Friday, December 11, 2009

The Medea Hypothesis Review: Part Six

A Quick Introduction

This is the sixth post on the Medea Hypothesis. Here I am delving into Chapter 8: Predicted Future Trends of Biomass. The previous posts can be found here, here, here, here, and here. The completed Medea Hypothesis Review Table of Contents is here.This will be the second to last post that summarizes the Medea Hypothesis. The next one will just be Ward’s own Summation (Chapter 9). Then I will do my critique. Afterwards, I will make an index post and then tie all this together on the side bar.

The Medea Hypothesis: Future Biomass Trends.

Based on the previous post and the idea that biomass has already peaked in the past, the obvious conclusion that Ward is going to draw is that the future is going to be a general downward slope for the biomass for the planetary biosphere from here on out. The rason he states is that life is drawing down the carbon dioxide levels over time, sequestering the carbon bit by bit, due to the less than perfect nature of carbon cycle. He bases his future trends and conclusions on the same Franck et al models he did before.

Projected Future CO2 Levels in the Deep Future

However, he gives more background about the history of the future of the biosphere and when life will die out. A long belief up until the 1980s was that life would persist, the whole of the complex life and the biosphere in general until the sun turned into a red giant and consumed the world. It turns out that a number of modelers over time have shown this may not be the case.

The first of these was James Lovelock, the so-called father of the Gaia Theory. He along with coauthors explored the time period that life would go extinct. That pointed out that too much CO2 is bad and that too little is also bad in their 1981 paper in Nature. They predicted that life would, based on the carbon cycle, go extinct approximately 100 million years in the future. They based their projection on when life the atmosphere would drop below 150 ppm of CO2.

Kasting et al followed up on the Lovelock article in 1992. They revised their model which they based on Lovelock’s with the information that had been developed since 1981 in the carbon-silicate cycle. They projected that the so-called critical CO2 point would take place around 550 million years rather than 100 million years. They also pointed out that this critical point would only affect the C3 photosynethic pathway plants. C4 plants and CAM plants would be just fine. However, the total amount of biomass would be decreasing from here on out.

Franck et all started following up in 1999. Their results varied with the error bars placing the critical 150 ppm CO2 550 to 850 million years from now. They also projected the global productivity was already falling and would continue to do so, reducing the complexity of life and the total biomass until its final extinction. The end, when it comes, they projected would come as a whimper rather than a bang.

There have been others that have worked on the same problem. They all, according to Ward, give predictions that the critical CO2 level will come between 500 million years from now to 1.5 billion years from now.

What Would the Deep Future Look Like?

Ward then discusses the differences between the different photosynthetic pathways. I’ll just link to C3 photosynthesis, C4 photosynthesis, and CAM photosynthesis. You can read about them there much better than I can write about them. He also states that the evolution of C4 plants only took place eight to ten million years ago (pg 119). C4 plants need a minimum of 10 ppm CO2.

“The formation of new photosynthetic pathways is a sure sign that long-term reduction in atmospheric CO2 is having a profound affect on the biosphere. The continued long-term reduction in CO2 over next hundreds of millions of years should produce a decisive change in the global floras.”

Pg 119, Chapter 8: Predicted Future Trends of Biomass.

Ward speculates that the world will transition gradually from C3 woody plants to C4 and CAM plants: he refers to CAM plants as “succulents and their ilk.” He posits that it is possible the world will just be grasslands which will be less productive than the forests of now. Then he also points out that there are ‘trees’ that are C4 plants: bamboos and palms. The forests may be still be present, just as bamboo and palms rather than the types of trees we are familiar with.

He accepts that it may be possible plants will develop other photosynthetic pathways to adapt to the ever lowering CO2 levels. He dismisses this as eventually they too will succumb to the ever lowering CO2 levels as well.

Ward paints a picture of what will happen when plants finally go extinct. The soils will cease to exist. Weathering will drop. The nutrients from plants that oceanic life depends on will cease. Life will slowly collapse even in the oceans to much simpler life. He basically posits a reverse Cambrian Explosion – an Antephytozoic Implosion. Complex life will all but end. Life will be reduced to microbial in nature very quickly. Once plant life goes extinct, Ward cites David Catling as stating that within 15 million years that after the extinction of plants that the atmospheric oxygen content will drop to 1%. This dooms animal life.

Wrap Up Of Future Trends

Ward blames life for the supposedly broken carbon cycle. He states that this supports the Medea Hypothesis and Chapter 8 is the predictions of the Medea Hypothesis. The next post will be a summation of the Medea Hypothesis. I will be pretty much just quoting Ward. It’s less than two pages to type in.


Anonymous said...

"He also states that the evolution of C4 plants only took place eight to ten million years ago (pg 119)."

What. It's at least from the Oligocene. And it's evolved independently forty-five freaking times.

I am a little burnt on the (mis)use of bad computer models -- see the recent Jared Diamond thread at James's LJ -- but I look forward to your summation.

(I will take a look at the physics paper this evening.)


Will Baird said...

Even better. There were some coprolites from the Jurassic with grass pollen in them recently. That needs to be confirmed, but if true...not good for Ward.

My critique is going to be rough. I sincerely hope he's trolling the ecofreak crowd. However, he may, in fact, believe this. If so...oy.

I will say based on this one I won't be picking up any more Ward books. Sloppy is the kindest thing I can say.

I saw the Diamond thread. I was going to link to it.

I am very, very burnt out from bad models. Part of the reason I want to get away from HPC. Which is sad. I like big iron.