Melting Giant Icebergs May Slow Global Warming

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Giant Icebergs Mother Nature has a way of balancing things out. That’s why nearly all natural phenomena are cyclical, with events peaking at one end of the cycle, and returning to a nadir at the other end, a natural “balancing act” if you will. Climatologists have been studying the global carbon cycle for decades, trying to get a better grip on how Mother Nature produces and recycles carbon, and how these processes are impacting carbon levels and leading to global warming.

In a surprise discovery, researchers announced earlier this week that giant icebergs actually play a major role in the Antarctic carbon cycle, as melting icebergs release minerals and other nutrients that lead to notably increased carbon-consuming phytoplankton populations.

The new study by authors Luis P.A.M. Duprat, Grant R. Bigg and David R. Wilton was published on Monday in Nature Geoscience.

More on how giant icebergs fight global warming

It turns out that as icebergs melt into the sea, they deposit nutrients, such as iron, that in effect fertilize microscopic marine plants that live at the water’s surface. Moreover, the blooming phytoplankton consumes carbon dioxide through photosynthesis, removing carbon from the atmosphere, and potentially slowing global warming.

Scientists have known about this phenomenon for years, but thought it was of relatively small overall impact in the carbon cycle. This new research shows that giant icebergs may be responsible for as much as 10 to 20% of carbon sequestration the Southern Ocean (Antarctic).

Bigg and his colleagues analyzed satellite images of 17 giant icebergs and the plume of phytoplankton surrounding them. The plume, brightly colored by the high chlorophyll in the blooms, extended as much as four to 10 times the length of an iceberg, and could last for as long as 30 days after the iceberg moved on.

Limited good news

Dr. Ronald S. Kaufmann, a marine and environmental scientist at the University of San Diego (not associated with the study) who has researched phytoplankton iceberg plumes. “I would hate for somebody to look at this and say, see it’s a negative feedback, we can do whatever we want and it’s not going to have an effect,” he explains in an interview with the Christian Science Monitor.

“This is moving the needle back in the other direction, there’s no question about that,” Kaufmann notes. “But, whether it’s moving it far enough and fast enough that people will still be able to produce lots and lots of greenhouse gases without worrying about the impacts of climate … I don’t think this is going to offset the burning of coal, for example.”

Study author Bigg also makes the point that the new research is only limited good news on global warming: “This isn’t a large enough effect to take all the carbon dioxide out that’s put in, but it will slow down that rate of increase.”

Statement from study author

“It’s another component of the climate change story,” Grant R. Bigg, a professor in Earth systems science at the University of Sheffield and an author of the new study, elaborates “If giant icebergs hadn’t existed, then the carbon dioxide in the atmosphere would have gone up even more than it currently has. It’s been something which has helped to slow down the rate of increase of carbon dioxide and therefore climate change.”

Bigg concludes his paper on a positive note: “If giant iceberg calving increases this century as expected, this negative feedback on the carbon cycle may become more important than we previously thought.”

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