Some 2.4 billion years ago

Around 2.4 billion years ago,cyanobacteria evolved to become our planet”s first photosynthesizers.

Finally , we had some oxygen producers, to make Earth”S atmosphere much more hospitable.

And the rest is histoy, folks.

Just kidding. we”ve still got a long way to go.

With all this new oxygen.

Earth”s atmosphere had much lower levels of carbon dioxide.

And that made the planet icy cold.

Much of our young world froze over as Earth saw its first ice age.