After the last IPCC (Intergovernmental Panel on Climate Change) reports synthesising 70 thousands of scientific publications and a million pages of scientific literature, it is certain that climate change is a significant threat to plant and animal health, with 3.3 billion people living in highly vulnerable areas. This climate change is caused by human activities and our use of fossil fuels driving global changes, such as the general increase of the climate temperature. However, the effects of those changes may vary in different areas, for example, land warms up faster than the oceans. The question that we want to answer today is what changes can be expected in Iceland, and how does it affect the wildlife that we observe during our tours?
Environmental changes in Iceland
Fig 1. Sea surface temperature (red) and salinity (blue), measured in Faxaflói bay in the west of Iceland.
Over the past 43 years, the Arctic has warmed up 4 times faster than the rest of the world. Scientists estimate with high confidence that between 2030 and 2050, the Arctic will be practically ice free in the summer. This is a massive shift of the environment that will drastically impact populations of wild animals depending on the ice, such as polar bears, narwhals, walrus, bearded seals, and ringed seals. Iceland is not directly in the Arctic but will be impacted by climate change in many ways. These changes include but are not limited to: increase of water temperature, rise in sea level, changes to salinity, CO2 concentration, pH, rainfall patterns, freshwater inputs, storm frequency and severity, wind speed, sea ice cover and large-scale ocean circulation patterns. Iceland, which earned its name by being partially covered in ice all year long, is losing 10 million tons of ice per year according to NASA, and might become completely ice-less in the future.
The melting of the Arctic is having a big impact on the Gulf stream with a 15% decrease, the first time in a millennium.
Fig 2. Affects of Gulf stream on Iceland
Impact on fish and krill
Icelandic waters are highly productive thanks to the different currents and the continuous sunlight in the summer. The change in all those environmental parameters could produce a shift in those productive locations. Food webs are highly connected and sensitive to change. A modification in the distribution of preys and/or predators can have cascading effects on the entire ecosystem. Studies in Iceland have reported a significant change in sea temperature and salinity, and concurrently a visible change in the fish and krill distribution. Capelin and sand eel populations have been decreasing as well as krill, particularly in the south and west of Iceland. In the meantime, the mackerel population has been extending its range.
Fig 3.Capelin
Like often in systemic changes, the danger comes from the combination of threats increasing the risk of extinction for species. Those changes in prey distribution can be combined with other threats related to climate change such as;
habitat reduction due to human activities in new ice-free areas,
additional competition due to temperate species expansion north-ward,
increase in predation
disease and parasite risks
other unanticipated threats.
Impact of climate change on cetaceans
Whales and dolphins´ position at the top of the food chain makes them an important part of north Atlantic Ocean ecosystems. They can indicate the health of an ecosystem by responding to environmental changes caused by climate change. These environmental and ecological changes might lead to a shift of cetacean species in Iceland. The increase of temperature seems to extend the range of warmer water species northwards, such as of striped dolphins, common dolphins, and Cuvier’s beaked whales. At the same time, they seem to unfortunately cause the range contraction of cold-water species such as white-beaked dolphins (fig. 4 below), which we often observe in Faxaflói bay.
Fig. 4. White-beaked dolphin
For migrating species like humpback whales, it is likely that they will arrive earlier or stay longer in their feeding grounds. It might also increase the rate of baleen whale breeding attempts.
The change of distribution of preys like krill, sand eel and capelin is expected to have a strong impact on cetacean distribution. Minke whales (Fig.5) seem to respond to the prey change - leaving Iceland continental shelf and focusing more on haddock and herring.
Fig. 5. Minke whale
Blue whale sightings have decreased in the west but are increasing in Skjálfandi Bay (Fig.6), Northeast Iceland, signalling a shift in distribution.
Fig. 6. Blue whale in Skjálfandi Bay
For humpback whales and fin whales, a general increase has been documented. The number of humpback whales coming and staying in Iceland even brought scientists to discuss the possibility of the establishment of a new breeding area!
Fig. 7. Humpback whale in Faxaflói
It is very difficult to know if those changes are related to global warming and the change of environmental conditions or to other factors. However, there seems to be a tendency for cetacean species to shift their distribution northward.
Impact of climate change on birds
For the many species of birds observed on our tours, climate change will also bring a multitude of threats.
By increasing the severity of storms, climate change increases adult mortality and the foraging difficulty. Storms also cause nest destruction, for example eroding the islands where puffins like to dig their burrows.
Fig. 8. Atlantic puffin burrows on Lundey
The decrease of sand eels, one of the main prey of Atlantic puffins, also has a vast impact on the population. Particularly in the south, prey availability is reduced during the breeding season.
For long living species like sea birds, adult mortality has a strong impact on the population. A long generation length (the average time between two consecutive generations) slows down the recovery after a few bad years. These animals have a high site fidelity, and so they rarely colonise new areas.
The risks induced by climate change for birds and particularly for auks include an increase of mammal predation like minks and rats. All of the following birds are facing several threats related to climate change that can combine and increase the risk of extinction. Their current breeding area is likely to become less suitable.
Black guillemot, Atlantic puffin, common guillemot, long tailed duck, harlequin duck, velvet scoters, eiders, phalaropes, Northern gannets, shags and cormorants, glaucus, great black backed gull, black legged kittiwake, great Northern diver, Northern fulmar, storm petrel, Arctic skua, Arctic tern.
Fig. 9 Atlantic puffins
Fig 10.Northern fulmar
Fig 11. Great black-backed gull
What to do about it?
For a long time, the stability of our climate has allowed ecosystems to flourish, giving us a perfectly suitable environment. In the last century, human activities and our uncontrolled use of fossil fuels have drastically damaged this balance. For birds, measures can be applied to treat the symptoms of climate change, such as exterminating invasive species, translocating populations, giving extra food during the breeding season, trying to make new colonies more attractive or artificially incubating eggs. For cetaceans it is more difficult to directly take action, and other threats such as overfishing, net entanglement, and vessel strikes are easier to prevent than to cure. However, to minimise this climate shift and to work on the cause and not on the symptoms, it is urgent to embrace moderation, and switch to low-carbon energy.
Written by Miquel Pons