Could iron dust stop global warming in its tracks?

Illustration for article titled Could iron dust stop global warming in its tracks?

The Ice Age can be explained by some well-placed specks of iron. Adding dust to the waters around Antarctica can supercharge plankton growth, causing global temperature drops. To stop climate change, we need a whole lot of iron filings.

Here's how the process works. Most of the time, the Southern Ocean is pretty much bereft of life, because there aren't enough resources to sustain plankton populations. However, every so often the Earth will slightly wobble on its axis - this is known as the Milankovitch cycle - and this has widespread climatic implications. The Earth begins to cool, the continents become more arid, and this in turn kicks up huge dust storms that, ultimately, end up in the Southern Ocean.

Those dust storms carry huge amounts of iron to the polar region, enough to jump-start the creation of massive amounts of plankton. These plankton get to work sucking up carbon dioxide, which is also crucial to keeping the planet cool over time. These iron deposits are enough to fuel entire Ice Ages, and you can probably see the possible application in today's warming world. Of course, we don't want to start dumping huge amounts of iron into the oceans unless we're pretty damn sure that it's going to work.


Now, thanks to research by Alfredo Martinez-Garcia of the Swiss Federal Institute of Technology, we have our most solid evidence yet. Analysis of marine cores taken from the southern Atlantic Ocean reveal that, going back four million years, dust levels are twice as high during periods of deep glaciation - in other words, during the Ice Ages - than they were normally. That's fairly compelling evidence that iron dust can have a major cooling effect on the planet's climate.

So far, we've done some minor experimentation with dumping iron filings into the ocean, but unfortunately we haven't produced anything more than some small plankton blooms. The issue may well be one of scale - this might be a solution that we have to commit to completely for it to work - and larger-scale experiments might now be in order. That's definitely risky, but at least it looks like the available evidence has tilted decidedly in its favor.

Nature via New Scientist. Image via.

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The main kind of plankton that they're trying to fertilize with iron is called Prochlorococcus ( [] ). It's the smallest photosynthetic organism known (less than a micron across), and wasn't even discovered until the 1980s. One of its discoverers, Prof. Sallie Chisholm of MIT ( [] ), is dead set against this fertilization idea. She knows as much about this creature as anyone on earth, and she knows she doesn't know enough to predict what would happen. She writes about it here: [] .

For instance, what actually happens to the plankton after they grow? The hope is that they sink to the bottom taking their carbon with them, but what if they just die and decay? That sucks all the oxygen out of the seawater and kills everything else, as in algae blooms. The decay produces methane, which is a much worse greenhouse gas than CO2.

More about this and Chisholm on my blog: [] .