New Evidence from Antarctica Fuels Debate About SolarEffect

Researchers have uncovered the firstconclusive evidence that variations in the output of the sun's energy haveinfluenced climatic change and ocean productivity in the Antarctic region.

The findings, which appear in the December issue of the Geological Societyof America Bulletin, are significant because they likely will fuel reneweddebate about the severity of the greenhouse effect, according to HamiltonCollege Associate Professor of Geology Eugene Domack, a lead investigator forthe study.

"These data take us one step closer to finding the geological fingerprint forgreenhouse warming," Domack said.

The data reported in this study correlate closely with well-known cycles thatreveal variations in the output of the sun's energy over the past 2,500 years.An unprecedented rise in the mean annual temperature for Antarctica -- 2.5degrees Celsius over the past 50 years -- is inconsistent with the cycle andhas led scientists to hypothesize about the role of greenhouse gases inaltering the natural variability of the system.

To help test the hypothesis, Domack has received a National Science Foundationgrant to extend scientists' knowledge of the paleohistory of the region from2,500 years to 14,000 years. The grant, Domack's fifth from the NSF in thepast decade, will fund an expedition in March 1998 to collect and then analyzesediment cores in the Belingshausen Sea. Approval to drill the site was basedon research conducted in Antarctica by former Hamilton undergraduate students,including 1993 graduate Matt Kirby.

Domack said the recent warming trend in the Antarctic has led to significantenvironmental changes in the region, including increases in melting across iceshelves and reductions in the annual coverage of sea ice. The ecosystem mayalso be affected. Scientists have documented changes in the distribution ofpenguin species and some plants.

"The area is clearly responding environmentally to what is the highest meantemperature increase of any region on earth," Domack said, "but we have toconduct additional research to pinpoint the cause."

Over the past decade, Domack's research in Antarctica has advanced scientists'understanding of the paleohistory of the region. Specifically, the data he andhis students have collected and analyzed have helped scientists compare modernchanges in the region to historical changes as documented in sediment corescollected from the sea floor.

"Productivity cycles of 200-300 years in the Antarctic Peninsula region:Understanding linkages among the sun, atmosphere, oceans, sea ice, and biota,"appears in the December issue of the GSA Bulletin. The article was prepared bysix Antarctic researchers.

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