The expedition was intense and felt more like going to the Moon than going on a typical research cruise. What took us by surprise were the many winter storms that battered the ice (and our ship and ice camp).
It has taken us years to collate these data but now we know the winter storms play a key role in the fate of Arctic sea ice, particularly in the Atlantic sector of the Arctic.
How winter storms amplify climate change
On average, about 10 extreme storms will reach all the way to the North Pole each winter. While these winter storms are short (they last on average 6-48 hours), they can be incredibly intense.
During a storm in winter 2015 we saw the air temperature rise from -40℃ (-40℉) to 0℃ (32℉) in just a day, and then fall back to -30℃ (-22℉) the next day, when cold Arctic air returned after the storm.
These storms bring heat, moisture and strong winds into the Arctic, and next we look at how they impact sea ice and its surroundings.
Warming and weakening the ice
The heat from the storms warms up the air, snow and ice, slowing down the growth of the ice. Moisture from the storms falls as snow on the ice. After the storm, the blanket of snow insulates the ice from the cold air, further slowing the growth of the ice for the remainder of winter.
The strong winds during the storms push the ice around and break it into pieces, making it more fragile and deforming it, more like a boulder field.
The strong winds also stir the ocean below the ice, mixing up warmer water from deeper waters to the surface where it melts the ice from below. This melting of the ice in the middle of winter can happen for several days after the storms when the air is already back to well below freezing.
Thinner ice, shelter for life and accelerated melting
The breakup of the ice opens big passages of open water between ice floes, called leads. In winter these passages end up refreezing rapidly, generating new super-thin ice.
These thinner refrozen patches of ice let more light through in the following spring, allowing ocean plants (phytoplankton) to bloom earlier.
The rougher sea ice landscape becomes a shelter for many ice-associated Arctic organisms, including ice algae, becoming biological hot spots in the following spring.
The broken up and deformed ice drifts faster, reaching warmer waters where it melts sooner and faster.
So really, winter storms precondition the ice to a faster melt in the following spring with an impact that continues well into the following season.
Why is Arctic sea ice declining?
The Arctic is particularly sensitive to human driven climate change. We know the decrease in sea ice is due to both the warming of the Arctic (air and ocean) and changing wind patterns that break up the ice cover.
But there are also amplifying mechanisms or “feedback” mechanisms, in which one natural process reinforces another. Their role in the decrease of sea ice is hard to predict. We now know winter storms in the Arctic contribute to these feedback mechanisms.
More storms ahead
Arctic winter storms are increasing in frequency and this is likely due to climate change.
With the thinner Arctic sea ice cover and shallower warmer water in the Arctic Ocean, the mechanisms we observed during the winter storms will likely strengthen and the overall impact of winter storms on Arctic ice is likely to increase in the future.
Two weeks ago, the Arctic sea ice reached its minimum extent for 2019, after another winter of intense winter storms. The minimum ice extent was effectively tied for second lowest since modern record-keeping began in the late 1970s, along with 2007 and 2016, reinforcing the long-term downward trend in Arctic ice extent. Arctic sea ice has been declining for at least 40 years, and amplifying mechanisms such as the winter storms are accelerating this retreat.
As highlighted in the recent IPCC Ocean and Cryopshere report, these changes in September sea ice are likely unprecedented for at least 1,000 years.
October 2nd, 2019
The total amount of Arctic sea ice in 2019 is tied for the second-lowest on record, according to new research from NASA.
According to data analysis conducted by NASA and the National Snow and Ice Data Centre (NSIDC), Arctic sea ice levels at the end of this summer drew level with 2007 and 2016 as the second-lowest levels since modern recording began in the late 1970s.
The Arctic ice cap grows and thickens during the autumn and winter months, and thins and shrinks in the following spring and summer.
Over the past few decades, as temperatures increase due to climate change, the Arctic ice cap has decreased in size year-round with rapid reductions in the minimum end-of-summer ice extent.
“This year’s minimum sea ice extent shows that there is no sign that the sea ice cover is rebounding,” NASA climate change senior scientist Claire Parkinson said. The long-term trend for the Arctic sea ice cap has been “definitively downward”, she added.
Walt Meier, a sea ice researcher at NSIDC, said that the beginning of August saw “record low ice levels for that time of the year, so a new minimum record low could have been in the offering”.
He added that the European heatwave “definitely affected land ice loss in Greenland” that saw its largest loss of volume in 60 years in just one day this summer.
