Le Groenland a commencé à se réchauffer il y a 19 000 ans

Une nouvelle étude publiée par la revue américaine Science pourrait répondre aux interrogations de nombreux scientifiques. Utilisant des procédés de mesures plus précis que ceux appliqués lors des analyses précédentes, elle affirme que le Groenland a commencé à se réchauffer il y a 19 000 ans.

L'évolution des températures sur cette immense île du nord de l'océan Atlantique provoquait la perplexité des climatologues : plusieurs études dataient le début de son réchauffement à il y a 12 000 ans, mais les diverses données recueillies contredisaient cette estimation.

ÉNERGIE SOLAIRE

Il y a 20 000 ans, durant la période la plus froide du dernier âge glaciaire, de vastes et épaisses couches de glace recouvraient l'Amérique du Nord et le nord de l'Europe. Les températures moyennes étaient environ quatre degrés inférieures à celles de l'ère pré-industriel.

Des changements dans l'orbite de la Terre autour du soleil, il y a 19 000 ans, ont augmenté la quantité d’énergie solaire reçue par le Groenland, entraînant la libération de fortes doses de dioxyde de carbone (CO2) dans l'atmosphère et provoquant un réchauffement global des températures sur la planète.

PÉRIODE HOLOCÈNE

Pour savoir quelle température il faisait sur la Terre à cette époque, les scientifiques peuvent se servir de la calotte glaciaire du Groenland comme d'un véritable livre, grâce aux couches de neige successives tombées chaque hiver.

Dans le cadre de cette recherche trois carottes de glace ont été prélevées et analysées avec un procédé plus précis que par le passé, a noté Christo Buizert de l'Université d'Etat d'Oregon (nord-ouest), le principal auteur de l'étude. Ces analyses ont permis de détecter un net réchauffement en réaction à l'augmentation du CO2 dans l'atmosphère.

Ainsi, selon cette dernière analyse sur la période allant de - 19 000 à - 12 000 ans, le Groenland a « gagné » environ cinq degrés, une variation très proche de celle indiquée par les modèles climatiques.

Cette montée des températures a marqué le commencement de la période holocène, avec un climat plus chaud et plus stable qui a permis l'essor de la civilisation humaine.
Le Monde.fr avec AFP
lemonde.fr
6/9/14 
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• Enhanced melting of Northern Greenland in a warm climate

• Polar ice melt 'accelerating' 

• Regarding his visit to Greenland, the Secretary-General said: “I was able to see for myself again the impact of climate change phenomenon. The icebergs and glaciers are melting rapidly. 

• Πώς οι πάγοι της Γροιλανδίας γλίτωσαν από την αρχαία υπερθέρμανση

Ban warns against escalation of crisis in Ukraine, saying ‘small sparks’ could ‘ignite larger flames’. - Visit to Greenland

UN, 28 March 2014 – Reiterating his strong call for a diplomatic solution to the crisis over Ukraine, United Nations Secretary-General Ban Ki-moon this evening warned the concerned parties – and the wider international community – that “at this time of heightened tensions, even small sparks can ignite larger flames of unintended consequences.”

“What started as a crisis in Ukraine, is now also a crisis over Ukraine. From the beginning, my objective has been to seek a peaceful and diplomatic solution to the crisis, in keeping with the fundamental principles of the United Nations Charter,” Mr. Ban told reporters following his briefing to the Security Council on his recent travels.

• The UN chief, on the road since 20 March, paid official visits to the capitals of both Ukraine and Russia, and also attended Nuclear Security Summit in The Hague, the Netherlands, and visited Greenland’s Ilulissat Icefjord, a UNESCO World Heritage Site.

On the Ukraine crisis, Mr. Ban said he had “strongly urged the Russian and Ukrainian leaders to de-escalate the situation, avoid hasty actions and immediately engage in direct and constructive dialogue to resolve all the problems.”
Answering a reporter’s question on Russia’s intent to send troops into southern and eastern Ukraine, the Secretary-General said President Vladimir Putin assured him that he had no such intention.
“I have been really trying to urge both parties to de-escalate the situation. Emotions were running high, as you will agree, and tensions have been very highly charged. Therefore, my immediate priority was to urge…the leaders of both [countries] to engage in direct dialogue,” said Mr. Ban.
“Now is the time for dialogue and peace,” he stated, adding that the UN will continue its efforts to find a solution to the Crimean crisis through diplomacy and the UN Human Rights Monitoring Mission, which has been on the ground in the region for nearly two weeks.
Mr. Ban expressed concern over the divisions that this crisis in creating among the international community, fearing it could “harm our ability to address other pressing concerns, conflicts and humanitarian emergencies.”
Citing Ukraine, Syria and the Central African Republic as some of the most important issues in need of resolution, the UN chief said: “I have also urged Members of the Security Council to address these issues as soon as possible, because there are so many, much more longer-term issues like the Millennium Development Goals, sustainable development and climate change.” 
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• Regarding his visit to Greenland, the Secretary-General said: “I was able to see for myself again the impact of climate change phenomenon. The icebergs and glaciers are melting rapidly.

