 10 000 years. Measurements are shown from atmospheric samples (red lines) and ice cores (other colours). The contemporary increase in concentration contributed to the recent increase of temperatures. (IPCC Report 2007)

Ricardo and Frédéric in front of a 
map of the Antarctic Peninsula. 
We met Ricardo Jaña on January 
the 31st, in the office of INACH 
located in Punta Arenas, Chile.
A river where there should not be

The ice sheet of Antarctic Peninsula is showing a clear response to contemporary global warming. Over the past hundred years the global increase of the planet temperatures was 0,74°C ; in the Antarctic Peninsula the increase was 3°C. Four times stronger warming.

During the expedition, the scientists discovered a very uncommon phenomenon : they found a river of water. Ricardo explains : “From time to time we observe water from melting ices, in small volumes, due to normal sporadic increase of temperatures. However the creation of a small river is exceptional. We do not know if this was already observed in the past, that close to the South Pole. We will research on it.”

The river, only 1 000km far from the pole. (Photo : INACH)
The other dimension

In a previous article we talked about the melting ices on land contributing to sea level rise. The glaciers of South America contribute, Greenland and Antarctica also do. It is estimated that the complete melting of Greenland ice sheet would raise sea level by 7 meters, Antarctica 57 meters – however a melting of entire Antarctica is unlikely to happen. Most probably the melting that will indeed occur will be irreversible.

The dimensions of the Antarctic glaciers are pretty different than those of Patagonian glaciers. For some Antarctic glaciers, the ongoing acceleration of the melting means even greater quantities of water released to the sea. “Several glaciers of West Antarctic will reach soon what we scientists call the tipping point : once certain conditions are met, the ongoing change accelerates and is irreversible”, says Ricardo. 

According to recent studies performed at Oxford University, the Pine Island Glacier in West Antarctica has already passed its tipping point and will contribute about 24 centimeters of water to the world's oceans by 2100.


Pine Island Glacier does not only release blocks of ice, it releases huge icebergs, every 5 to 10 years. It is part of the natural lifecycle of the glacier, though globally more and more ice is released to the sea. In the next few months a new large iceberg will break off the glacier. It is actually bigger than New York City, around 900km²...The following picture from NASA shows the ongoing crack.


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