Economic and Human Dimensions of Climate Variability and Climate Change: Insights from the First Three Years of Research

Abstract

JISAO/SMA Climate Impacts Group: An Integrated Assessment of Climate Variability and Climate Change on the Pacific Northwest. Paper prepared for the NOAA Economics and Human Dimensions Meeting, Tucson, AZ, April 26-28, 1999.

Our research team studies the natural climate variability of the Pacific Northwest (PNW) using, primarily, instrumental records of temperature, precipitation, streamflow and snowpack. In addition, we have collected paleoclimate data spanning the last several hundred years (using tree ring data) and plan to add lake sediment data spanning the last 10,000 years. Climate variations occur on a range of timescales. The dominant one for temperature and precipitation is the familiar seasonal pattern. Another important timescale is 2-7 years, the period of the El Nino Southern Oscillation (ENSO), and in fact we have found many connections between ENSO and the regional climate of the PNW. The Pacific Decadal Oscillation (PDO) is a pattern of variability with a longer timescale, with reversals in phase occurring every 2-3 decades. In addition to natural climate variability, we also study the potential impacts of human activities on the global and regional climate. Our research team is charged with providing the PNW regional contribution to the U.S. Global Change Research Program (USGCRP). There is no doubt that carbon dioxide in the atmosphere is increasing, and that it will continue to increase for the foreseeable future. Increasing carbon dioxide will, almost certainly, lead eventually to an increase in global mean temperature. This does not imply that the mean temperature everywhere will rise; regional impacts of global climate change may be subtle and surprising. Part of our purpose is to leam how global climate change might impact the PNW, given our understanding of past climate variability and its impacts. We think that the regional impacts of climate change will not be experienced as changes in conditions per se, but rather as changes in patterns of climate variability.