Warmer Temperatures May Cause Arctic Treeline to Spread 500 Kilometers North

According to the Conservation of Arctic Flora and Fauna (CAFF) group, the Arctic is “greening” faster than expected. By the year 2100, the presence of trees in the Arctic may spread north by 500 kilometers (300 miles), completely reshaping the landscape and wildlife dependent upon it.

The predicted northern drift of the Arctic treeline could eliminate up to 51% of the current tundra, with wide-ranging negative impacts for local biodiversity. As temperatures warm, southern species, such as certain species of Arctic goose, have already exceeded their environment’s carrying capacity.

Conversely, populations of northern species, like the oft-cited polar bear, continue to decline. The CAFF group highlights these implications in their report, The Arctic Biodiversity Trends – 2010: Selected Indicators of Change.
“The plant communities that make up tundra ecosystems– various species of grasses, sedges, mosses, and lichens– are, in some places, being replaced by species typical of more southern locations, such as evergreen shrubs,” the report stated. “Depending on the magnitude of change, the resulting ecosystems may no longer be considered “Arctic”. The result may be that many of the species that thrive in the Arctic today may not be able to survive there in the future.”

The northern spread of trees is attributed to warming trends – temperatures in the Arctic are rising at twice the global average rate. As snow and ice recede, increasing amounts of soil and water are exposed to the Sun. Unlike ice, which is reflective, the darker soil and water absorb a greater portion of the Sun’s energy.

This has impacted a number of Arctic ecosystems. Permafrost in the northern peatlands, which in addition to supporting unique wildlife also holds vast quantities of organic carbon, is decreasing significantly, in both duration and breadth. In the last three decades, Arctic seasonal minimal ice extent has decreased by as much as 45,000 square kilometers annually.

The CAFF report discussed the loss of ice, stating  “Sea ice, however, is being lost at a faster rate than projected by even the most pessimistic of climate change scenarios, such as those reported by the Intergovernmental Panel on Climate Change (IPCC).”

The study received renewed attention as the Arctic Council met in Nuuk, Greenland on Thursday. The Council is made up of the eight nations whose land borders the Arctic Ocean –  Canada, Denmark, Finland, Iceland, Norway, Russia, Sweden and the United States. In addition to discussing environmental issues, the Council signed an agreement that will coordinate search-and-rescue missions across 13 million miles of northern ocean.  Experiencing record ice melt, the Arctic Ocean continues to become increasingly accessible by ships, resulting in some disputes over territorial claims.

The “Search-and Rescue” accord sets a precedent as the first legally binding agreement produced within the forum of the Arctic Council. Secretary of State Hillary Clinton spoke on the importance of cooperation amongst the Arctic Council states.

“The melting of sea ice, for example, will result in more shipping, fishing, and tourism, and the possibility to develop newly accessible oil and gas reserves. We seek to pursue these opportunities in a smart, sustainable way that preserves the Arctic environment and ecosystem,” she said. “For more than 15 years, the Arctic Council has established itself as the region’s preeminent intergovernmental body, and the United States is committed to this forum.”

Secretary Clinton was the first Secretary of State to attend the bi-annual meeting, indicating the increasing importance placed on Arctic issues by the United States.

A working group of the Arctic Council, the Arctic Monitoring and Assessment Programme has also released a report on the state of the Arctic cryosphere. The result of a multi-year study, key findings include that Arctic summers are experiencing temperatures warmer than anything seen in the last 2,000 years, the average rate of ice melt is increasing decade over decade, and that the Arctic Ocean may experience mostly ice-free summers within this century.  

The Report also highlighted possible global implications of Arctic warming, stating that if current warming trends prevail, the Arctic may become a net carbon dioxide and methane emitter.

Photo Credit: John Sonntag/Wallops Flight Facility nasa.gov/mission_pages/icebridge/news/spr10/index.html

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