Climatologist: Global warming theory based on skewed data

Copyright 1999 Associated Press January 26, 1999

The theory of global warming is based on skewed data, state Climatologist Harry Hillaker told Legislative members in charge of environmental policy.

Scientist have noted that the average global temperature has risen about 4 degrees since 1977, causing many to sound the alarm of global warming caused by greenhouse gases such as carbon monoxide.

Iowa's historical temperature data has mirrored global data since 1884, Hillaker told members of the Senate Natural Resources and Environment Committee and House Environmental Protection Committee.

Both matched up until 1977 when temperatures taken on land-based stations worldwide began rising faster than temperatures in Iowa. Taking into account year-to-year fluctuations, Iowa's temperature has been stable for the last 50 years, Hillaker said.

"I think we're measuring urbanization, not global warming," Hillaker said, conceding that the upward global trend is subject to much debate.

Satellite global temperature measurements since 1977 closely mirror Iowa's fluctuations, Hillaker said in a report titled "Historical Iowa Temperature Trends."

The difference between satellite and land temperature measurements could be caused by what's known as the "urban heat island" effect, Hillaker said.

Urban areas, due to pavement, buildings and concrete are warmer that the surrounding rural areas.

"They're taking measurements from long-record sites, which means big cities," Hillaker said.

The State Climatologist Office, founded in 1874, is the longest continuously operating state weather agency in the United States.

Among the issues facing the Legislature this year that could impact greenhouse gases is a proposal to require all gasoline sold in Iowa contain 10 percent ethanol.

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