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RogueRose
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Is recycling worth it?
The more I learn about chemistry and see how various materials are turned into other compounds, especially under pressure and heat (often in the
absence of O2 or even air in general) it seems that the process of recycling may be a total waste of energy for many applications, especially when
cross contamination becomes a problem within the feedstocks (metals getting build-ups of lead and such, plastics getting other plastics mixed in).
From what I've learned from reviewing most industrial processes is that most of them mirror many natural processes within the earth. By throwing
everything into a landfill and covering it, with lots & lots earth, it eventually breaks down into more usable products.
I've seen so many articles about how much pollution there is from the recycling process, that it is a net pollution producer, even with the "new"
products it produces. Supposedly the research says that very few products are really worth recycling as extraction is much more expensive than the
recycling process and most of those products are metals that are used, and some minerals like K and P. Al, Ti, Cu, Sn, Pb even the "lowly" Fe are all
examples of cost efficient materials that can be recycled, but there are others as well.
I've read that plastics and petro-chemical derived products (styrene and others) are best left landfilled (in lined landfills - clay lined) then
allowed to decomp naturally under heat and pressure. Extraction of CH4 can be done, or it can be left to bond in the "soup" producing other compounds
which could be mined many years down the road.
I have a feeling that many of the crude oil deposits are old landfills from 10,000+ years ago possibly .
I don't know, I just see so much time and effort put into recycling and now I understand how chemistry works, I see it as even more ineffective.
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vmelkon
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Huh? What are your sources?
Mines will eventually run out since nothing last forever. From what I heard, bauxite mines will run out soon (source of Al2O3) and gallium also comes
from it. There are no gallium mines.
For glass, it is cheaper to melt it and reform it since it takes less energy than making new glass.
Wood and paper is not worth recycling since they grow trees specially for that.
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NEMO-Chemistry
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Isnt Helium another element that is in serious trouble of running out? I saw a periodic tables vid on you tube, they have spent a great deal of cash
trying to reuse Helium from the labs. I cant remember the figures but at the current rate of use, Helium will be very hard to get pretty soon.
As for oil deposits being landfill sites from X years ago......On the one hand your right, in the sense that millions of years ago trees etc got
buried, so I guess thats kind of landfill, but as far as deliberate landfill being responsible for oil deposits, i think thats a long way off the
reality.
The bigger question of recycling being worth it.
As pointed out everything apart from stupidity is a finite resource, surely its better to reuse rather than keep raping the earth for what we need?
Also as in the case of plastics, if more were collected and recycled, then maybe the oceans and waterways wouldnt be so choked up with the stuff?
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mayko
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Renewability is definitely an important consideration, but it's not the only one: virgin pulp production is a messy and energy intensive process, and
landfill space is finite.
https://en.wikipedia.org/wiki/Paper_recycling#Rationale_for_...
Another point about disposal of paper and other biomass is, landfills are often anoxic, meaning that bacterial decomposition is anaerobic and slow. It
also tends to release reduced carbon compounds such as methane, which do have the potential for reclamation as fuel. However, it's not at all obvious
that landfill digestion is inherently more efficient than an engineered industrial process on the same feedstock would/could be.
https://www.epa.gov/lmop/basic-information-about-landfill-ga...
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phlogiston
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We live in a special period of human history.
Natural resources are abundant. We can relatively cheaply obtain any element we need.
This will not last. Some day in the future, eventually, we will deplete the last mines for certain elements.
By then, we will be fighting over the last bits. Today, we are occasionally squabbling a bit over oil. But in a long term perspective, fuels for
energy are not an issue. We already know many methods to generate electrical power, it is a resource that cannot be depleted. In fact, using oil
merely to burn it for energy is a waste we may come to regret. The wars that we will be having over the elements that are -really- finite in supply
will be unprecedented.
The ability to recycle with incredible efficiency, and technologies that limit the use of critical elements to the very minimum will make or break
future economies. Survival of the fittest.
Of all the elements, Helium is particularly worrying, because recycling will not save us. He released into the atmosphere does not only become
hopelessly diluted, but actually evaporates into space, lost forever.
[Edited on 7-10-2017 by phlogiston]
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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Melgar
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This is something I actually know quite a lot about, for various reasons, and I have to say, quite a bit of incorrect information here.
