Rapid Arctic Warming Increases Sea Level Rise Projections
Three things you should know:
1. Since the 1980s, temperatures have increased twice as much in the Arctic as they have in the rest of the world. The past six years (2005 – 2010) have been the warmest period ever recorded in the Arctic.
2. The warm climate is causing changes in Arctic ice, snow and permafrost cover in ways that are causing warming to accelerate.
Climate change is having a larger impact on snow and ice in the Arctic than previously thought, according to a new study from the Arctic Monitoring and Assessment Program. Credit: Patrick Kelley/U.S. Coast Guard.
3. Arctic snow, ice and permafrost melting is occurring faster now than scientists thought even just a couple of years ago, and this rapid melting will have consequences for regional climate and sea level rise in the United States.
What the new science says:
Scientists have known for decades that global climate change has been having an outsized impact on the Arctic, but according to a new assessment from the Arctic Monitoring and Assessment Program — part of the Arctic Council — changes in the planet’s vast northern region have been more dramatic than expected.
The new Snow, Water, Ice and Permafrost in the Arctic (SWIPA) study offers the most up-to-date review of how quickly some of the Arctic’s hallmark features are changing. The study found that the past six-year period, between 2005-2010, has been warmer than any other recorded time in the Arctic, where records extend back to the 1880s. The study found that Arctic warming is accelerating, in large part because of feedbacks caused by the melting of ice and snow cover.
According to one of the study’s key findings:
There is evidence that two components of the Arctic cryosphere (the part of the earth that is frozen for some or all of the year) — snow and sea ice — are interacting with the climate system to accelerate warming.
As average Arctic temperatures warm, more sea ice has been melting during the summer than in previous decades. With more melting, the Arctic Ocean absorbs more of the sun’s rays and gets warmer, which delays ice from growing back again until later in the fall. But with less sea ice present in the autumn to reflect sunlight back to space, the entire region warms up even more, exacerbating and perpetuating the cycle.
This “feedback loop,” where an initial warming causes changes that promote additional warming, is something researchers anticipated would happen in the Arctic, but it has finally been confirmed by the SWIPA study.
The rate at which sea ice is now melting, measured in this new Arctic assessment, is also faster than what previous studies have reported. In particular, the 2007 Fourth Assessment report from the U.N. Intergovernmental Panel on Climate Change (IPCC) underestimated how quickly sea ice would disappear.
Another rapid change occurring in the Arctic has been melting of snow and ice on land masses, and from glaciers, particular the Greenland Ice Sheet. The SWIPA study calculated that melting from Arctic glaciers, ice caps and the Greenland Ice Sheet contributed over 40 percent of the global sea level rise during each year between 2003 and 2008. This newly-measured Arctic input to sea level rise is also higher than what scientists had previously identified.
What makes this important?
For many years the Arctic has been a poster child for global climate change. That’s because one of the planet’s most visible warming-related changes is taking place in the Far North — the amount of sea ice covering the Arctic Ocean has been declining for at least 30 years, for example.
The rapid melting in the Arctic is not just a symbol of climate change, however. It introduces several new issues that never would have arisen if the Arctic stayed largely frozen. For example, as more sea ice is lost, trans-Arctic voyages are now possible, leading to disagreements on who can lay claim to the Arctic waters. And as snow, ice and permafrost melt in the Arctic, exploration for vast stores of oil, gas and valuable minerals is becoming more economical — yet researchers don't know how the Arctic ecosystem might respond to industrial development.
These potential problems are topics for discussion at a high-level meeting of the Arctic Council, starting today in Greenland. The Council is an intergovernmental panel that works to foster cooperation between Arctic countries, but it does not have the authority to force states to take particular actions. The member countries of the Arctic Council — the U.S., Canada, Russia, Iceland, Norway, Denmark, Finland, and Sweden — have all sent delegates to discuss the Arctic's future, and observers from other nations are attending as well. The U.S. is being represented by Secretary of State Hillary Clinton and Interior Secretary Ken Salazar, and this is the first time that such high-ranking American officials have participated in an Arctic Council meeting.
Even though the changes taking place in the Arctic seem far away, scientists warn that the impacts will also be felt farther south. One reason is because melting glaciers contribute to sea level rise around the world.
In September 2010, the extent of sea ice coverage in the Arctic reached its lowest point of the year. At that time, the ice extent was more than 2 million square miles less than the average minimum coverage between 1979 and 2000. Credit: NSIDC.
In 2007, when the IPCC released its fourth assessment of global climate change, it estimated that sea level rise would reach between 6.5 inches and two feet by 2100 — but that estimate was based on a rate of ice melting that is much lower than what the latest research now shows, particularly from the Greenland Ice Sheet. The new SWIPA study suggests that global sea level rise could more realistically be between three and five feet by 2100. That range of sea level rise may not affect all areas of the U.S. coast, but a lot of property will be placed at risk of severe flooding.
Moreover, several climate patterns originate in the Arctic and influence weather around the world. As northern temperatures climb, these patterns can change and this may affect weather around the world. For example, scientists have hypothesized that over the past few years, the warming waters of the Arctic Ocean have altered weather patterns during the winter, sending cool air farther south than usual into North America.