Monthly Archives: June 2014

climate sensitivity or no climate sensitivity

The Antarctic is about to set a record for measured sea ice extent in the modern Satellite era. which means there is more ice at the South Pole in the last 34 years then ever before measured.

This is at the same time that CO2 levels have risen from 328 to 401 ppm, a rise of 2 ppm/year which has been put down to increased burning of fossil fuel.

CO2 is known to cause a warming effect in the atmosphere due to its absorption of Infra red radiation, as do all the other gases and water both as a gas and a vapor. The effect of an increase in CO2 levels is postulated to cause a 1 degree rise in temperature for a doubling of the CO level from 35 years ago.

This rise in temperature of the earth at sea surface level for a doubling of CO2 is referred to as the Climate Sensitivity [CS].  The Climate Sensitivity which is easy to define is in practice impossible to estimate or measure.

The reasons involve Natural Variation, which can also be looked at as not being able to measure the multiple effects of winds , waves, currents, forests, deserts, cloud and albedo to mention just some with precision hence the weather daily, weekly and seasonally cannot be fully predicted. Another is the presence of positive and negative feedbacks in the climate system which are even harder to work out.

Some people have stated that Climate Sensitivity cannot be negative, that there must be some positive increment to a forcing and any feedbacks must of necessity be less than the original input.

A measure of the degree of warming is logically that cold areas should warm up and areas of ice should melt.

Here is the conundrum. The Antarctic sea ice should be melting. At a Climate Sensitivity of 1  the world temperature should be 0.7 degrees warmer over the last 35 years and this should show in retreating Antarctic Sea Ice extent.

The fact that the area of Sea Ice is now 1.8 square million kilometers greater than the average over the last 35 years on its own would imply a negative Climate Sensitivity to CO2 increase.

There are arguments why this might not be correct.

We might be having a very, very long lasting natural variation in temperature which is overriding CS.
Temperature changes are different in the 2 hemispheres due to different land mass sizes.
Numerous other explanations have been attempted which fall over for 2 reasons.

The first is that all of them involve measures which are inherently counter intuitive. An example would be hot seas cause more clouds which cause more snow which cause more ice buildup. This logic loop is ultimately self defeating, two plausible ideas  are put together but the outcome fails due to the argument on climate sensitivity above. An input should not usually cause a bigger feedback than the input itself.

Other arguments include trade winds blowing faster put forward ten tears ago and trade winds blowing slower put forward last year. Ozone holes are another argument  which fails the logic test. Melting causing fresh water which is lighter and sinks allowing colder water to form more ice. Melting glaciers is another.

The second reason is that there are so many of these counter intuitive arguments still around with few in the close knit Antarctic community having the gumption to say no, this is wrong. Hence we have nearly 10 reasons for why there is more ice in the Antarctic. If even half of them were right this would mean that there should be 5 times as much ice in the Antarctic as there currently is.

This leads to the question then of is it possible that there are feedback loops that prevent our climate from  changing too drastically whatever the local  input. With the input of palaeontology it is obvious that the earth has had massive eons of life producing the fossil fuels in the first place, possibly for over a billion years. The earth’s atmosphere may originally have been devoid of Oxygen and CO2 [see stromatolites]. The upheavals of the earth’s crust have had super volcanoes and eras where burning coal would have produced more CO2 than mankind could ever produce. Yet we are here.

CO2 does warm the air, rising levels with no negative feedbacks should cause a rise in the earth’s temperature, yet one of the biggest, easiest to measure objective measurements says very plainly this is not happening.  There may be a bit of transfer of heat to the Northern Hemisphere for the North South divide to exist that is not yet understood. The most likely answer is that Climate sensitivity is a lot lower than most climate scientists are prepared to admit.

a doubling of CO
2
(which amounts to a forcing of 3.7 W/m2) would result in 1 °C global warming