More evidence for global warming on Earth

Posted by David Eicher
on Tuesday, December 12, 2006

Sitting around in the office at Astronomy 20 years ago, our editors used to joke about stories in the magazine centered on Earth. But then it struck us, why limit ourselves to just the other planets? Why not study important Earth stories in the pages of Astronomy? After all, Earth is a planet, too!

Stories about planet Earth used to be pure science pieces. Now, in the last decade or so, they have become increasingly political as well. On the first day of the American Geophysical Union (AGU) meeting in San Francisco, Earth science met Earth politics once again, head-on. At the outset of the coming together of 12,000 scientists for a week of papers and talks on geology and related subjects, global warming took center stage.

Carbon dioxide emissions from fossil-fuel burning, say scientists from the National Center for Atmospheric Research, will reduce the density of Earth's atmosphere some 3 percent by the year 2017. The finding blasts another loud warning about global warming to a polarized public, at least much of which doesn't seem to believe the warnings of scientific findings on the subject. Summarized and publicized in former vice president Al Gore's recent movie An Inconvenient Truth, the alarm bells over global warming seem to be seen by much of the general public as nothing to worry about. Or at least they're seen by many politicians, whether or not they have connections to the fossil fuel industry, as too complex to understand or respond to.

Ironically, Gore will address attendees of the AGU meeting on Thursday. In the meantime, many papers being presented at the meeting concentrate on further evidence of the dangers posed by human altering of Earth's climate. This morning's study, announced in a press conference, was just the most significant of the day. "We're seeing climate change manifest itself in the upper as well as lower atmosphere," says NCAR scientist Stan Solomon, one of the study's authors. "This shows the far-ranging impacts of greenhouse gas emissions."

Significant changes in different levels of Earth's atmosphere provide further evidence of greenhouse-gas-driven warming, confirmation that the current emissions are giving humans a new, uncontrolled, and unpredictable experiment - the genie is out of the bottle.

Recent observations reported by the NCAR scientists show the thermosphere, from 60 to 400 miles above Earth's surface, is thinning. This confirms a 1989 prediction that the thermosphere is cooling and contracting due to higher carbon dioxide levels.

What will happen if the difference continues to widen over the next decade? NCAR scientists will watch closely to see if the changes continue. Many further studies and papers later in the week promise to address the global warming issue, tucked in and around Gore's speech to the whole crowd.

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