ALGAE, OCEANS, RAIN, 500PPM's NASTY CONSEQUENCES


These excerpts are from the November/December issue of Update, the magazine for members of the New York Academy of sciences, in an article about James Lovelock's latest book The Revenger of Gaia.'

'In 2001, the Amsterdam declaration on Global Change ... said: "The Earth System behaves as a single, self-regulating system comprised of physical, chemical, biological and human components. The interactions and feedbacks between the component parts are complex and exhibit multi-sclae temporal and spatial variability." '

'Take the ocean and algae. Above 4 degrees Celsius water expands as it warms, and if it is warmed from above by the sunlight, the top layer of the ocean absorbs the sun's heat and expands to form a lighter layer than the cooler waters running beneath. That layer forms when the sun is strong enough to raise the surface temperature above about 10 degrees Celsius. What then happens is that the surface layer remains stable and does not mix with the lower layers. The surface layer has a depth of only about 30 to 100 metres and it puts a tremendous constraint on ocean life. In the course of a warm season all the nutrients in it can get used up, and their dead bodies sink to the bottom, leaving only small, starving populations of algae. "This is why warm and tropical waters are so clear and blue; they are the deserts of the ocean."

'Algae are unusually influential in the Earth's climate. They remove carbon-dioxide from the air and use it for growth in a process called pumping down. They are also the source of the gas dimethyl sulphide, which oxidises in the air to become the tiny nuclei that seed the droplets of clouds. Algae face threats on several fronts. Besides warming waters, there is a threshold of carbon-dioxide abundance at which they fail to be able to engage the removal process. This occurs at about 500 parts per million (ppm). According to Lovelock, at our present rate of growth we will reach 500ppm within the next 40 years.' [It is now 380ppm, increasing at over 2.5ppm per year, rising.]