Verbal Remarks DANIEL L. ALBRITTON, DIRECTOR OCEANIC AND ATMOSPHERIC RESEARCH NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION BEFORE THE COMMITTEE ON SCIENCE UNITED STATES HOUSE OF REPRESENTATIVES March 14, 2001 "Climate Change: An Update of the Scientific Understanding" Background points ... • There is long-standing knowledge that is known with extremely high confidence. > There is a natural greenhouse effect. It keeps the Earth warmer than it would be otherwise. > Greenhouse gases are increasing in the atmosphere because of human activities, and they are increasingly trapping more heat within the climate system. Question: What are the consequences? • Today: An updated answer based on the IPCC report "Climate Change: 2001 The Scientific Basis". > Three major findings ... 1 There is a growing collective picture of a Points ... Relative "Confidence Index" Global temperatures: Up 0.4-0.8°C over the past 100 years, • Other observed changes are consistent with this warming. > Glaciers are retreating. > The amount of snow cover is decreasing. > Average sea level has risen 0.1-0.2 meter. Question: What is the cause(s) of the observing warming? 2 There is new and stronger evidence that most 50 years is attributable to human activities. • Key factors since the 1995 IPCC report: > Five additional years of data. > The new 1000-year record: A context for the changes of the past century Question: What could all of this mean for the future? 2000 |