Climate change

Threats from a changing climate range from changes in sea temperature and the freshening of the seawater because of melting ice and increased rainfalls, to sea level rise, loss of icy polar habitats and the decline of krill populations in key areas.

While whales, dolphins and porpoises have some capacity to adapt to this changing environment, the climate is now changing at such a fast pace that it is unclear to what extent they will be able to adjust.

Projected change impacts include:

• less available habitat for several cetacean species unable to move into colder waters;

• acidification of oceans as they absorb growing quantities of CO2;

• an increased susceptibility of cetaceans to diseases;

• reduced reproductive success, body condition and survival rates.

For cetaceans, climate change impacts are more apparent in the Arctic and the Antarctic.

Arctic

Cetaceans that rely on polar icy waters for their habitat and food resources – such as belugas, narwhal and bowhead whales – are likely to be dramatically affected by the reduction of sea ice cover. 

Also, as sea ice cover decreases, there will be more human activities such as commercial shipping, oil, gas and mining exploration and development, and military activities in previously untouched areas of the Arctic. This will result in much greater risks from oil and chemical spills, worse acoustic disturbance and more collisions between whales and ships.

Antarctic

The Southern Ocean surround Antarctica, is critical feeding area for a range of species such as humpback whales that migrate here each summer to the largest animal on Earth - the critical endangered Antarctic blue whale. They are here to forage on krill - a key species in the Antarctic food web.

Ocean temperatures in West Antarctica along the Antarctic Peninsula have risen by more than 2.7°C since the 1970s—about five times the global rate of warming. Melting sea ice poses a grave threat to krill which feed on phytoplankton growing beneath the ice.

Antarctic krill are contracting southward by as much as 440 km (4 degrees latitude) as their suitable habitat recedes due to climate change along the Peninsula and Scotia Sea. This shift in krill distribution is likely to drain energy from migrating whales, with potential long-term effects on body condition, reproductive fitness and population abundance.