Climate change is increasing the Risk of a California Megaflood

by Andrea Malmberg

I thought I would try to explain why water vapor may be the Earth's most abundant greenhouse gas. Though increased water vapor doesn't cause global warming, it's a consequence of it. It's responsible for about half of Earth's greenhouse effect — the process that occurs when gases in Earth's atmosphere trap the Sun's heat. 

The total atmospheric water vapor is increasing 1 - 2% per decade. For every degree Celsius that Earth's atmospheric temperature rises, the amount of water vapor in the atmosphere can increase by about 7%. 

While the laws of thermodynamics are interesting, I always need to bring it down to the decisions that can happen at the soil surface.

When all of the world's grasslands are healthy (that includes the vast swaths of land that are now farmed in the Pacific/Intermountain West - half left fallow every other year), we should expect 6-8% SOM. 1% SOM holds an estimated 16,000-28,000 gallons of water. When we are depleting these grasslands through our management decisions and creating landscapes that contain 1% or less SOM, that water @100,000 gallons/acre (20,000 gallons x 5 = 100,000 gallons per acre) is going into the atmosphere and not cycling beneficially.

The more water vapor that air contains, the more energy it holds. Atmospheric rivers are actually created, and this energy fuels extreme weather events. 

More evaporation from the land also dries soils. When water from intense storms falls on hard, bare soil, it runs off into rivers and streams, taking soil with it instead of being absorbed. And this, more than how much precipitation you get in any given year, is the cause of drought. We always want to say when asked, "How much rain did you get?" "All of it!"

I'm certainly not an authority on this, and I hope it opens dialogue. As a rancher, I simply see the benefits of getting water and carbon back in the soil where they belong. Photosynthesizing plants are how we can do this.