It's not caused by CO2--it's caused by H2O.

That nasty dihydrogen monoxide. Is there any evil it's not capable of, any problem of which it's not, at root, the cause? It's got to be the most deadly substance on the planet.

How many more must die before we get the message? We must wean ourselves off it as soon as possible.

I blame our space program--putting tons!!!1one of DHMO into our upper atmosphere.

Obviously, whatever is going wrong with the planet, is all the fault of capitalism and humanity. We should kill off 90% of our population and go live in some caves.

Only 90%? Well, I guess that would be a good start.

The Tunguska Event is to blame! Cool, no hot! I wonder if Vladimir Shaidurov is related to Sergei Televishenko, that famous Soviet inventor of the television. And we Yanks think we are at the center of the universe.

But if he is correct, we are in a big heap of trouble.

That said, and setting global warming aside, increased CO2 concentrations are turning the oceans acidic (read here) and that is very bad news even if increased CO2 has zero impact on the global climate.

Hrm...

I think that there's something to this theory that's at least worth looking into further, but I'm not sure exactly how it would impact the world and the way we do things.

I mean, if water vapour is part of the "greenhouse gasses" equation, is it really such a good idea to get hydrogen cars up and running, since they release, well, water vapour as their exhaust?

I've always suspected that hydrogen cars with water vapour exhaust were a questionable idea, since it could possibly increase cloud cover and cause climate issues. This doesn't make me think that they're any better of an idea now, either.

I've always suspected that hydrogen cars with water vapour exhaust were a questionable idea, since it could possibly increase cloud cover and cause climate issues. This doesn't make me think that they're any better of an idea now, either.

You're kidding, right? Just playing along with the DHMO meme, right? There may be legitimate environmental reasons why Hydrogen cars are not desirable, but a water vapor exhaust is not one of them.

I think one of the problems with sarcasm and parody on the internet is there are so many people out there who really think some of this stuff is true.

I'll give you the benefit of the doubt and play along: More cloud cover would be beneficial in the daytime as it reflects sunlight, thus cooling the Earth. At night it is harmful as it traps heat, preventing the Earth from naturally radiating excess heat to space. Thus the true solution is that Hydrogen cars can only be allowed to operate during daylight hours.

-S

Stephen: Well, albedo change is a real thing, and at some level a real concern.

But all the hydrogen cars in the world (a world where all the cars are hydrogen powered!) still, of course, wouldn't be a blip compared to evaporation from the oceans, so you're quite right.

Re. the "acidic oceans" thing, where's Caldeira's research, rather than press releases? And can anyone write on the subject without passing along, breathlessly, things prefaced with "could", with no estimate of actual probability? And when the worst harm they predict is "it might make corals more unhappy"?

Shoddy, shoddy work, especially for something from Stanford.

No, I wasn't playing to the DHMO meme. While they might not create the same amount of cloud cover as oceanic evaporation, there is still sound theory behind the idea that man-made clouds are causing local climate changes in some areas.

There are plenty of serious non-spoof articles around regarding this matter, quite a few of them focused around airplane contrails. I can't imagine that adding even more steam to the atmosphere and increasing cloud cover would necessarily be a good thing for the earth, even if it doesn't contribute to global warming. I personally prefer sunny skies, but that's just me.

Rand

You only wish you were joking about the 90% thing.

Check this website:

http://www.thegeorgiaguidestones.com/Message.htm

Dennis

I mean, if water vapour is part of the "greenhouse gasses" equation, is it really such a good idea to get hydrogen cars up and running, since they release, well, water vapour as their exhaust?

Water vapor is, and always has been, a very important part of global warming simulations. In case you didn't notice, 3/4 of the Earth's surface is covered with water, and the vapor pressure of that water changes with increasing temperature. There's a positive feedback from this water that has always been in models. The extra forcing from CO2 alone is only a fraction of the forcing that's projected as CO2 increases.

Also, you are repeating a bit of foolishness when you worry about H2O emissions from combustion. The water vapor content of the atmosphere is controlled by evaporation and condensation, not by the total quantity of H2O in the environment. This is because there's an effectively unlimited supply of water in the oceans. This is in contrast to CO2, where the reservoir that quickly exchanges with the atmosphere is much more limited and (in the case of dissolved CO2 in surface waters) closer to being saturated. As a result, CO2 emission causes cumulative buildup in the atmosphere (until processes operating over thousands of years can transfer it to less quickly equilibrated reservoirs); H2O emission from combustion only has a temporary effect before rain/etc. dumps the water back to the surface.

Noctilucent clouds have actually been increasing recently, which seems counter to the idea that warming has been due to their absence. If anything, high altitude clouds should increase warming, since they are above the altitude at which the atmosphere becomes optically thin to far infrared radiation, and therefore they would reflect some of this IR back down. (Clouds at low altitude that reflect sunlight before it can thermalize would, in contrast, have a net cooling effect.)

Oh, and the mesosphere is very dry, so rocket launches could become a dominant source of water there sooner than you might think. I suspect high altitude water is going to be the limiting factor on how much payload can be lofted into space by rocket, which would be ironic for those with an environmental fetish for hydrogen-fueled rockets. Note that once the rocket is above the mesosphere, most of the exhaust gases (which overwhelmingly returns to the atmosphere, for launches to LEO) will eventually convect/diffuse down through the mesosphere.

To clear up an apparent contradiction in the previous post: the water vapor content of the troposphere is controlled by evaporation/condensation. At high altitude, water comes from things like methane oxidation and occasional injections from the troposphere. So, combustion sources in the upper atmosphere could be important.