One of nature's oldest carbon capture devices is also one of its most prodigious

Scientific American has a great article on the ability of the fern-like plant species Azolla to sequester carbon dioxide from the atmosphere. The most amazing stat from the article to me is that:

"Azolla bloomed and died like this in cycles for roughly 1 million years," over which period of time carbon dioxide level "dropped from between 25,000 and 35,000 [parts per million] to between 15,000 and 16,000 ppm."


Azolla. Source: Scientific American

What's so amazing about this?

  1. How much CO2 was in the atmosphere. Humans start to feel drowsiness and reduced cognitive function at about 1000 ppm CO2.
  2. How long it took to draw down these CO2 levels to the <600ppm levels of the past 2.5 million years. 50 million years is a long time -- especially given that scientists predict that only 50 years of unabated emissions will cause CO2 concentrations to rise above the 600 ppm levels not seen in recorded human history.
  3. The fact that the biological systems are capable of sequestering massive amounts of CO2: 1 pmm of CO2 weighs roughly 2 billion tons.