Having personally been to Antarctica, the North Pole, and Iceland, Mr. Ban noted that Greenland’s Ilulissat Icefjord “is the fastest moving glacier in the world,” and, while he admires the people of Greenland’s ability to live harmoniously with nature, the effects of global warming – melting glaciers, extreme weather patterns and rising sea levels – are starting to “seriously threaten” their livelihoods.
Mr. Ban called on all world leaders to come to his 23 September climate change summit with “strong political will.”
As for the Nuclear Security Summit, the Secretary-General said that he had joined other world leaders in The Hague in highlighting the need for vigilance regarding the risk of nuclear terrorism. “International cooperation will be crucial not only in avoiding the proliferation of nuclear materials, but also in advancing nuclear disarmament – the best guarantee against this threat,” he declared.
[un.org]
28/3/14

Japan's largest oil companies set to explore the Arctic

Japan's largest oil companies Inpex and JX Nippon Oil & Gas Exploration are getting ready to carry out geological exploration of the Arctic.
If they are successful, these companies will become the first Japanese corporations to produce oil in this region.

The geological survey will be carried out on the territory of Greenland.


For Japan, which has almost no natural resources of its own, exploration and production of oil in the Arctic will help the country to lower its dependency on other countries for energy resources.

At present, almost all the oil consumed in Japan is imported from other countries, with 80% of the imports from the Middle East alone.
 http://indian.ruvr.ru/news/2013_12_22/Japans-largest-oil-companies-set-to-explore-the-Arctic-1610/
22/12/13
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Related:

• The Battle for the Arctic /Η αντιπαράθεση με το λιώσιμο των πάγων στην Αρκτικη

• Arctic Council Signs Oil Spill Response Deal

• Russland will weiter nach Arktis-Öl bohren...

• Αρκτική: Θέατρο επιχειρήσεων ετοιμάζουν οι ισχυροί...

• Η επιστημονική μάχη πίσω από την γεωπολιτική στην Αρκτική.

Could volcanoes be causing Antarctic ice loss?

AFP - Accelerating ice loss from the Antarctic ice sheet could be due in part to active volcanoes under the frozen continent's eastern part, a study said on Sunday.
From 2002 to 2011, the average annual rate of Antarctic icesheet loss increased from about 30 billion tonnes to about 147 billion tonnes, the UN's panel of climate scientists reported in September.
The icesheet is a mass of glacial land ice -- one such sheet covers most of Greenland and the other Antarctica, and together they contain most of the freshwater on Earth.
The sheets are constantly moving, slowly flowing downhill and seawards under their own weight. Portions that extend out over the water are called ice shelf.

Previous research has blamed warmer seas swirling in a circular fashion around Antarctica for the quicker pace of icesheet loss from the southernmost continent.
These waters erode ice shelves, went the theory. And as more of the shelves disappeared, the quicker the sheet would flow and lose ice to the sea.
But in a new paper in the journal Nature Geoscience geologists led by Amanda Lough at Washington University in St. Louis, Missouri, suggested that, in West Antarctica, the faster flow may be also be due to volcanoes.
These heat the underside of the ice, causing melting that lubricates the flow, they suggested.
Evidence for this comes from recently deployed sensors that recorded two "swarms" of seismic activity under Mary Byrd Land, a highland region of West Antarctica, in 2010 and 2011.
Using ice-penetrating radar, the team found an intriguing elliptically-shaped deposit, measuring about 1,000 square kilometres (386 square miles) in the area, at a depth of 1,400 metres (4,550 feet).

• The deposit is believed to be volcanic ash, spewed out by an enormous eruption some 8,000 years ago -- an estimate reached on the assumption it has since been covered by ice accumulating at the rate of 12.5 centimetres (five inches) a year.

