What deserts can teach about global warming

This is an interesting article from a retired physicist. The comments on earth age and evolution are errant (and the later assumption tangential to the argument). What took my notice was this comment:

Anyone who has lived in a desert area where the relative humidity is frequently below 5%, knows that dry air is a lousy green house gas. It can be 115 degrees F (46 degrees C) during the day yet cool off so rapidly that a sweater is needed two or three hours after sunset. Despite the heat sink of the ground with rocks hot enough to fry an egg, the heat is radiated rapidly away through the dry air to the clear night sky. Since dry desert air has about the same .04% concentration of carbon dioxide as air everywhere else, it is not credible to conclude that carbon dioxide is causing global warming.

Water vapor is the most effective greenhouse gas by far. With high humidity, even without cloud cover, the night air cools at a rate so slow as to be nearly imperceptible, particularly if you are trying to sleep without air conditioning.

While not disproving global warming by itself, this statement reminds us how much more important water is to atmospheric temperature than carbon dioxide.