The Rate of Change

I well remember the huffing and puffing over the release of James Hansen’s paper “Target Atmospheric CO2: Where Should Humanity Aim?” :-

http://www.columbia.edu/~jeh1/2008/TargetCO2_20080407.pdf

“…Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciation occurring when CO2 fell to 425 +/- 75 ppm…”

The sceptic-deniers laughed and scoffed and said things to the effect that clearly there’s nothing to worry about that the current concentration of Carbon Dioxide in the air is over 390 parts per million – it won’t melt the polar ice caps.

What the sceptic-deniers haven’t understood, or pretend not to have understood, is that it is a combination of factors that caused major lasting glaciation on Earth. Yes, the level of Carbon Dioxide in the air is important. But the rate of change of Carbon Dioxide in the atmosphere is a significant component.

If the levels of Carbon Dioxide in the atmosphere change rapidly, the heating or cooling effect is amplified, in effect. You have to take account of the relative change in levels of Carbon Dioxide, not just its level at any particular point in time.

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The Sum of Complexity

As Dr Judith Curry has tried to communicate to me, the physical science of Climatology is full of deep complexity, with strong ranging on a number of processes.

Just to take a typical example – the Hurricane storm track in the Caribbean. Different years produce different levels of risk, and a constantly updated projection is needed as short-term relevant climatic factors shift.

But despite the likelihood of any particular Tropical Depression forming, the range of its strength and the eventual pathway, there is still a clearly identifiable track that storms take – that Stephen Schneider called “Hurricane Alley”.

This kind of “big picture” of regional and even global phenomena means that we can safely scale out from the inner workings of individual changes in air pressure, prevailing winds and humidity and take in the larger-scale, longer-term trends.

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Antarctica Is Melting : Official

Oh, you know, the Arctic Sea Ice is in a “death spiral”, but good old Antarctica is holding firm – ice sheets as strong as ever, colder and more concrete a Polar Ice Cap than ever before.

Wrong.

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