Understanding how we cause climate change

By | 12 Sep 2011

Photo of smoking chimney stacks in London, CanadaDr Tom Mole (former Chief Research Scientist at CSIRO) delivered this address to the Humanist Society of Victoria on 11 September 2011.


The belief systems which dominate present day society are not the various religions and atheism, but cause-and-effect reason (science) and free-market philosophy (institutionalised greed). Nowhere is this more obvious than in the debate on climate change.

We need a shared understanding of what drives climate change. Understanding comes from ideas about the flow of energy to and from (our domicile) the surface of earth, and about the behaviour of carbon dioxide and the various materials derived from it. The fossilisation of carbon below the surface, the abundance of the resulting fossil fuels, and our ridiculously profligate exploitation of the fossil fuels are important elements of the understanding.

The Solar System

Climate is driven by the flow of energy, in the form of electromagnetic radiation, to and from the earth, especially from the sun. Accordingly our understanding has to start with the solar system. Earth is one of the planets orbiting the sun. The sun and all of the planets, likewise the moon, are roughly spherical, because liquids, left to their own devices, form into spherical shapes. Thus the planets must have in the past been very hot, molten bodies. The sun is still incredibly hot and gives off light and heat. The planets and moons do not give off light, but reflect sunlight.

Earth has a diameter of around 13 thousand kilometres, and is in orbit about 150 million kilometres from the sun, which has a diameter of about one-and-a-half million kilometres. The moon has a diameter of about 3 thousand kilometres and is in orbit about three hundred thousand kilometres from earth. Earth rotates on its axis once each day, so that a point on the surface away from the poles is warmed by the sun for about half of the day and cools for the other half.

Solar Radiation

The sun emits a wide spectrum of radiation to the solar system, including the earth, and beyond. What concerns us is the visible (and near-ultraviolet) radiation. This may be reflected by light-coloured surfaces, such as clouds and ice, but otherwise passes through the atmosphere and is absorbed by darker surfaces and warms up those surfaces. Solar radiation heats the surface of the earth and its water bodies, leads to the evaporation of water and the movement of water vapour in the atmosphere, hence to rain and snow.

Radiation of Heat

Warm surfaces cool by emitting infra-red radiation. The permanent gases of the atmosphere are transparent to infra-red radiation, but many other materials absorb (and in turn re-emit) the infra-red. Thus water (vapour and liquid), carbon dioxide, methane and nitrogen oxides absorb radiated heat, protecting the earth from incoming radiation and returning outgoing radiation to the earth. These greenhouse gases serve as an insulating blanket. In the absence of greenhouse gases earth’s surface would cool rapidly after sunset, just as does the surface of the moon, which has neither atmosphere nor greenhouse gases.

Climate Change Denial

The processes described above are beyond reasonable dispute, even by those who deny that climate change is man-made. The processes involve large energy flows. And these flows are not steady ones. Radiation from the sun is not constant in the short or long term, and radiation from the earth is altered by extra-terrestrial events and by volcanic events. The earth has a history of large changes in climate, ice ages, change in atmospheric constitution, extinctions and continental drift. Why then think that the burning of fossil fuels by mankind is significant in comparison to all this? The denial case it that mankind is a fly on the wall not a determinant of climate change.

The other element in denial (and probably the elephant in the room) is the Panglossian, economic view. We enjoy an affluent world in which the law of supply and demand rules. Why look for threats that rock the boat? As I have said, the main belief systems of today are science and the free market. They can be in conflict.

Earth and its Life

Earth has a diameter of about 13 thousand kilometres, but mostly consists of hot igneous rocks, capped by a thickness of only a few kilometres of the mostly sedimentary rocks, separating the igneous rocks from the atmosphere and the oceans.

This rock must have been derived from the igneous rocks of earth’s interior. The crust of the earth is superficially firm, but moves slowly but steadily on the interior. Earthquakes, the growth of mountain chains, volcanoes and continental drift are all evidence of this. These events are a mechanism for release of the heat of the interior of the earth

Weathering of rocks, both igneous and sedimentary, can involve acid and alkaline subterranean water, and particularly rainfall and surface water, which may contain acid gases such as carbon dioxide and nitrogen oxides. Life on earth also plays a role in weathering and creating the sedimentary rocks of the earth’s crust.

Life comprises plants, which essentially use atmospheric carbon dioxide and sunlight to generate oxygen and carbohydrates and the other constituents of plants, and animals, which essentially feed on plants and each other, so obtaining their carbohydrates and other constituents. It is old and accepted wisdom that oxidation of plant and animal material to carbon dioxide provides a converse process to photosynthesis, so setting up the carbon cycle. What we need to realise is that fossilisation of the carbon of living material is an important element in the carbon cycle. Our consumption of the fossilised carbon is at the heart of the climate change problem.

Carbohydrates, break down to methane and carbon dioxide given enough time (as much as hundreds of million years) and elevated temperatures of deep burial. Coal also results (from fossilisation of trees), as does oil (from plant and animal lipids). These materials are not simply found in particular pockets, but are widespread throughout the sedimentary rocks and even in the depths of the oceans.

Much attention has been focused on scarcity arising from the depletion of resources of coal, gas, and particularly oil. The true problem is the abundance of the resources and climatic consequences of our over-exploitation of them.

Living things have never been merely flies on the wall in the disposition of earth’s crust. For example shell fish have accumulated calcium (presumably weathered from igneous rocks and washed into shallow ocean waters) along with carbon dioxide to form shells of calcium carbonate. The resulting fossils are responsible for enormous deposits of limestone, as in Western Victoria and South Australia. Sometimes the deposits are thrust high in the air by plate tectonics as mountain ranges, such as the Alps and Rockies. The barrier reef is a pimple by comparison.

Fossil fuels, likewise, are widely dispersed through sedimentary rocks. We have mostly thought of them as nature’s bounty, found as oil and natural gas at modest depths, which can be tapped by drilling and used, and again found as seams of coal at shallow depths, as in parts of Queensland, which can be consumed locally or shipped to Asia. The reality is that fossil fuels, particularly natural gas, are far more widely distributed. The rush to tap shale gas in the US and coal seam gas in Australia are testament to this.

Global Industrial Development

Industrialisation has proceeded from clearing forests as a source of timber, fuel and charcoal, to mining of coal on a modest scale to provide steam power, to the present. Now coal is mined on a prodigious scale for metallurgy and electricity generation, and oil and gas are tapped almost as rapidly as possible wherever possible, for use as fuel. In so doing, more and more of the earth’s fossil carbon is turned into carbon dioxide to be accommodated in the atmosphere and the oceans, with serious effects upon the radiant cooling of earth’s surface.

Homo sapiens is doing what life on earth has always done: contributing to reordering of the earth’s crust and redistribution between the crust, the oceans, and the atmosphere. The new factor is that present day homo sapiens does so on a global, industrial scale. If you doubt this, take a peep over the edge of the Yallourn or Anglesea open cuts.

Most of us perceive a problem. Is the answer for reason to fold its cards and admit that greed wins? Is it to applaud political sleight of hand which does not really address the problem? Is it to move with reasonable speed to a less energy-intensive society. which regulates mining of fossil carbon and is selective about its consumption? Is present day Australia destined to be regarded by future generations as cursed by the Queensland sickness?

Copyright © 2011 Dr Tom Mole