Dec. 10, 2018

Moisture in the Atmosphere and Global Warming

Intense heat can imperil cars and airplanes, evaporate drinking water supplies, and halt outdoor labor such as farm work and construction. We live in a warming world, but temperature affects many ecological factors. One of the more profound aspects of a warming world is the impact of warmer temperatures on moisture in the atmosphere which effects humidity and heat index. Simply stated, a warmer atmosphere can hold more water vapor, and an atmosphere with more water vapor can produce more precipitation. Just as a bigger bucket can hold and dump more water, a warmer atmosphere can hold more water vapor and therefore dump more water when it rains. So far this year, we have had record rainfall in the south and Midwest. More extreme rainstorms will pose a challenge for those who manage drinking water supplies, those who grow crops or raise livestock, and those who oversee our roads and railways. It’s something we’ll need to build for, warn for, and work on.

There is also evidence that tropical cyclones are slowing down. I wonder if the mass of the increased moisture makes storms move more slowly. Slower storms can dump more rain on a place, and when that place is coastal land, it can bring catastrophic flooding. We definitely saw this with Harvey and Florence. The precipitation from Harvey was so large, meteorologists had to add another color on their precipitation maps. I also wonder if higher water vapor in the atmosphere has been incorporated into the climate prediction models that meteorologists use to predict and warn the public, especially flood warnings. It seems as though severe flooding has not been predicted well in my neck of the woods.


  • For each 1.8°F (1°C) of warming, saturated air contains 7 percent more water vapor on average.
  • Sea surface temperatures have risen by 0.5–0.6 °C since the 1950s, and over the oceans this has led to 4 percent more water vapor in the atmosphere since the 1970s.
  • Surface air moisture content has increased since 1976, consistent with changes in atmospheric temperature.
  • Observed moisture increases are largest in the tropics and in the extra-tropics during summer over both land and ocean.
  • The northern hemisphere is tending toward increasingly warmer and more humid summers, and the global area covered by extreme water vapor is increasing significantly.
  • Increased atmospheric moisture content may also affect the El Niño Southern Oscillation (ENSO) by intensifying regional precipitation variability, and associated extreme precipitation and drought events, which is a major driver of inter-annual climate variability.
  • The increase in atmospheric moisture content increases the risk of extreme precipitation events. The air is on average warmer and moister than it was prior to about 1970 and will likely led to a 5 to 10 percent effect on precipitation and storms that is greatly amplified in extremes.

So, this is anecdotal and purely speculation, but I have noticed that I have to call the air conditioner repair man almost every year these days. I’m having much more condensation in my trays up in the attic and we also seem to have to add Freon more frequently to the system. We recently had to buy a new refrigerator and researched to find the brand with the most dependable ice maker. That ice maker is constantly freezing up and I wonder if it may be an excess water vapor problem. In addition, the heat index during our summers seems to be higher. Being outdoors in the summer feels more like a sauna than it did when I was younger though that could be a combination of global warming and getting older;)

Moisture in the atmosphere is just one of the effects of global warming, but it is an example of how important it is to look at the whole picture of the environment. Warmer temperatures can also lead to a chain reaction of other changes around the world. That's because increasing air temperature also affects the oceans, weather patterns, snow and ice, and plants and animals. The warmer it gets, the more severe the impacts on people and the environment will be. Warmer temperatures affect agriculture, energy, water supplies, health, wildlife, ecosystems and even recreation.