Canada – June 6th, 2013
Contrary to the name global warming, we do not see temperatures increasing everywhere in the world. In the Arctic region western North America and Siberia are following the global trend of warming, but in areas of Hudson Bay and Greenland the temperature on average has been decreasing over the last 50 years during the winter months.
Ecosystems in these areas and the organisms that live there may become threatened by this climate cooling. Reserachers are still working on understanding the causes of the cooling, including changing patterns in ocean and air currents due to climate change. In many areas they have experienced an average decrease in temperature of 4°C . This decrease in temperature may not sound like a large amount, but it is enough to disturb the natural cycles of the Arctic, and the unqiue ecosystems found there.
One of the most extraordinary systems of the Arctic that is being threatened by climate change are polynyas, which is the Russian word for ice hole. These are open areas of water surrounded by pack ice. They occur where ocean currents, wind, and upwelling warm water prevent ice from forming at the surface. In the Arctic Ocean these open areas can be surrounded by sea ice that is greater than 2 meters thick! Many Arctic polynyas are small at only a few square kilometers, and some are large, such as the North Water Polynya, which is about 50,000 km2.
These regions are important to many local species such as polar bears, marine mammals, and seabirds. Many animals have adapted to not migrate south during the winter months, and instead use polynyas as refuge from the miles and miles of ice and snow.
In some areas abrupt climate change is contributing to climate cooling in areas such as south east Hudson’s Bay where polynyas are freezing over more often than seen in the past. For the species that depend on these areas this means that their holes of refuge disappear when needed most. While in other areas climate change is causing ploynyas to open earlier in the season. This may lead to increased primary productivity in some areas, but the reduction sea ice will have negative impacts on ice dependant species (click here for more information).