Part 3 of Earth as an Ecosystem
In the framework of climate change, water is a bit of a Goldilocks situation where too much or too little becomes disruptive, so we want just the right amount in our ecosystems. A farmer might long for the rain to water his parched land, but too much water creates flooding, washing away his crops. Even in a world where oceans and seas cover 71 percent of the planet’s surface, too much seawater is a threat. Then there is the water in the ground, which supplies the needs of vast agricultural complexes. Both over pumping and drought-reduced recharge currently impact the water supplies for America’s breadbasket and other critical agricultural regions.
The Ogallala
Hidden beneath the high plains of America’s mid-continent is the Ogallala aquifer. It stretches from South Dakota to West Texas and provides water to parts of eight separate states. One-sixth of the world’s grain production, and America’s breadbasket, depend on groundwater from the Ogallala aquifer. However, we ask too much of this natural wonder, which currently supplies 30 percent of all irrigation water in the United States. Because water doesn’t magically appear below the ground, the aquifer must continually recharge from surface water. Unfortunately, the recharge rate for the aquifer is slower than the rate of withdrawal.
The Ogallala aquifer has stored as much water as Lake Huron (29 billion acre-feet) in the past. But sadly, many parts of the aquifer are in decline, thus leading to falling water levels, dry wells, and the aquifer’s failure to meet annual demand. Water volumes in western Kansas, for example, are down by 60 percent from original levels.
The decline of the Ogallala aquifer is only partially due to climate change. Its decline is also driven by insatiable demand and poor water management. This aquifer has historically been the backbone of a vibrant farming economy, and rural farming communities across America’s breadbasket depend on its water. Increasing water demand and shrinking supplies of recharge water are challenging lifestyles and damaging local economies.
Megadrought
Another manifestation of climate change is a two-decade drought in America’s west, leaving many regions hot, dry, and thirsty. But the situation may get worse before it gets better. Tree ring data tell us megadroughts have occurred four times in the past 1200 years. The current drought started in the year 2000, and the period between 2000 and 2018 was the second driest 19-year period on record since the 800s.
While it is true that natural causes facilitate the occurrence of megadroughts, this does not mean human influences aren’t also at work. Anthropocene climate change and global warming are human-induced changes that amplify the severity of this megadrought.
Global warming has increased the average global temperature by about one degree Celsius over the long-term trend. But this number averages out both larger and smaller regional trends. Average annual temperatures in the American West have increased by 1.2 degrees Celsius over the norm. Higher temperatures result in more moisture loss, so global warming works to amplify the drought severity.
Researchers attribute up to 50 percent of the severity of the current drought to human activity. Climate change affects the distribution of water on our continents. There will be winners and losers as water resources become scarce in areas where large populations depend on both surface and groundwater supplies’ continued presence
Sources
The Ogallala Aquifer, Sustaining Life (By William House; Earthsphere on Medium) – https://medium.com/earthsphere/the-ogallala-aquifer-sustaining-life-340ab2c44a79?source=friends_link&sk=b215c6fa3bc9220eaf7bcbe976b5cdfd
Hot and dry in the Western USA, a megadrought in progress (Source: ArcheanWeb) – https://archeanweb.com/2020/04/21/hot-and-dry-in-the-western-usa-a-megadrought-in-progress/
Feature Image: That’s What This Desert Needs- a Lake! (By cogdogblog) (Modified) – https://commons.wikimedia.org/wiki/File:That%27s_What_This_Desert_Needs-_a_Lake!_(15016748476).jpg – This file is licensed under the Creative Commons Attribution 2.0 Generic license. – https://creativecommons.org/licenses/by/2.0/deed.en
