Would burning biofuels affect global warming?

<div class='quotetop'>QUOTE(burritos @ Sep 12 2007, 05:28 PM) [snapback]511562[/snapback]</div>

Yes to prior posted response that carbonate rock is the largest carbon reservoir on the earth, by far. So, your mental model that the carbon must be either in biomass, fossil fuel or atmosphere is not complete. Most of the carbon is in (e.g.) limestone, chalk, marble. And the ocean contributes as well.

You have to be careful when you look at sources showing the size of earth's carbon reservoirs because some will only show what's active, ie, the immediate surface of the earth, plus ocean. In other words, they will essentially talk about the soil, not the rock.

But here, this guy seems to get it right:

http://www.gcrio.org/USGCRP/sustain/tans.html

Using his units, if the atmosphere has 50 units of carbon, plants and soils hold about 200, the ocean has 3100, and rocks hold about 5,000,000. Not a typo -- that's pretty much in line with my recollection of it. He also gives a clear explanation of why the rocks don't much matter in the short run -- the exchange with the biosphere/atmosphere is small in any given year. But of course as stated above they matter greatly in the long run.

Now, are fuels derived from biomass carbon-neutral? Hmmm. I'd say the right answer depends on the fuel and the timeframe. So what happens if we use biomass I think has to depend on how its produced.

If we took the desert, watered and fertilized, harvested and burned that new biomass annually, then I guess it has to be pretty much a wash in terms of atmospheric C02. The carbon we burned from this year's harvest had to have come out of the atmosphere. We would introduce a tiny little cycle similar to what is seen in atmospheric C02 due to the annual spring uptake of carbon by norther hemisphere deciduous forests (except that involves about 100 gigatons and we burn maybe 8 gigatons a year, so you wouldn't see ours compared to Mother Nature's). But year on year it would have to be neutral.

And I guess, not knowing any more, that would hold true for any land now growing annual crops, to a close approximation. The carbon in the crop at the end of the year pretty much had to come out of the air during the year, except insofaras you might get net carbon release from destroying the organic matter in the soil (ie, think of converting pasture land to crops, where the ground ends up dead bare at the end of the year when cropped, but contains much more biomass when retained as pasture. That would be net carbon release). Anyway, barring that, I'd buy that that was carbon neutral.

But, say, a massive switch to heating with firewood would not be, at least not until the forest had regrown. Total standing timber would be reduced, total carbon in the biosphere would fall, and the result would be an increase in atmosheric C02 until that was absorbed back into the biosphere/oceans.

Finally, its worth saying that any excess carbon we inject into the atmosphere takes a pretty long time to get re-absorbed into the biosphere. Without going into detail, I think the "bomb carbon" provides the most direct evidence that it takes quite a while. So, it's not like if you chopped down all the trees and burned them, that (say) the oceans would just rapidly absorb the resulting atmospheric C02 in a coupe of years. Instead, it would take quite a while for them to suck that back out of the air. Here's a good graph of the bomb carbon (excess C14 produced by above-ground nuclear tests circa 1962):

http://en.wikipedia.org/wiki/Image:Radioca..._bomb_spike.svg

Now 45 years later, the roughly 100% excess C14 has been reduced to about 15%. And that's almost certainly clearing faster than the excess fossil-fuel carbon that we inject each year.

To put the whole mess into perspective about release and re-absorbtion, the reason we haven't flooded the atmosphere with C02 is not that Nature sucks it back up really fast, its that our annual output is small. I don't have the exact numbers in hand, but there are about 800 gigatons of carbon in the atmosphere, our annual emissions amout to about 8 gigatons. And presently, Nature absorbs about 4 or 5, so the net increase each year is only maybe 3 or 4, something like that. BUT -- and this is the key to getting it -- 4 absorbed out of the entire excess atmospheric carbon built up since the start of the industrial revolution where total atmospheric C went from 600 gigatons pre-industrial-revolution to about 800 now. So, of the "disequilbrium" 200 gigatons, Nature absorbs 4 or 5 every year. So, the story is that we emit 8 each year, and of the 200 cumulative excess, Nature aborbs 4 or 5, for a net 3 or 4 gigaton increase in atmospheric carbon year year.

