THE ALPINE GLACIERS LIVING ON BORROWED TIME

THE ALPINE GLACIERS LIVING ON BORROWED TIME

ANALYSIS – In the Alps, the mel­ting of the gla­ciers is the most obvious sign of glo­bal war­ming. Some of them are already doo­med, such as the gla­cier of Sarennes above the Alpe d’Huez. While the 5th report of the IPCC* on cli­mate change is relea­sed today, cli­mate experts are rai­sing the alarm. Once again.
Glacier de Sarennes en 1906… et en 2005. © E.Thibert LGGE

The gla­cier of Sarennes in 1906… and in 2005.
© E.Thibert LGGE

It is one of the indi­ca­tors for cli­mate change in alti­tude and one of the most obser­ved gla­ciers in the world.
Studied since 1906, fre­quently ana­ly­sed since 1948 by the scien­ti­fic com­mu­nity, the gla­cier of Sarennes, situa­ted in the mas­sif of the Grandes Rousses, is now a mere sha­dow of itself, doo­med to disap­pear from the alpine land­scape by 2020.
The conclu­sion is clear. Between the snow falls in win­ter and the sum­mer melting/thawing, the gla­cier has lost every year on ave­rage about 1,5 metre of ice thi­ck­ness in the last thirty years. And since the mid eigh­ties, the tha­wing has increa­sed. « Over the last ten years, we’ve lost each year the equi­va­lent of a 3‑metre-layer of ice », observes Emmanuel Thibert, resear­cher at the Irstea (the natio­nal ins­ti­tute of research in sciences and tech­no­lo­gies of the envi­ron­ment and agri­cul­ture, ex-Cemagref). The ins­ti­tute has indeed, in col­la­bo­ra­tion with the gla­cio­logy and geo­phy­sics labo­ra­tory of the envi­ron­ment at Joseph-Fourier’s uni­ver­sity (LGGE), ela­bo­ra­ted a real data­base on the evo­lu­tion of gla­ciers (1). Every year for ten years now, 10 % of the ice thi­ck­ness of the gla­cier of Sarenne is disappearing.
The cli­mate is war­ming up… fas­ter and faster
Evolution de la mer de Glace de Chamonix. © IGN

Evolution of the Mer de Glace of Chamonix.
© IGN

In forty years, the alpine gla­ciers have already lost one quar­ter of their sur­face area. What will be left at the end of the cen­tury ? Assuming there is an increase in tem­pe­ra­ture of 3°C by 2100, only gla­ciers higher than 4000 metres will remain. The most famous of them, the Mer de Glace of Chamonix, would conti­nue its retrac­tion, from 800 metres to 1.2 Km in the next twenty years.
In the Alps, the tha­wing of the gla­ciers is cer­tainly the most obvious sign of cli­mate change. And the cli­mate is war­ming up fas­ter and fas­ter, as the experts of the IPCC* confirm in their 5th report relea­sed today.

The war­mest decade in a century

« The cli­mate is war­ming up conti­nuously », attests Gerhard Krinner, Director of Research at the CNRS and one of the main authors of the GIEC’s 5th report. « Each decade since 1850 has been war­mer than the pre­vious one. » And if war­ming has slo­wed down these last ten years, accor­ding to the scien­tists, it has not yet stop­ped com­ple­tely, as shown with the conti­nuous rising of sea levels and the tha­wing of glaciers.
Le glacier de Sarenne mi-ombre mi-soleil. © Cédric Colomban

The gla­cier of Sarenne semi-shade semi-light.
© Cédric Colomban

The assess­ment of ice masses is the­re­fore a key wit­ness to cli­mate change in the mid and long term. This is an essen­tial baro­me­ter while the scien­ti­fic com­mu­nity is still facing unk­nowns. Predicting the future cli­mate in the short term is a chal­lenge for resear­chers. « We know how the cli­mate will react in fifty years », conti­nues Gerhard Krinner, « but we can­not pre­dict today if the sum­mer 2014 will be scor­ching or not. »
However, one thing is cer­tain. For one cen­tury now and the first tem­pe­ra­ture rea­dings in 1880, the earth has lived its war­mest decade. The ave­rage glo­bal tem­pe­ra­ture has thus increa­sed by 0,8°C since the end of the 19th cen­tury, lea­ding to ever higher green­house gas emis­sions. And by the end of the 21st cen­tury, the ther­mo­me­ter could go up by 1,5 to 2°C, accor­ding to esti­mates of the climatologists.

A new inter­na­tio­nal agree­ment… in 2015
Sur le glacier de Sarenne… © Cédric Colomban

On the gla­cier of Sarenne…
© Cédric Colomban

The IPCC* is giving a fifth war­ning. « It is extre­mely likely that we are the main cause of the glo­bal war­ming obser­ved since the mid 20th cen­tury », indi­cate the inter­na­tio­nal experts in the sum­mary of their report conveyed to the policy-makers. And they rub it in sta­ting that : « Climate change will require sub­stan­tial and sus­tai­nable reduc­tions of green­house gas emissions ».

The mes­sage is clear, before the upco­ming inter­na­tio­nal confe­rence, plan­ned in Paris in 2015 which should lead to a new agree­ment to try and keep glo­bal war­ming under the thre­shold of +2 °C. « We think that a tem­pe­ra­ture increase of 2 °C remains mana­geable. This is not neces­sa­rily the opi­nion of the IPCC*! », under­lines Gerhard Krinner. « This is a poli­ti­cal objec­tive. Even if we want to res­pect this objec­tive, we need to take action, and this very urgently. »
Patricia Cerinsek
Translation by Sandra Bailly, Translator / Desktop Publishing specialist
Phone : +33 (0)6 95 87 15 27 – email : sandra.bailly79 [at] gmail​.com

(1) Five gla­ciers – Sarennes, Saint-Sorlin and Gébroulaz in Savoie, Argentière and the Mer de glace in Haute-Savoie – are part of the net­work Glacioclim, an envi­ron­men­tal research obser­va­tory, focu­sing on the study of gla­ciers and climate.
(2) This is the first sec­tion of the ana­ly­sis of the IPCC*, dea­ling with the cli­mate sciences. A second sec­tion rela­ted to the vul­ne­ra­bi­lity of human acti­vi­ties and their adap­ta­tion to cli­mate change, will be the topic of a report in March 2014 ; at last, a third sec­tion concer­ning the neces­sary mea­sures for redu­cing the impact of cli­mate war­ming, is expec­ted for April 2014. The glo­bal syn­the­sis report will be publi­shed at the end of October 2014.
N.B : The increase of 1,5 to 2 °C of glo­bal ave­rage tem­pe­ra­tures at the end of the 21st cen­tury is the most « opti­mis­tic » sce­na­rio of the IPCC*. In the pes­si­mis­tic ver­sion, the ther­mo­me­ter should go up to 4,8 °C. Up to now, we have noted that the pes­si­mis­tic sce­na­rio prevailed…
* IPCC : Intergovernmental Panel on Climate Change

Patricia Cerinsek

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