Two new studies, both published in Science, have drawn attention to a previously unforeseen problem of global climate change. As ocean temperatures rise, many species will be forced to move toward colder waters.
For many aquatic creatures, namely fish, crustaceans, and coral, water temperature is linked to metabolism. As the temperature rises, their metabolism increases, but that requires them to take in more oxygen, which there’s less of in warm water than cold. The logical step is for such creatures to seek colder water in order to breathe more easily, but that comes with a number of potential problems.
For one, they will be forced into new ecosystems. New predators could decimate incoming populations, or the opposite could happen, and incoming predators could destroy existing populations. Incoming species would also have to compete with indigenous species, which would be better suited to the environment, and most likely win. The result would be huge population die-offs, and probably extinctions as well. Researchers suggest that a number of species could be displaced from as much as 25% of their current ranges as they shift towards the poles.
Coral faces another problem. As they require sunlight to survive, coral in colder waters would have to stick to shallower, coastal regions, as sunlight does not penetrate as deeply in colder climates, especially during winter. This would result in smaller reefs with less biodiversity. Corals are already in danger in their native warmer waters from a problem called coral bleaching. During coral bleaching, corals eject important algae due to the increased temperature of the water, the lack of which leads to coral dying off. The one-two punch of increasing tropical water temperatures and too little room to grow in colder waters could devastate coral populations throughout the world.
Until now, many scientists had hoped that creatures from warmer temperatures could survive by shifting their ranges, but that seems unlikely now. Luckily, there’s still time to do something about carbon emissions and reduce climate change over the next century.