Or, at least, that's the way I think it works.

 

<div class='quotetop'>QUOTE(burritos @ Sep 12 2007, 05:28 PM) [snapback]511562[/snapback]</div>

Yes to prior posted response that carbonate rock is the largest carbon reservoir on the earth, by far. So, your mental model that the carbon must be either in biomass, fossil fuel or atmosphere is not complete. Most of the carbon is in (e.g.) limestone, chalk, marble. And the ocean contributes as well.

You have to be careful when you look at sources showing the size of earth's carbon reservoirs because some will only show what's active, ie, the immediate surface of the earth, plus ocean. In other words, they will essentially talk about the soil, not the rock.

But here, this guy seems to get it right:

http://www.gcrio.org/USGCRP/sustain/tans.html

Using his units, if the atmosphere has 50 units of carbon, plants and soils hold about 200, the ocean has 3100, and rocks hold about 5,000,000. Not a typo -- that's pretty much in line with my recollection of it. He also gives a clear explanation of why the rocks don't much matter in the short run -- the exchange with the biosphere/atmosphere is small in any given year. But of course as stated above they matter greatly in the long run.

Now, are fuels derived from biomass carbon-neutral? Hmmm. I'd say the right answer depends on the fuel and the timeframe. So what happens if we use biomass I think has to depend on how its produced.

If we took the desert, watered and fertilized, harvested and burned that new biomass annually, then I guess it has to be pretty much a wash in terms of atmospheric C02. The carbon we burned from this year's harvest had to have come out of the atmosphere. We would introduce a tiny little cycle similar to what is seen in atmospheric C02 due to the annual spring uptake of carbon by norther hemisphere deciduous forests (except that involves about 100 gigatons and we burn maybe 8 gigatons a year, so you wouldn't see ours compared to Mother Nature's). But year on year it would have to be neutral.

And I guess, not knowing any more, that would hold true for any land now growing annual crops, to a close approximation. The carbon in the crop at the end of the year pretty much had to come out of the air during the year, except insofaras you might get net carbon release from destroying the organic matter in the soil (ie, think of converting pasture land to crops, where the ground ends up dead bare at the end of the year when cropped, but contains much more biomass when retained as pasture. That would be net carbon release). Anyway, barring that, I'd buy that that was carbon neutral.

But, say, a massive switch to heating with firewood would not be, at least not until the forest had regrown. Total standing timber would be reduced, total carbon in the biosphere would fall, and the result would be an increase in atmosheric C02 until that was absorbed back into the biosphere/oceans.

Finally, its worth saying that any excess carbon we inject into the atmosphere takes a pretty long time to get re-absorbed into the biosphere. Without going into detail, I think the "bomb carbon" provides the most direct evidence that it takes quite a while. So, it's not like if you chopped down all the trees and burned them, that (say) the oceans would just rapidly absorb the resulting atmospheric C02 in a coupe of years. Instead, it would take quite a while for them to suck that back out of the air. Here's a good graph of the bomb carbon (excess C14 produced by above-ground nuclear tests circa 1962):

http://en.wikipedia.org/wiki/Image:Radioca..._bomb_spike.svg

Now 45 years later, the roughly 100% excess C14 has been reduced to about 15%. And that's almost certainly clearing faster than the excess fossil-fuel carbon that we inject each year.

