I think the primary source of long term natural reductions in carbon dioxide is rock weathering, but it is extremely slow. If we don't want to wait for millions of years we can try to hurry the process by pulverizing rocks to expose more surface area. This would be one of the safer forms of geoengineering, but it's still somewhat slow, and probably quite expensive.
No, not MUCH long, but only a teeny tiny bit longer, unless you're talking about life developing in the accretion disk of the central black hole. You can easily see this by noting that stars near the center of the Andromeda galaxy don't show a pronounced red-shift compared to those near the rim.
they argued about how many angles could dance on the head of a pin.
Sounds like "they" were mathematicians. Surely it would be some sort of transfinite number, but with the uncertainty of the continuum hypothesis I guess it is the kind of thing that you could argue about forever.
It is VERY hard to beat the efficiency of mother nature on this one: 6CO2 + 6H2O + Light = C6H12O6 (Glucose) + 6O2
If you're using plants to make glucose, or perhaps something a little easier to use for energy or as a feedstock, it's not that hard to be more efficient. When you take into account the energy a plant uses living they are quite poor net energy collectors. They are, however, very cheap. Algae can be more efficient, but are more expensive; and the same is even more true for good solar collectors.
There is also 'transmission' loss in delivering gasoline to stations and pumping it into vehicles. The loss is not enough make the system uneconomic, and I think this is also true for electric vehicles.
That would roughly be the result, which demonstrates why this is likely to be insufficient while we are still burning much fossil fuel.
There are other proposals that might be more effective, such as pulverizing certain rocks (serpentine?) and getting them to absorb the carbon dioxide from the air. This has the advantage of creating a stable and non-toxic end product that doesn't need any long term care.
If we're serious about reducing the carbon dioxide level by growing trees, we'll have to cut them down and store the wood somewhere where it won't decay. We will also have to replenish the trace elements taken from the soil by those trees so we can grow more. This could work to slowly remove the excess carbon dioxide we've released, but I don't think it would be feasible to keep up with our current rate of emissions.
China has a strong program of non-fossil energy, including wind, solar and nuclear. Just because they aren't willing to sign agreements doesn't mean they are doing nothing. The same could be said for the USA.
It doesn't matter when the elements formed, we just have to know what their relative abundances were then and compare that to the current state.
The neodymium system is complicated, as are all real world measurements to some extent, so consider an idealized system. Suppose that uranium consisted of a single isotope with a half life of four billion years, and it decays to lead. Now further assume that zircons when they form contain some uranium but no lead at all, because its atoms cannot fit into the crystal lattice. If we measure the uranium and lead in a zircon and find that uranium and lead levels are equal then it must have formed four billion years ago, since that is the half life and half the uranium has decayed.
Wikipedia has an indirect link to a 2002 paper where a microscopic nanotube was found to have a tensile strength of 0.15 TPa, which is easily strong enough. Even if that was wrong, I see no reason to expect the theoretical calculations to be so far off as to make a perfect structure lack enough strength. Whether they would last long enough to be useful in a space environment, with all the high energy radiation there, is something I wonder about. Can they be repaired in place as fast as they decay, or how much of a cable's life would be spent hauling up its replacement?
It does seem much too early for the Japanese (or LiftPort) to be getting serious about building a space elevator. I suspect that is more for the buzz, and the genuine hope is that the research dollars they generate will pay off in more mundane uses of super strength materials.
That is almost exactly the idea behind the space elevator. Two changes: You need to extend cable both up and down to keep the center of mass stable, and the station stays where it started and an inert mass is used for tension at the far end.
No scientist would dispute the larger warming effect of water vapor. Without it the world would be far too cold for us. That doesn't change the effect expected, and probably seen, from carbon dioxide.
It hardly even matters that your 25 times is an exaggeration. Since the absorption spectra of water vapor and carbon dioxide overlap there are several ways to assign the warming caused by each. Perhaps the most informative way is to say that water (vapor plus clouds) is the cause of up to 90% of the warming, carbon dioxide for up to 30%, and just ignore the fact that they add up to over 100%.
Spell a word wrong? Oh hey, what's that little red line underneath the word? huh, let's check it out. Oh hey! Whaddya know? "alot" isn't a word at all, is it? Huh, now I know!
I've seen evidence of people trying to fix that very error after Firefox started including a spell checker by default. After looking at the first few alternatives offered they apparently chose "allot"!
Slashdot Mirror
I think the primary source of long term natural reductions in carbon dioxide is rock weathering, but it is extremely slow. If we don't want to wait for millions of years we can try to hurry the process by pulverizing rocks to expose more surface area. This would be one of the safer forms of geoengineering, but it's still somewhat slow, and probably quite expensive.
No, not MUCH long, but only a teeny tiny bit longer, unless you're talking about life developing in the accretion disk of the central black hole. You can easily see this by noting that stars near the center of the Andromeda galaxy don't show a pronounced red-shift compared to those near the rim.
they argued about how many angles could dance on the head of a pin.
