It is official now. The mystery behind the greening of Arctic ice is a fallout of the massive bloom of phytoplankton under the sea.
At the core of the toxic growth of phytoplankton are consequences of global warming. There is a massive erosion of area covered under sea ice, and there is heavy thinning of sea ice.
Strong sea ice cover used to be a buffer against sunlight reaching the water below, preventing plankton growth, as the bulk of the sunlight used to be reflected back into space.
The loss of Arctic ice has been increasing progressively over the decades. The color of sea ice is also changing — white to darker hues. This is because more sunlight has started penetrating the water beneath, the study said.
The research has been published in Science Advances.
Arctic Facing Effects Of Global Warming
Aiding the growth of phytoplankton has been the expansion of dark pools of water on the surface of the Arctic ice. They are called melt ponds that erode the reflectivity of ice.
"Our big question was, how much sunlight gets transmitted through the sea ice, both as a function of thickness, which has been decreasing, and the melt pond percentage, which has been increasing," noted Chris Horvat, the first author of the study. Horvat is attached to the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS).
Horvat notes the trend of zero potential for plankton growth to vast regions of the Arctic engulfing in plankton boom. A comparison will be adequate — in 1997, just 3 percent of Arctic sea ice allowed plankton growth. Today, the summer months are seeing 30 percent of the Arctic ice under sub-ice blooms.
The rapid thinning of Arctic sea ice, also due to global warming, and is letting more sunlight penetrate the water beneath, SEAS said.
Plankton As Core Of Arctic Food Web
The SEAS researchers used mathematical modeling for the study and also looked at the impact and disruption caused to the Arctic food chain from the plankton growth.
Considering the inability of satellites to pierce through the ice to study the subsurface conditions, Horvat used mathematical modeling and did computer simulations for concrete findings. Sea ice conditions were evaluated from 1986 until 2015, and they saw ice thickness had been declining and melt pools were expanding.
Phytoplankton is significant as the base of Arctic food web. Their growth obviously attracts more fish and larger predators. That eventually paves way for more food to the local communities in the Arctic.
Plankton includes algae, bacteria, protozoa, archaea, and animals that drift and inhabit the waters. These are the source of food to marine animals such as the whales and fish.
There are many subgroups that constitute the larger plankton family. They include the phytoplankton living near the water surface and assisting the process of photosynthesis, microplankton, bacterioplankton, and the zooplankton.
As for the depletion of Arctic ice, the latest estimates suggest a record erosion of sea ice levels to 14.1 million square kilometers compared 15.4 million square kilometers that existed between 1981 and 2010.
The temperature rise in Arctic has been sporadic in recent years. Compared to the temperature levels from 1961 and 1990, the average temperature surged up to 11 degrees Celsius.