The Great London:
Arctic

Beneath the Aurora Borealis an oil tanker glides through the night past the Coast Guard ice breaker Amundsen and vanishes into the maze of shoals and straits of the Northwest Passage, navigating waters that for millennia were frozen over this time of year.

Warming has forced a retreat of the polar ice cap, opening up a sea route through the Canadian Arctic Archipelago and connecting the Atlantic and Pacific Oceans for several months of the year.

Commander Alain Lacerte is at the helm as the vessel navigates the Queen Maud Gulf, poring over charts that date from the 1950s and making course corrections with the help of GPS.

"Where it's white (on the chart), it means the area hasn't been surveyed," he explains -- leaning over a map that is mostly white. "Most of the far north hasn't been surveyed, so our maps are unreliable."

The crew constantly take radar and multi-beam sonar measurements and check their position.

"We don't want any shoals named after us," says the old sea dog from behind his spectacles.

Almost the size of the European Union, the Canadian Arctic seabed remains largely uncharted. The waters are also shallow and navigating unknown parts can be deadly -- even when the north is ice-free.

Today, taking this route cuts 7,000 kilometers (4,350 miles) off a trip from London to Tokyo, saving time and fuel.

'Never imagined this'

Since the 15th century there have been a dozen expeditions seeking a faster shipping route from Europe to Asia through the north.

The Norwegian explorer Roald Amundsen was the first to cross the Northwest Passage, on board the Gjoa, in an expedition that took three years, finishing in 1906.

Afterward interest in the waterway waned. An average of one ship per year attempted to make the crossing over the past century.

But thawing of the polar ice promises Arctic nations new opportunities to open ocean trade routes and offshore oil fields.

In the summer months the Amundsen is used by Canadian government scientists -- among them Roger Provost, a Canadian Ice Service meteorologist -- as well as a network of scientists led by the ArcticNet organization.

Provost looked with amazement from the wheelhouse at the lack of any ice cover around the coast guard ship.

"Anyone who still denies climate change is real has their head in the ground, they're blind," he said.

In 37 years of Arctic exploration, he said he "never imagined ever seeing this," pointing to satellite images showing a clear path through the Queen Maud Gulf and the M'Clintock Channel, where the Amundsen is headed.

Almost 112 years ago to the day, the explorer Amundsen got stuck in the pack ice here. And in 1979, Provost recalls, another Canadian Coast Guard ice-breaker had to cut short its inaugural journey, unable to push beyond this point through thick ice.

Over the past five years the number of cargo and cruise ships, tankers and others crossing the Passage climbed to 117.

In 2010, Canada imposed shipping regulations on seafarers going through the Passage, but the United States and the European Union do not recognize Canada's ownership of the waterway, considering it international waters.

'Completely disappear'

The ice cover has steadily retreated over the past decade, with this year set to be the hottest on record, according to the US National Oceanic and Atmospheric Administration.

The previous year saw average global temperatures rise one degree Celsius -- but by three degrees in the Arctic.

What most worries Provost is the loss of "multi-year ice," formed over centuries. "In a few years it will completely disappear," he forecast.

"It's a tragedy for all humanity what is happening."

Glaciologist Lauren Candlish said: "We're now in the transition phase, from having multi-year ice through the entire summer, to a seasonally ice free Arctic."

Poring over data on her computer in a nook of the ship the University of Manitoba researcher says: "It's a different Arctic now. Less predictable, with more fluctuations."

The last such melting occurred "before the last ice age," from AD 100,000 to AD 10,000, she noted.

Most aboard the ship doubt we are headed for an Arctic shipping boom predicted by many, as the weather remains unpredictable and harsh. But there is sure to be an increase, which raises concerns for the environment.

"When it was covered in ice, this ecosystem was not threatened," says Provost. The Arctic is a unique and diverse ecosystem that is home to whales, seals, polar bears, walruses and several bird species.

"A massive oil spill like the one in the Gulf of Mexico in 2010 must never happen in the Arctic," he said. "The consequences would be much more serious."

