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3 Understanding Change in the Polar Regions
Pages 22-40

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From page 22...
... to understand the nature of changes we are experiencing today within the context of the past, in order to discriminate between anthropogenic and natural variability and (2) to understand global linkages and the coordinated impact of changes on climate and weather patterns, ecosystems, and human endeavors across the planet.
From page 23...
... . Changing environmental conditions affect systems we use every day, from the impact of snow on the mobility of vehicles and freeze/thaw destruction of roadways to icing of aircraft wings, and these pose engineering challenges.
From page 24...
... Continued loss of summer sea ice could increase ship access in the Northwest Passage along the northern shores of Canada and the Northern Sea Route (Northeast Passage) along the Arctic coast of Russia (INSROP, 1999)
From page 25...
... There are concerns that environmental or social change could lead to problems with food safety and availability and circumpolar health in general. Understanding societal changes in the polar regions can provide lessons relevant to the broader science community as well as to the residents of lower latitudes who also face the impacts of social and environmental changes.
From page 26...
... Seasonal and interannual variations of sea ice can alter surface air temperatures in excess of 20°C locally, with far-reaching consequences. Surface warming melts ice and snow-covered surfaces, which normally are highly reflective, increasing the absorption of sunlight and, in turn, increasing the warming and melting.
From page 27...
... Water cycle Research indicates enhanced precipitation over the Antarctic peninsula and increased river runoff in northern Eurasia. Carbon cycle A decrease in sea ice extent will decrease ice algal production with impacts on higher trophic levels.
From page 28...
... The loss of summer sea ice not only endangers ice-endemic species like polar bears and the food web producing their prey but also will impact the biological cycles of the entire Arctic from the coast to the deep sea (Gradinger, 1995)
From page 29...
... These prominent circulation patterns have exhibited trends in recent decades that have a clear imprint on the spatial pattern of changes in air temperature, sea ice, snow cover, and storms, as well as many other components of the environment (e.g., Thompson and Solomon, 2002)
From page 30...
... . Sea ice concentration estimates derived from passive microwave satellite data.
From page 31...
... Looking ahead, some climate models predict a total loss of multiyear sea ice in the north by 2100 (USGCRP, 2001)
From page 32...
... . Recent ecosystem studies in the Ross Sea, Antarctica, suggest that changes in ice extent and nutrient availability influence phytoplankton species' growth and the subsequent recycling of carbon in surface waters or deposition and sequestration of carbon to depth (DiTullio et al., 2000; DiTullio and Dunbar, 2003)
From page 33...
... . In fact, the polar regions may already be harbingers of impending global change, but we cannot be certain because of limited understanding of the environmen FIGURE 3-4 Projections of composite mean September Arctic sea ice changes extent based on the IPCC 2001 B2 scenario in five general circulation models: Canadian Climate Centre for Modelling and Analysis, Max-Plank Institute, Geophysical Fluid Dynamics Laboratory, Hadley Centre, and National Center for Atmospheric Research for the Arctic Climate Impact Assessment.
From page 34...
... . These polar region field lines pass close to, and indeed often form, the boundary of Earth's space environment -- the magnetosphere -- with the expanding solar atmosphere (the solar wind in the interplanetary medium)
From page 35...
... Nevertheless, the motions of these highly tenuous plasmas drive powerful electrical currents, and during disturbed periods, the Earth's magnetosphere can dissipate well in excess of 100 billion watts of power -- a power output comparable to that of all the electric power plants operating in the United States. of proxy data from high northern latitudes in combination with climate modeling has shown that the warming during the twentieth century was most likely a result of increased levels of greenhouse gases, as opposed to solar variability and volcanic aerosols (Overpeck et al., 1997)
From page 36...
... Yet much smaller changes of only a degree or two, which are known to have occurred in between the so-called Medieval Warm Period and the Little Ice Age, were sufficient to cause Scandinavian settlers to colonize Greenland during the warm periods and then to abandon those farms during the cold. Many past examples of societal collapse involved rapid change to some degree (NRC, 2002)
From page 37...
... Paleobiology Just as the chemistry of polar ice reveals much about the environments of the past, the layered chemical and biological histories preserved in the ice also preserve evidence of past ecosystems. Ice coring studies have shown that in some cases metabolically active microbes may exist in small liquid water veins in solid glacial ice (Price, 2000)
From page 38...
... We must look on longer timescales to understand how climate can respond to more substantial natural forcings. Paleo data indicate that feedbacks in the polar regions have been responsible for enormous environmental change owing to alterations in the Earth's atmospheric composition and incoming solar distribution, the buildup of ice sheets, and continental drift (Crowley and North, 1996)
From page 39...
... Similar abrupt climate changes happened repeatedly through the ice age and even into the warmth of the last 10,000 years -- Richard Alley on the Matanuska almost like a climatic bungee-jumper on the ice-age roller coaster." Glacier in Alaska. SOURCE: Currently, Alley is part of a team finishing up a study of an ice core Todd Johnston.
From page 40...
... Too much warming could melt the great ice sheets in Greenland and Antarctica, with much more impact on the coasts. If Greenland were to melt, sea level would rise a bit more than 20 feet, which without sea walls, would put Miami, Florida, mostly under water.


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