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Climate Change Impacts on the United States (Nov 2000)

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  • npat1
    Climate Change Impacts on the United States The Potential Consequences of Climate Variability and Change Overview: Key Findings By the National Assessment
    Message 1 of 1 , Oct 7 2:49 PM
      Climate Change Impacts on the United States

      The Potential Consequences of Climate Variability and Change
      Overview: Key Findings By the National Assessment Synthesis Team, US
      Global Change Research Program - Published in 2000

      The National Assessment Overview and Foundation Reports were produced
      by the National Assessment Synthesis Team, an advisory committee
      chartered under the Federal Advisory Committee Act, and were not
      subjected to OSTP's Information Quality Act Guidelines. The National
      Assessment was forwarded to the President and Congress in November
      2000 for their consideration.

      1. Increased warming
      Assuming continued growth in world greenhouse gas emissions, the
      primary climate models used in this Assessment project that
      temperatures in the US will rise 5-9�F (3-5�C) on average in the next
      100 years. A wider range of outcomes is possible.

      2. Differing regional impacts
      Climate change will vary widely across the US. Temperature increases
      will vary somewhat from one region to the next. Heavy and extreme
      precipitation events are likely to become more frequent, yet some
      regions will get drier. The potential impacts of climate change will
      also vary widely across the nation.

      3. Vulnerable ecosystems
      Many ecosystems are highly vulnerable to the projected rate and
      magnitude of climate change. A few, such as alpine meadows in the
      Rocky Mountains and some barrier islands, are likely to disappear
      entirely in some areas. Others, such as forests of the Southeast, are
      likely to experience major species shifts or break up into a mosaic of
      grasslands, woodlands, and forests. The goods and services lost
      through the disappearance or fragmentation of certain ecosystems are
      likely to be costly or impossible to replace.

      4. Widespread water concerns
      Water is an issue in every region, but the nature of the
      vulnerabilities varies. Drought is an important concern in every
      region. Floods and water quality are concerns in many regions.
      Snowpack changes are especially important in the West, Pacific
      Northwest, and Alaska.

      5. Secure food supply
      At the national level, the agriculture sector is likely to be able to
      adapt to climate change. Overall, US crop productivity is very likely
      to increase over the next few decades, but the gains will not be
      uniform across the nation. Falling prices and competitive pressures
      are very likely to stress some farmers, while benefiting consumers.

      6. Near-term increase in forest growth
      Forest productivity is likely to increase over the next several
      decades in some areas as trees respond to higher carbon dioxide
      levels. Over the longer term, changes in larger-scale processes such
      as fire, insects, droughts, and disease will possibly decrease forest
      productivity. In addition, climate change is likely to cause long-term
      shifts in forest species, such as sugar maples moving north out of the

      7. Increased damage in coastal and permafrost areas
      Climate change and the resulting rise in sea level are likely to
      exacerbate threats to buildings, roads, powerlines, and other
      infrastructure in climatically sensitive places. For example,
      infrastructure damage is related to permafrost melting in Alaska, and
      to sea-level rise and storm surge in low-lying coastal areas.

      8. Adaptation determines health outcomes
      A range of negative health impacts is possible from climate change,
      but adaptation is likely to help protect much of the US population.
      Maintaining our nation's public health and community infrastructure,
      from water treatment systems to emergency shelters, will be important
      for minimizing the impacts of water-borne diseases, heat stress, air
      pollution, extreme weather events, and diseases transmitted by
      insects, ticks, and rodents.

      9. Other stresses magnified by climate change
      Climate change will very likely magnify the cumulative impacts of
      other stresses, such as air and water pollution and habitat
      destruction due to human development patterns. For some systems, such
      as coral reefs, the combined effects of climate change and other
      stresses are very likely to exceed a critical threshold, bringing
      large, possibly irreversible impacts.

      10. Uncertainties remain and surprises are expected
      Significant uncertainties remain in the science underlying regional
      climate changes and their impacts. Further research would improve
      understanding and our ability to project societal and ecosystem
      impacts, and provide the public with additional useful information
      about options for adaptation. However, it is likely that some aspects
      and impacts of climate change will be totally unanticipated as complex
      systems respond to ongoing climate change in unforeseeable ways.

      US Climate Change Science Program / US Global Change Research Program,
      Suite 250, 1717 Pennsylvania Ave, NW, Washington, DC 20006.

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