National Assessment of the Consequences of Climate Variability and Change for the United States

• Main Author: C. Maccracken
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Global warming; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.168.3979; http://climate.dot.gov/documents/workshop1002/maccracken.pdf

limate is an important influence on both the environment and society. Year-to-year variations are reflected in such things as the number and intensity of storms, the amount of water flowing in rivers, the extent and duration of snow cover, ocean-current induced changes in the height of sea level, and the intensity of waves that strike coastal regions and erode the shoreline. These factors in turn determine agricultural productivity, the occurrence of floods and droughts, the safety of communities, and the general productivity of society. Science now suggests that human activities are causing the natural climate to change, mainly by inducing global warming and an associated intensification of the global hydrologic cycle. Although the details are still emerging about the magnitude, regional pattern, and timing of the changes projected for the next century, that climate will be changing is widely recognized. Indeed, temperatures have increased in many areas, Arctic sea ice is much thinner, continental snow cover is not lasting as long in the spring, and total precipitation is increasing, with more rainfall occurring in intense downpours. These changes also appear to be affecting the distribution of plants and wildlife. There is evidence of a longer growing season in northern areas and changing ranges for butterflies and other species.