A single drop of seawater holds millions of phytoplankton, a mix of algae, bacteria, and protocellular creatures. Across the world’s oceans these photosynthesizing microbes pump out more than half of the planet’s oxygen, while slowing climate change by capturing an estimated 25% of the carbon dioxide (CO2) released from humanity’s burning of fossil fuels. But the scale of this vital chemistry is mostly a guess, and there’s little sense of how it will change as temperatures rise. “What’s happening out there? We have no idea really,” says Susan Wijffels, a physical oceanographer at the Woods Hole Oceanographic Institution.
Soon, 500 drifting ocean floats studded with biogeochemical sensors will deliver answers. Today, the National Science Foundation (NSF) announced it will spend $53 million to fund the new floats, marking the first major expansion of the Argo array, a set of 4000 floats that for 15 years has tracked rising ocean temperatures. “This is going to be revolutionary,” says Wijffels, a leader of the original Argo program. In addition to standard Argo measurements of temperature and salinity, the new floats will have sensors measuring oxygen, sunlight, particles, chlorophyll (a gauge of phytoplankton abundance), nitrate (a key nutrient), and pH (acidity). Researchers will be watching that last reading closely, because acidity reflects both the ocean’s uptake of CO2 and its pernicious effect.
Researchers plan to begin deploying the new floats next year in the equatorial Pacific, where El Niño and La Niña drive large temperature swings every year or two. The floats could show how the swings affect the ability of phytoplankton to soak up carbon, offering clues to how a warming climate will change the ocean’s overall carbon uptake.
Source: Science Mag
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