The Azolla event occurred 49 million years ago in the Arctic Ocean, where the freshwater fern Azolla colonized a thin layer of fresh water, sequestering carbon dioxide and causing the Earth’s greenhouse effect to break. The event led to a shift from a “hothouse earth” to a “frozen earth” dynamic, culminating in the current ice age.
The Azolla event was a catastrophic biogeological event that occurred approximately 49 million years ago (the Middle Eocene) in the Arctic Ocean, which was warm and ice-free at the time. The Arctic Ocean was blocked on all sides by continents, as Greenland, Europe, Asia and North America were all connected to the north. This body of water became stagnant, just like the Black Sea today. Large amounts of rain carried nutrients and fresh water into the Arctic Ocean (some might call it the Arctic Sea), creating a thin layer of fresh water at the surface.
This layer of fresh water would ultimately prove to have a major impact on the planet’s climate. Shortly after its formation, it was colonized extensively by the freshwater fern Azolla. This species is sometimes considered a “super plant” due to its rapid reproduction – it can double its biomass in 2-3 days under optimal conditions – and excellent nitrogen and carbon fixation capabilities, up to one ton per acre per year of nitrogen and six tons per acre per year of carbon. As Azolla began to cover the 4,000,000 square kilometers (1,544,000 sq mi) basin, the Azolla event began, as dead ferns began to sink to the seabed, where anoxic conditions, caused by lack of column mixing water, made debris was fossilized without being digested by bacteria.
After 800,000 years of fern formation, carbon and nitrogen fixation, and carbon sequestration at the bottom of the Arctic Sea, the Azolla event has begun to impact global carbon dioxide levels. The carbon dioxide content in the atmosphere has dropped from 3500ppm (parts per million) to just 650ppm. Carbon dioxide sequestered by the Azolla event caused the Earth’s greenhouse effect to break, and the poles began to cool rapidly. Prior to the Azolla event, the average surface water temperature in the Arctic Ocean was 13 degrees C (55.4 degrees F), and after that it was -9 degrees C (15.8 degrees F), which continues to be the average today.
The Azolla event has had a huge impact on climate models up to the present day. The fundamental “hothouse earth” dynamic has given way to a “frozen earth” dynamic, whereby the formation of glaciers has made the earth’s surface more reflective, further cooling it. The entire previously forested continent of Antarctica slowly began to freeze. The effect culminated in an ice age that began about 23 million years ago and continues to the present day. Although we are currently in the midst of an ice age, the fact that the contemporary period is an interglacial means that continental glaciers are limited to Greenland and Antarctica. For most of human history, glaciers covered large parts of North America and Eurasia.
Protect your devices with Threat Protection by NordVPN
