2011-06-15 01:16:19Nominee for most absurd denier meme -- "If it weren't for humans, the Earth would be barren"
John Hartz
John Hartz
john.hartz@hotmail...
99.95.221.238

The following was posted earlier today on the comment thread to "Are progressives in denial about climate change?", Huffington Post,  June 10, 2011.

"Of course, for hundreds of millions of years the earth was sequesteri­ng that carbon and atmospheri­c CO2 levels dropped until a couple of million years ago we entered the Pleistocen­e Ice Age and a very large portion of the earth became unfit for flora or fauna. The CO2 that all life on earth depends on almost ran completely out before man started releasing the precious element back into our atmosphere­. Now the seas are rising at a rate of 4 inches per century and the climate zones are moving out to higher latitudes - maybe 50 miles per century. The 680,000 cubic mile Greenland Ice Sheet is losing 47 cubic miles a year and in another 14,500 years could once again become forest."

 

2011-06-15 03:59:47
Rob Honeycutt

robhon@mac...
98.207.62.223

That's so funny.  I ran into almost the identical argument on Peter Sinclair's channel when a guy told me that "all plant life stops below 300ppm."  I pointed out that the past million years or more CO2 levels have been below 290ppm.  Then he changed it to 190ppm.

I wonder where this is coming from.

2011-06-15 05:47:54
Paul D

chillcast@googlemail...
82.18.130.183

He posted a second comment to qualify "The CO2 that all life on earth depends on almost ran completely out":

"CO2 is plant food and is necessary for plants to produce sugar and protein. Animals need the sugar and protein the plants produce. I don't know what the lowest threshold of CO2 that plants can endure, but with 97% of the CO2 gone, it is likely that without man or some other mechanism the threshold would be reached in another 10 or 20 million years and all life on earth would be extinguished. On the other hand higher CO2 levels allow the earth to support more plant life and therefore food for more animal life. And the recession of the glaciers produces more habitat."

 

2011-06-15 06:10:23My initial repsonse...
John Hartz
John Hartz
john.hartz@hotmail...
99.95.221.238

to what "Sawdustking" had posted was a tad lame and partially incorrect.

I subsequently did a little digging and discovered an exellent explanation of what drove CO2 increases in the paleoclimate in Chapter 8: "Target Carbon Dioxide: Where Should Humanity Aim?" of James Hansen's "Storms of my Grandchildren."

The primary cause, according to Hansen, was the grinding action of colliding tetonic plates. Has this explaination been detailed in a SkS blog post or posts? I do not recall seeing it in any of the articles that I have read.

2011-06-15 06:19:36
Rob Honeycutt

robhon@mac...
98.207.62.223

Rock weathering is presented here along with the Ordovician.

Richard Alley also does a good job of explaining it in his AGU lecture The Biggest Control Knob.

2011-06-15 07:35:58Rob
John Hartz
John Hartz
john.hartz@hotmail...
99.95.221.238

Thanks for the references.

I actually watched Alley's presentation before I perused Hansen's book. Alley does a good job of explaining why and how CO2 concentrations decline, but, in my opinion, glosses over why and how they increase.

2011-06-15 07:40:55
Paul D

chillcast@googlemail...
82.18.130.183

The CO2 thermostat is in David Archers lectures.

http://geoflop.uchicago.edu/forecast/docs/lectures.html

2011-06-15 07:51:03
Rob Painting
Rob
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118.93.21.7

Badger see Chris Colose's post; Understanding Solar Evolution Part 2:Planets

2011-06-15 20:24:54Timescales
James Wight

jameswight@southernphone.com...
112.213.161.21

Badger, on timescales of 107 years it is the balance between volcanism, weathering/sedimentation, and fossil fuel formation that causes CO2 to rise or fall. The negative weathering feedback operates on timescales of 105 years. On timescales of 102-103 years warming causes CO2 to be released from the oceans, vegetation and permafrost (and methane hydrates?).

2011-06-15 22:21:21Paul, Rob & James
John Hartz
John Hartz
john.hartz@hotmail...
99.95.221.238

Thanks for all the quality info. Perhaps it should be bottled into a SkS article?

2011-06-15 22:29:45Antother post by "Sawdustking"
John Hartz
John Hartz
john.hartz@hotmail...
99.95.221.238

This denial blogger spins quite a tale that appers very logical on the surface. I can't help but wonder if the Climate Denial Spin Machine hasn't developed this narrative using focus groups.

Over the past half a billion years the atmospheri­c CO2 levels had steadily declined from 6000ppm to less than 200ppm (this rose to a pre-indust­rial 260ppm during the current Holocene Interglaci­al Period). As we just agreed, the breathing out of CO2 by oxygen breathing organisms does not contribute to atmospheri­c levels. This is true whether the organism is a 200 lb man or a single celled marine organism, so your second point is moot. As is your third because forests are quickly replaced after fires, recapturin­g the carbon released by the fire.

As far as volcanoes, sure there were eruptions, but they did not compensate for the amount of carbon sequestere­d by anoxic zones where dead organisms couldn't be consumed and their carbon released back into the atmosphere­. All this sequestere­d carbon went on to become oil and coal.

CO2 is plant food and is necessary for plants to produce sugar and protein. Animals need the sugar and protein the plants produce. I don't know what the lowest threshold of CO2 that plants can endure, but with 97% of the CO2 gone, it is likely that without man or some other mechanism the threshold would be reached in another 10 or 20 million years and all life on earth would be extinguish­ed. On the other hand higher CO2 levels allow the earth to support more plant life and therefore food for more animal life. And the recession of the glaciers produces more habitat.