Effects of global warming on marine mammals

The effect of global warming on marine life and mammals is a growing concern. Many of the effects of global warming are currently unknown due to unpredictability, but many are becoming increasingly evident today. Some effects are very direct such as loss of habitat, temperature stress, and exposure to severe weather. Other effects are more indirect, such as changes in host pathogen associations, changes in body condition because of predator–prey interaction, changes in exposure to toxins and CO2 emissions, and increased human interactions.[1] Marine mammals that have been affected by climate change include walruses, seals, polar bears and many more.[2]


Marine mammals have evolved to live in oceans, but climate change is affecting their natural habitat.[3][4][5][6] Some species may not adapt fast enough, which might lead to their extinction.[7]

Ocean Warming Temperatures

During the last century, the global average land and sea surface temperature has increased due to an increased greenhouse effect from human activities.[8] Warming has even reached depths of more than 700 meters[9] (30% of ocean warming over the past decade has occurred in the deeper oceans below 700 meters).[10][11] Many marine mammal species require specific temperature ranges to survive. Ocean warming will therefore lead to increased species migration, as endangered species look for a more suitable habitat. If a species cannot successfully migrate to a suitable environment, unless it learns to adapt to rising ocean temperatures, it will face extinction. Sea level rise is also important when assessing the impacts of global warming on marine mammals, since it affects coastal environments that marine mammals species rely.[12]

Primary Productivity

Changes in temperatures change the location of areas with high primary productivity. Primary producers, such as plankton,[13][14][15][16] are the main food source for marine mammals such as some whales. Species migration will therefore be directly affected by locations of high primary productivity. Water temperature changes also affect ocean turbulence, which has a major impact on the dispersion of plankton and other primary producers.[17] Due to global warming and increased glacier melt, Thermohaline circulation patterns may be altered by increasing amounts of freshwater released into oceans and, therefore, changing ocean salinity. Thermohaline circulation is responsible for bringing up cold, nutrient-rich water from the depths of the ocean, a process known as upwelling[18]

Specific marine life and mammals being impacted

Polar bears are one of the marine mammals that are most at risk due to climate change. The biggest issue for polar bears related to climate change is the melting of ice as a result of increasing temperatures. When the ice melts, polar bears lose their habitat and food sources. Although polar bears have been known to eat more than 80 species of animals, most of their diet consists of seals, which are also endangered by global warming.[19] There have been an increasing number of polar bear drownings because they become exhausted by having to swim farther to find ice or prey.[20]

Not only are marine mammals impacted by climate change but so is other marine life. An example of this could be Coral. When coral is introduced to warming ocean temperatures changes, runoff and pollution, overexposure to sunlight extremely low tides and other stresses, the coral will expel an algae growing on them. They have a symbiotic relationship with the algae. When the coral expels the algae it becomes bleached or "completely white". This is called Coral Bleaching. The coral then become more vulnerable to disease and death. [21] Coral reefs make up a large part of our oceans ecosystems that are teaming with life. One of the main homes of coral are in coral reefs. Climate change has caused a synergy between ocean acidification, ocean warming temperatures, and expansions of the oxygen minimum zone that will increase a sensitivity and vulnerability, that will move coral reef resources toward extinction.[22]


  1. Burek, Kathy A.; Gulland, Frances M. D.; O'Hara, Todd M. (2008). "Effects of Climate Change on Arctic Marine Mammal Health" (PDF). Ecological Applications. 18 (2): S126–S134. doi:10.1890/06-0553.1. ISSN 1051-0761. JSTOR 40062160. PMID 18494366.
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