Imagine flying to Tahiti, then taking a cruise from there to Hawaii.
Sounds like a super vacation, right? Seven scientists from the University of Maryland took off last week for the central Pacific Ocean with just that itinerary.
But for the Maryland researchers and about two dozen others from around the country, there will be little leisure time as they prepare to embark Tuesday on their 37-day cruise. They will be scouring the sea for clues to the role oceans play in global warming.
"People think it's 'The Love Boat,' but everybody is working 18 hours a day," said Dr. Michael Roman, chief scientist for the cruise and a biological oceanographer from the university's Horn Point Environmental Laboratory in Cambridge.
The expedition, aboard a new 274-foot research vessel owned ** by the University of Washington, is part of a three-year study paid for by $20 million-plus in taxpayers' money. The project will send a multinational fleet of ships and planes crisscrossing the equatorial Pacific Ocean, and this cruise, funded by the National Science Foundation, is one of six planned this year for the ship, the R/V Thomas G. Thompson.
The goal of this scientific quest is a better understanding of just how much carbon dioxide the ocean removes from the atmosphere. The biological, chemical and physical interactions between air and sea are poorly understood now, but researchers think they could be keys to making more accurate predictions about the rate and effects of global warming.
Concern about global warming has grown in recent years because of the buildup in the atmosphere of "greenhouse gases," carbon dioxide and methane mainly, which can trap heat from the sun-baked Earth. Spurred by fossil fuel burning and deforestation, carbon dioxide has increased 25 percent since preindustrial times, and methane has doubled, according to the World Resources Institute.
But while many scientists believe that global warming is inevitable, if not already under way, there is still a great deal of debate, chiefly over how high temperatures will go and what impact that will have on sea level, on plants and animals, and on civilization.
"The big unknown is how much carbon dioxide is going into the oceans," said Dr. Roman. With their vast floating populations of algae and tiny plants called phytoplankton, the seas appear to consume huge quantities of carbon dioxide. That may offset some of the greenhouse gas buildup, some scientists theorize.
"We know if the ocean didn't absorb carbon dioxide, there'd be twice as much carbon dioxide in the atmosphere by now," said Dr. Hugh J. Ducklow, a marine microbiologist from Horn Point on the expedition. "We don't know what's the ultimate capacity of the ocean to keep doing that." The ocean flux study already has looked at the North Atlantic Ocean, and there are plans in the next few years to tackle the other major oceans.
Oddly enough, the equatorial Pacific seems to be giving off more carbon dioxide than it absorbs, and that is one reason for this cruise.
"There would be a lot more carbon dioxide going into the atmosphere from there if there wasn't so much photosynthesis," Dr. Roman said, referring to the process by which plants "breathe in" carbon dioxide.
But even though that sun-drenched stretch of ocean is extremely rich in nutrients, which is what algae feed on, the aquatic plant growth there is lower than might be expected.
The scientists on this and other cruises will be working on about 40 different projects studying everything from the atmospheric chemistry to the feeding habits of the tiny critters in the water to the ocean's bottom some four miles deep.
Dr. Roman and another Horn Point researcher, Dr. Diane K. Stoecker, will be focusing on zooplankton, the tiny shrimplike animals that graze on the minute plants.
One possible explanation for why the equatorial Pacific does not absorb more carbon dioxide may be that the phytoplankton are being eaten almost as fast as they can grow, explained Dr. Stoecker.
Scientists on the cruise will be kept busy round the clock collecting bacteria and plankton, water samples and temperature readings. Some of their data will be analyzed on the spot, aboard the high-tech $28.5 million research ship. But the rest will be carried home with them after the vessel docks in Honolulu next month for processing in their own laboratories.
The information collected on this and the other research expeditions will be used to refine sophisticated computer models of the Earth's climate. In the short run, a better understanding of the Pacific could improve long-range weather forecasting, scientists say.
It may be years before scientists have definitive answers to some of their questions about global warming, Dr. Ducklow said. "It's going to be another decade or so before we have enough information and models that are capable of convincing the skeptics," he said.