How Fungi Saved the World

For all that we humans worry about saving the world, it was mushrooms that rescued an Earth that had drowned in wood for 40 million years, and even gave us the coal to jumpstart modern civilization:

Here is the crux of our problem: lignin made the lycopod trees a little too successful. Because their leaves were lofted above many herbivores and their trunks were made inedible by lignin, lycopods were virtually impervious to harm. They grew and died in vast quantities, and their trunks piled up in swamps, eventually becoming submerged and locking huge quantities of carbon dioxide out of the atmosphere for good in the form of coal. Without any decomposition to recycle this carbon, atmospheric carbon dioxide levels crashed, leading to global cooling and making it much harder for plants to grow. Atmospheric oxygen concentration, in turn, soared to an estimated 35%, much higher than the 20% of modern times.