Feedbacks in the Climate System


         It is easy to transpose the terms positive and negative feedbacks when discussing a dynamic system, I have managed to fall into this trap myself on several occasions while writing this blog, so for the sake of clarity I will define the terms and then apply these terms to the climate system.

         Negative Feedback: is processes within a system that oppose change by applying a opposition to the force making the change thereby reducing the amplitude/attenuating the output of the system. By extrapolation any dynamic system such as the earths climate, which has existed for billions of years, is dominated by negative feedback, otherwise our climate would have shown extreme behaviour.

          Positive Feedback: is that process which amplifies the change and in the most extreme instance causes runaway change. By extrapolation positive feedback is largely absent from the climate system, but it can be shown that in a few instances some positive feedback has been present.

          There are 2 scenarios which are defined by paleoclimatologists called greenhouse and icehouse earth in which positive feedbacks could have caused a climate flip, but only one state icehouse earth or SNOWBALL EARTH has been described in the scientific literature. Changes to and from the Snowball earth must have included positive feedbacks see http://www.snowballearth.org/ for discussion of the processes. My theory suggests that another example of positive feedback is ICE AGES, which is a less extreme form of Snowball earth.

          Milankovitch theory attempts to describe ice ages using orbital dynamics. This is only valid when the average temperature of earth falls below a fixed temperature which is defined on the following graph as 0 degC Vostock equivalent  (0 degC polar ocean equivalent)

It can be seen from this graph that average temperatures above 0 degC Vostok, are dominated by negative feedbacks, and that average temperatures below o degC Vostok have positive feedbacks, such that as the ave temperature falls climate changes are amplified.

Conclusion:

           Based on the fact that 0 degC Vostok is the current baseline any changes that increase temperature i.e. Insolation or CO2 will be opposed by negative feedbacks, then any claims of runaway warming are alarmist propaganda.

           As 0 degC Vostok is the key temperature it can be inferred that ice is the enemy of life.

           Temperatures between 0 degC and 100 degC imply linear response and low climate sensitivity. By extrapolation positive feedbacks may only become dangerous to the earths climate when the temperature of the earth approaches one of the limits defined as either the freezing point or the boiling point of water. When the average temperature of the earth is consistent with water as a liquid the climate is more stable, and amicable to life

Mad Mike

Junceira

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About madmikedavies

Retired Communications Engineer, living in Portugal. Interests are Cosmology, Earth Sciences, Organic farming, Climatology, Football, Golf, Birdwatching, and Dogs
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One Response to Feedbacks in the Climate System

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