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Carbon release from permafrost, the bad news

post #1 of 8
Thread Starter 

Spencer can say what he wants to about cloud feedbacks, but releasing lots of methane won't be a good thing ...

 

Nature: Vol 459|28 May 2009| doi:10.1038/nature08031

 

The effect of permafrost thaw on old carbon release and net carbon exchange from tundra

 

Edward A. G. Schuur, Jason G. Vogel, Kathryn G. Crummer, Hanna Lee, James O. Sickman & T. E. Osterkamp

 

Permafrost soils in boreal and Arctic ecosystems store almost twice as much carbon as is currently present in the atmosphere. Permafrost thaw and the microbial decomposition of previously frozen organic carbon is considered one of the most likely positive climate feedbacks from terrestrial ecosystems to the atmosphere in a warmer world. The rate of carbon release from permafrost soils is highly uncertain, but it is crucial for predicting the strength and timing of this carbon-cycle feedback effect, and thus how important permafrost thaw will be for climate change this century and beyond. Sustained transfers of carbon to the atmosphere that could cause a significant positive feedback to climate change must come from old carbon, which forms the bulk of the permafrost carbon pool that accumulated over thousands of years. Here we measure net ecosystem carbon exchange and the radiocarbon age of ecosystem respiration in a tundra landscape undergoing permafrost thaw to determine the influence of old carbon loss on ecosystem carbon balance. We find that areas that thawed over the past 15 years had 40 per cent more annual losses of old carbon than minimally thawed areas, but had overall net ecosystem carbon uptake as increased plant growth offset these losses. In contrast, areas that thawed decades earlier lost even more old carbon, a 78 per cent increase over minimally thawed areas; this old carbon loss contributed to overall net ecosystem carbon release despite increased plant growth. Our data document significant losses of soil carbon with permafrost thaw that, over decadal timescales, overwhelms increased plant carbon uptake at rates that could make permafrost a large biospheric carbon source in a warmer world.

 

post #2 of 8

Ugh, whenever I hear about methane feedback I feel like closing my eyes and humming a Bob Marley song. Serious carbon reductions require serious optimism, and if this feedback ever takes off then there is essentially no hope for preventing serious warming.

 

Though it would open the door for some entertaining irony, as future skeptics would be talking about how global warming could not be man-made because we are warming by too much too fast

post #3 of 8

Yeah this is another reason why I don't buy Spencer's arguments.  With all the positive feedbacks from melting permafrost, melting ice, saturating carbon sinks, and so on, to think that a cloud feedback which may be positive or negative is somehow going to save us just seems ridiculously optimistic to me.

post #4 of 8

I am not sure why you need to "buy" anything? Why don't you evaluate the scientific reasons behind his arguments? You claim to be a sort of scientist, aren't you? The clouds seems to be working just fine for the last billion of years... Because of this fact, I do not understand why you people are so concerned about warming that never goes too high, according to historical proxies? I would be much more concerned about falling into iceball state.

 

Are you familiar with works of Ray Pierrehumbert? The works that show that if you drop CO2 to about 100ppm (which, according to their model would reduce the overall greenhouse effect to the point that all oceans and lands will start freezing), the Earth will be covered by 5-m thick ice in 50 years or something, and become an ice ball? But this is not the whole story. Did you know that, after the icebal forms, if you increase CO2 concentrations in the same model even up to 20% ( 200,000 ppm), the Earth will never recover, and remain as ice ball. Does not it worry you? What conclusion[s] can be drawn from this research? What would be your opinion?

post #5 of 8

 

Quote:
Originally Posted by AlTekhasski View Post

I am not sure why you need to "buy" anything? Why don't you evaluate the scientific reasons behind his arguments? You claim to be a sort of scientist, aren't you?

 

Gee, I'm so confused as to what I've been doing so far...

 

Quote:

The clouds seems to be working just fine for the last billion of years... Because of this fact, I do not understand why you people are so concerned about warming that never goes too high, according to historical proxies?

 

Atmospheric CO2 also hasn't been over 280 ppm for millions of years.  I don't understand why "skeptics" expect the same result from different atmospheric conditions.

 

Quote:

if you drop CO2 to about 100ppm (which, according to their model would reduce the overall greenhouse effect to the point that all oceans and lands will start freezing), the Earth will be covered by 5-m thick ice in 50 years or something, and become an ice ball? But this is not the whole story. Did you know that, after the icebal forms, if you increase CO2 concentrations in the same model even up to 20% ( 200,000 ppm), the Earth will never recover, and remain as ice ball. Does not it worry you? What conclusion[s] can be drawn from this research? What would be your opinion?
 

