Here is an open letter to aspiring climate scientists concerning the scientific method among other things.
Is anyone bothered by the fact that scientists manipulated data to fit desired outcomes? Can we trust scientists to follow a procedure that can be replicated? These climate scientists can't even replicate their published data. This is disturbing.
I don't think a large percentage of the human population lives in the desert. There are a few desert areas with sizable populations (Las Vegas, parts of California and the Middle East), but most deserts are fairly empty of people because of the lack of freshwater. The Arabian Peninsula is mostly empty, as is the Gobi Desert, the Sahara Desert, the Kalahari Desert, Antarctica (which is technically mostly desert), and much of the American Southwest. Not sure where you're going with this, Ralph.
Air takes as much water as it can hold from available sources (primarily the ocean) and rains out what it can't hold. If you put a bunch of extra water into the air over deserts, it would just move sideways with the wind, and rain out over a mountain. Water cycles in and out of the air very rapidly, unlike CO2 and other greenhouse gases. You are trying to inject a variable into consideration that is largely moot, because its effects are short-lived and don't accumulate, unlike CO2, which does. Whatever water vapor humans are injecting into the atmosphere doesn't stay there more than a couple of weeks.
As long as we are actively spraying that water into the air, particularly at high altitude, it does seem to have an aggravating effect on global warming, but the climate models already take water vapor into account, to the extent that they understand it. They admit that the global warming contribution from contrail enhancement of cirrus clouds is not well understood, but that doesn't mean they're just ignoring it. Just because you think climate scientists are missing something doesn't mean that they are, or specifically that they're missing your idea. Maybe you should give the IPCC another chance, since they seem well aware of your concerns.
Again, you seem to be assuming that the climate scientists are amateurs who don't know how to write computer simulations/models, when in fact, that's what many of them do professionally for extended periods. That doesn't mean they're all perfect at it, but it's silly to assume they don't know what they're doing in their own field of expertise. It's also silly to assume that you've thought of something they've missed. It's possible, but unlikely. I invite you to review the Dunning-Krueger Effect.
When you refer to "band" jet engine combustion water vapor, do you mean to suggest that jet engine combustion is banned at night? That's the first I've heard of such a thing. Lots of jets fly at night. Not as many as during the day because of lower passenger demand at night, not because of any ban. An unplanned experiment was done after 9/11 when aviation across and into and out of the US was shut down for three days. The lessened cloud cover allowed temperature ranges to expand because heat was more able to radiate into space at night and daytime temperatures were higher because the sun was not as obscured.
All told, the IPCC has estimated that aviation is responsible for 2% of human CO2 emissions and 3.5% of overall AGW, taking high-altitude water vapor into consideration. Low altitude human emissions of water vapor don't seem to significantly alter atmospheric concentrations of H2O.
Bottom line: Climate scientists are well aware of water vapor and include it in their attempts to understand climate change.
I don't think a large percentage of the human population lives in the desert.
As one who lives in the heart of the desert Southwestern U.S. I can guarantee you that a very tiny percentage of our population lives in the desert.
There are a couple of large cities like Phoenix and Vegas, but once you factor in the hundreds of square miles of nothing around them, it's pretty sparse.
A very telltale sign is that we speak of desert heat saying, "But it's a dry heat." Which it normally is, until you get to Vegas or Phoenix. Then the humidity is unbearable. Why so much humidity just in these cities? The human activity that Ralph mentions. A million swimming pools plus a million people watering their lawns plus a million businesses watering their lawns equals a giant-ass pocket of humidity (to go with the giant-ass ad very visible cloud of smog) over these metropolitan areas. A pocket that noticeably goes away as you drive away from them into the remote areas.
That is, if you believe human beings are capable of having an impact on the climate. If you don't, then the only other explanation is that these random brown clouds of who-knows-what and random pockets of humidity in the desert are indeed purely random. And humans just coincidentally happened to build their major cities right under them.
Pioneer #1: "Hey guys, let's build our town over there where it's nice, clean air and the 100f+ heat is bearable because it's low humidity."
Pioneer #2: "No way! Let's build over there under that huge brown cloud of toxins of unknown origin, where there's tons of humidity because heat plus humidity makes 100f+ so much more comfortable."