Global sea-level rise
The NASA findings come the same month as a new landmark UN report found that global sea level is rising twice as fast as it did during the 20th century.
The new special report from the Intergovernmental Panel on Climate Change (IPCC) also found that the rise in sea levels is expected to continue for centuries to come.
Even if emissions are sharply reduced and global warming is limited to below the 2C target outlined in the Paris Agreement, the report notes that sea levels could rise by up to 60 cm by 2100.
If greenhouse gas emissions continue to increase significantly, sea-level rise could be anywhere between 60 to 110 cm, the UN body warned.
The warming atmosphere is causing glaciers and ice sheets to melt, as well as the acidification of ocean waters as seas have absorbed between 20 to 30 per cent of carbon emissions since the 1980s.
Telescope wins funding reprieve The US National Science Foundation (NSF) will continue to fund operations at the Green Bank Observatory in West Virginia, which is home to the world’s largest fully steerable radio telescope. In a decision announced during a 23 September briefing, the agency said that it would give the facility US$37 million over the next five years. The move comes seven years after an NSF committee recommended that the agency divest from the observatory to free up money for newer telescopes. But subsequent studies showed that Green Bank remains a cutting-edge astronomical facility and is worth the investment, NSF officials said at the briefing. The observatory currently receives $8.4 million per year from the NSF; under the new agreement, the amount will drop slightly but will never be below $7 million annually.
Arctic thaw Arctic sea ice reached its second-lowest extent ever observed on 18 September, the US National Snow and Ice Data Center in Boulder, Colorado, said on 23 September. The minimum ice extent for the summer of 2019 was 4.15 million square kilometres, tying it with 2007 and 2016 for the second-lowest minimum seen since satellite observations began in 1979. Heavy ice loss this spring in areas including the Bering Sea set the stage for extremely low ice levels in July and early August. The rate of loss slowed in mid-August, moving 2019 away from record territory and into the number-two slot. The worst year on record was 2012, when just 3.41 million square kilometres of Arctic sea ice lingered at the end of the melting season. All 13 of the lowest Arctic sea-ice extents have been recorded in the past 13 years.
Climate pledges Dozens of governments and organizations pledged to do more to combat global warming at the United Nations climate summit in New York City on 23 September. During the meeting, 77 countries and more than 100 cities committed to achieving net‑zero carbon emissions by mid-century. And a coalition of development banks said that it would mobilize US$1 trillion for clean energy in 20 of the poorest countries by 2025. Environmentalists said that the commitments weren’t enough to limit average global temperature increases to 1.5–2 °C above pre-industrial levels. In light of perceived inaction by the world’s nations, 16 youth activists, including Swedish campaigner Greta Thunberg, filed a legal complaint on 23 September with the UN Committee on the Rights of the Child. They allege that Argentina, Brazil, France, Germany and Turkey have violated their human rights by not taking adequate action to stop climate change. Separately, Russia, one of the world’s largest emitters of greenhouse gases, announced on 23 September that it would formally accept the Paris climate agreement, becoming the 187th party to do so.
Climate cash A billionaire California couple has given the California Institute of Technology (Caltech) in Pasadena US$750 million for research on climate change and sustainability. The donation, one of the biggest ever to a US university, comes from Stewart and Lynda Resnick, who built their fortune in wine, juice, drinking water, fruit and nuts in drought-stressed California. The gift will support research in fields such as climate science, energy, biofuels and decomposable plastics. The Resnicks’ best-known brands include FIJI water and POM pomegranate juices, which are packaged in plastic. Caltech said the funds will be used to construct a sustainability resource centre where scientists from various fields will work together to solve environmental problems. Its four topics of focus will be solar energy and electricity, climate change, water resources and engineering the biosphere.
EU petition Thousands of European scientists are protesting against the omission of ‘research’ from the job title of the European Union’s new science-policy chief. Last month, Bulgarian political scientist Mariya Gabriel was nominated to lead the European Commission’s Directorate General for Innovation and Youth, previously called Research and Innovation. More than 9,000 researchers, including 18 Nobel laureates, have signed an open letter calling on the European Parliament and the European Commission to add ‘research’ and ‘education’ to the title. Gabriel will succeed Carlos Moedas, the outgoing commissioner for research, science and innovation. She will be in charge of EU research policies, including Horizon Europe, the bloc’s next major research programme. Scientists fear that the “innovation and youth” title might signify an increased emphasis on research with direct economic benefits, at the expense of pure science.