Thursday, April 25, 2024

Melting Arctic Sea Ice

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Melting Arctic Sea Ice

In 2011 the Canadian Ice Service (CIS) observed the second lowest Canadian Arctic summer sea ice level on record. Climate change is melting sea ice at an alarming rate.

In 2011 the Canadian Ice Service (CIS) observed the second lowest Canadian Arctic summer sea ice level on record since satellite mapping began in late 1978. The impact of melting Arctic ice, a result of climate change, has far-reaching consequences for this fragile ecosystem and its inhabitants.
The Arctic is seen by many climatologists as the fastest changing place on the planet. In September 2011, sea ice in the Canadian Arctic reached its lowest point of the year at 4.33 million km2. The sea ice rapidly froze in October to 7.10 million km2, 330,000 km2 higher than 2007, the year of the lowest recorded sea ice average.
Reaching new lows
This past September sea ice coverage in the northern shipping route also set a new record low. In October 2011, while ice began to grow in the area, ice coverage remained lower than normal, according to Henry Lau, spokesperson for Environment Canada.
The United States’ National Snow and Ice Data Center (NSIDC) released similar results. Since 1979 September’s Arctic sea ice extent has declined by 12 percent per decade. The Arctic ice cap grows every winter as the sun sets for several months, and it shrinks each summer as the sun rises higher in the northern sky. The Arctic sea ice reaches its lowest levels annually in September.
While in 2011 the sea ice extent did not break NSIDC’s 2007 record low, the sea ice area as measured by the microwave radiometer on NASA\’s Aqua satellite did drop slightly lower than 2007 levels for about 10 days in early September.
These numbers are no surprise to climatologists, who have used satellite imagery to watch the sea ice decrease for over 30 years. Most agree that this is the direct result of global climate change, which is being driven by an increase in greenhouse gas accumulation in the atmosphere, leading to a subsequent warming of underwater ocean currents.
Climate models have suggested that the Arctic could lose almost all of its summer ice cover by 2100. But in recent years ice extent has declined faster than the models predicted, according to the NSIDC.
Why is the ice melting?
The Arctic has traditionally been a dry, cold environment with a lot of sea ice. As the Arctic warms, the resulting open ocean helps to create local evaporation and a warmer atmosphere that can hold more moisture. This creates a water vapour feedback. As the Arctic climate drastically changes from cold and dry to increased clouds and water vapour, Arctic air is warming at a much faster rate than anywhere else on the planet.
The “albedo feedback” is one of the main culprits, according to Shawn Marshall, a glaciologist and climatologist from the University of Calgary. Albedo refers to the reflective power of a surface. Simply put, ice and snow are far more reflective than water.
In the Arctic reflective snow and ice are being replaced with open water, which is totally dark and absorbs sunlight. For every bit of snow and ice that is replaced with open ocean, less heat is reflected back into space, which increases the amount of solar energy absorbed, leading to more warming.
“This is something you don’t see in the tropics,” says Marshall, who has studied ice dynamics and their sensitivity to climate change in field projects, including Ellesmere Island in the Canadian high Arctic. “If you’re off Vancouver Island, things are warming up, but you’re not changing from ice to open ocean, so you don’t get that big feedback.”
On thin ice
Arctic sea ice has also been gradually decreasing in thickness. The process of melting the ice cover has begun earlier than normal, while the ice begins to refreeze later in the fall. This essentially extends the summer melt season while decreasing the winter freeze season, which causes the ocean to absorb more solar radiation from the sun, explains John Yackel, sea ice geophysicist and climatologist from the University of Calgary.
“If we start growing ice later than we used to, we can only grow it so thick because we only have so many winter days,” says Yackel. “Therefore, we’re seeing a reduction in the ice.”
In the Victorian era, the Northwest Passage was nothing more than a myth: an intangible, tactical route through the unpredictable ice sheets of the Arctic. Through these channels, boats often became victims of an encounter with multi-year ice—ice that survives at least one summer melt season and is often more than 3 m (10 ft) thick.
Shipping hazards
This past year shipping routes in the Canadian Arctic archipelago were not completely ice-free. The presence of multi-year ice, which is harder than steel, has posed and will continue to pose a danger to shipping in this region, according to CIS.
