Interesting article by Diana Hayward on yesterday’s ABC Science page:
The key section:
That climatic catastrophe was a global thawing of what Professor Brocks calls a “Snowball Earth”.
Fifty million years before the algae began to bloom the Earth’s oceans were frozen.
But a global heating event caused the glaciers to melt and as they did they released nutrients into the ocean.
“This increased phosphate fertiliser in the oceans,” Professor Brocks said.
And when the Earth cooled to more hospitable levels it created perfect conditions for algae to spread.
“It appears this huge release of nutrients after the melting of this snowball Earth event triggered the evolution of this larger algae and replaced bacteria.”
“Algae are incredibly large in comparison to bacteria. And you need large and nutritious organisms at the base of the food webs to create the burst of energy towards higher and bigger organisms,” Professor Brocks said.
So it all started with global warming and the subsequent explosion in algae.