Paper is actually the one thing that it actually IS economical to recycle! Do you know how many countries there are out there with no forests left
that buy that stuff up by the container ship? To be fair, there are roughly three: China, Japan, and South Korea, but the point is that they'll buy
as much used paper as we can supply them, and reducing our trade deficit with those countries is always good.
Helium comes from natural gas, where alpha particles from radioactive isotopes in rock have been collecting for eons. Nobody bothers to extract it
right now, because it's not economical. The US has natural gas fields that are particularly high in helium, and so stockpiled a bunch of it during
the Cold War, that they're now gradually selling off because it turned out to be less important than they expected it to be. We could always go back
to extracting helium from natural gas again though. And assuming nuclear fusion ever becomes a reality, that'd be another potential helium source,
although probably only a minor one.
Plastic makes up only a small fraction of our fossil fuel usage. What will probably happen eventually is, fossil fuels become too expensive to use
for fuel, but they'll still be economical to extract as a chemical feedstock.
A lot of people have this misconception that we're "using up" all the resources of this planet, when in fact, virtually nothing has ever left this
planet since it's existed. It just got rearranged into other things. We can always mine landfills if we need to. The technology wouldn't be that
complex, and we'd develop it when we needed it. Energy isn't a major problem either; when there's enough pressure that the NIMBY crowd acquiesces, we
can finally transition fossil fuel power plants to nuclear ones, using renewables to supplement. France has already done this, without any major
incidents. If uranium wasn't so cheap that it's not economical to reclaim unburnt actinides from it, then we'd do that, and thus eliminate the waste
issue.
But to answer the original question about plastic: PETE and polyethylene are the only two commercial plastics that it's ever economical to recycle.
Depending on the price of oil, these plastics fluctuate between being worth recycling and not being worth recycling. However, if you're familiar with
the little recycle numbers on the bottom of plastic containers, they're in order, roughly, of 1 = most economical to recycle to higher numbers being
less economical.
There are a lot of alarmists out there insisting that we'll go to war over resource scarcity, but that seems a bit unlikely. After all, in the event
of a war, the countries with the most resources would totally destroy the ones without any, so it wouldn't be much of a fight. The more likely
scenario is that the prices go up really high, and people have to change their lifestyles a lot. But that's already happened a few times in the past,
and it's sucked, but we've been able to deal with it.
edit: The one thing that we'd have a tough time replacing is diesel engines. For container ships, we could power those with nuclear reactors. This
could happen with trains as well. Cars can be electric, but trucks and airplanes are right at the point in the middle where electric motors aren't
powerful enough and nuclear reactors are way too much. Biofuels are kind of a shitty option, since it means using land for fuel rather than food.
Only time will tell, I guess.
[Edited on 10/7/17 by Melgar]
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elementcollector1
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What most people don't understand about 'resource scarcity' and resource crises is that they're not a static number, but rather a dynamic function of
the grade of ore that is being mined and the abundance of said ore. Less of the more concentrated ore means that we simply turn to the less
concentrated and spend more energy to extract from that. The only 'resource crises' that may occur are when countries decide to hoard a particularly
useful resource and thus dominate the market (as is currently the case with China and rare earth elements).
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Melgar
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Quote: Originally posted by elementcollector1  | | What most people don't understand about 'resource scarcity' and resource crises is that they're not a static number, but rather a dynamic function of
the grade of ore that is being mined and the abundance of said ore. Less of the more concentrated ore means that we simply turn to the less
concentrated and spend more energy to extract from that. The only 'resource crises' that may occur are when countries decide to hoard a particularly
useful resource and thus dominate the market (as is currently the case with China and rare earth elements). |
Exactly. This just happened with oil. As soon as it became economical to extract oil from oil shale and tar sands, the US and Canada started doing
it. This forced Saudi Arabia and Venezuela to lower their prices, and actually cut back their spending considerably because they were no longer
making as much money. But the alternative would have been supplying an even smaller fraction of the market and losing even more relevance.
The issue with China and rare-earth mining isn't so much that they're the only ones that have them, it's that they're the only ones who are willing to
generate the amount of pollution necessary to extract them. Rare earth metals aren't actually rare, after all, the issue is that the only ore that
contains them, doesn't contain that much of them. So a LOT of ore has to be processed to obtain them. China actually tried to cut off Japan from
their rare earth exports, and as a result, a bunch of mines reopened in the US and Australia. The only way China can dominate the market is by
keeping their prices low. I read an article on this recently. I can't find the one I read, but here is a very similar one:
http://www.hcn.org/issues/47.11/why-rare-earth-mining-in-the...