While the Northwest Passage is becoming increasingly ice-free in general, more dangerous multi-year ice from the Canadian high Arctic islands, such as the Queen Elizabeth Islands and the Arctic Basin proper, is flowing southward into some of the shipping channels. Even though seasonal ice is melting sooner, it has not meant less ice in terms of navigation. This is what Yackel calls a “drain trap.”
“When there are warm years in the Arctic and the first-year ice does melt out, some of that old, really thick ice that has been building up and growing for many years has a chance now to lump south into the Canadian archipelago channels—and that’s why the shipping is quite hazardous,” Yackel says.
Eventually, a complete reduction of the ice cover out of the Canadian archipelago may occur. But for the foreseeable future, Yackel expects large incursions of the large, multi-year ice to create hazards in the passageways for boats.
Long-term prognosis
Over time, however, the ice cover will continue to retreat and thin, which will potentially lead to a summer ?when there may not be any ice in the Canadian archipelago region. Yackel estimates this could happen in the next 30 to 40 years.
The Inuit
The change in ice is being watched closely by the Inuit people as it has the potential to impact their traditional hunting and fishing grounds, their homes, and their survival. Yackel, who has taught in Inuit schools during his expeditions, worries that the ice might be changing faster than the Inuit are prepared for.
“School kids still go out with fathers and grandfathers to hunt on the ice,” Yackel explains. “[The] are occurring within a generation cycle,” he says. “They have memory now of how ice used to be and how it’s changed. It’s a pretty scary prospect from their perspective.”
The result of decreased sea ice will trickle through the entire food chain, from plankton and algae to seals, walruses, whales, and polar bears. Every species will be affected. Some will thrive; others will perish.
Yackel suggests that polar bears will suffer significantly because they rely on seals who need an ice cover to birth their pups. Seals may adapt, but it’s the ability of the polar bears to adjust to the seals’ adaptations that has many Arctic ecologists and biologists concerned.
Potential positive effects
“There will be more light energy available, which means that some of the primary productivity—such as algae and some of the parts of the food chain at the bottom—will likely prosper in areas where they have never prospered before,” Yackel says. “This will mean new niches and new ecosystems.”
With a decrease in Arctic sea ice reaching historical highs, eventually the Northwest Passage—a series of waterways amidst the Canadian Arctic archipelago—is expected to become increasingly navigable by ships. This will create an opportunity for the area to become a frontier point for science and also for development.
These circumstances create new opportunities for making commercial use of the Arctic in areas such as fishing, maritime shipping, and the exploitation of natural resources, particularly oil and gas. Many climatologists urge that scientific research needs to be completed first to protect this fragile ecosystem.
Can the negative effects be reversed?
The effects of global climate change in the Arctic can, potentially, be reversed through natural causes and human influences. Some scientists have suggested that sulphate be injected into the atmosphere to reflect sunlight back into space. Both the albedo and cloud effects could work in reverse, providing the ice with the ability to recover.
However, these solutions are not expected this century, Marshall says, as most climatologists simply expect additional warming.

Persistent organic pollutants
Their name says it all. Persistent organic pollutants (POPs) are manmade organic compounds that do not break down in the environment. Industrial chemicals such as pesticides are examples of POPs.
Travelling through the atmosphere, POPs have found their way to Canada’s Arctic where they accumulate in humans and wildlife. Government restrictions on the production and use of POPs have decreased their presence in the air.
But as Arctic ice melts at an unprecedented rate, over the past 20 years POPs have been released from melting ice and water back into the atmosphere. Researchers believe that climate change and the warming of the Arctic could undo the efforts to reduce exposure to these toxic chemicals.
Canada’s threatened polar bears
More than 70 percent of the world’s polar bears live in the Canadian Arctic.
In November 2011 the Canadian Federal Government classified polar bears as “a species of special concern” under the Species at Risk Act (SARA). This means officials must create a detailed management plan within three years. However, critics say this classification is inadequate. Polar bears are listed at one step above “not at risk” when they actually fit the “threatened” criteria.
Their biggest threat is melting Arctic ice. The polar bear populations in areas such as Western Hudson Bay and Davis Strait are at great risk.
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