Arctic melting faster than predicted: Sea levels to rise
Washington – Sea levels could rise up to 5 feet by the end of this century, driven by warming in the Arctic and the resulting melt of snow and ice, according to a new study by the International Arctic Monitoring and Assessment Program (AMAP). This is more than two and a half times higher than the 2007 projection of a half to two feet by the Intergovernmental Panel on Climate Change.
“The largest and most permanent bodies of ice in the Arctic – multi-year sea ice, mountain glaciers, ice caps and the Greenland Ice Sheet – have all been declining faster since 2000 than they did in the previous decade, ” according to the Arctic study. “The Arctic Ocean is projected to become nearly ice-free in summer within this century, likely within the next 30 to 40 years.”
The Arctic temperature increase and the decline of snow and ice feed upon themselves, in an accelerating feedback loop that is causing more rapid melting and sea level rise. The reflective Arctic ice and snow act as a protective shield, sending solar radiation into space. As the ice and snow disappears it is replaced by darker seawater or land, which absorbs more of the incoming radiation. This absorbed energy is released as heat during the summer months, further adding to Arctic warming, which in turn accelerates melting.
Among the feedbacks of greatest concern is the melting of Arctic permafrost (permanently frozen ground). Circumpolar permafrost regions contain the equivalent of about 6,000 billion tonnes of CO2. As more permafrost melts due to increasing Arctic temperatures, more of the gases that were previously trapped in the frozen ground are released.
According to the report, the temperature in the Arctic permafrost has increased by up to 2˚C over the past two to three decades. This warming has caused the southern boundary for melting permafrost to move steadily northward, by 19 to 50 miles in Russia and by more than 80 miles in Quebec.
The combination of these changes could lead to “run-away” feedbacks that could push past other critical tipping points in Earth’s climate system including the loss of Hindu-Kush-Himalaya-Tibetan glaciers, which provide the head-waters for most major river systems of Asia, (the source of freshwater for hundreds of millions of people), and the die-off of the Amazon forest.
In addition to the global impacts, the increasing temperatures in the Arctic are expected to create fundamental changes in Arctic ecosystems, possibly erasing entire habitats. This will contribute to species extinctions, and dramatically impact Arctic societies, creating challenges for local communities and traditional ways of life.
Emissions of black carbon soot – produced mostly from diesel engines and burning of biomass – also contribute to the Arctic problem by darkening snow and ice and reducing their ability to reflect the sun’s radiation. Recent studies indicate that black carbon may be responsible for 50% of Arctic warming, or nearly 1.0ºC of the 1.9ºC warming since 1890.
“Slowing the feedback mechanisms will not be easy or simple, but there’s no alternative.” said Durwood Zaelke, President of the Institute for Governance & Sustainable Development. “Without the Arctic, we’re facing an extremely grave and uncertain future.”
Combating this threat to the Arctic and the globe requires tackling the problem of climate change. This in turn requires cutting emissions of CO2, the principal greenhouse gas, protecting and expanding forests and other “sinks” to absorb CO2, and developing other strategies to draw down current excess CO2 from the atmosphere on a time scale of decades rather than the thousands of years the natural cycle takes to remove CO2 from the atmosphere. It also requires cutting the other global warming gases along with black carbon soot. These other non-CO2 climate pollutants can complement cuts in CO2. Both are needed to win the battle against global warming.
According to a recent UNEP/WMO report, full implementation of a package of sixteen emission reduction measures targeting black carbon and ozone precursors, including methane, can cut the rate of global warming in half for the next 30 to 60 years, and by two-thirds in the Arctic.
- Arctic melt accelerating, sea-level climate report says (theglobeandmail.com)
- Report confirms Arctic melt accelerating (cbsnews.com)
- A new research report shows effects of climate change in the Arctic are more extensive than expected (scienceblog.com)