Ancient Upheavals Show How To Geoengineer A Stable Climate

... The second example, the Azolla event, was only discovered in the last 20 years, and was extremely specific in its mechanism. In the early Eocene, global surface temperatures were 8 ℃ higher than today. Tropical forests extended almost to the poles, and atmospheric CO2 concentration was 3500 ppm, in contrast to today’s 400 ppm. Around 49 million years ago, the global climate suddenly cooled by 6 ℃, with a simultaneous drop of atmospheric CO2 to 650 ppm. The cause of this drop in temperature and CO2 was unknown until a convincing hypothesis was proposed in 2004:The Arctic Coring Expedition took advantage of reduced ice cover to take core samples from the Lomonosov Ridge, in the Northern Arctic Ocean.

To their surprise, they discovered huge deposits of the freshwater aquatic fern Azolla locked under the seabed. These deposits, up to 20 meters deep, were laid down 49 million years ago, sustained over 800,000 years, and exactly coinciding with the observed drop in temperature and CO2. Noting this correlation, the researchers proposed a causal link, now widely accepted, between the strange growth of Azolla, and the massive drawdown in atmospheric carbon dioxide, accounting for the sudden global cooling in the Eocene.

Azolla is incapable of growth in salt water, and so was only able to grow in huge volumes in the Arctic Ocean due to a set of unusual factors involving a freshwater surface layer. These factors also ensured that the carbon absorbed by the fern through photosynthesis was sequestered on the seabed rather than being returned to the atmosphere when the plants decomposed.

During the Eocene, the Arctic Ocean had limited water exchange with the rest of the world oceans, and received the flow of a number of large rivers. The lower density freshwater from these rivers pooled on the surface, causing a low salinity layer to form. This layer prevented mixing of the water column, and created a seabed with extremely low oxygen levels, while also enabling Azolla to proliferate across the surface. As a floating plant with leaves above the water, Azolla had direct access to atmospheric CO2. Additionally, and unusually among ferns, Azolla is able to fix nitrogen directly from the atmosphere using a bacterial symbiosis, removing a further limitation to growth. Most decomposing organisms require oxygen for their metabolism, and this was severely depleted on the seabed. Therefore, when the ferns died and sank, they were preserved intact until buried by sediment, and the carbon they had absorbed in life was locked into the sedimentary rock under the sea. Ironically, much of the oil and natural gas resources currently under active exploration in the Arctic are composed of these Azolla deposits.

GOOGLE GEOENGINEERING GROUP moderator Andrew Lockley

ran the Palladium lnk and has invited comments from militatnt vegans bent on
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