"Together, these observations provide strong evidence for ongoing magmatic activity and demonstrate that volcanism continues to migrate southwards."
Several volcanoes were known to exist in West Antarctica, but none were thought to be active.
"Eruptions at this site are unlikely to penetrate the 1.2 to two-km (0.75-1.2-mile) -thick overlying ice, but would generate large volumes of melt water that could significantly affect ice stream flow," said the study.
france24.com
17/11/13

Polar ice melt 'accelerating'

 

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Glaciers and icebergs are believed to be melting at the fastest rate recorded in decades.
A group of scientists has discovered that polar ice is melting three times faster than it was twenty years ago.

More than 20 polar research teams that have been studying ice in Greenland and Antarctica say the melting is already causing sea levels to rise.
Al Jazeera's Emma Hayward reports.

Source:

Al Jazeera

30/11/12
 ΣΧΕΤΙΚΑ:

• The Battle for the Arctic /Η αντιπαράθεση με το λιώσιμο των πάγων στην Αρκτικη

• Πολιτική αντιπαράθεση για το λιώσιμο των πάγων στην Αρκτικη

• Αρκτική χωρίς πάγους βλέπουν οι επιστήμονες την επόμενη δεκαετία

• Γεωτρήσεις βόρεια της Αλάσκα. Η Shell ανεβάζει τον πυρετό του μαύρου χρυσού στην Αρκτική

• AΡΚΤΙΚΗ: ΑΝΗΣΥΧΙΑ ΓΙΑ ΤΟ ΠΕΡΙΒΑΛΛΟΝ ΚΑΙ ΤΙΣ ΠΛΟΥΤΟΠΑΡΑΓΩΓΙΚΕΣ ΠΗΓΕΣ

• Το αρκτικό στρατηγικό άνοιγμα για τη ΝΑ Μεσόγειο.

  • EXXON MOBIL: Υπερβολικοί οι φόβοι για την κλιματική αλλαγή

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Enhanced melting of Northern Greenland in a warm climate

Simulated ice thickness for the Greenland ice sheet for the last interglacial period (~126 thousand years before present). This was the most recent period with relatively warm temperatures at high northern latitudes, not unlike what is expected for the 21st century from projections of global warming. Circles show locations with ice core data.
 (Credit: Image courtesy of University of Bergen)
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ScienceDaily (Nov. 9, 2012) — In a new study from the Bjerknes Centre for Climate Research, scientists show how the northern part of the Greenland ice sheet might be very vulnerable to a warming climate
The study is based on simulations with a state of the art global climate model and a dynamic ice sheet model of the last interglacial warm period. This period (~126 thousand years before present) is the most recent in Earth's history with temperatures warmer than present in the Arctic region, and has frequently been used as an analogue for a future greenhouse climate. During this period we know that the Greenland ice sheet was significantly reduced in size compared to today.

The model simulations show an extreme retreat of the northern part of the Greenland ice cap in response to the warm interglacial climate, a climate not unlike what we expect on Greenland in the very near future. This result is surprising, as temperatures on the north part of Greenland are colder than in the south. However, increased precipitation compensates for much of the increased melting of the southern part of the ice sheet in a warmer climate.
Today, most scientists expect that the southern part of the Greenland ice sheet is most vulnerable to a changing climate. In particular, there are several studies monitoring ice streams and fjord temperatures along the coast of southern Greenland. However, the new results indicate that the northern part of Greenland, at the fringe of the Arctic Ocean, should be particularly closely. In this area part of the ice sheet is grounded below sea level, and can respond rapidly once it starts receding.
If the Greenland ice sheet were to melt completely, it would result in an increase in mean global sea level by about 7 meters. However, the sea level impact of the observed recent accelerated melt of the ice sheet, as well as future projections of melt from the ice sheet, are not implemented by the current generation of climate models included in the IPCC effort.


Enhanced melting of Northern Greenland in a warm climate
9/11/12

Northernmost Lake Resurrected Due to Warming

Kate Andries

National Geographic News

Published October 17, 2012

The world's northernmost lake, situated near the coast of Greenland (map), is coming back to life.
Populations of microscopic algae, called diatoms, have been absent from the lake Kaffeklubben Sø for over 2,000 years. But a new study has found that the diatoms are returning, thanks to global warming...........Northernmost Lake Resurrected Due to Warming