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SWIM
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Melgar is right on on most counts.
But I'd lay pretty heavy odds we won't be seeing nuclear trains any time soon.
The whole 'TERRORISTS BLOW UP NUCLEAR POWERED TRAIN IN MAJOR CITY' scenario, while unlikely, would have the anti-nuke interests shitting sea urchins.
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NEMO-Chemistry
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I am more a any waste person, dosnt matter to me if its sand or gold, i just prefer not to waste anything.
i do kind of question the validity of nothing ever goes away its just changed. While it is technically correct, its a bit of a mute point. Eat a mars
bar and yes its turned into something else, but that dosnt mean its going to useful as a mars bar anymore.
The other point with plastics and waste in general, part the reason they couldnt find that plane in the ocean, was the shear volume of crap floating
around in it, dosnt matter if its recycled or not, surely its just wrong to go around dumping and releasing things that end up harming the
environment?
I am a bit of a tree huger i confess, but topics like oil are so emotive i dont really discuss them, everyone is entitled to an opinion and i respect
that. But even if we dont recycle, I would like to see alot less waste. Say you had a magic bank account, and no matter what you spend it would top
itself back up, to me that dosnt mean you got to spend money like a man with no arms.
So to me its not a question of running out as such, but more a question of greed and using more than we need to use just for the sake of it. Even with
my fume hood, i tend to try and neutralize gases produced in the fume hood rather than release them to the atmosphere, the amounts i produce are
minuscule, but on a personal level i prefer where possible to not pollute if i can avoid it.
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Melgar
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For recycling, a lot of people will put everything plastic in the recycle, including things like foam egg cartons. Well, the people at the recycling
center now have to waste their time separating out those foam egg cartons and throwing them in the regular garbage where they should have been put in
the first place. So people who think they're helping by putting virtually everything in recycle, are actually wasting other people's time. I just
wanted to make that point, in case anyone is unaware of it.
| Quote: Originally posted by SWIM | Melgar is right on on most counts.
But I'd lay pretty heavy odds we won't be seeing nuclear trains any time soon.
The whole 'TERRORISTS BLOW UP NUCLEAR POWERED TRAIN IN MAJOR CITY' scenario, while unlikely, would have the anti-nuke interests shitting sea urchins.
|
I was thinking of it more from an engineering perspective. When the first nuclear reactors were built, we didn't really understand what we were doing
very well, and made a lot of mistakes. As a result, a lot of people are scared of nuclear power, either for that reason, or because they conflate
nuclear power with nuclear weapons. But if it ever comes down to not having a choice, that faction is just going to have to be steamrolled, and China
will probably lead the way on that. So say, China is safely operating nuclear-powered trains, and the US has gone back to using mule teams for
transportation. If it ever came to that, I think we might change our minds.
| Quote: Originally posted by NEMO-Chemistry | | So to me its not a question of running out as such, but more a question of greed and using more than we need to use just for the sake of it. Even with
my fume hood, i tend to try and neutralize gases produced in the fume hood rather than release them to the atmosphere, the amounts i produce are
minuscule, but on a personal level i prefer where possible to not pollute if i can avoid it. |
One thing to think about though: it's excessive consumption that's been pulling the world out of poverty, believe it or not. The more you buy, the
more money gets put into the economy, and the more people are able to support themselves by making and transporting that stuff. I know it's our
instinct to limit our consumption, but it's probably more important to be mindful of what we consume and where the money we spend is going. Likewise,
limiting your emissions of HCl or NH3 means nothing, limiting your NOx and SO2 emissions means a little, and not starting any smoky fires that contain
halogenated compounds probably means more than everything else combined.
| Quote: | | i do kind of question the validity of nothing ever goes away its just changed. While it is technically correct, its a bit of a mute point. Eat a mars
bar and yes its turned into something else, but that dosnt mean its going to useful as a mars bar anymore. |
Well, a Mars bar is mostly sugar, meaning that it'll eventually mostly wind up in the atmosphere as CO2. And that CO2 will be pulled out of the
atmosphere by plants, and many of those plants will be crops, and so forth. Mars bars are actually made of all-renewable resources, so it's just a
matter of allowing the cycle to continue.
