Thursday, February 16, 2006

Permian Climate Atmospheric Chemistry Model

[Edit: This was the presentation of 10:30am: (video from NCAR) J. Kiehl: Simulations of Latest Permian Atmospheric Chemistry: Implications for Terrestrial Mass Extinction at the CCSM Paleo Climate Working Group meeting]

[Second Edit: This has been submitted to a journal ( Paleooceanography) already.
Modeling the response to changes in tropospheric methane concentration:  application to the Permian-Triassic boundary.

J.-F. Lamarque, J. T. Kiehl, C. A. Shields, B. A. Boville, and D. E.

Most of the work on the Permian has concentrated on the ocean. This is something new and wanted to look at the atmosphere, especially the release of all that methane, and its possible effects on land extinctions. Used was the CCSM 3 Finite Volume CAM variant, but fully coupled with the ocean model variant (non finite volume CAM) didn't produce the exact same results. It's being investigated as to why.

Two studies completed so far. The first is the methane effects on ozone and the same for hydrogen sulfide on the same. The first one has been submitted to a journal and the second is on its way.

The ozone gets thrashed. A huge amount of cloud cover takes place in the poles, btw. Rather interesting so far. UV B radiation massively increased based on the models. This is uberbad for genetic material and there is evidence through pollen that support this based on fossils and experiments with modern pollen samples.

Pangea had a heat index average of 32 C and in the tropics it was 72 C average! (O.o) The atmosphere was full of moisture! This is a bit confusing becauses of the presence of all those interior deserts. Thena gain, if the temperature was 72 C, I think I understand why they were deserts. Holy shibbit!

Damnit, don't use modern data as a source of atmospheric data for past climate sims. This is like Carlos' post on ecologies from the Paleozoic and using modern ecologies to do analyses on the previous ecologies.

First study concludes that a massive injection of methane kills the ozone and then the increase of hydrogen sulfide increases the life time of methane in the atmosphere by wiping out the OH- in the atmosphere.

The Siberian Traps warm the world through the emission of CO2 over 100k's years. The oceans get their anoxic state. This increases the hydrogen sulfide in the ocean and atmosphere. This increases the life time of methane in the atmosphere. The heating then stimulates alot of that methane in the ocean. This jacks up the temperature and wipes out the ozone. This lets the UVB to wipe out the terrestrial ecosystems. The hydrogen sulfide is the difference that makes the CH4 model realistic because it greatly reduces the amount of methane necessary.



Carlos said...

Shoot, I am missing this.

Carlos said...

Okay, this has some implications for paleobiochemistry.

Let's see, from memory, the Carboniferous and Permian had an amazingly high O2 content, allowing the very large invertebrates of the period to thrive. Combine that with a high humidity, 40 C to a freaking 72 C ?! environment... there's nothing comparable today. Nothing at all.

It sounds like fungus heaven, except we know from the massive amount of coal from that era that dead plant matter was barely touched by fungus.

Photosynthesis in land plants may have been wildly different from today's plants. High humidity => less need to worry about transpiration water loss. High heat => different sets of enzyme reactions become possible. High O2 => more competition with CO2 in the carbon-fixing enzyme Rubisco.

Really wild speculation: Lovelock showed that there are biogenic feedback effects which regulate Earth's climate at least a little. Is the Permian endgame what happens to a biosphere in a time period before these biological feedback cycles develop?

The past is a different planet.

Will Baird said...

The PT Boundary separates us from a really different world. I am thinking, based on some fossils, that the KT does as well. Not just because of the cliamte so much as the ecology is going to be a lot different than people think of it. Reading about deinosuchus and the dog sized mammal from the Jurassic has made me think that the Mesozoic was actually as complex, if not more so, in terms of lifeform types as the Cenozoic and their roles. Your book on paleoecology could answer some of that.

Anyways, the plants of the Permian, iirc, were either conifers or tree ferns. IIRC, the PT Event killed an awful lot of plant life as well and that might have done in the different form of photosynthesis.

Hypothesis, fungus as we know it arose during the extinction event. Testable?

As for your thoughts about the feedback cycle not having developed...mmm...I'd guess, yes. Reason being is that the O2 level went nuts for a while there to levels that would be considered impossible today if not for the fossil evidence. Then we have a wild schwing the other way with the PT Event.

I wonder what the Triassic extinction was exactly? How did species fair through that? Could it be that was the beginning of the regulation? The KT and Eocene-Oligocene events might have some evidence to shed more light too. After I'm done Olmecing, the next book is on extinctions...I smell a future top level post...