Gaby
Was the air on Earth millions of years ago the same as it is today? Only eyewitnesses could answer that question. And, believe it or not, they’ve been found. These witnesses are icebergs—floating mountains of ice that are millions of years old.
What’s particularly fascinating is that icebergs are composed of 3 percent air, which is released as they melt. Scientists have studied this air and discovered that the oxygen content in the air trapped in young icebergs is the same as that in our modern atmosphere. However, the air contained in older icebergs has significantly less oxygen.
Why is that? Because our atmosphere was created by plants. They absorb carbon dioxide and release oxygen. These oxygen-producing factories generate about 10 trillion tons of life-giving gas each year. If all plants were to die, within about three years, after depleting the oxygen reserves of the atmosphere, both humans and animals would perish.
This is what the icebergs reveal—born in a time when there were fewer plants on Earth and the atmosphere was poorer in oxygen.
