The effects of climate change are being felt in the Arctic more immediately and severely than in most other regions in the world. Even inferentially, the Arctic is warming at a rate that is two times that of the global average. The thing that is most visible and catches the world’s attention is the lessening of Arctic sea ice along with permafrost and the changing Arctic weather, leading to a rapid decline also in glacial ice in Greenland. However, climate change also affects Arctic marine mammals, uniquely adapted to seasonal sea ice formations in the Arctic.
Examining Climate Change Impacts in the Current Context
The seas around the British Isles are progressively becoming warmer, and in recent findings, this has incidentally occurred together with a northward shift in zooplankton (Beaugrand et al., 2010) and sea fish (Cheung et al., 2009) populations. The boundaries to the north and south of the areas where these species reside are where these changes have been reported to be the most evident.
Along with the movement of these populations, similar movements have also been reported among some cetacean species of marine mammals. For example, some species of dolphins inhabiting warmer waters such as the short-beaked common dolphin and the striped dolphin have extended their habitat range northwards off the coast of western Britain towards the northern reaches of the North Sea and are present there even during winters.
Among other warm water marine mammals, the beaked whale for instance was recorded for the first time in these waters in 1993, Fraser’s dolphin in 1996 and the dwarf sperm whale in 2011. Since 1980, 10 out of 11 strandings of the pygmy sperm whale have occurred at the coasts of Britain and Ireland (Deaville & Jepson, 2011). Cuvier’s beaked whale, another warm water species, had registered 18 strandings at the coasts of the British Isles between January and April 2008 (Dolman et al., 2010). These strandings have occurred much further northwards than could be expected for these species, although no direct link to climate change could be directly deduced.
Interestingly however, such an increased frequency has not been recorded for species whose habitats range northwards of the British Isles. For example, it has been greater than a century since the bowhead whale has been reported southwards. Similarly narwhal whales have not been reported since 1949, and just 3 reports of beluga whales have surfaced since the 1970s (Evans, 2008). However it must be remembered that sightings are limited also by the vastness of the oceans and the limited nature of human involvement here. Strandings however are much easier to document than sightings. These strandings could be said to be possibly caused by decadal climatic cycles such as the North Atlantic Oscillation and need not necessarily be the result of long term climate change.
Although tracking cetacean species in the open ocean is a bit difficult, studies of breeding, population changes and movement, and feeding habits of seals are much easier compared to cetacean species among marine mammals. This becomes more important that seals are hugely dependent on sea ice, one of the principal variables of climate change, where seals frequently surface and spend time on.
Although several studies have tried to link climate change to changes in seal populations, no clear evidence can be said to connect the two. An entire gamut of factors besides climate can also be involved in fashioning the food habits for example of Arctic seal populations, with fishing depleting food resources for seals as an instance. However, warming seas have had major impacts on seal populations, such as the recent report of domoic acid in faecal samples from harbour seals in the North Sea, which is a neurotoxic acid produced by diatomaceous algae that could have been produced due to the warming of the sea.
Sea ice importantly acts as breeding grounds for Arctic seals, where seal pups can be conceived and reared by seal populations. In the period between 1998 and 2003 in the Barents Sea, about 360,000 seal pups were produced annually. However, in the period between 2009 and 2010, only 160,000 seal pups were produced annually based on estimates. This again cannot be directly attributed to climate change, but a significant role in this was played by the conditions of sea ice in the White Sea after 2003 (Haug & Oigard, 2012).
However, in the East Greenland Sea northwards from Jan Mayen, a Norwegian volcanic island situated in the Arctic Ocean, the dramatic change in sea ice conditions had led to a great decline in the populations of hooded seals from the 1940s till 1980. Since 1980, the hooded seal populations have maintained a population between 10 and 15 per cent of the population size recorded in the 1920s. The population progressively declined also between 1997 and 2007 (Haug & Oigard, 2012). In these periods, although hooded seals were heavily harvested, which is now prohibited, the reduction in suitable sea ice as sanctuaries for hooded seal populations also is a significant factor (Evans & Bjorge, 2013).
Climate Change and its Possibilities
Climate change can have a profound effect on the availability of sea ice, which acts as a marine habitat, most notably for seals. The destruction of sea ice as habitat can lead to an extensive redistribution of species dependent on sea ice and the corresponding effects on species dependent on these species. The progress of global warming in the Arctic has introduced changes in the volume and extent of sea ice cover and also deterioration, fragmentation and an altered seasonality of sea ice (Wang & Overland, 2009), and this is an effect that can be observed even in present times.
