Scientists in Antarctica studying carbon cycle, the key to climate change

Chilean and Spanish scientists have set up a monitoring device on the Antarctic Peninsula with the aim of measuring the annual carbon cycle between the atmosphere and the ocean and learning about the function of marine microorganisms in the recycling of carbon dioxide.

The scientists - within the framework of Antarctica Scientific Expedition No. 55, which has been under way for the past two months - submerged a sediment trap in the frigid waters south of Doumer Island at a maximum depth of 200 meters (656 feet) and it will remain in place there to collect data on the physical, chemical and biological characteristics of the ocean water and the life therein.

The sediment trap is a cylinder that captures the particulate materials that drifts down through the water toward the ocean bottom over a certain period of time.

The device has sensors to measure the acidity, temperature, salinity and oxygen content, as well as one measuring the difference between CO2 pressure in the atmosphere and its level 200 m underwater.

The study has special relevance because most of the oceanographic scientific work performed in Antarctica so far has been in open waters and there is little understanding of the flow of particles within the annual cycles of closed coastal systems or the potential impact that the retreat of glaciers - which is being caused largely by global warming - will have on those systems.

“The information we have right now about the role of key species of zooplankton in the water column is scanty. For example, what’s the role of krill, sea squirts and other organisms? Who’s doing the work of exporting organic material to the ocean bed? Those are some of the questions we’re looking to answer,” said one of the mission leaders, Chilean oceanographer Humberto Gonzalez.

He heads the IDEAL high latitude marine ecosystems research center at Chile’s Universidad Austral, which is mounting the project in cooperation with the IDM-CSIC Ocean Sciences Institute in Barcelona, Spain.

The sediment trap captures microorganisms that participate in the carbon cycle, like phytoplankton and zooplankton, which absorb CO2 from the atmosphere and deposit it on the ocean floor in a process that is key to understanding climate change.

“We call that flow of carbon down to the ocean floor the biological carbon pump, in which carbon in the atmosphere is captured by phytoplankton. That phytoplankton is eaten by zooplankton and their feces goes into the water columns that go down to the ocean floor,” Gonzalez told EFE.

Regularity in the compilation of data is what interests the experts, given that “almost all the scientific information (collected so far is from) November to February, the rest of the year is like a black box,” Gonzalez said.

The expedition’s aim is to set up the sediment trap to gather information over the entire year, even when the ice advances during the austral winter and covers the bay.

“After that, when we’ve gotten a decade’s worth (of data), for example, we can start to study the interannual variability, which is super-important because it’s going to allow us to improve the climate change models and future forecasts,” the Chilean scientist said.

The expedition will be able to return to Antarctica the year after next during the same season, when the ice no longer covers the bay, and retrieve the first annual set of data, with which the scientists expect to be able to see what the prime periods of CO2 recycling are.

“What we as humans want is for the CO2 that’s in the atmosphere to be on the ocean floor, because it’s one of the most important greenhouse gases,” Gonzalez said.