To put the whole mess into perspective about release and re-absorbtion, the reason we haven't flooded the atmosphere with C02 is not that Nature sucks it back up really fast, its that our annual output is small. I don't have the exact numbers in hand, but there are about 800 gigatons of carbon in the atmosphere, our annual emissions amout to about 8 gigatons. And presently, Nature absorbs about 4 or 5, so the net increase each year is only maybe 3 or 4, something like that. BUT -- and this is the key to getting it -- 4 absorbed out of the entire excess atmospheric carbon built up since the start of the industrial revolution where total atmospheric C went from 600 gigatons pre-industrial-revolution to about 800 now. So, of the "disequilbrium" 200 gigatons, Nature absorbs 4 or 5 every year. So, the story is that we emit 8 each year, and of the 200 cumulative excess, Nature aborbs 4 or 5, for a net 3 or 4 gigaton increase in atmospheric carbon year year.

Or, at least, that's the way I think it works.

 

<div class='quotetop'>QUOTE(burritos @ Sep 12 2007, 07:23 PM) [snapback]511646[/snapback]</div>

I am not a geologist, so I don't have the 'how they know' information down to the exact primary research that is published, but I am a scientist (in training as a graduate student) and microbiology is my primary area of research, and as such biogeochemistry is an related area to study.

Yes, before life, the evirons were toxic and uninhabitable (as far as what most scientists define as uninhabitable). There was storms, volcanic blasts, lightning, heat, astoroid bombardments, etc. How exactly life formed is not completely known. One theory that several scientists have and still are investigating is the amino acid to enzyme to RNA to DNA to tada life theory, though there are several other theoreis and several theories within theories and they all have comparable strengths and weaknesses (honestly, I doubt there will ever be consensus). Anyways, yes, they do know that the first life derived their energy solely on chemicals (well, it isn't exactly you go back in time and say, "see", but based on genomic evidence and the conditions of early earth it is fairly obvious). Photosynthesis was developed by microbes about 3.5 billion years ago, and this is based on the geological record of banded iron formation, the dating of fossils that resemble cyanobacteria mats, and is supported by the genomics. From the fossil and geological record, it appears that photosynthesis really took off once it developed (in those cyanobacteria). So, photosynthetic single-celled organism did become the primary molders of the environment. The oxygen they produced was absorbed completely by rocks for the first 1.5 billion years of their existence (there was a large sink of oxygen), but then they changed the atmosphere dramatically, forming high levels of O2 in the atmosphere, burying a lot carbon that erupted in volcanos during all of the time before them, stabilized the climate, and allowed more complicated life forms to develop, such as us. (though, I haven't heard anyone give them credit for making that much of the water)

There are lots of things that are unknown, but no one is debating the development and dominance of photosynthetic activities as far as I know it. Carbon in the fossil fuels today came from millions of years of life, that mostly absorbed carbon from the atmosphere, that was released by volcanic activity. The main point is that all of that carbon wasn't in the atmosphere at the same time; it was released by volcanoes all throughout those millions of years, and it was absorbed by life all throughout those millions of years. The carbon released was on average equal to the carbon sequestered. This stuff is well-known to the point that it has been published in basic biogeochemistry textbooks for a couple decades and no one has been able to challenge it. We are goofing that relative balance up by digging up all of the carbon and putting it back into the atmosphere.

Global warming will be detrimental to life as we know it if we allow it to happen, and that is why we should care. I am sure some life could exists past us in a hotter, more extreme Earth, but we are not robust creatures - we need large amounts of organic carbon to sustain us. And that is why we should care. We have the smarts to keep us alive and living well, why screw that up for a couple centuries of cheap energy??

 

<div class='quotetop'>QUOTE(burritos @ Sep 12 2007, 07:23 PM) [snapback]511646[/snapback]</div>

I am not a geologist, so I don't have the 'how they know' information down to the exact primary research that is published, but I am a scientist (in training as a graduate student) and microbiology is my primary area of research, and as such biogeochemistry is an related area to study.

