Sea ice seems to be changing faster than ever, prompting greater concern over global warming and the problems it is certain to cause. But researchers conducting a study with the University of Toronto Mississauga (UTM) have a new method of tracking sea ice long-term, revealing that over the last 150 years, sea ice decreased faster than ever. These new findings are definitely thought provoking.
Coralline Algae Track Changes in Arctic Sea Ice
Working with colleagues from Washington’s Smithsonian Institution, Newfoundland, and Germany, Jochen Halfar, who is an associate professor at UTM’s Chemical and Physical Sciences Department, has discovered that coralline algae can be used to keep track of changes in Arctic sea ice. “We found the algal record shows a dramatic decrease in ice cover over the last 150 years.”
The team focused on collecting and analyzing samples of the long-lived algae Clathromorphum Compactum, which is widely distributed throughout the Arctic and sub-Arctic oceans, and which forms thick, stony calcite crusts on the seafloor at depths of fifteen to seventeen meters. This algae’s growth rates are dependent upon water temperature, as well as upon the amount of life that they receive. When snow-covered sea ice covers the water where the algae is present, the plants stop growing due to cold, dark conditions. When the sea ice melts away during the summer, algal growth continues.
Clathromorphum Compactum can live for hundreds of years, and this is of great value to scientists, as the continuous cycles of growth and dormancy result in visible layers similar to a tree’s growth rings. These layers can be used to determine the amount of time the plants spend in each phase of growth and dormancy. In addition to counting the rings, the researchers used radiocarbon dating to confirm accuracy.
During a period known as the Little Ice Age, which was a time of global cooling that lasted from the middle of the 16th century to the middle of the 19th century, the algae grew in extremely narrow increments due to extensive sea ice cover. As the Little Ice Age came to an end, the growth bands became wider. This is not what has scientists expressing alarm over global warming; the fact that algal growth rings are twice the thickness that they were in 1850 however, is cause for concern. Even worse, growth rings have become even thicker over the past few centuries, bearing witness to warming on a massive scale.
Halfar states that the coralline algae represent a new method for reconstructing climate evidence, and he also states that they are vital to increasing knowledge of the planet’s past climate record. Before the algae were discovered and studied, observational records extended for only 150 years; truly reliable evidence in the form of satellite imagery has only been available since the late 1970s. These algae, which can live to be more than a thousand years old, can now provide us with information about climate, water temperature, and sea ice coverage. Having access to this information will allow scientists to continue gathering important evidence elected officials can use to implement the change that’s needed to reverse the alarming warming trend.