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NEMO-Chemistry
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Hmmm interesting perspective.
Only thing i can really comment on is what happens in my lab, i try and not release anything if i can help it. So looks like some is wasted effort and
some is the correct thing to do, on balance i can live with the wasted effort, seeing as it saves brain power working out what is ok to release and
what is not.
No idea why i chose a mars bar!! looks like a piss poor choice now 
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Twospoons
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That totally made my day. Thankyou!
Helicopter: "helico" -> spiral, "pter" -> with wings
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metalresearcher
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Plastics are the worst polluters. Ocean islands full of plastics, because we (the industry and big corporations ) wrap almost everything in disposable
plastics.Most products can however be wrapped in recycled paper or cardboard which is far easier to recycle. There should be a total ban on disposable
plastic packaging, unless strictly necessary such as e.g. medical instruments.
And another issue is the greediness of most of us. We consume far more resources than needed. Let's first start with energy and resource conservation
so less crap has to be recycled.
And finally, waste which really has to be landfilled or incinerated, can that not better be 'incinerated' in an electric arc furnace with very high
temperatures (>3000ºC) so by far the most toxic compounds are reduced to simple compounds. That will result in just molten metals, rock and gases
for further processing.
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elementcollector1
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| Quote: Originally posted by metalresearcher | Plastics are the worst polluters. Ocean islands full of plastics, because we (the industry and big corporations ) wrap almost everything in disposable
plastics.Most products can however be wrapped in recycled paper or cardboard which is far easier to recycle. There should be a total ban on disposable
plastic packaging, unless strictly necessary such as e.g. medical instruments.
And another issue is the greediness of most of us. We consume far more resources than needed. Let's first start with energy and resource conservation
so less crap has to be recycled.
And finally, waste which really has to be landfilled or incinerated, can that not better be 'incinerated' in an electric arc furnace with very high
temperatures (>3000ºC) so by far the most toxic compounds are reduced to simple compounds. That will result in just molten metals, rock and gases
for further processing.
|
Several things are wrong about this post, so let's go through them in order.
While the Pacific Garbage Patch is indeed a thing, let us first consider the alternative scenario, which as you say would be solely restricting
plastic packaging to medical instruments. With food production as it is right now (and even if it was considerably lower), this means food would be
spoiling at triple the current rate, wasting extreme amounts of viable food. From a 'waste not, want not' standpoint, that's not helpful.
Second, plastic packaging is often next to impossible to recycle anyway because most polymers used are blended with others in the final product.
Consider the humble ketchup bottle: It is composed of seven layers of different polymers, one of which protects against UV, one of which
provides a rigid backbone, one of which prevents contaminants leaching into food, at least two of which serve as adhesives between the other layers
(which otherwise don't really bond well), and so on. Now consider the act of attempting to separate all seven layers so that they can be recycled
individually, and you gain some understanding of the technical challenges that are very typically found in plastics recycling industries. Those
plastic packages that are marked with a recycling symbol are some of the few that are single-polymer in nature, and thus are much easier to deal with.
Separation of physical, single-polymer objects is a much, much less arduous task than chemical separation of multi-polymer objects.
The 'greediness' you speak of is more a product of the attitude of the times than any static resource consumption issue. Newer generations are living
far more frugally than their predecessors, because we're more aware of the detriment to the planet (and also have less money for a variety of other
reasons).
As to the point regarding waste incineration... you do know what gases are produced by burning trash, right? Here's a hint: They're not at
all friendly to humans. And 3000 degrees is a bit ridiculous to shoot for in a recycling operation, in my opinion - the energy required to reach and
maintain that temperature far outstrips anything you'd get back from burning the trash, by Carnot efficiency if nothing else.
An ideal resource-consumption world, in my opinion at least, would consist of bioplastics that fulfill their intended use and then degrade naturally
in the environment, cheap metals such as steel and aluminum being used in more applications (reducing the annual primary production energy of more
expensive metals), and semiconductors that don't have such an enormous cost-to-mass ratio in production (though that last one is unlikely, all things
considered). Trash would be recycled by some means of atomic separation (very sci-fi, I know) that would then stockpile the atomic products to
recombine into something else (be it filler material for buildings, household 3D printers, or something similar).