Author: Clement Sabourin | Source: AFP [October 20, 2015]

Arctic sea ice has reached its lowest winter point since satellite observations began in the late 1970s, raising concerns about faster ice melt and rising seas due to global warming, US officials said Thursday.

The maximum extent of sea ice observed was 5.6 million square miles (14.5 million square kilometers) on February 25, earlier than scientists had expected, said the report by the National Snow and Ice Data Center.

"It is also the lowest in the satellite record," the NSIDC said.

Below-average ice conditions were observed everywhere except in the Labrador Sea and Davis Strait.

The sea ice was about 425,000 square miles below the average from 1981 to 2010, a loss equal to more than twice the size of Sweden.

It was also 50,200 square miles below the previous lowest maximum that occurred in 2011.

Environmentalists said the report offered more evidence of worsening global warming, and urged action to curb the burning of fossil fuels that send greenhouse gases into the atmosphere.

"This is further evidence that global warming and its impacts have not stopped despite the inaccurate and misleading claims of climate change 'skeptics,'" said Bob Ward of the Grantham Research Institute on Climate Change and the Environment at the London School of Economics and Political Science.

"The gradual disappearance of ice is having profound consequences for people, animals and plants in the polar regions, as well as around the world, through sea level rise."

The World Wildlife Fund said the loss of sea ice means trouble for a vast web of life that depends on it, from polar bears to marine creatures.

"Today's chilling news from the Arctic should be a wakeup call for all of us," said Samantha Smith, leader of the WWF Global Climate and Energy Initiative.

"Climate change won't stop at the Arctic Circle. Unless we make dramatic cuts in polluting gases, we will end up with a climate that is unrecognizable, unpredictable and damaging for natural systems and people."

The NSIDC said much of the ice loss could be attributed to an unusually warm February in parts of Russia and Alaska, and that it was still possible that a late-season surge of ice growth could occur.

A detailed analysis of the winter sea ice from 2014 to 2015 is due to be released in early April.

Source: AFP [March 19, 2015]

For each ton of carbon dioxide (CO2) that any person on our planet emits, 3 m² of Arctic summer sea ice disappear. This is the finding of a new study that has been published in the journal Science this week by Dr. Dirk Notz, leader of Max Planck research group "Sea Ice in the Earth System" at the Max Planck Institute for Metorology (MPI-M) and by Prof. Julienne Stroeve from the National Snow and Ice Data Centre in Boulder, Colorado, and the University College London, UK. These numbers allow one for the first time to grasp the individual contribution to global climate change. The study also explains why climate models usually simulate a lower sensitivity - and concludes that the 2 °C global warming target will not allow Arctic summer sea ice to survive.

The rapid retreat of Arctic sea ice is one of the most direct indicators of the ongoing climate change on our planet. Over the past forty years, the ice cover in summer has shrunk by more than half, with climate model simulations predicting that the remaining half might be gone by mid century unless greenhouse gas emissions are reduced rapidly. However, a number of studies have indicated that climate models underestimate the loss of Arctic sea ice, which is why the models might not be the most suitable tools to quantify the future evolution of the ice cover.

To address this issue, a new study in the >journal Science now derives the future evolution of Arctic summer sea ice directly from the observational record. To do so, the authors examine the link between carbon-dioxide emissions and the area of Arctic summer sea ice, and find that both are linearly related. "The observed numbers are very simple", explains lead author Dirk Notz. "For each ton of carbon dioxide that a person emits anywhere on this planet, 3 m² of Arctic summer sea ice disappear." And his co-author Julienne Stroeve from adds: "So far, climate change has often felt like a rather abstract notion. Our results allow us to overcome this perception. For example, it is now straight-forward to calculate that the carbon dioxide emissions for each seat on a return flight from, say, London to San Francisco causes about 5 m² of Arctic sea ice to disappear."

The study also explains the linear relationship between carbon-dioxide emissions and sea-ice loss. "Put simply, for each ton of carbon dioxide emission, the climate warms a little bit. To compensate for this warming, the sea-ice edge moves northward to a region with less incoming solar radiation. This then causes the sea-ice area to shrink. Simple geometric reasons cause these processes to combine to the observed linearity", explains Notz.

