It has been 40 million years since the waters around Antarctica have been warm enough to sustain populations of sharks and other fish, but they may return this century due to the effects of global warming. If they do, the impact on Antarctic ecology could be serious, according to biology professors Cheryl Wilga and Brad Seibel.

The professors analyzed the physiological adaptations and metabolism of sharks and other warm-water predators and concluded that an increase of just a few degrees Celsius could make Antarctic waters hospitable to some species.

The waters around the Antarctic Peninsula remain within a few degrees of freezing year round, but in the last 50 years the temperature there has increased by 1 to 2° C, which is about double or triple the global average.

The water only needs to remain above freezing year round for it to become habitable to some sharks.

“There are few prey-crushing predators in Antarctic waters. As a result, the Antarctic seafloor has been dominated by relatively soft-bodied, slow-moving invertebrates, just as in ancient oceans.

While the researchers don’t believe that the arrival of sharks and bony fishes in Antarctica will lead to widespread species extinctions, Wilga and Seibel say that it will certainly lead to dramatic changes in the population numbers and proportions of species found there. Shrimp, ribbon worms, and brittle stars will likely be the most vulnerable.