The world's oceans act as a huge sponge for the carbon dioxide released into the atmosphere by human activities, but all of that extra CO2 increases the acidity in the waters, which can be harmful to the organisms that call the sea home.
While researchers have been studying the increasing acidity of the earth's oceans and its affects on marine life, the polar regions have been a little more difficult for data gathering because of the thick ice during the winters. While scientists have been able to test CO2 levels in the summer in the Southern Ocean around Antarctica, winter levels have been unknown.
A team of scientists from Virginia Institute of Marine Science is on its way to solving the mystery thanks to a new high-tech mooring it just deployed in the Southern Ocean for year-round measurements. The mooring, which is a line anchored to the seafloor at a depth 1,600 feet -- about he height of the Empire State Building -- and held aloft by floats at the surface, includes instruments that reach no farther than 60 feet below the surface to avoid the ice that will cover it during winter.The sensors on the mooring will measure levels of dissolved CO2 in the water every three hours as well pH, temperature, salinity and dissolved oxygen. The mooring will remain in the sea for six months, storing all of the data on a waterproof memory card that will be collected at the end of the deployment.
This mooring will be retrieved in May -- late fall in Antarctica -- and immediately replaced with another identical mooring for collecting the next half of a year's data.
"The autonomous sensors will allow us to monitor the full annual cycle of carbon dioxide in Antarctica's coastal waters, for the first time," said Dr. Elizabeth Shadwick, an assistant professor at the Virginia Institute of Marine Science.
The Southern Ocean stores almost half of the carbon emissions from human-made sources, so these measurements are incredibly important to the overall understanding of climate change. So far, the ocean surface in warmer areas around the world has matched the increase in atmospheric CO2, but its unclear whether polar seas are doing the same since ice covers the surface in the winter, shielding it from the atmosphere for months at a time.
Prediction models based on summer time measurements show increasing acidity by 2070 that would have a major impact on animals with shells and animals at the bottom of the food chain that would then work its way up to affecting the large animals that depend on them for food.
This high-tech mooring will give the scientists clearer data about the pH levels year-round, which could move that timeline up, making immediate action more urgent to protect the animals that inhabit the polar seas.