Massive icebergs release vast trail of nutrients that act as fertilizers for CO2-guzzling algae
Thomson Reuters Posted: Jan 13, 2016 10:31 AM ET Last Updated: Jan 13, 2016 12:32 PM ET
The biggest icebergs breaking off Antarctica unexpectedly help to slow global warming as they melt away into the chill Southern Ocean, scientists say.
The rare Manhattan-sized icebergs, which may become more frequent in coming decades because of climate change, release a vast trail of iron and other nutrients that act as fertilizers for algae and other tiny plant-like organisms in the ocean.
These extract carbon dioxide from the atmosphere as they grow, a natural ally for human efforts to limit the pace of
climate change blamed on man-made greenhouse gas emissions.
Ocean blooms in the wake of giant icebergs off Antarctica absorbed 10 to 40 million tonnes of carbon a year, the study estimated, roughly equivalent to annual man-made greenhouse gas emissions of countries such as Sweden or New Zealand.
Until now, the impact of ocean fertilization from the demise of giant icebergs, defined as floating chunks of ice longer than 18 kilometres or almost the length of Manhattan, had been judged small and localized.
“We were very surprised to find that the impact can extend up to 1,000 kilometres,” (625 miles) from the icebergs, Prof. Grant Bigg of the University of Sheffield, an author of the study published in the journal Nature Geoscience, told Reuters.