Instead of delusions about CO2 as the planet’s climate “control knob”, Viv Forbes provides us a wise, sane view how the carbon cycle works, and what we know and don’t know about it. And rather than exaggerate the effects of humans recycling fossil fuels, he puts the carbon cycling sources and sinks into a sensible perspective. His recent article is entitled: Carbon Delusions and Limited Models

The IPCC models misread the positive and negative temperature feedbacks from water vapour (the main greenhouse gas) and their accounting for natural processes in the carbon cycle is based on very incomplete knowledge and numerous unproven assumptions.

The dreaded “greenhouse gases” (carbon dioxide and methane) are natural gases. Man did not create them — they occur naturally in comets and planets, and have been far more plentiful in previous atmospheres on Earth. They are abundant in the oceans and the atmosphere, and are buried in deposits of gas, oil, coal, shale, methane clathrates and vast beds of limestone. Land and sea plants absorb CO2 and micro-organisms absorb methane in the deep ocean.

Earth emits natural carbon-bearing gases in huge and largely unknown and unpredictable quantities. Carbon dioxide, carbon monoxide and various hydrocarbons such as ethane, methane and propane bubble out of the ocean floor, seep out of swamps, bubble naturally out of rivers, are released in oil seeps, water wells and bores, and are sometimes delivered via water pipes into drinking water. They are also released whenever carbon-bearing rocks such as coal and shale are eroded naturally, catch fire or are disturbed by earthquakes, construction activities or mining. The vast offshore deposits of frozen methane are released naturally when geothermal heat or volcanic intrusions melt the ice containing the methane.

Earth also entombs carbon in sediments and organic matter transported from the land by rivers and buried in swamps and deltas or swept from the land into the oceans by typhoons and tsunamis. These will eventually become limestone, shale and coal deposits, probably containing fossil evidence of a long-gone human era.

Earth’s total supply of carbon does not change, it just moves continually around the great carbon cycle residing temporarily as gases, liquids or solids in the atmosphere, oceans, biosphere and lithosphere.

Currently the supplies of carbon dioxide in the atmosphere are recovering gently from record lows. No one knows exactly where it is all coming from but limited measurements and extrapolations indicate that about 96% of the CO2 added annually to the atmosphere is from nature. The only part of the carbon cycle that is measured with reasonable accuracy is the remaining 4% of atmospheric CO2 produced through man’s recycling of coal, oil and gas.

Summary:

Note in the diagram above (from Wikipedia), that despite the huge natural fluxes of CO2 (amounts only guesstimated), a net annual increase of 4 Gt is blithely attributed to humans. Once again humans imagine that their activity is decisive and somehow more important than massive natural processes.

I think it is a kind “urban myth” adopted by people living in cities, with little experience of nature beyond green spaces within an artificial environment. Additionally, many spend their time in the virtual reality of cyberspace.

At some level nature has become the “other” to be feared. Natural forces are presently restrained by bricks and mortar, but are always a risk to break through. Naively some think nature can be placated if we change our ways, another egoistic delusion.

Footnote from Chapter 6 IPCC WGI Fifth Assessment Report:

“The change of gross terrestrial fluxes (red arrows of Gross Photosynthesis and Total Respiration and Fires) has been estimated from CMIP5 model results (Section 6.4). The change in air-sea exchange fluxes (red arrows of ocean atmosphere gas exchange) have been estimated from the difference in atmospheric partial pressure of CO 2 since 1750 (Sarmiento and Gruber, 2006). Individual gross fluxes and their changes since the beginning of the Industrial Era have typical uncertainties of more than 20%.”

From Table 6.1 Chapter 6 IPCC WGI Fifth Assessment Report

Ocean-to-atmosphere flux –155 ± 30 Land-to-atmosphere flux 30 ± 45 Partitioned as follows: Net land use change 180 ± 80 Residual terrestrial flux –150 ± 90