VIEWPOINT
Research at the Extremes
by Deborah A. Bronk and Patricia L. Yager

At a remote field lab on the island of Hawaii in 1957, Charles Keeling began measuring carbon dioxide (CO2) concentrations in the atmosphere. The trend of increasing CO2 he documented over the next 40 years provided the foundation for some of the most important questions in science today.

It's also what sent two of us from UGA's marine sciences department to opposite ends of the Earth - Debbie Bronk to Antarctica and Patricia Yager to the Arctic.

The scientific rationale for these polar projects was simple. An increase in CO2 in the atmosphere, largely attributable to human industry, is suspected to be the cause of global warming. The polar regions will likely be especially sensitive, with average temperatures predicted to increase by as much as 7 to 11 F in the next 50 to 100 years. Temperature increases of this magnitude will have an enormous impact on the polar ocean and therefore the movement of carbon on the planet.

In the ocean, plant-like organisms called phytoplankton take up carbon as CO2 through photosynthesis. The more phytoplankton produced in a given region, the more CO2 will be sequestered within their cells and therefore removed from the water. Ultimately, the CO2 removed from the water is replaced by diffusion of CO2 from the atmosphere. When the cells die and sink, the carbon they contain is removed from the carbon cycle for long periods, thus providing one important "sink" for atmospheric CO2.

Relatively little is known about how the oceans will respond to CO2 increases and what their response will mean to the Earth's climate. Scientists needed a better understanding of carbon cycling in the polar oceans to answer these questions.

The National Science Foundation responded to this need by funding the Southern Ocean-Joint Global Ocean Flux Study, which supports Bronk's work in Antarctica, and the Arctic System Science program, which funds Yager's research.

Research in remote polar regions involves substantial logistical challenges that make it both time consuming and expensive. All supplies and equipment needed for our research had to be shipped to the staging areas - Lyttleton, New Zealand, for the Antarctic cruise and Tuktoyaktuk, Canada, for the Arctic expedition. There are no stores to visit, so planning is critical; insomnia and compulsive fretting should be added to the job description of any polar researcher.

We each studied different aspects of the marine carbon cycle at our respective study sites. After reading the travel logs of the great polar explorers, we were prepared for the extreme hardship and suffering of working at the poles. Comparatively, our actual work on the ship and ice was a bit of a let down. Down Gortex parkas, insulated boots and four hot meals a day made the trip slightly less than the women- against-nature we envisioned. It was cold however, and after a few weeks, the occasional 14 F day felt positively balmy.

In Antarctica, Bronk focused on how nitrogen controls how fast phytoplankton grow and take up carbon - much like how the nitrogen fertilizers control the growth of a lawn. The Antarctic research consisted of four six-week cruises aboard the 320-foot icebreaker RV Nathaniel Palmer.

On the ship, water samples were collected throughout the upper 500 feet of the water column, and uptake rates of a number of nitrogen-containing compounds were measured as an indication of how fast the phytoplankton were growing.

Results to date indicate that iron, another element required by phytoplankton, rather than nitrogen is a more important control on phytoplankton growth in this region.

In the Arctic, Yager and her collaborators conducted a year-long analysis of the ecosystem beneath the sea ice. Part of a larger expedition, the work involved freezing the 322-foot Canadian ice-breaker Des Groseilliers into the sea ice about 300 miles north of Alaska and allowing it to drift with the ice floes for a full year.

Preliminary results suggest that the carbon cycle of seasonally ice-free ecosystems is quite different from that associated with perennial ice-cover, and that as global warming begins to change the ice-cover, dramatic changes in the arctic carbon cycle will likely occur.

Despite the challenges, polar research is critically important and very rewarding. If the scientific community is to understand and predict the consequences of global CO2 increases, a comprehensive understanding of the biological and physical processes of the polar regions is essential. Our work at the poles has provided useful information but it's only a start. In Georgia, there are wet years, dry years, hot years and mild years. We need to determine to what degree the polar regions change from year to year. Continued funding will be needed to monitor longer-term trends in the processes we studied.

Due to the high cost of sending scientists into these extreme regions, it's critical to develop new technologies and expand satellite coverage to allow remote observations of the regions via unmanned instruments. Only through concerted long-term study will scientists have the information and ability to detect the changes predicted by our present understanding of polar oceanography and to understand the impact of continued release of industrial CO2.

Deborah Bronk is an associate professor in UGA's marine
sciences department. Her publications include articles on nitrogen cycling from the cellular to the global scale representing work in regions from the Caribbean Sea to the Southern Ocean.

Patricia Yager is an assistant professor in UGA's marine
sciences department. Her publications include articles on microbial ecology and biogeochemistry of high-latitude and deep-sea ecosystems.