Fix Hothouse Earth Just Like Last Time

The world has been a hothouse most of the last 540 million years. Humanity can mimic what naturally occurred to turn a hothouse Earth 15C warmer than today into a -9C ice age. We can just do a little less aggressively and in more precise amounts to cool 1.2C.

A Smithsonian Institution project has tried to reconstruct temperatures for the Phanerozoic Eon (aka the last half a billion years). Preliminary results released in 2019 showed warm temperatures dominating most of that time, with global temperatures repeatedly rising above 80°F and even 90°F—much too warm for ice sheets or perennial sea ice. About 250 million years ago, around the equator of the supercontinent Pangea, it was even too hot for peat swamps.

Over 98% of the last 540 million years the earth has been far warmer than it is today.

When it is very hot, there were tropical forests and jungles over much of the Earth.

Over the last 100 million years, global temperatures have peaked twice. One spike was the Cretaceous Hot Greenhouse roughly 92 million years ago, about 25 million years before Earth’s last dinosaurs went extinct. Widespread volcanic activity may have boosted atmospheric carbon dioxide. Temperatures were so high that champsosaurs (crocodile-like reptiles) lived as far north as the Canadian Arctic, and warm-temperature forests thrived near the South Pole.

Another hothouse period was the Paleocene-Eocene Thermal Maximum (PETM) about 55-56 million years ago. Though not quite as hot as the Cretaceous hothouse, the PETM brought rapidly rising temperatures. During much of the Paleocene and early Eocene, the poles were free of ice caps, and palm trees and crocodiles lived above the Arctic Circle.

The Paleocene-Eocene Thermal Maximum (PETM) warming period was bout 20,000 to 50,000 years long and it lasted for 200,000 years.

A PBS special discussed the PETM but focused on the fact that human-based global warming is acting faster than whatever caused the PETM. The PBS special glosses over the Azolla event. The Azolla event is the theory that this plant grew and covered the Arctic and then sank to the bottom of the ocean taking trillions of tons of carbon to the bottom and ending a warming event that is 12C-15C degrees warmer than we have today.

They skipped over the outline of the solution to our current issues. We could bioengineer Azolla to grow very well in saltwater. We generate a trillion tons of it and have it sink to the bottom of the ocean. Then we follow up to cancel out the 40 billion tons per year of CO2 we are generating. The extra CO2 gets removed and we are at 1850 levels. Cheap, easy, fast and mimicking nature’s solution to excess CO2.

800,000 years of Azolla bloom episodes and a 4 million square kilometer basin to cover. Carbon was sequestered by plant burial to account for the observed 80% drop in CO2 by this one phenomenon alone. Other factors almost certainly played a role. This drop initiated the switch from a greenhouse to the current icehouse Earth. The Arctic cooled from an average sea-surface temperature of 13 °C to today’s −9 °C.

Grow bioengineered Azolla, seaweed, kelp or create massive algae blooms and sink them to the bottom of the ocean. Algae blooms can be created in a day using iron fertilization. 100 tons of iron dust was placed into the ocean and it generated a 10 million ton algae bloom. It only took 5 guys on a small “Jaws” movie sized boat to sequester more carbon than the billion-dollar Weyborne project to capture fossil fuel emissions to sequester a million tons.

We should use the tried and true and natural method of planetary scale cooling. Grow and sink the right amount of plants to remove up to trillions of tons of CO2. Plant and algae growth is the proven way to remove CO2 from the atmosphere for billions of years. The world has cycled through dozens of cooling events. Grow a lot of plants and sink them in the ocean. The carbon gets stored at the bottom of the ocean and compressed at high pressures and then becomes part of the earth’s crust. We know that it works, it is good for the environment, it works at scale and it stays cooled for millions of years.

SOURCES-, PBS, Curiosity stream, wikipedia
Written by Brian Wang,