Climate models also simulate the observed linear relationship between sea-ice area and CO2 emissions. However, they usually have a much lower sensitivity of the ice cover than has been observed. The Science study finds that this is most likely because the models underestimate the atmospheric warming in the Arctic that is induced by a given carbon-dioxide emission. "It seems that it's not primarily the sea-ice models that are responsible for the mismatch. The ice just melts too slow in the models because their Arctic warming is too weak", says Stroeve.

Regarding the future evolution of Arctic sea ice, the new study finds that the internationally agreed 2 °C global warming target is not sufficient to allow Arctic summer sea ice to survive. Given the observed sensitivity of the ice cover, the sea ice is gone throughout September once another 1000 gigatons of carbon dioxide have been emitted. This amount of emissions is usually taken as a rough estimate of the allowable emissions to reach the 2 °C global-warming target. Only for the much lower emissions that would allow one to keep global warming below 1.5 °C, as called for by the Paris agreement, Arctic summer sea ice has a realistic chance of long-term survival, the study concludes. 

Source: Max Planck Society [November 04, 2016]

The build-up and subsequent release of warm, stagnant water from the deep Arctic Ocean and Nordic Seas played a role in ending the last Ice Age within the Arctic region, according to new research led by a UCL scientist.

The study, published today in Science, examined how the circulation of the ocean north of Iceland -- the combined Arctic Ocean and Nordic Seas, called the Arctic Mediterranean -- changed since the end of the last Ice Age (~20,000-30,000 years ago).

Today, the ocean is cooled by the atmosphere during winter, producing large volumes of dense water that sink and flush through the deep Arctic Mediterranean. However, in contrast to the vigorous circulation of today, the research found that during the last Ice Age, the deep Arctic Mediterranean became like a giant stagnant pond, with deep waters not being replenished for up to 10,000 years.

This is thought to have been caused by the thick and extensive layer of sea ice and fresh water that covered much of the Arctic Mediterranean during the Ice Age, preventing the atmosphere from cooling and densifying the underlying ocean.

Dr David Thornalley (UCL Geography) said: "As well as being stagnant, these deep waters were also warm. Sitting around at the bottom of the ocean, they slowly accumulated geothermal heat from the seafloor, until a critical point was reached when the ocean became unstable.

"Suddenly, the heat previously stored in the deep Arctic Mediterranean was released to the upper ocean. The timing of this event coincides with the occurrence of evidence for a massive release of meltwater into the Nordic Seas. We hypothesize that this input of melt water was caused by the release of deep ocean heat, which melted icebergs, sea-ice and surrounding marine-terminating ice sheets."

This study highlights the important impact that changes in ocean circulation can have on climate, due to the ocean's capacity to redistribute vast quantities of heat around the globe. For example, scientists are currently concerned that ongoing changes in ocean circulation may result in warmer subsurface water that will cause enhanced melting and retreat of certain ice sheets in Greenland and Antarctica.

Dr Thornalley added: "To help predict the role of the ocean in future climate change, it is useful to investigate how ocean circulation changed in the past and what the associated climate effects were."

In this study, researchers from UCL, Woods Hole Oceanographic Institute and other partner institutions analysed the composition of calcite shells of small single-celled organisms (called foraminifera) that are found in ocean floor sediment. The shells of these organisms record the chemistry of the deep ocean at the time they were living, enabling the researchers to reconstruct past changes in ocean circulation.

By measuring the radiocarbon content of these shells, the research team was able to determine how rapidly deep water was being formed in the Arctic Mediterranean. A number of different techniques were then used to constrain past temperature changes, including measuring the ratio of magnesium and calcium, and the arrangement of isotopes of carbon and oxygen within the calcite shells of the foraminifera, both of which vary according to the temperature of the water in which the foraminifera grew.

A warmer, deep Arctic Mediterranean during glacial times has been suggested in previous studies, too. As summarised by co-author Dr Henning Bauch (GEOMAR/Germany) "It is good to see that new, independent proxy data would give strong support now to these former hypotheses."

Source: University College London [August 13, 2015]