What Happens to the Antarctic Ocean with 1 Degrees Celsius of Warming?

Scientists have discovered “massive impacts” on marine life in the Antarctic Ocean when waters are warmed by 1 degree Celsius, including a doubling in growth of some species and a drop in overall biodiversity, according to a new study in the journal Current Biology.

Previously, the only way scientists could study the impact of warming temperatures on small marine organisms, such as those that live on the sea floor, was in laboratory and tank experiments. But “that’s quite removed from their natural setting,” Gail Ashton, lead author of the new study, told Popular Science. Instead, Ashton and her colleagues at the British Antarctic Survey (BAS) spent six years creating a technology that could heat a small test plot of actual ocean by 1 degree and 2 degrees Celsius, the projected increases in ocean temperature from climate change over the next 50 and 100 years respectively. A heating device was placed 50 feet below the surface in a shallow part of the Antarctic Ocean, and researchers documented what happened to sea life over a nine-month period.

The scientists reported that 1-degree of warming “substantially changed” marine life on the seafloor. One species of bryozoan (Fenestrulina rugula), a type of aquatic invertebrate, grew rapidly and ended up dominating the study area within two months, causing an overall decline in biodiversity. Spiral tube worms also thrived within the 1-degree plot. Marine life’s response to a 2 degrees temperature rise was more variable, the scientists said.

The extent of the changes caused by the warming “surprised us all,” Ashton said. “We were thinking we’d need to do some statistical analyses to tease out the differences, but when you look at the photos it is very clear that the growth is very different on the treated panels.”

Changes to seafloor organisms over a nine-month period in normal, 1-, and 2-degree Celsius ocean warming.

Changes to seafloor organisms over a nine-month period in normal, 1-, and 2-degree Celsius ocean warming. Ashton et al 2017.

The scientists now plan to take their technology and study warming in other parts of the globe, including the Arctic.

“Such large changes in communities, in response to conditions that are forecast within our lifetimes, is quite remarkable,” Simon Morley, an ecophysiologist at BAS and a co-author of the new study, said in a statement. “Understanding which species will be the winners and losers is key as we try to predict the impact of climate change on life in the ocean.”