April 6, 2007:  The Intergovernmental Panel on Climate Change (IPCC) today released its Working Group II Summary for Policymakers to the Fourth Assessment Report of the IPCC, in which it details the many effects climate change  may have on the natural and human environment.  The report draws from the work of hundreds of scientists from over 70 countries, and was approved by over 100 nations.  It builds off of the findings of the Working Group I report, which stated that evidence of warming is unequivocal, and humans are very likely the cause.

The report details impacts by region as well as systems and sectors.  For North America, including the U.S., the report details several impacts, including:

• Decreased snowpack, exacerbating competition for scarce water resources in western mountains;
• Increased impacts on forests from pests, diseases and fire;
• Increased frequency, intensity and duration of heat waves in major cities; and
  
• Increasing vulnerability of coastal communities and habitats.

Some additional highlights of the report:

• Many natural systems are being affected by regional climate changes;
• It is likely that human-induced warming has already had a recognizable impact on many physical and biological systems;
• Some large-scale climate events have the potential to cause very large impacts;
• Sustainable development can reduce vulnerability to climate change, and climate change could impede nations' abilities to achieve sustainable development pathways;
• Impacts of climate change, aggregated and discouted to the present, are very likely to impose net annual costs which will increase over time as global temperatures increase;
  
• Many impacts can be avoided, reduced or delayed by mitigation