This can have consequences such as reduced fitness of sea ice dependent species and altered parameters determining populations for these species (Laidre et al., 2015). This is important given that less land is available in the Arctic than in the Antarctic. There thus is an imminent chance of restructured food webs in the Arctic due to this form of habitat change and the introduction of new alien invasive species from the temperate seas (Moore, 2016).
The decline of sea ice in the Arctic is also creating greater opportunity for human activity, with many detrimental effects on marine mammals. The long and growing seasonal open water in the Arctic is leading for example towards oil and gas exploration, commercial fishing, shipping, tourism and military operations. Arctic marine mammals are now more vulnerable to threats such as ship-strikes, fishing, pollution, etc.
Possible effects of climate change on Earth’s oceans could also include alterations in water, nutrient cycles and energy pathways in these oceans (Macdonald et al., 2005). Also, atmospheric and oceanic circulation patterns could be altered by climate change (Schmittner, 2005). These can have severe ecological and biological consequences for oceanic ecosystems, especially Arctic ecosystems – where the effects of climate change are the most immediate and severe. These changes to Arctic ecosystems can then cascade throughout other ecosystems on Earth.
There can be no reliable quantification of long-term risks at present, although they can range from positive to mild to negative for Arctic marine mammals. The severest effects are most likely to occur for those marine mammals with inflexible needs and those marine mammals dependent on specific habitat types (Laidre et al., 2008).
Undergoing severe negative impacts of climate change could lead to species of marine mammals experiencing a reduction in population, with more extreme effects such as degradation of organs within a range of habitats and even extinction being possible. Polar bears that swim and fish in the Arctic could possibly feature as an example of these negative effects, with the Centre for Biological Diversity (2017) warning that two-thirds of the global polar bear population could be extinct by 2050 if global warming continues to melt Arctic ice habitats.
However there could be multiple negative impacts on Arctic marine mammals, most of which involve major changes in the Arctic habitat. What is difficult to predict however is the full extent of the effects of habitat degradation on Arctic marine mammals because of the overall unpredictability of climate change’s domino effects on Arctic habitats and anthropogenic effects on climate change that are yet to be fully reigned in along with a host of other factors.
Most effects however, are most likely to be treated as concurrent risk factors. Most models of climate change usually are used to generate physical changes due to climate change (Ragen, Huntington & Hovelsrud, 2008). Although the extent of the biological and ecological effects on Arctic marine mammals cannot be fully anticipated, policy on conservation is being planned based on the anticipated changes that can be observed.
Apart from regulating greenhouse gas emissions more tightly, which form part of the preventive steps towards conservation, most conservation aims at mitigating the effects of climate change. Most of these measures are short-term measures placed concurrently to tendencies of the impacts of climate change on Arctic marine mammals in our case.
To begin with, many fishing prohibitions have been introduced on marine mammals also with a view to protecting their prey species, which is especially relevant with the reduction in sea ice. Mitigation measures are also species-specific, with captive care of animals with poor health or slow growth, vaccination against diseases, protection of multiple stocks and populations to ensure survival, protection of key reproductive habitats and the cleaning of contaminants are some of the conservation measures that have been adopted by policymakers and conservationists alike for protecting marine mammals from the adverse effects of climate change.
Some other conservation measures that have been introduced include removal of predators for species on the brink of disappearance, restrictions on the passage of ships, regulations on resource extraction, coastal development, tourism and on military activities. Declaring certain regions as marine protected areas might be useful in conserving certain habitats and also in greatly minimizing the adverse effects of anthropogenic activity. These would require extensive zoning, buffers and and also management of these areas. These marine protected areas should also crucially protect marine mammals against habitat change.
Other conservation efforts are focused on conserving genetic diversity among certain species, identification of stock populations, prevention and isolation of habitats, regulations centred on human activity, and monitoring of population statuses of marine mammals (Ragen, Huntington & Hovelsrud, 2008). Of these, the last i.e. taking stock of populations and documenting them would enable informed decisions in checking the effects of climate change in the Arctic. This would enable better precautionary and adaptive solutions in tackling the effects of climate change on the Arctic.