CLIMATE CHANGE AND NORTH AMERICAN WATERS – an OVERVIEW

• Main Author: J. P. Bruce
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Pacific; Climate change; North Atlantic; North Atlantic oscillation
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.595.4901; http://wilsoncenter.org/sites/default/files/Climate Change and Water - Bruce1.pdf

The global climate system, and its changing decadal manifestations over North America, is driven by a number of forcing factors “external ” to the system. Year to year variations are driven by internal factors. Among the dominant internal factors are the natural modes of climate variability, El Niño-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the North Atlantic Oscillation (NAO), and the Arctic Oscillation (AO). It has been shown that until the mid 1960s, natural external factors, especially changes in the amount of solar energy reaching earth and volcanic emissions, were important in driving changes in global and North American mean air temperatures and sea temperatures. However, by that time, (mid 1960s), greenhouse gas concentrations had increased, due to human activities, to the point where they effectively overwhelmed the natural factors. Since about 1970, the relatively rapid warming has been driven mainly by greenhouse gas concentrations and this is expected to continue and accelerate. (IPCC-WG1, 2007, G.A. Meehl, 2004) (See Fig. 1) Thus the overall trend in climatic factors