4 ms·

"Planting a tree does capture carbon. However, when it dies and rots, all the carbon gets re-released over time back into the atmosphere." Not all the carbon.

by johnr2 7y ago

"Planting a tree does capture carbon. However, when it dies and rots, all the carbon gets re-released over time back into the atmosphere." Not all the carbon. Some of it stays in the ground to eventually form more fossil fuel.

rleigh 7y ago
Not really, not in any meaningful quantity. That only happened once, on a geological timescale (the carboniferous period). During that period, there was no breakdown of dead trees; fungi and bacteria hadn't evolved the enzymes to break it down at that point, so it just sat there, piling up layer upon layer, and eventually got turned into coal seams and oil reservoirs deep underground. Consider just how long it took to get buried deep under all that strata. Millions of years. That process will never happen again. Life subsequently evolved to break trees and all plant matter down fast, on the order of years for a whole tree. Much faster if it's chopped into smaller bits. It is ultimately metabolised by saprophytes and returned to the atmosphere. Very little is sequestered away. Consider that the layer between rock and atmosphere is just a thin film. Bare in some places, a few inches to a few feet deep in others. That's the biosphere, the bit of the planet that is living. That's the store the carbon has to be sunk into. There are some places which do sequester some carbon. Peat bog would be one example. But when you look at how much a peat bog sequesters in a year though the slow growth of sphagnum mosses, heather and the other lichens and plants found there, it's a tiny drop in the ocean compared with the amount of CO2 we are pumping out daily. It's also not going to be super stable. It could catch fire if there's a really dry summer, for example. Higher CO2 levels in the atmosphere will encourage plant growth. There are plenty of scientific experiments to show a direct correlation between CO2 concentration and crop size and dry weight. That's been known for decades. We learned this on a plant science course over two decades back. But there isn't a stable store for all the excess carbon we have released to be sequestered on a meaningful timescale, and the existing biosphere isn't going to be able to expand sufficiently to compensate or to store it long term. It's going to be cycled back into the atmosphere. We have spent the last few hundred years ceaselessly burning unimaginably large quantities of stored carbon which took millions of years to originally deposit. There's no magic bullet to reverting to the pre-industrial state. The effects of this, and any corrective action, will take place on timescales much longer than a human lifetime. As a species, we aren't very good at dealing with problems which can't be solved in a decade or two.
- Theodores 7y ago
  I wish I could mod your comment up 1000 times. That small detail about the Carboniferous Period is something nobody has told me before, which makes me wonder how many people in this debate know their subject.
  - nkurz 7y ago
    From what I can tell, the "trees came before tree-eating-fungi" theory is discredited: Popular press: https://arstechnica.com/science/2016/01/why-was-most-of-the-earths-coal-made-all-at-once/ https://arstechnica.com/science/2016/01/why-was-most-of-the-... Full paper: https://www.pnas.org/content/113/9/2442 https://www.pnas.org/content/113/9/2442 Contextual overview: https://www.pnas.org/content/113/9/2334 https://www.pnas.org/content/113/9/2334

by johnr2 7y ago

rleigh 7y ago

Not really, not in any meaningful quantity. That only happened once, on a geological timescale (the carboniferous period). During that period, there was no breakdown of dead trees; fungi and bacteria hadn't evolved the enzymes to break it down at that point, so it just sat there, piling up layer upon layer, and eventually got turned into coal seams and oil reservoirs deep underground. Consider just how long it took to get buried deep under all that strata. Millions of years. That process will never happen again. Life subsequently evolved to break trees and all plant matter down fast, on the order of years for a whole tree. Much faster if it's chopped into smaller bits. It is ultimately metabolised by saprophytes and returned to the atmosphere. Very little is sequestered away. Consider that the layer between rock and atmosphere is just a thin film. Bare in some places, a few inches to a few feet deep in others. That's the biosphere, the bit of the planet that is living. That's the store the carbon has to be sunk into. There are some places which do sequester some carbon. Peat bog would be one example. But when you look at how much a peat bog sequesters in a year though the slow growth of sphagnum mosses, heather and the other lichens and plants found there, it's a tiny drop in the ocean compared with the amount of CO2 we are pumping out daily. It's also not going to be super stable. It could catch fire if there's a really dry summer, for example. Higher CO2 levels in the atmosphere will encourage plant growth. There are plenty of scientific experiments to show a direct correlation between CO2 concentration and crop size and dry weight. That's been known for decades. We learned this on a plant science course over two decades back. But there isn't a stable store for all the excess carbon we have released to be sequestered on a meaningful timescale, and the existing biosphere isn't going to be able to expand sufficiently to compensate or to store it long term. It's going to be cycled back into the atmosphere. We have spent the last few hundred years ceaselessly burning unimaginably large quantities of stored carbon which took millions of years to originally deposit. There's no magic bullet to reverting to the pre-industrial state. The effects of this, and any corrective action, will take place on timescales much longer than a human lifetime. As a species, we aren't very good at dealing with problems which can't be solved in a decade or two.

Theodores 7y ago
I wish I could mod your comment up 1000 times. That small detail about the Carboniferous Period is something nobody has told me before, which makes me wonder how many people in this debate know their subject.
- nkurz 7y ago
  From what I can tell, the "trees came before tree-eating-fungi" theory is discredited: Popular press: https://arstechnica.com/science/2016/01/why-was-most-of-the-earths-coal-made-all-at-once/ https://arstechnica.com/science/2016/01/why-was-most-of-the-... Full paper: https://www.pnas.org/content/113/9/2442 https://www.pnas.org/content/113/9/2442 Contextual overview: https://www.pnas.org/content/113/9/2334 https://www.pnas.org/content/113/9/2334