Drought vs. Desertification

August 11th, 2021

Water truly is a miraculous substance. Did you know that only 1% of all the water on Earth is freshwater and available for human use? Did you know the adult human body is about 60% water? We’re all feeling the stress of water scarcity this summer, and rural residents are especially vulnerable.

Folks depending on wells and surface water are watching creeks and wells run dry. Remember that change in nature is often nonlinear: this is the inevitable result of a long-term climatic trend brought about by our centuries-long consumption of fossil fuels. The explosion of illegal cannabis grows (an estimated 3,000-4,000 in the County) likely was the catalyst here, the final stressor. But we also have to acknowledge that we, all of us, collectively pump groundwater faster than it can recharge. This is unsustainable.

Aridification/desertification is "the degree to which a climate lacks effective, life-promoting moisture" (Glossary of Meteorology, American Meteorological Society). This is different from drought, which is "a period of abnormally dry weather sufficiently long enough to cause a serious hydrological imbalance". Even though Weaverville experienced a torrential monsoon on Friday, July 30th, deluging nearly 1” of rain in 30 minutes, that was just a drop in the bucket of the freshwater deficit we’ve accrued.

We are not in a drought. We are in the process of aridification and ecological succession. This will unfold over decades and centuries, but unfold it will. We have pushed the ball off the top of the hill and it is rolling into a valley.

            I consulted the Climate Prediction Center for this article and, although I wasn’t surprised, my heart sank at the winter forecast: less than average precipitation, higher than average temperatures. There will be no drought-buster this winter. Next summer will be worse. We won’t replenish our supplies until we have a massive drought-busting year, most likely when the next El Niño event occurs. Hopefully. Although cyclical, they occur somewhat irregularly. This video explains El Niño and La Niña: https://www.youtube.com/watch?v=wVlfyhs64IY&t=89s.

            To understand aridification, we must understand evaporation (liquid transforming to gas) and evapotranspiration (water evaporating from soil moisture/transpiring from vegetation). As Earth’s atmosphere warms, more energy is available to break the liquid molecular bonds, and more water vaporizes. Solar energy combined with thermal energy re-radiated back down to Earth’s surface from GHGs allows for more moisture to become vapor. More heat = more evaporation.

Here in the aridifying West, evaporation is a vastly larger flux than precipitation. I highly recommend reading this paper: https://www.pnas.org/content/117/22/11856.

            Interestingly enough, warm air holds more moisture than cold air. Water itself is a greenhouse gas! We’ll explore atmospheric chemistry in great detail in a later edition, but molecules with multiple chemical bonds (CH4 has four bonds, CO2 and H2O have two bonds) can capture and store energy (i.e. thermal energy) in those bonds, and release it back into the environment in all directions, including back down to Earth’s surface. Here’s a video about the greenhouse effect: https://www.youtube.com/watch?v=SN5-DnOHQmE&t=140s.

            This causes a positive feedback loop, wherein more heat leads to more evaporation, which increases water vapor in the atmosphere, which traps more heat, and increases the temperature, causing more evaporation . . .

            Increased thermal energy has intensified the hydrological cycle. It’s no coincidence that Boston and NYC had torrential downpours and near-Biblical flooding around the same time the PNW was shattering heat-wave records. As sea-surface temperatures grow warmer, hurricanes grow stronger. More energy = more intense storms.

This is simple chemistry. These are the laws of the physical natural world we inhabit. We need to be prepared. Here are some steps we can take:

1)     Obtain rainwater-capturing infrastructure! Acquire tanks and piping to harvest rainwater. 1” of rain over 1,000 ft2 of impermeable surface = 600 gallons.

2)     Recycle gray water and limit non-food/non-livestock watering.

3)     Coordinate with neighbors and stagger groundwater pumping times. This avoids cumulative impacts.

4)     Advocate for receiving aid via the California Disaster Assistance Act.

We only have one home planet. Take care of yourselves and each other.

Image sourced from: https://www.sciencenewsforstudents.org/article/scientists-say-desert