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Explore the intricate relationship between polar warming, ecological impacts, and human well-being in the rapidly transforming Arctic region. Discover the effects of shrinking glaciers, earlier spring snowmelt, and diminishing sea ice on global warming. Delve into the expansion of forests and changing permafrost dynamics. Investigate carbon sequestration shifts and the increasing methane efflux. Gain insights into the escalating wildfires and the complex feedback mechanisms influencing climate change. Assess the mixed economic impacts and the overall uncertainty surrounding the magnitude of global-to-arctic warming effects.
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The Changing Terrestrial Arctic Terry Chapin
Global to arctic Mann et al. Polar amplification Chapman and Walsh
Polar warming is driven by global processes • Is mitigation of impacts the only option? • Can SEARCH make the case that • Warming has significant ecological impacts? • Warming is affecting human well-being? • Within the Arctic? • Beyond the Arctic?
Aerial extent of glaciers is decreasing (decreasing albedo) (positive feedback to warming) European arctic Russian arctic Total arctic American arctic Hinzman
Spring snowmelt is earlier • Decreased albedo • Positive feedback to warming
Sea ice is less extensive • Decreased albedo • Positive feedback to warming • Together these changes in physical environment contribute to polar amplification of global warming
Forests are expanding Lloyd and Fastie
Forests are expanding • Decreased albedo • Less masking of snow • Darker, more complex canopy • Positive feedback to warming
1949 1949 Shrub density has increased 2000 Sturm Chandler River, 50 miles S. of Umiat: Sturm, Racine and Tape: Fifty Years of Change in Arctic Alaskan Shrub Abundance
Indigenous observations indicate that shrub expansion is widespread
--- __ --- __ --- __ --- __ Jia et al. GRL, in press
Simulated increase in July temperature due to shrub expansion Chapin , Lynch et al.
Relationship of air temperature to thaw depth depends on surface properties Hinkel, Brown and Nelson
Permafrost temperatures are warming warmer air altered thermal insulation Osterkamp and Romanovsky
Permafrost is thawing in many places, not just southern margins
Hydrology is changing (confirmed by indigenous observations) Hinzman
Tundra is becoming drier (in places) Oechel and Vourlitis
Carbon sequestration is changing (complexity reflects feedbacks) Oechel et al.
CO2 efflux is sensitive to warming • Increased sequestration in wet areas • Increased carbon loss in dry areas • Net effect uncertain • Probably positive feedback to warming
Methane efflux is increasing • Positive feedback to warming • Sensitive to hydrology • Overall trace-gas effect is a positive feedback to warming
Area burned in W. North America has doubled in last 20 years Kasischki
Fire effects on climate • Releases carbon to atmosphere • (positive feedback) • Reduces masking of snow • (increased winter albedo, negative feedback) • Increases vegetation albedo • (negative summer feedback)
Warming effects on human well-being Economic impacts are a mixed bag
Warming effects on arctic well-being (cultural effects generally negative)
Warming effects on global well-being Economic effects generally negative Magnitude still uncertain
Global-to-arctic: important, understood Arctic-to-global: poorly understood (Arctic nations)