Friday, November 21, 2014
Viv Forbes: Carbon Capture and Burial – a Biocidal Policy
There are four non-toxic gases-of-life in Earth’s protective atmospheric blanket. None should be captured and buried.
The most abundant is nitrogen – 78%. If there was no nitrogen there would be no plant or animal protein and a very different world.
Next most abundant is oxygen – 21%. Without oxygen most of today’s animal life would die within minutes. Both nitrogen and oxygen can moderate climate by absorbing surface heat and transferring it aloft by convection.
Then comes marvellous water, whose vapour comprises a variable 0.1 - 4% of the atmosphere, while liquid water fills the oceans, lakes and rivers that cover 70% of Earth’s surface and makes all clouds, snow and ice. Water vapour is Earth’s most effective “Greenhouse gas”, except in the very dry air at the poles. Water and water vapour moderate the extremes of temperature on Earth, cooling the hot tropics by evaporation and convection and, by delaying the loss of surface heat, often keep nights warmer than they would otherwise be.
The rarest gas-of-life is carbon dioxide with just 0.04% (400 ppm) of the atmosphere - a tiny amount which is almost the lowest it has ever been in the long history of the planet. Most life probably evolved at levels of 1,000 ppm or more and the dinosaurs flourished in air with 1,800 ppm of CO2. However, this trace gas provides the building blocks for all life on Earth. Without carbon dioxide all plants would die, quickly followed by all animals. It is also a temperature moderating “Greenhouse gas” but generally less effective than water vapour.
Earth’s biosphere is often stressed by having insufficient natural supplies of the two rarest of these gases of life – water vapour and carbon dioxide. In particular, plant life would benefit from considerably more carbon dioxide than is currently present in the atmosphere – at 150 ppm plant growth ceases, at 2,000 ppm (five times current levels) plants thrive; and 400 million years ago, life flourished with 4,500 ppm CO2. US submariners live comfortably in air with 5,000 ppm and human lungs exhale air with about 45,000 ppm CO2.
Unfortunately, natural processes are continually capturing the rarest gas of life, carbon dioxide, and burying its contained carbon under oceans and lakes.
Earth is composed mainly of igneous rocks – molten magmas at depth and solid igneous rocks like basalt, granite and gabbro near the surface.
Natural processes of erosion are continually degrading these primary rocks, producing gravel, sand, silt and clay which are moved via rivers towards the sea. Floods also sweep dead plant and animal material into lakes and oceans. As these suspended erosion products meet still water, the solid materials are deposited as sandstones, shales and carbonaceous beds. This process removes carbon dioxide from the biosphere, burying it in the lithosphere.
Carbon dioxide is very soluble in rain and surface water, forming carbonic acid which can react with minerals in rocks and water-borne sediments - this forms carbonates which settle to the floor of the oceans as extensive beds of marl, limestone, dolomite and magnesite. Much carbonate is also tied up in corals, shells and animal skeletons, much of which gets buried when the animal dies. This natural process of capture and burial has the greatest effect on the rarest gas of life - carbon dioxide.
Volcanism can release carbon dioxide, methane and other hydrocarbons from buried deposits. The volcanic heat drives volatile gases from strata such as coal seams, limestones, oil shales and methane clathrates, thus returning buried carbon compounds to the biosphere. Submarine volcanoes can also warm the ocean, thus driving off some of the ocean’s vast store of dissolved carbon dioxide. Without this return segment of the carbon cycle, carbon dioxide levels would sink inexorably to levels unable to support healthy plant growth.
However, in a piece of serendipity, man’s use of hydrocarbons and carbonate rocks is returning a small part of the naturally sequestered carbon dioxide to the biosphere which needs it urgently. Hopefully this may also delay Earth’s inevitable return to the recurring ice age episodes typical of the era in which we live.
Those advocating “Carbon Capture and Burial” want humans to waste energy to capture, compress, pump and bury valuable carbon dioxide. They have no concern for life on earth, and their real aim is to make the use of carbon fuels like coal, oil and gas so expensive that all industrial activity will shrink, thus restricting the footprint of pesky industrious humans on the earth.
They are the real enemies of the biosphere, particularly the human component of it.
at 9:58 PM