Since the early 1990s, satellite data has recorded regular rises in sea levels all over the world due to the warming of seas and oceans in addition to other phenomena such as El Niño. The National Oceanic and Atmospheric Administration (NOAA), warned in its report published in December 2019 that the Arctic has experienced a heat wave two times faster than the world average.
The arctic heat
The average temperature recorded on the surface of the arctic land between October 2018 and September 2019 was the second highest, behind 2016. This wave is mainly due to global warming which has caused longer periods of ice melt and less glacier masses. In particular, the mean sea surface temperature for August 2019 was significantly higher than the August average for the 1982-2010 period, in the Beaufort, Chukchi, Laptev and Baffin seas.
The impacts of arctic heat on marine organisms
The most dangerous and irreversible consequences of global warming are particularly pronounced in the Arctic. The rapid loss of ice of sea surfaces and rising temperatures are changing the distribution and abundance of many marine organisms.
Studies of population changes of arctic species tend to focus on mammals such as polar bears. Mammals have more potential to move around to adapt to changing resource availability than other species.
Indeed, polar bears have been known for their ability to disperse over very long distances and therefore adapt to a changing Arctic. However, recent research suggested that this species has already surpassed its ability to adapt to climate change and long periods of fasting, and their ability to adjust long-term adaptations remains uncertain.
According to records, the sharp increase in sea surface temperature was recorded in the northwest, mid-east and south-east of Greenland in the period 1993-2018. The narwhal is a species of cetacean that has an original distribution in these seas.
Narwhal occurs primarily in the High Arctic and Subarctic regions of the North Atlantic and adjacent waters. It is distributed widely from around Franz Josef Land in the east, around Svalbard, along East Greenland, in central and northern parts of West Greenland, along the east coast of Baffin Island, in the Canadian high Arctic archipelago, and in northern Hudson Bay and Hudson Strait.
This species was the subject of several studies as its population is in great decline. One of the recent studies attempted to assess thermal exposure and its impact on the distribution of narwhals; where 144 narwhals were tracked via satellite at 17 abundance sites.
Study results suggested that rising sea temperatures generated low abundance of narwhals in the middle-east and south-east Greenland where average summer temperatures were the highest (6.3 ° C) , with a total number of individuals less than 2000 compared to the cold waters of the Canadian Arctic Archipelago (0.7 ° C) that recorded larger populations of narwhals, more than 40 000 individuals for the period 1993- 2018.
In addition to changes in their natural habitats, narwhals had been hunted by humans in Greenland and Canada for centuries, and their predation by polar bears and orcas has doubled.