When building computer models to understand global weather patterns and project climate change, scientists look at a lot of variables. There’s surface pressure, temperature, water vapor, cloud cover and land surface area, not to mention pollution levels. But one thing scientists have almost never included is the activity of seabirds.
These birds are top predators in their ecosystem, constantly hovering above the waves in search of food. As new research has shown, however, these seemingly insignificant activities serve a vital function in cooling our planet, and thus regulating climate change.
Gabrielle Nevitt, professor of neurobiology, physiology and behavior at UC Davis and co-author of a recently published paper on the topic, has been researching ocean birds for 25 years. During that time, he was the first to demonstrate that marine top predators actually depend on their nose more than their eyes when searching for food in the featureless ocean.
“When phytoplankton are eaten by grazing crustaceans called krill, they release a chemical signal that calls in krill-eating birds,” explains a UC Davis press release. This is pretty cool all by itself, but as Nevitt discovered, it’s not the only thing accomplished by the dimethyl sulfide, or DMS, released by the plankton. This chemical signal also forms sulfur compounds in the atmosphere that promotes cloud formation and helps cool the planet.
The CLAW hypothesis states that “warming oceans lead to more growth of green phytoplankton, which in turn release a precursor to DMS when they die. Rising levels of DMS in the atmosphere cause cloud formation, and clouds reflect sunlight, helping to cool the planet. It’s a negative feedback loop to control the planet’s temperature,” the release explains. Seabirds help by consuming the grazers and fertilizing the phytoplankton with their iron-rich droppings–a metal that’s scarce in the Southern Ocean.
According to Nevitt and her co-author, graduate student Matthew Savoca, this research is significant for several reasons. First, it demonstrates that predatory seabirds and phytoplankton–at opposite ends of the food chain–both perform important functions that support the ocean’s ability to absorb carbon, as well as the formation of cooling clouds. Second, it underscores the need for ocean conservation, especially with regard to seabirds.
“Numbers of these birds are declining, with almost half of species listed as vulnerable, endangered or critically endangered,” explains the researchers. Failure to protect them could make for significant disruption of marine productivity in the coming years of climate change. Once again scientific research reinforces the sad reality that our disregard for the health of wildlife and ecosystems only harms our own chances for survival.
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