UA Climate Expert Testifies Before Congress

The climate has changed throughout the Earth's history, but average Northern Hemisphere temperatures in the second half of the 20th century were likely warmer than in any other 50-year period in the past 1,000 years, a University of Arizona scientist told lawmakers.

Lisa Graumlich, director of the UA's School of Natural Resources and the Environment, testified May 6 before the U.S. Select Committee on Energy Independence and Global Warming. A video with selected parts of the testimony will be available on the committee's website.

Graumlich testified that the combination of climate records used in estimating Northern Hemisphere temperature trends--such as lake sediments, ice cores, coral growth bands and historical documents--obtained by independent research groups, has led to a clear indication that the later 20th century is the warmest period in the past 500 to 1,000 years.

"Given that we know that climate has changed throughout the Earth's history, it is critical to put the recent warming trend into the context of the natural variability of the Earth's climate system," Graumlich stated in a written copy of her testimony.

"The rise in temperatures since the 1970s, along with other evidence of warming (e.g. melting of snow and ice, sea level rise) support one of the key findings of [an Intergovernmental Panel on Climate Change working group] that the 'warming of the climate system is unequivocal.'"

Contact name: 
Lisa Graumlich
Released date: 
Jun 10 2010