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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17 February 2012

Glaciers at your feet



© RTimages - Fotolia.com
Piscola is one of the national drinks in Chile. It is a mix of the aromatic spirit Pisco and cola! Now let’s have an experiment : fill a glass with ice cubes, add Pisco and cola, up to the top of the glass and wait one hour. Observe : the ice disappeared however the glass has not overflew. Why? Because the volume of ice water is quite the same as liquid water.

So does it mean that sea level is not rising because of melting Arctic, which is a big ice cube floating on the Arctic ocean? Basically yes. The contribution from its melting is minor to sea level rise.

However reducing ice masses which are on land do impact sea level…

The glaciers as indicators

Tongue of the glacier Viedma, one of the
biggest glaciers in Argentinian Patagonia.
Glaciers provide among the most visible indications of the effects of climate change. The volume of a glacier is clearly determined by the climate. As the local temperatures increase, the volume of the glacier decreases.

All around the world, the retreat of the glaciers has accelerated during the last decades. Strongest mass losses are observed in Patagonia, Alaska, northwest USA and southwest Canada. In France, half the glaciers of Pyrénées Mountains disappeared during 20th century. In 1930 Colombia had 14 glaciers ; today 8 of them have disappeared. Actually most inter-tropical glaciers are very likely to disappear by 2025 (Ramírez et al., 2001).

 




 A 30 meters high block of ice 
detaches from the glacier 
Perito Moreno (Argentinian Patagonia).
In few words, a glacier retreats when
more ice is lost at the front of the glacier than created at the top. 


Southern Patagonian icefield, one of the largest fields of ice on the planet

When we met Dr. Juan Carlos Aravena, he was about to take an airplane to Antarctica, the day after. Juan Carlos works at the institute CEQUA (Centro de Estudios del Cuaternario), as researcher in glaciology and paleoecology. The institute is a governmental research office, dedicated to study environment evolution in the southern part of South America and in Antarctica.
We met Juan Carlos Aravena on February the 1st
at CEQUA office, in Punta Arenas, Chilean Patagonia.
Click to enlarge
(Picture : Rivera et al., 2012)
Juan Carlos explains : “the Southern Patagonian icefield is one the biggest ice masses on Earth, after Antarctica and Greenland". As an example he adds : “the glacier Jorge Montt, located in Southern Patagonian icefield, has shown a dramatic retreat during the last century. It is one of the glaciers that is the most studied in the region. During 2011 the Chilean Centro de Estudios Cientificos (CECS) installed a camera there taking 6 pictures a day, and from to time to time a scan of the glacier is performed with laser, from a plane”. The following picture shows the evolution of the front of the glacier, since 1898.



Stored before on land, going down to the sea…

The Southern Patagonian icefield
Enlarge
(Google Maps)
There are several consequences to the volume decreasing of the glaciers. One of them is the water storage and supply – we talked about water availability in a previous article. “Another key consequence is the contribution to sea level rise”, says Juan Carlos. Patagonian icefields are considered to be amongst the glaciated areas which have contributed the largest proportion of melt water to sea level rise in the second part of the 20th century (Rignot et al., 2003).

Two main factors contribute to observed sea level rise. The first is thermal expansion : as ocean water warms, it expands. The second is from the contribution of ice based on land, due to increased melting. And the major store of water on land is found in Antarctica, Greenland and glaciers.

Between 1930 and 2010, a sea level rise of 18 cm was observed, and the rate of rise has clearly been higher compared to before 1850. According to the 2007 report of the Intergovernmental Panel on Climate Change (IPCC), the sea level rise could be up to 59cm by the end of 21st century. However less conservative recent studies bring more worrying conclusions : 80cm according to W.T. Pfeffer for instance (Pfeffer et al., 2008).
Sea level in the past and as projected for the future.
Over many centuries, sea level could rise by several meters. (IPCC, 2007)
Maldives buying new land

As the oceans rise, low-lying coastal areas will disappear and flooding of these areas will become more common. Loss of land and flooding will have substantial impact on local wildlife, and on humans of course : migrations of populations, social impacts, effects on health, agriculture, tourism for instance. 

More than half of the world's population currently lives in a coastal region. The delta regions are particularly vulnerable. Only 50 cm sea level rise by 2100 will hit one in ten humans around the world. China, USA, India, Bangladesh and Japan will be ones of the most concerned countries (McGranahan et al.,2007).
Relative vulnerability of coastal deltas as shown by the
indicative population potentially displaced by current sea-level trends to 2050 :
Extreme =>1 million ; High = 1 million to 50 000; Medium = 50 000 to 5 000
(Ericson et al., 2006)
As small Pacific Islands are the subject of much concern in view of their vulnerability to sea level rise, several archipelagos - like Tuvalu - have started to be very active these last years in order to warn the international community. 

In Maldives, the highest point of the country is at 3 meters above sea level. End of 2008, one of the first decisions of recently elected President Mohamed Nasheed was to create a sovereign fund with the purpose of adapting to climate change. The fund is supplied from taxes on tourism benefits. Part of it is used to buy land in Sri Lanka and India as anticipation to possible migration of population…

 




Few meters 
and Manhattan would not look the same!
New York City will adapt probably by building walls and dikes.
(Picture : Heidi Cullen)

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7 February 2012

Torres del Paine, the role of the forests

“Plant a tree, plant a tree” they say!... What about also protecting old trees?

The Chilean National Park Torres del Paine is an outstanding piece of nature, composed of mountains, glaciers, lakes, rivers and native forests. It is one of the most visited places in Chile.

A large fire started in the middle of Torres del Paine Park last December the 27th, causing major environmental damages. The park partially re-opened on the 4th of January and we were there two days later. At the gate of the park, a forest ranger told us : “This fire is a catastrophe. Most of the rangers working here are local people, the situation has severely affected the surrounding community.”

More than 170 km² were burnt down ; 36% of burnt area was native forest. The fire represents one of the biggest destructions of forest of these last decades in Chile. Even at the beginning of February, the fire was not yet completely under control. 

Forests dry up

Climate change increases vegetation fire risk since extended periods without rain brings droughts, such as El Niño in the Pacific Ocean. Additionally this fire risk rises due to land-use change, like deforestation. A declining trend in precipitation has been observed in southern Chile in the past decades. This, combined with the exceptional hot summer 2011-2012, created the conditions for a large and persistent fire in Torres del Paine. 

Forest fires occur from human or natural causes. Human causes include accidental fires or intentional fires such as : farmers establishing new plantations, small and controlled fires by forest keepers to prevent larger fires or even criminal fires. Torres del Paine fire started as an accident caused by a visitor of the park.

“There is no smoke without fire” 

Forest fires release big quantities of carbon dioxide which is one of the greenhouse gases that contribute to climate change. Carbon is stored in the trees as they grow. Many decades are necessary to store large quantities of carbon in forests ; however in just a few days of fire it can all be released. One hectare of tropical forest that is burnt down approximately releases 500 tons of carbon dioxide. 

Preserving the forest allows to retain great quantities of carbon dioxide : planting new trees is good, protecting old ones is even better!

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Some figures about Forests and Climate Change 

Every year 130 000 km² of forest disappear. This is equivalent to the surface of Greece.

Forests on Earth contain as much carbon as the entire atmosphere.

There is more carbon in forests and soils than in all the oil reservoirs of the planet.

In the Amazon, the estimated human health cost of fires increased from 3.4 million US dollars in 1996 to 10.7 million US dollars in 1999 (Cardoso de Mendonça et al., 2004).

National Park Torres del Paine.

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