The Northwest Passage: a Shortcut to Greater Arctic Warming

The thermometer will hit upper nineties again today in Washington, DC., but it’s been a pretty mild summer until now – in fact, July was slightly cooler than average. That wasn’t the case up north, way up north, in Tuktoyaktuk, Northwest Territories, Canada. In this seaside town 1,500 miles north of Seattle and well within the Arctic Circle, the thermometer hit 86 degrees Fahrenheit late last month making the Arctic Sea warm enough to swim in.

Over the last 100 years, the Arctic has warmed at twice the rate of the rest of the globe. The extent of summer sea ice has decreased by 40% since measurements began in 1979 and reached a record low in 2007. This summer’s melting is on par with 2007 and it’s not over yet. At the current rate, scientists predict that the Arctic will be completely free of summer sea ice by 2040.

Credit: Associated Press

Credit: Associated Press

Some marvel at the opening of the fabled “Northwest Passage,” the shortcut to the East long-sought by European navigators. But loss of sea ice doesn’t only affect the Arctic region; it leads to greater warming of the globe as a whole. White sea ice reflects more sunlight than darker seawater. As the ice melts, more seawater is exposed, which absorbs more radiation. This, in turn causes more warming and more melting in what is known as a positive feedback loop.

Clean white ice reflects the sun, while the darker water absorbs it.

Clean white ice reflects the sun, while the darker water absorbs it.

Although it is proceeding at a faster rate, Arctic warming is a manifestation global warming and can only be addressed in the long-term by significant reductions in atmospheric CO2. However, because CO2 is a long-lived gas – remaining in the atmosphere for centuries after it is emitted – even dramatic reductions in emissions won’t take effect fast enough to save the Arctic.

Thankfully, there are actions we can take to give us some breathing room until the impacts of CO2 reductions can be felt. Several short-lived pollutants (SLPs) appear to be responsible for as much Arctic warming as CO2 but remain in the atmosphere for much less time. The longest-lived is methane, which sticks around for about a decade; the shortest, black carbon (BC), which remains aloft for about a week. Because they are short-lived, reductions in these pollutants will be felt much sooner than reductions in CO2.

BC is a by-product of incomplete combustion.  As in the Himalayas (see previous post), BC warms the Arctic in two ways. First, it absorbs heat in the atmosphere. Second, when it settles on snow or ice, it darkens it, absorbing more sunlight than the clean, white snow would. Because BC is so short-lived in the atmosphere, it can’t travel very far from its origins. The BC that settles in the Arctic comes from neighboring Europe and North America. In these regions, the largest sources of are inefficient diesel engines and agricultural burning. Increased shipping traffic, fueled by diesel engines through a newly-opened Arctic Sea, will deliver BC directly to the Arctic atmosphere and ice.

Recent studies have confirmed the impact of BC on Arctic warming and several Northern nations have taken notice. In April 2009, the Arctic Council, comprised of the eight nations that ring the North Pole, noted the role that SLPs play in Arctic climate change and established a task force to recommend immediate actions that can be taken to reduce emissions. Last month, the G8 leaders committed to take “rapid action to reduce other significant climate forcing agents, such as black carbon.” Taken sooner rather than later, such actions may well bring cool summer days back to the North Pole.

The Clean Air Task Force and Clean Air-Cool Planet are two of the organizations that are working with the Arctic Council Nations  to identify rapid actions that can be taken to reduce SLP emissions to the Arctic. Visit their websites (listed under “Organizations” at right) to learn more.

Leave a Reply