Scientists concerned with the mechanisms of the Global Warming debate have been watching Earth’s oceans closely of late. The reason for this is that the world’s oceans play a significant and measurable role in slowing the rate of global climate change. A recent study, published Wednesday in Global Biogeochemical Cycles, has produced a new model that will allow climate scientists to better understand how big a part the Earth’s oceans play in this climate cycle and what exactly that part entails.
The oceans of Earth, or more precisely, the microscopic plankton and algae that live in the oceans, are the major players in the carbon cycle of terrestrial seas. As carbon filters down out of the air and is trapped in the water, usually in the form of animal waste and in algae which eat carbon dioxide, it slowly descends from the sun-lit surfaces of the water down to the depths of the ocean. Carbon sequestered in this way can be kept out of circulation in the bottom of Earth’s oceans for millennia, similar to the way in which carbon on land is sequestered in fossil fuel deposits like oil, coal, and peat…which were themselves often ancient seabeds.
There has been concern for some time that the phytoplankton and zooplankton which are responsible for eating a large proportion of the carbon that is taken in by Earth’s seas are vulnerable to die-off due to rising temperatures in the oceans. These tiny plankton exist at the bottom of the oceanic food chain and contribute greatly to the sequestration of carbon by cycling the deposits into feces, which then sink to the ocean floor. Because of this fact, their role is of great interest to scientists who study what they call the “biological pump” of Earth’s seas.
The newest study of this part of the carbon cycle, taken on by UC Santa Barbara’s Earth Research Institute, was led by Director David Siegel. Siegel has stated that his new study is unique in its approach because it focuses on the food chain and measures the net production of organic matter–i.e. wastes–from the carbons dissolved in the water. It is also a unique study of the oceanic carbon cycle in that this food-based model allows scientists to actually monitor in physical terms the health of the oceans’ biological pumping system. In effect, the role of terrestrial oceans in the Global Climate Change model can now be directly measured.
With this study, scientists have been given a tool to gauge exactly how well Earth’s saltwater algae, phytoplankton and zooplankton populations are doing, and how efficiently they are sequestering the carbon that falls into the world’s oceans. This is big news for groups who are concerned with the health of the oceans with regard to slowing the speed of Global Climate Change. As the oceans of the Earth are one of the biggest engines of transport and sequestration of carbon on the planet, this model will have great import for future studies.
The annual emissions of fossil fuels on Earth roughly equal six gigatons at last estimate. Carbon emissions released from the burning of these fuels is of late measured at about nine gigatons per year. This new model shows that the oceans of Earth in their present state of health can convert a flux of approximately six of those gigatons to a sequestered state. The math shows how important these tiny oceanic organisms are to the carbon cycle, and how important the oceans themselves are in their role as measurable recyclers of emissions in the science of global climate change.
By Kat Turner