Sounds like "they" were mathematicians. Surely it would be some sort of transfinite number, but with the uncertainty of the continuum hypothesis I guess it is the kind of thing that you could argue about forever.
Boeing a/c do have a lot of computer controls, but they can all be easily overwritten by the CO/FO flying the a/c.
That actually sounds worse, but you probably meant overridden.
It is VERY hard to beat the efficiency of mother nature on this one:
6CO2 + 6H2O + Light = C6H12O6 (Glucose) + 6O2
If you're using plants to make glucose, or perhaps something a little easier to use for energy or as a feedstock, it's not that hard to be more efficient. When you take into account the energy a plant uses living they are quite poor net energy collectors. They are, however, very cheap. Algae can be more efficient, but are more expensive; and the same is even more true for good solar collectors.
I'm getting the big box now, no matter how I select reply. I hope something got fixed, and this isn't just random variation.
2006 (what I could find) electric power source breakdown for California:
16% coal
19% hydro
41% natural gas
13% nuclear
11% renewables
It's not just him. I get the small comment box too.
There is also 'transmission' loss in delivering gasoline to stations and pumping it into vehicles. The loss is not enough make the system uneconomic, and I think this is also true for electric vehicles.
I know, we could call it coal!
That would roughly be the result, which demonstrates why this is likely to be insufficient while we are still burning much fossil fuel.
There are other proposals that might be more effective, such as pulverizing certain rocks (serpentine?) and getting them to absorb the carbon dioxide from the air. This has the advantage of creating a stable and non-toxic end product that doesn't need any long term care.
If we're serious about reducing the carbon dioxide level by growing trees, we'll have to cut them down and store the wood somewhere where it won't decay. We will also have to replenish the trace elements taken from the soil by those trees so we can grow more. This could work to slowly remove the excess carbon dioxide we've released, but I don't think it would be feasible to keep up with our current rate of emissions.
the warming trend peaked in the 1930's
Your link fails to make clear that the records it mentions are for the USA only, the global peak for that data set remained 1998.
5kW x 2mill homes = 10 MegaWatts
Try 10,000 megawatts.
China has a strong program of non-fossil energy, including wind, solar and nuclear. Just because they aren't willing to sign agreements doesn't mean they are doing nothing. The same could be said for the USA.
It doesn't matter when the elements formed, we just have to know what their relative abundances were then and compare that to the current state.
The neodymium system is complicated, as are all real world measurements to some extent, so consider an idealized system. Suppose that uranium consisted of a single isotope with a half life of four billion years, and it decays to lead. Now further assume that zircons when they form contain some uranium but no lead at all, because its atoms cannot fit into the crystal lattice. If we measure the uranium and lead in a zircon and find that uranium and lead levels are equal then it must have formed four billion years ago, since that is the half life and half the uranium has decayed.
Educate yourself: http://en.wikipedia.org/wiki/Samarium-neodymium_dating
Wikipedia has an indirect link to a 2002 paper where a microscopic nanotube was found to have a tensile strength of 0.15 TPa, which is easily strong enough. Even if that was wrong, I see no reason to expect the theoretical calculations to be so far off as to make a perfect structure lack enough strength. Whether they would last long enough to be useful in a space environment, with all the high energy radiation there, is something I wonder about. Can they be repaired in place as fast as they decay, or how much of a cable's life would be spent hauling up its replacement?
It does seem much too early for the Japanese (or LiftPort) to be getting serious about building a space elevator. I suspect that is more for the buzz, and the genuine hope is that the research dollars they generate will pay off in more mundane uses of super strength materials.
Currently there is no material strong enough to hold 36000 km of its self.
You are ignoring taper. Even Kevlar would work with a taper of tens of thousands, and allowing for no safety margin
That is almost exactly the idea behind the space elevator. Two changes: You need to extend cable both up and down to keep the center of mass stable, and the station stays where it started and an inert mass is used for tension at the far end.
Comcast is promising 160 Mega Bits per second, not Giga Bytes. That makes you off by, let's see, a factor of 8000. Not even close enough for /.
No scientist would dispute the larger warming effect of water vapor. Without it the world would be far too cold for us. That doesn't change the effect expected, and probably seen, from carbon dioxide.
It hardly even matters that your 25 times is an exaggeration. Since the absorption spectra of water vapor and carbon dioxide overlap there are several ways to assign the warming caused by each. Perhaps the most informative way is to say that water (vapor plus clouds) is the cause of up to 90% of the warming, carbon dioxide for up to 30%, and just ignore the fact that they add up to over 100%.
The down side of this is that it sets up a system where people who are wrongly convicted end up getting harsher sentences than those who are guilty.
You're not allowed to engage in such barter without paying taxes. There's little chance of the IRS discovering your foul deed, so why worry?
According to your link, the new Advanced CANDU Reactor does used enriched fuel.
I've seen evidence of people trying to fix that very error after Firefox started including a spell checker by default. After looking at the first few alternatives offered they apparently chose "allot"!