Oceans are the lifeblood of our planet and plankton its red blood cells…and both are dying…fast!If oceans are the lifeblood of our planet, then plankton are its red blood cells. Unfortunately, plankton has declined up to 40 percent since 1950—a rate that is only increasing due to climate change. “Phytoplankton are a critical part of our planetary life support system,” Boris Worm of Canada’s Dalhousie University commented. “They produced half of the oxygen we breathe, draw down surface CO2, and ultimately support all of our fisheries.“An ocean with less phytoplankton will function differently,” Worm added. His colleague, Marlon Lewis, notes that plankton are the equivalent of grass, trees, and other plants that make the land green. “It’s frightening to realize we have lost nearly half of the oceans’ green plants,” Lewis told reporters. The problem is only expected to get worse. Climate change is warming the oceans about 0.2C per decade on average. This warm water tends to stay on the top layer because it is lighter. That’s a problem for plankton, which depends on light and can only live in the top 100 to 200 meters. Plankton runs out of nutrients to feed on unless cold, deeper waters are mixed with water near the surface. But ocean stratification has been widely observed in the past decade. It is in larger areas of the world’s oceans.
So what make plankton so important? Not only do they feed nearly every living species in the ocean, but they also absorb and sequester CO2 from the atmosphere and play a key role in cloud formation. They produce dimethyl sulfide, a chemical floats to the ocean’s surface, breaking down into sulfur compounds that become nuclei around which clouds form.
Worm, Lewis and their colleague Daniel Boyce found that most phytoplankton declines occurred in polar and tropical regions, and in the open oceans where most phytoplankton production occurs. They discovered a direct correlation between rising sea surface temperatures and the decline in phytoplankton growth throughout most of the globe. This has also led to a decline in the number of species in tropical waters and increases in the number of species in temperate waters.
Unless we start cutting global emissions by five percent per annum, our ecosystem could be at risk.