Yes, before life, the evirons were toxic and uninhabitable (as far as what most scientists define as uninhabitable). There was storms, volcanic blasts, lightning, heat, astoroid bombardments, etc. How exactly life formed is not completely known. One theory that several scientists have and still are investigating is the amino acid to enzyme to RNA to DNA to tada life theory, though there are several other theoreis and several theories within theories and they all have comparable strengths and weaknesses (honestly, I doubt there will ever be consensus). Anyways, yes, they do know that the first life derived their energy solely on chemicals (well, it isn't exactly you go back in time and say, "see", but based on genomic evidence and the conditions of early earth it is fairly obvious). Photosynthesis was developed by microbes about 3.5 billion years ago, and this is based on the geological record of banded iron formation, the dating of fossils that resemble cyanobacteria mats, and is supported by the genomics. From the fossil and geological record, it appears that photosynthesis really took off once it developed (in those cyanobacteria). So, photosynthetic single-celled organism did become the primary molders of the environment. The oxygen they produced was absorbed completely by rocks for the first 1.5 billion years of their existence (there was a large sink of oxygen), but then they changed the atmosphere dramatically, forming high levels of O2 in the atmosphere, burying a lot carbon that erupted in volcanos during all of the time before them, stabilized the climate, and allowed more complicated life forms to develop, such as us. (though, I haven't heard anyone give them credit for making that much of the water)

There are lots of things that are unknown, but no one is debating the development and dominance of photosynthetic activities as far as I know it. Carbon in the fossil fuels today came from millions of years of life, that mostly absorbed carbon from the atmosphere, that was released by volcanic activity. The main point is that all of that carbon wasn't in the atmosphere at the same time; it was released by volcanoes all throughout those millions of years, and it was absorbed by life all throughout those millions of years. The carbon released was on average equal to the carbon sequestered. This stuff is well-known to the point that it has been published in basic biogeochemistry textbooks for a couple decades and no one has been able to challenge it. We are goofing that relative balance up by digging up all of the carbon and putting it back into the atmosphere.

Global warming will be detrimental to life as we know it if we allow it to happen, and that is why we should care. I am sure some life could exists past us in a hotter, more extreme Earth, but we are not robust creatures - we need large amounts of organic carbon to sustain us. And that is why we should care. We have the smarts to keep us alive and living well, why screw that up for a couple centuries of cheap energy??

 

<div class='quotetop'>QUOTE(n8kwx @ Sep 12 2007, 05:50 PM) [snapback]511600[/snapback]</div>

Thought they were pretty obvious and self-evident, the original post seemed rather facetious. I didn't think he was looking for a serious answer. I figured it was more rhetorical and that the original poster was just making fun of the "Global Warming is a Myth" people. Besides, I figured others would explain the holes if it became necessary.

 

<div class='quotetop'>QUOTE(n8kwx @ Sep 12 2007, 05:50 PM) [snapback]511600[/snapback]</div>

Thought they were pretty obvious and self-evident, the original post seemed rather facetious. I didn't think he was looking for a serious answer. I figured it was more rhetorical and that the original poster was just making fun of the "Global Warming is a Myth" people. Besides, I figured others would explain the holes if it became necessary.

 

<div class='quotetop'>QUOTE(burritos @ Sep 12 2007, 08:23 PM) [snapback]511646[/snapback]</div>

It will not be brains that darwin will be selecting, it will be the humans with the most efficient sweat glands.

 

<div class='quotetop'>QUOTE(burritos @ Sep 12 2007, 08:23 PM) [snapback]511646[/snapback]</div>

It will not be brains that darwin will be selecting, it will be the humans with the most efficient sweat glands.

 

There is one other issue with most biofuels:

WATER.

It doesn't make much news yet, but it is getting to be a bigger and bigger problem. So even if biofuels were carbon neutral, it doesn't make much sense to waste water reserves to power our cars.

 

There is one other issue with most biofuels:

WATER.

It doesn't make much news yet, but it is getting to be a bigger and bigger problem. So even if biofuels were carbon neutral, it doesn't make much sense to waste water reserves to power our cars.