Humpback whales were facing the tangible possibility of extinction after decades of being overhunted – but following a slow recovery in numbers, climate change may be their next foe.
Scientists have revealed in a new study that sea surface temperature increases could see their current breeding areas no longer safe by 2100.
During summer, the species feed in colder waters in places such as Alaska, Scandinavia and Antarctica – moving to warmer waters to breed.
This is believed to be because warmer waters help whale calves grow stronger and quicker than in colder temperatures. Currently, all humpback breeding areas worldwide are in temperatures between 21°C and 28°C.
The researchers revealed that under a scenario where limited efforts are made to reduce global warming, whale breeding areas would have a 36% chance of rising above 28°C. However, if current fossil fuel exploits continue at the same rate, this figure rises to a 69% chance.
One of the researchers from the University of Hawaii, Hannah von Hammerstein, said: “We expected to see some of the breeding grounds impacted. But when we looked at our projections and saw breeding ground after breeding ground come up red, it was quite jaw-dropping.”
In the 20th century alone, it’s estimated that close to 250,000 humpback whales were hunted – leaving the population to a mere few thousand.
Following bans to hunting, their numbers have recovered slightly to the tens of thousands – but the researchers are worried that this change to their environment will be too difficult to cope with for the species.
The scientists explained that they are not sure where the whales would turn if their habitats become untenable and cannot see any nearby areas that would suit the necessary conditions.
Von Hammerstein added that there are still opportunities to stop this outcome: “I don’t purely see [the scenario] as negative because the results also show that by implementing mitigation measures and reducing emissions, so much can be won.”
Frontiers in Marine Science was where the scientists published their report.