Transcript Anthropogenic Effects on the Arctic

Anthropogenic Effects on the Arctic
Sarah Large ‘14, Sara Miller ‘15, Denise Bruesewitz
Department of Environmental Studies, Colby College, Waterville, ME
The Arctic
• The most northern region of the world; polar region between 60°- 90°N
• Characterized by glaciers, ice and snow, and tundra ecosystems
• The Arctic is known for its bountiful resources: arctic mammals such as seal
and polar bears, and arctic minerals such as oil, gas, and metal ores.
• The Arctic is a sensitive location that has been affected greatly by climate
change and the anthropogenic factors that contribute to global warming.
• Three of the major impacts are rising average surface temperatures, melting
permafrost and the dangers that follow, and the loss of biodiversity.
Biodiversity Loss
•Changes in both land and water and its uses influence biodiversity in the
Arctic.
•Warming terrestrial environments, decreased area and thickness of sea ice,
as well as increased seawater temperatures will also result in changes in the
distribution, diversity, and productivity of species in the arctic.
•Climate change has caused habitat extent to shrink, which limits the spatial
adaptability of species. In addition, the abundance and diversity of species
in the Arctic is being affected by their limiting accessibility to resources.
•Projected decrease in sea-ice extent and thickness will result in increased
accessibility to the open ocean and surrounding coastal areas, making it
easier to exploit marine and coastal species over a larger area for a greater
portion of the year.
•The formerly high productivity of the Arctic ecosystems is decreasing due
to warmer air temperatures and water temperatures, and melting sea ice.
•Effects on individual species have cascading influences on the food web
throughout the entire biome.
•Exploitation of species, land and water management, and pollution from
development are the key issues threatening biodiversity in the Arctic
•Many populations of charismatic arctic species have been over-exploited
over the last few hundred years.
•Vast effects on migratory species and their management as well as effects
by non-native species resulting in biological invasions are becoming
problematic.
Permafrost
•Permafrost is soil, rock, and sediment that remains below 0° C for two
or more consecutive years.
•Permafrost underlies most surfaces in the terrestrial Arctic
Permafrost Melt
•Rising surface temperatures in the Arctic are causing permafrost to melt.
•Permafrost temperatures over most of the sub-arctic land have increased
by several tenths of a °C up to 2°C during the past few decades.
•Depth of top layer of permafrost that thaws each year in the warm
season, or the active layer, is getting deeper in many areas.
•Permafrost degradation is projected to spread over 10-20% of the
present permafrost area within the next 100 years.
Figure 1. Present and projected vegetation and minimum sea ice extent for arctic and neighboring
regions. Vegetation map based on floristic surveys and projected vegetation for 2090-2100.
Figure 3. Image to the left shows the locations and type of permafrost that exists in the Arctic.
Image to the right shows the expected changes in Arctic temperatures by the year 2090. Blue
solid line is current permafrost boundary. Blue dashed line is projected permafrost boundary
by 2090.
Rising Surface Temperatures
•Average surface temperature is increasing twice as fast as the rest of the world
•Warming of about 3-7°C over the next 100 years due to increased global
concentrations of carbon dioxide and other greenhouse gases emitted by
human activities, primarily fossil fuel burning.
•Average surface temperature increased from 1900 to 1940, decreased from
1940 to 1970, and increased from 1970 to the present.
•The variation in Arctic surface temperatures since 1900 are explained by the
increased atmospheric greenhouse gases, aerosol emissions, as well as volcanic
eruptions.
•Reported that methane caused a warming impact of about 0.04 degree C per
decade.
Figure 2. Projected Global and Arctic Surface Air Temperature Change. This graph shows average
temperatures projected by the five ACIA climate models for the B2 emissions scenario.
Impacts Of Permafrost Melt
•As permafrost melts the land cracks and produces large holes, called
thermokarsts, and all the carbon and methane trapped in the once frozen
permafrost is released into the atmosphere.
•Freshwater habitats are disappearing and changing due to permafrost
melt which is causing species to shift how they are using aquatic habitats.
•Lumber, oil, and gas transportation season have been cut short because
of unsafe road conditions due to the ground thawing.
Cases and Species Experiencing Biodiversity Loss
•Commercial fish landings in Canada decreased from 1.61 million tons in
1989 to 1.00 million tons in 1998.
•Fivefold decline in cod stock in the Arctic ocean
•Large declines in the herring stock in the Norwegian Sea
•Polar bears, seals, seabirds, and many more arctic mammals rely on
diminishing sea ice for hunting and habitat.
•Caribou, reindeer, lemming, and small rodent populations have decreased
due to the loss of tundra vegetation.
•Collapse of small rodent populations have lead to a decrease in bird
populations and carnivores such as the arctic fox, raptors, and snowy owls.
“Climate change in polar regions is expected to be among the largest and most
rapid of any region on the Earth, and will cause major physical, ecological,
sociological, and economic impacts, especially in the arctic, Antarctic Peninsula,
and Southern Ocean (high confidence).” – IPCC, 2001
Effects on the Arctic are Global
•Due to snow and ice melt more land and water are exposed. Therefore
more of the sun’s energy is absorbed, further warming the planet. This
cycle acts as a positive feedback loop.
•The desalination of the Arctic Ocean due to added freshwater from
melting glaciers could alter the global ocean circulation patterns.
•Alterations in the exchange and storage of greenhouse gases in the
Arctic, on land and in the ocean, contribute to the increase in global
temperatures.
•Impacts of Arctic climate change will have implications for biodiversity
around the world because migratory species depend on breeding and
feeding grounds in the Arctic.
•Increased access to the Arctic Ocean due to sea ice melt will allow
transportation routes to be open for longer periods of the year and reach
areas that have never been explored before.