Study, which shows microscopic plants keep planet warm, offers new considerations for iron fertilization efforts in the oceans
The ecological importance of phytoplankton, microscopic plants that free-float through the worldâ€™s oceans, is well known. Among their key roles, the one-celled organisms are the major source of sustenance for animal life in the seas.
Now, in a new study conducted by researchers at Scripps Institution of Oceanography at the University of California, San Diego, our understanding of the significance of phytoplankton has been taken to a new level.
Robert Frouin and Sam Iacobellis have argued in a paper published in the Journal of Geophysical Research that phytoplankton exert a significant and previously uncalculated influence on Earthâ€™s climate.
The Frouin-Iacobellis study uses satellite imagery to show that phytoplankton, which are said to inhabit three-quarters of Earthâ€™s surface, hold a fundamental warming influence on the planet by capturing and absorbing the sunâ€™s radiation. The authors show that radiation that otherwise might be reflected back to space is absorbed by phytoplankton and results in a global climate warmer by 0.1 to 0.6 degrees Fahrenheit (compared with an open seawater scenario without phytoplankton).
â€śOur paper shows that if we did not have phytoplankton in the ocean, we would have a cooler climate. This is a problem that we have to look at more carefully if we want to conduct more accurate predictions of climate change,â€? said Frouin, a research meteorologist at Scripps. â€śCertainly the effect we have shown from phytoplankton is not negligible, so we need to look at it closely.â€?
â€śEventually, I hope that incorporating this new information will lead to better predictions of future climate, and that will help policymakers make more far-sighted decisions,â€? said Iacobellis, a member of the Climate Research Division at Scripps.
Furthermore, in the paper Frouin and Iacobellis argue that the impact of phytoplankton extends beyond its warming influence. Changes in Earthâ€™s surface reflection caused by increases or decreases in phytoplankton concentrations may significantly affect the interactions of the planetâ€™s climate system with human-produced concentrations of greenhouse gases and aerosols.
They also argue that the climatological significance of phytoplankton is increased or decreased from region to region, since the magnitude of phytoplankton concentrations ultimately will dictate the strength of their warming influence.
The new findings, constructed through modeling designs and satellite imagery data from the Coastal Zone Color Scanner, also hold implications for ongoing discussions of reducing global warming through ocean â€śfertilization.â€? Such efforts have held that global warming may be decreased by fertilizing the oceans with iron, which would lead to an increase in the oceanâ€™s biological pump. Through such an increase, the argument holds, phytoplankton would be able to draw carbon dioxide out of the atmosphere and therefore reduce global warming.
Frouin and Iacobellis, however, believe their new findings may run counter to those arguments.
â€śWe are saying that if you increase the amount of phytoplankton in the ocean, which would probably be a consequence of this iron fertilization, instead you would contribute to warming the ocean by absorbing more radiation,â€? said Frouin.
â€śYou would exert a negative feedback because you would go in the opposite direction of the effect that you want, which is to decrease global warming,â€? said
Iacobellis. â€śThink about this: If you fertilize the ocean you will take up more carbon dioxide, but you are going to get more phytoplankton. Our numbers at least give a start to rough calculations of how much of your initial decrease in temperature is going to be negated by our increase. Weâ€™re not saying that (iron fertilization) idea should be off the table, but this new information is something that should be considered.â€?
Last year Frouin and Iacobellis published a study detailing the extent to which ocean whitecaps influence climate by reflecting solar radiation from Earthâ€™s surface. They say the consequences from the new phytoplankton study are an order of
The results were calculated through average impacts of phytoplankton on a broad, global scale, but the authors say detailed analyses will show varying results due to the fact that various types of phytoplankton species absorb more radiation than others. Some, in fact, reflect the sunâ€™s radiation rather than absorb it. Also to be determined are the complex biological feedback consequences that lead to more or less phytoplankton in certain areas.
â€śThis just shows how intricate the climate system is,â€? said Iacobellis. â€śItâ€™s like a ball of yarn all pushed together. Itâ€™s difficult to unpiece the climate or put together what might happen in the future when all these things act together. One by itself may not be that important but when thousands of these small things act together, then?â€?
The research was supported by NASA, the Department of Energy, and the California Space Institute.
Journalists may request a copy of the paper from Emily Crum at email@example.com.
Scripps Institution of Oceanography at the University of California, San Diego, is one of the oldest, largest, and most important centers for global science research and graduate training in the world. The scientific scope of the institution has grown since its founding in 1903. A century of Scripps science has had an invaluable impact on oceanography, on understanding of the earth, and on society. More than 300 research programs are under way today in a wide range of scientific areas. Scripps operates one of the largest U.S. academic fleets with four oceanographic research ships and one research platform for worldwide exploration. Now plunging boldly into the 21st century, Scripps will celebrate its centennial in 2003.