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
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Melgar
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To add to this:
The plastic that's in the ocean is all crap that people didn't properly dispose of. If you use something plastic, and throw it in the regular
garbage, it doesn't end up in the ocean. It probably gets landfilled or incinerated, as it should. Anyone feel like guessing what countries
contributed the most to ocean garbage? Number one is China; no surprise there. Next is Indonesia. The Philippines are next. Then Thailand. Then
Vietnam. All developing countries in Asia that have a lot of coastline, and haven't gotten their shit together yet as far as properly managing their
garbage. So if you want to do something about garbage in the ocean, you have to first realize that it's actually not your own garbage that's the
problem, assuming you live in one of the more developed countries.
Garbage incinerators actually generate energy, and don't require any external power. They just have to get hot enough that the activation energy is
surpassed for oxidizing whatever is in them. The ash can be processed and collected, and would presumably be high in metal oxides of the sort that
are useful to people. I'm not sure if this is done in existing waste incinerators, but it could be done. The main consideration in incinerator
design is that the flue gas has to be cooled fairly quickly so that it doesn't form things like halocarbons.
Decreasing our energy consumption, at least in the form of electricity from the grid, is a bit pointless. After all, there are seven billion people
in the world, and denying them the sorts of things that we already have would be hypocritical. There's really no getting around the fact that energy
consumption is going to keep increasing indefinitely, so the solution here is just to stop generating electricity from fossil fuels. There are dozens
of better ways to generate electricity, and we need to hold onto those fossil fuels and stretch their supply out as long as possible.
Incidentally, does anyone know what event geologists predict will make life on Earth impossible, and when that will happen? It's actually the end of
plate tectonic activity, in about a billion years. When Earth's tectonic plates stop moving, carbonate rock will no longer cycle through Earth's
mantle, and the CO2 emissions from volcanic activity will stop. Plants will use up all the CO2 in the air, it'll get buried in sediment, and
eventually carbon will stop circulating in the environment. Since life is carbon-based, that's a problem. Fortunately, humans are here to save the
day, and have been digging up carbon and putting it back into the environment! Now, not only have we made it so that our current interglacial period
will probably last indefinitely (ie, no upcoming ice age to worry about), but there's going to be a whole lot more life on this planet! They've
already shown that in semi-arid regions, carbon fertilization of the atmosphere has resulted in increased plant growth.* The only downsides are that
weather will be less predictable, and there will be more really hot days every year. The other problems are all either negligible or very easily
managed, because of how slowly they're happening.
* Plants have to "spend" water in order to get carbon. CO2 reduction via photosynthesis actually reduces carbonic acid, but that means exposing water
to the air to allow them to combine. This can be a problem in dry climates. However, if there's more carbon in the atmosphere, less water needs to
be used to collect it, and so plant growth is possible in drier regions.
The first step in the process of learning something is admitting that you don't know it already.
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SWIM
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| Quote: Originally posted by Melgar | To add to this:
Incidentally, does anyone know what event geologists predict will make life on Earth impossible, and when that will happen? It's actually the end of
plate tectonic activity, in about a billion years. When Earth's tectonic plates stop moving, carbonate rock will no longer cycle through Earth's
mantle, and the CO2 emissions from volcanic activity will stop. Plants will use up all the CO2 in the air, it'll get buried in sediment, and
eventually carbon will stop circulating in the environment. Since life is carbon-based, that's a problem. |
If life on Earth would be impossible without tectonic activity, then doesn't that also mean terraforming mars would be useless? No tectonic activity
there, if I'm not mistaken.
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Melgar
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| Quote: Originally posted by SWIM | If life on Earth would be impossible without tectonic activity, then doesn't that also mean terraforming mars would be useless? No tectonic activity
there, if I'm not mistaken.
|
Well, life on Earth as it is now won't be possible in a billion years, but of course, life will evolve in the interim. Maybe plants will
evolve the ability to extract carbon from carbonate minerals, rather than from the air?
Terraforming Mars would require huge amounts of volatiles, like nitrogen (either N2 or NH3), water, CO2, etc. The only way this might be possible is
by slingshotting Kuiper Belt Objects towards Mars and either crashing them into the planet or fragmenting them so that there are a whole bunch of
little impacts instead of one big one. So instead of relying on natural processes to keep the atmosphere at a steady state, people would have to
figure out how to do that.
