These images from NASA’s Earth Observatory show changes in sea surface temperature (top) and phytoplankton productivity (bottom) between 2000 and 2004. Places where temperatures rose between 2000 and 2004 (red areas, top image) are the same places where productivity dropped (red areas, bottom image). A new study shows warming is linked to a 40 percent drop in phytoplankton since 1950.
Half of all the organic matter on our planet is produced by microscopic plants living near the surface of the world’s oceans. And if a new study published Thursday in Nature is right, these phytoplankton are in significant decline as a result of climate change.
The tiny plants play a critical role in Earth’s biogeochemical cycles, adding oxygen to the atmosphere and removing carbon dioxide. In fact, every day, photosynthesis by phytoplankton removes more than 100 million tons of carbon dioxide from the atmosphere into the ocean. They are also the base of the marine food chain, providing food for zooplankton, which are in turn eaten by fish.
In other words, mess with phytoplankton and you really are messing with a vital component of Earth’s life support systems. We obviously do so at our peril.
The new study shows that as sea surface temperatures have been heating up, the mass of phytoplankton in the surface waters of the world’s oceans has declined at a rate of about 1 percent per year since 1899. The researchers from Dalhousie University in Halifax, Canada also found that since 1950, about 40 percent of the word’s marine phytoplankton have disappeared.
“This is a definite wake-up call that our oceans are becoming increasingly stressed and this is another indicator of that,” said lead author Daniel Boyce, a marine ecologist and doctoral student at Dalhousie. Quoted in an article in the Globe and Mail, he said, “It’s quite shocking to think that there’s been a 40-per-cent decline at the base of the food chain over the past 50 years. I think it’s absolutely cause for concern.”
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