Negative Feedbacks In Climate: Natural Cycles Dominate

A thermostat in a heating/cooling system is a good example of negative feedback. You set your desired temperature(s), and depend upon the thermostat mechanism to keep the system within set limits.

Earth's climate depends upon negative feedback mechanisms as well--otherwise, life would not be possible. Current atmospheric CO2 levels are low, in a true historical sense. During the age of the dinosaur, CO2 levels were up to 12 times higher than current levels. Other periods of massive vulcanism over the eons have led to much higher atmospheric CO2 levels. Why did CO2 levels moderate themselves? The answer lies in negative feedbacks. The earth possesses many methods of modulating levels of CO2.

In the introduction to their important new study published in the July 2007 issue of Limnology and Oceanography, Hutchins et al. (2007) note that Trichodesmium species and other diazotrophic cyanobacteria support a large fraction of the total biological productivity of earth's tropical and subtropical seas, and that they exert a significant influence on the planet's carbon cycle by supplying much of the nitrogen that enables marine phytoplankton to maintain a level of productivity that removes vast amounts of CO2 from the atmosphere. Hence, they speculated that if either an increase in the air's CO2 content or its temperature led to an increase in oceanic N2 fixation, it could also lead to the biological extraction of more CO2 from the atmosphere and a tempering of the CO2 greenhouse effect via this negative feedback process.

CO2 Science
For life to have continued on Earth for so long, the climate--and atmospheric gas levels--must be dominated by negative feedbacks, rather like your thermostat. The earth's biosphere expands to compensate for increased TSI (total solar irradiance) during stronger sun cycles. A warming of the ocean leads to release of more CO2 which fertilises more ocean and land plant growth. During weaker sun cycles--such as the upcoming cycle 25--the ocean cools and absorbs more CO2, and the biosphere shrinks in response to less incoming energy and available CO2.

CO2 is a rather weak greenhouse gas, and its effect is eclipsed by solar variability and other greenhouse gases--particularly water. Now that we understand that most of the northern ice cap melting is due to changing wind patterns and soot effect from Chinese and other Asian coal burning, we can further understand the minor role CO2 plays in climate.



Given the poor understanding of the dominant factors in climate variability--negative feedbacks and solar influence--the dismal predictive abilities of current GCMs are not surprising. As long as much of the best funded climate research blindly follows the false belief that CO2 forcing dominates climate, we will waste a great deal of money on a futile pursuit. Should the carbon trading schemes of Al Gore and his cronies ever be instituted on the grand scale Gore desires, the resources of Earth will truly be squandered.

For fascinating further reading, see here.