Every time I bring this up, some know-it-all has to point out that without a magnetic field, Mars would lose its atmosphere. This is true, however it
would be over a time period of hundreds of millions of years, and would happen too slow for people to notice.
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Texium
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With the right ratio of plants to animals plus whatever amount of fossil fuel emissions we're still producing, wouldn't life still be possible with
the good ol cycle of photosynthesis and respiration? Sure there'd be less oxygen in the air, but we can live just fine with a lower concentration of
oxygen, other than people at higher elevations, perhaps.
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Texium
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Thread Moved
10-10-2017 at 13:26 |
SWIM
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| Quote: Originally posted by Melgar | | Quote: Originally posted by SWIM | If life on Earth would be impossible without tectonic activity, then doesn't that also mean terraforming mars would be useless? No tectonic activity
there, if I'm not mistaken.
|
Well, life on Earth as it is now won't be possible in a billion years, but of course, life will evolve in the interim. Maybe plants will
evolve the ability to extract carbon from carbonate minerals, rather than from the air?
Terraforming Mars would require huge amounts of volatiles, like nitrogen (either N2 or NH3), water, CO2, etc. The only way this might be possible is
by slingshotting Kuiper Belt Objects towards Mars and either crashing them into the planet or fragmenting them so that there are a whole bunch of
little impacts instead of one big one. So instead of relying on natural processes to keep the atmosphere at a steady state, people would have to
figure out how to do that.
Every time I bring this up, some know-it-all has to point out that without a magnetic field, Mars would lose its atmosphere. This is true, however it
would be over a time period of hundreds of millions of years, and would happen too slow for people to notice. |
I think I see your point about mars. Just keep occasionally replenishing the gasses the same way we got them there in the first place(every few
million years or so). I don't think anybody ever told me this before, or I just didnt absorb it.
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Melgar
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| Quote: Originally posted by zts16 | | With the right ratio of plants to animals plus whatever amount of fossil fuel emissions we're still producing, wouldn't life still be possible with
the good ol cycle of photosynthesis and respiration? Sure there'd be less oxygen in the air, but we can live just fine with a lower concentration of
oxygen, other than people at higher elevations, perhaps. |
Yeah, when geologists came up with that timeline, it was assuming only natural processes that are currently occurring. Most of the carbon on Earth is
actually in the form of carbonate rocks though, like a HUGE majority of it. The atmosphere contains about 600 gigatons of carbon. The ocean seems
relatively vast, with 40,000 gigatons or so. But the lithosphere dwarfs them all with about 100,000,000 gigatons of it, mostly as carbonate
minerals.
The issue actually isn't with Earth losing its atmosphere, it's with the carbon sinks absorbing all of Earth's carbon such that there's none left.
Plants are what have gotten CO2 levels this low, and they've been evolving to require lower and lower CO2 concentrations. I don't know how much you
know about agriculture, but corn, sugarcane, sorghum, bamboo, and a few other grasses can outgrow just about anything out there, because they use C4
photosynthesis. This is a chemical pathway that works better with a low-carbon atmosphere. Basically, a little extra energy is spent to make sure
carbon can't escape once it's been captured. All the plants that produce healthy foods, like fresh fruits and vegetables, use the C3 photosynthesis
pathway, which evolved under higher CO2 concentrations, and is less efficient in a low-carbon atmosphere.
The first step in the process of learning something is admitting that you don't know it already.
I'm givin' the spam shields max power at full warp, but they just dinna have the power! We're gonna have to evacuate to new forum software!
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mayko
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| Quote: Originally posted by Melgar | Now, not only have we made it so that our current interglacial period will probably last indefinitely (ie, no upcoming ice age to worry about), but
there's going to be a whole lot more life on this planet! They've already shown that in semi-arid regions, carbon fertilization of the atmosphere has
resulted in increased plant growth.* The only downsides are that weather will be less predictable, and there will be more really hot days every year.
The other problems are all either negligible or very easily managed, because of how slowly they're happening.
