Thursday, August 13, 2009

What is Medean Life? (Part Two)

This is the second post in my consideration of The Medea Hypothesis. I am slowly working my way towards a commentary and criticism of the tMH. Please be patient. I have alot going on. It's finished and The Medea Hypothesis Review TOC is here.

Dr Peter Ward in his recent book, The Medea Hypothesis, proposes a counter point to the popular and often misinterpreted Gaia Hypothesis. In a previous post, I quoted Ward as to what he considers to be the main characteristics of Medean Life. There are three that are really, really worth reiterating plus one that was missed because it wasn't with the other defining traits of "medean life:"

1. Life is NOT a part of a self correcting or self regulating system. Life is actually suicidal and that life's interactions with the environment mostly, by and large, make it less friendly for life's continued existence.

2. Diversity of life is completely divorced from the total biomass. In fact, a lot of what Ward seems to argue is that the more diverse life is, the less biomass there is. Over time, the total biomass is decreasing due to life using up its available resources and as a consequence (or so I am interpreting his writing) the diversity increases as life must find new ways of exploiting what's left.

3. Every time a 'breakthrough' takes place for life in either exploiting some new energy source or some new way of organizing itself, there's an initial BOOM of biomass and then a drop off with a steady decline over time following.

4. Resource plundering/competitive poisoning (hyper-darwinism?). This one wasn't mentioned earlier because it wasn't with the standard definition section of what Medean Life was supposed to be. All life takes, hoards, plunders resources to the detriment of all others and often poisons everything else around it to further its advantage. The anaerobic bacteria that produces hydrogen sulfide is a good example. The black walnut or eucalyptus is another pair. Humanity is the pinnacle of this, but not an exception like is normally portrayed. Oceanic eutrophication (hypoxia/anoxia of the lower depths) is another example according to Ward, although, he breaks it out into its own category, it really is just another example of plunder/poisoning.
So if these are the basic characteristics, boiled down and as interpreted by me, what are the feedbacks that life is producing to make things worse for itself. The main feedback cycle that is on Ward's mind is the carbon cycle and global warming. With his experience with the Permian Extinction, the writing of Under the Green Sky and his upcoming book The Flooded Earth, global climate change looms large on Ward's mind these days. It is Ward's hypothesis that positive feedback cycles predominate the carbon cycle. Here are the ones he lists:

1. Increased atmospheric carbon dioxide increases photosynthesis. This increases carbon sequestration (negative feedback, CO2 goes up, amount of CO2 sequestered corrects for this, at least somewhat)

2. Increased temperature (from increased CO2) leads to increased soil respiration, which moves a lot of the organic carbon in the soil into the atmosphere (positive feedback, warmer leads to more carbon coming from soil, which leads to warmer still)

3. Warmer temperatures increase fire frequency, which replaces older trees with younger ones, which in turn releases more carbon into the atmosphere (another positive feedback)

4. Warming may lead to drying, which will cause greater desertification which will in turn cause sparser vegetation which will increase dust clouds and over all planetary albedo, causing cooling (negative feedback)

5. Higher atmospheric carbon may cause increased selection for drought resistant vegetation which will cause more intrusions of shrub and other dry climate resistant plants intruding into desert regions which will decrease albedo and dust clouds (positive feedback)

6. Warming leads to tundra being replaced by boreal forest. This decreases planetary albedo (positive feedback)

7. Warming soil produces more methane than cooler soil. As the world warms, the soil produces more which warms the earth more. (positive feedback)

8. Warming soil increases the production of Nitrous oxide (positive feedback)

9. Warming polar regions cause release of methane and carbon dioxide buried in the peatlands, etc. (positive feedback)

The Medea Hypothesis, Chapter 4, Medean Feedbacks and Global Processes, pages 57-58.

What Ward doesn't mention here also is that the models he is relying on for the Pre-Phanerozoic and into the future, deep future, are based on the level of CO2 being higher in the past, much higher. In fact, he states that the main suicidal tendency of life is the using up and drawing down of the carbon dioxide levels. A form of biological plundering, if you will. Finally, Ward states that there is no way to directly measure the carbon dioxide content of the paleoatmosphere and therefore the models are essential and predictive (red flags there, but we'll get there at the end of the Medean Life posts when I do some commentary).


Anonymous said...

Is he using a non-inappropriate carbon cycle model this time?


Will Baird said...

He's using two different models and a paper really... deriving some conclusions from them.

Kirchner 2002: The Gaia hypothesis: Fact, theory, and wishful thinking, Climate Change 52: 391-408.

The models are from Berner's work and Franck et al that you and I have been reviewing. Berner for the Phanerozoic and Franck for before and "after".

There's a big hammer coming for all this, but I want to make sure I get the serious main points out before I get out the big hammer, ahem, make my commentary.