Quadrant Online - Opening closed minds

The end of scientific consensus

The Royal Society, which is Britain’s top dog in science (indeed many scientists would say the world), has just published a report signalling the end of claims of a consensus by some climate scientists and some governments that the world faces dangerous warming unless governments act quickly to reduce emissions of greenhouse gases.
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In the latter category, for example, the acknowledgment that the uptake of CO2 by the land and oceans is “very poorly understood” is tantamount to saying that it is not possible to predict with any confidence the future concentration levels of CO2 in the atmosphere.
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However, perhaps the most devastating statement for alarmists is that “It is not possible to determine exactly how much the Earth will warm or exactly how the climate will change in the future”. This leaves in doubt what policy should be adopted, and when, to reduce emissions. The report’s acceptance that uncertainty exists about the effect clouds have on temperatures is one important reason for delaying action. Another is the acknowledgement of poor scientific understanding in various other areas, such as the likely extent of reductions in ice sheets in Greenland and West Antarctica from any further temperature increases. Yet another is the admission that “there is little confidence” in projections by models of climate change in regions, including Western Europe. This also suggests that predictions of worsening drought conditions in the Murray Darling Basin have no scientific basis.

What's the carbon footprint of ... a volcano? | Environment | guardian.co.uk

Over time, however, the cooling effect fades faster than the greenhouse warming caused by the CO2 (which stays in the atmosphere for hundreds of years) so whether the warming effect or the cooling effect is greater depends on the time scale you consider – a bit like the difference between planes and cars.

[But why doesn't this CO2 stay in the atmosphere for "hundreds of years"?]

The vertical distribution of carbon dioxide in the air around a group of trees fluctuates with the time of the day. Photosynthesis is shut off at night and as a consequence the respiration from the soil can raise the concentration of carbon dioxide at ground level to as much as 400 ppm, while the CO2 concentration at treetop level can drop to 305 ppm at noon owing to photosynthetic uptake