 

No, that doesn't worry me.  Does it worry you that if a large meteor hits the Earth it could cause mass extinctions?  Actually, that's probably a more reaslitic scenario than a 100 ppm decrease in atmospheric CO2 given its current rate of increase.

post #6 of 8

 

Quote:
Originally Posted by AlTekhasski View Post

Are you familiar with works of Ray Pierrehumbert? The works that show that if you drop CO2 to about 100ppm (which, according to their model would reduce the overall greenhouse effect to the point that all oceans and lands will start freezing), the Earth will be covered by 5-m thick ice in 50 years or something, and become an ice ball? But this is not the whole story. Did you know that, after the icebal forms, if you increase CO2 concentrations in the same model even up to 20% ( 200,000 ppm), the Earth will never recover, and remain as ice ball. Does not it worry you? What conclusion[s] can be drawn from this research? What would be your opinion?


An iceball Earth would be very bad, what's your point? Nobody is saying that global warming is the absolute worst thing that could ever possibly befall humanity, of course there are worse things out there. Just because something is not the worst possible thing, does that mean it cannot deserve some concern? 

 

Or is your logic that just because one extreme is bad, the other extreme must therefore be good? That's like saying water shortages can never be a problem because if the entire world were water then we would all drown. It's like something a 7 year old would say.

post #7 of 8

Nature is balance - if something goes out of balance (conditions change), a new balance point is found. If there aren't any more dino's running around (or people for that matter) nature could care less.

 

When you have an outside influence (man making a mess with all kinds of pollution) nature starts toward a new balance point.

 

If mankind wants to stay around a while longer it seems to be common sense not to mess up the balance any more that necessary for survival. That means reducing the levels of 'mess' we are already making.

 

In an engineering company working on mundane items you have great difficulty in achieving concensus about much of anything. With the widely varied group talking about climate change there is no chance for wide agreement - too many characters working from some illogical basis toward an even more illogical conclusion.

 

 

post #8 of 8
Thread Starter 

 

Quote:
Originally Posted by AlTekhasski View Post

I am not sure why you need to "buy" anything? Why don't you evaluate the scientific reasons behind his arguments? You claim to be a sort of scientist, aren't you? The clouds seems to be working just fine for the last billion of years... Because of this fact, I do not understand why you people are so concerned about warming that never goes too high, according to historical proxies? I would be much more concerned about falling into iceball state.

 

Are you familiar with works of Ray Pierrehumbert? The works that show that if you drop CO2 to about 100ppm (which, according to their model would reduce the overall greenhouse effect to the point that all oceans and lands will start freezing), the Earth will be covered by 5-m thick ice in 50 years or something, and become an ice ball? But this is not the whole story. Did you know that, after the icebal forms, if you increase CO2 concentrations in the same model even up to 20% ( 200,000 ppm), the Earth will never recover, and remain as ice ball. Does not it worry you? What conclusion[s] can be drawn from this research? What would be your opinion?

 

My opinion is along the lines of what Pierrehumbert says in his articles (e.g., the Nature paper in 2004:  "High levels of atmospheric carbon dioxide necessary for the termination of global glaciation" Nature, 429: 646-649), namely that some other feedback effect operates along with CO2 to cause the deglaciation.  Given what is going on in the arctic in the modern era, where the observed warming is nearly double what would be predicted based on the radiative forcing from CO2 alone, I think a plausible case can be made that volcanic dust/soot might provide such a forcing in a hard snowball Earth scenario. 

 

First, in the arctic, one of the things people are increasingly focusing on to explain a lot of the observed warming is soot, transported from Siberia, China, and Eastern Europe.  Soot is dark, highly active as a positive forcing when in the atmosphere, and really decreases albedo when deposited on snow.  These effects give it a huge potential to warm up cold environments. 

 

In a hard snowball scenario, precipitation would be nil (think of Antarctica, which is largely a desert).  So volcanic ash would build up on top of all the ice along with the CO2 in the atmosphere.  Eventually, given the increase in radiative forcing and decrease in albedo from the volcanic particulates would be enough to trigger a deglaciation.  This effect was not modeled in the Pierrehumbert studies (either the Comptes Rendus paper in 2007 or Nature in 2004, btw). 

 

The conclusions to be drawn are that CO2 is an important factor in global climate, but not the only factor.  This is old old news. 

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