First of all, greenhouse gases are a good thing. Without them our planet would be around 60 degrees colder and we would probably not exist. Over the last 200 years, however, greenhouse gases have increased in volume causing greater warming impact on the planet. Although we tend to concentrate on carbon dioxide as the culprit the actual inventory of greenhouse gases consists of 6 primary sources. They are (in order of prevalence) Water Vapor, Carbon Dioxide, Methane, Ozone, Nitrous Oxide, and Synthetics (CFC’s, HFC’s, PFC’s, and SF6).
Water vapor is a gas, and it is the most influential greenhouse gas. That is to say that it is the primary force that retains heat in the atmosphere. It is generally believed that water vapor averages around 1% of the total atmosphere, thus making it 25 times more prevalent by volume than carbon dioxide’s 0.039%. Water vapor is also widely believed to contribute 55 to 70 percent of global greenhouse influence. Yet water vapor is not blamed in global warming scenarios for good reasons: Water vapor acts as a greenhouse gas until it reaches high concentrations, then it forms clouds and acts part time as a coolant. Water vapor moves with temperature change - it increases in warmer zones and precipitates from cooler zones. This movement occurs almost instantly; therefore water vapor cannot cause a warming trend. It simply reacts to it. It is considered a feedback gas to global warming, not a causal gas. As global temperatures increase, water vapor also increases due to relative humidity. Thus, water vapor supports higher temperatures as a new normal, exacerbating the trend and making it more difficult to reverse. Conversely, warm and humid regions (particularly closer to the equator) do not get warmer because the other greenhouse gases are not influential enough to overpower the more prevalent water vapor. For this reason, global warming is evidenced almost exclusively in polar, glacial, desert and mountain regions where water vapor is least prevalent. The term Global Warming is therefore a misnomer. A more correct term may be “Regional Warming”. This is best illustrated by the climate of the Eocene maximum, approximately 50 million years ago, when the average temperature of the earth shot up by as much as 16F degrees and carbon dioxide was 4 times more prevalent. During this period, geologic evidence indicates abundant life forms and forests had grown near the poles while equatorial regions appeared nearly the same as they are now. Temperatures had never been as consistent across the planet as they were during the Eocene.
As greenhouse gases warm the colder and dryer regions of the planet we see receding ice caps, shorter durations of sea ice, and surprisingly in some cases – more precipitation. In Boulder, Colorado for example, NOAA has identified significant and measurable rise in water vapor concentration over the last 40 years, trending to as much as 0.1 percent per year, or a full percent over 10 years. Consequently, increasing humidity is causing portions of Colorado to experience greater rain and snow despite a warming climate. Because water vapor continues to support and elevate the current temperatures, we are unlikely to reverse the trend even if we were to eliminate greenhouse emissions. And for what? Life was abundent and widespread during the Eocene epoch, so reversing warming trends do not necessarily help living conditions.
Despite the fact that global warming is underway and essentially irreversible, we continue to hope for a better outcome. Building design engineers are not making adjustments to drainage calculations or roof loading to compensate for inevitably greater precipitation. Coastal cities are not making allowances for inevitably rising sea levels or inevitably more severe hurricanes. It is time to forget about the argument of who is causing global warming as well as how to reverse it. Neither conversation is worth having. It is time to plan for the change that we all know is happening right before our eyes.Tony F.
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