Microfossils battling against the freezing of the planet might sound like the worst (or best) eighties cartoon ever, but this is a scientific dispute. Some say that the entire Earth froze over several hundreds of millions of years ago, causing a mass die-off of ice-incompatible species (most of them). Now new results dispute those events.
The idea of "Snowball Earth" is that of a positive-feedback-freezing
mechanism. If enough of the ocean is covered in ice, the
lighter-colored surface will reflect more of the Sun's energy back into
space, cooling the planet and causing more glaciation until the entire
Earth is covered. Triggers for this effect include a lack of
greenhouse gases like CO2. With the Earth entirely frozen, CO2 is no
longer absorbed by plant cover, and could slowly build back up until
everything thaws again.
Scientists from UC Santa Barbara delved deep into the Grand Canyon to recover microfossils from the periods around the Planet Snowball events. Their results seem to show that the die-offs and drop in fossil record diversityoccurred some fifteen million years before the freezing - meaning that the icing of the oceans certainly didn't help, but they weren't the cause. Instead their is evidence of "eutrophication", where one species gets a massive boost due to an abundance of some nutrient and crowds out all the other species - similar to the effects in fertilizer-polluted coastal waters.
Of course, there is some way for this story to go. The key problem in Snowball evidence has always been nailing down the dates, and there will have to be the required round of peer response to see how this evidence is interpreted. But if nothing else, you now know it's scientifically possible for the entire planet to freeze - luckily we seem to be going the other way.
Microfossils challenge snowball earth
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