* Plants have to "spend" water in order to get carbon. CO2 reduction via photosynthesis actually reduces carbonic acid, but that means exposing water
to the air to allow them to combine. This can be a problem in dry climates. However, if there's more carbon in the atmosphere, less water needs to
be used to collect it, and so plant growth is possible in drier regions. |
This seems simplified and overly optimistic. You are correct that carbon fertilization is a real effect, and that it has led to some greening of some
marginal environments. However, older estimates of carbon fertilization have been high by as much as a factor of two (eg, http://science.sciencemag.org/content/312/5782/1918 ), because they were based on measurements in carefully controlled environments, rather than
in the field. This methodological bias has also masked other side effects of CO2 fertilization, such as susceptibility to insect pests (eg, http://www.pnas.org/content/105/13/5129.abstract ). Changes in nutrient content due to CO2 fertilization have also been known for a while, and
have popped up in the headlines recently (eg, http://www.npr.org/sections/thesalt/2017/08/02/540650904/car... ).
You list two major downsides; I'm not sure what you mean by weather being less predictable, but extreme heat is not good for plant growth (nor for
humans, wildlife, or infrastructure). This is especially true when paired with drought, which is a consequence of an accelerated hydrological cycle in
a warming world; perversely, so is flooding, which is also less than optimal for plants. Other impacts you’ve written off as negligible include
increased wildfires, soil salination from rising sea level, and disrupted pollinator phenology (again, not encouraging), as well as more complex
ecosystem-level interactions (consider the climate-driven devastation which bark beetle outbreaks have done to conifer forrests: https://www.fs.usda.gov/ccrc/topics/bark-beetles-and-climate...)
Thusfar, we’ve only been considering land plants, which is a little parochial given that most of the planet’s photosynthesis takes place in the
ocean. Ocean photosynthesizers are not generally carbon-limited (and certainly not water-limited); the limiting factor for their growth is often a
micronutrient (iron in particular; eg, http://www.nature.com/nature/journal/v407/n6805/abs/407695a0...). Photosynthesizers tend to deplete these nutrients from the sunlit layer, and
they are replenished by upwelling from below. However, warmer oceans tend to stratify thermally, inhibiting upwelling and surface photosynthetic
growth with it (this is why tropical waters are so nice and clear: there isn’t much growing in them). In a warming world, these low-productivity
regions are expected to spread.
Another consideration is the chemical impact of dissolved CO2 on ocean life, called ocean acidification. What a falling pH will mean for
photosynthesizers specifically (especially non-calcifying ones) is not yet clear, but it’s expected to have severe impacts on much ocean life,
especially corals and coral reefs (which provide food and other ecosystem services to millions worldwide, including some of the poorest among us).
Some of this likely could be mitigated, to some extent, but that would take political will which is running in the wrong direction at the moment.
al-khemie is not a terrorist organization
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Melgar
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Cool! Someone is actually responding to me with facts, rather than just writing me off as nuts immediately! This really should have its own thread
though, so I started one here:
http://www.sciencemadness.org/talk/viewthread.php?tid=77469#...
The first step in the process of learning something is admitting that you don't know it already.
I'm givin' the spam shields max power at full warp, but they just dinna have the power! We're gonna have to evacuate to new forum software!
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Melgar
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| Quote: Originally posted by zts16 | | With the right ratio of plants to animals plus whatever amount of fossil fuel emissions we're still producing, wouldn't life still be possible with
the good ol cycle of photosynthesis and respiration? Sure there'd be less oxygen in the air, but we can live just fine with a lower concentration of
oxygen, other than people at higher elevations, perhaps. |
I got that information from this wikipedia page:
https://en.wikipedia.org/wiki/Timeline_of_the_far_future
Basically, the sun has been steadily getting hotter, and as a result, eventually the oceans will evaporate such that subduction zones are no longer
underwater. This increase in friction between dry continental and oceanic plates will slow, and then stop plate tectonics. As erosion occurs, exposed
rock will react with atmospheric CO2 and remove it from the environment. Previously, the sediment would have been pushed into the Earth's magma,
heating and calcining the carbonate rock, and freeing the CO2, to be released in volcanic eruptions. Without this cycle though, it just stays as
carbonate rock.
The first step in the process of learning something is admitting that you don't know it already.
I'm givin' the spam shields max power at full warp, but they just dinna have the power! We're gonna have to evacuate to new forum software!
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Magpie
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This is a fantastic discussion and would get an A+ as a class paper. I'm sorry I have nothing to contribute to such sophisticated arguments.
The single most important condition for a successful synthesis is good mixing - Nicodem
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j_sum1
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