“Instead of speaking of a shortage of supply we could just as truly say that there is a longage of demand.”
Biologist Garrett Hardin
Our rain and snow come from the sky, however much of the water gets up there by transpiration from plants and trees. So many people appreciate Colorado that they move here, causing the built space (housed, roads etc.) displaces fields and trees. Therefore, there is less water making it up to the sky to form clouds.
However, that’s probably a minor reason for the 25+ year drought affecting western North America. This dearth of water isn’t only the worst drought of this century; it is the worst drought in 1200 years! No wonder it is called a megadrought. Furthermore, it’s not just affecting southwestern Colorado, but much of western North America and has expanded to cover much of the US.
Yes, there are periodic climatic variations that cause dry years, then wet years. El niño/la niña is one such variation, but it has been overwhelmed by another factor—climate heating.
Climate chaos has already caused many weird weather patterns in southwest Colorado this year. First we had summer in March, then we experienced winter in April. However, one thing is constant—it has been dry. In early March of this year the snowpack was at historic lows. Then record high temperatures later that month melted much of the snow that remained. If you look west to the La Plata Mountains, their silver plate has been worn off.
How much of this drought is due to climate chaos? Scientists have estimated that about half is anthropogenic. An article published in 2020 found that 46% of the megadrought could be accounted for by climactic heating. It has become hotter since then, so perhaps more than half is due to anthropogenic heating. My understanding is that the other half is due to the normal variation in precipitation.
There is less water is coming from the sky and less water on the surface—which is how a drought is usually defined. What about under the ground? There the water supply is hidden and more difficult to measure, of course. However, we know that some aquifers have been almost sucked dry. The Ogallala aquifer, for instance, has been tapped by so many wells for crop irrigation that in some places the water level has dropped 300 feet!
Satellite measurements have shown that the Earth’s surface has fallen many feet in areas such as southern Florida, largely because the underground water has been removed. Although we think of the Amazon as being the ultimate of wetness and high humidity, some trees are suffering from dryness, leading to overheating and their death. Amazonia has been called “the lungs of the Earth”, but if the drought worsens, those lungs may stop breathing.
The term “water crisis” has been used so often that readers are jaded. Furthermore, a “crisis” implies resolution is possible, but in some areas the drought is so severe that resolution seems impossible. Thus, a new term has been coined for these dire situations, “water bankruptcy”. It is defined as: “…human-water systems whose water use persistently exceeds hydrological carrying capacity [so] damages are irreparable….” Examples include parts of Mexico, Egypt and India.
Human activities have decreased precipitation, especially in the North American Southwest. In addition, excess numbers of people have exceeded the carrying capacity of fresh water supplies. One group of humanity is causing this drought by using fossil fuels, and another group of humanity is suffering from water bankruptcy. Fewer people would help with both problems.
© Richard Grossman MD, 2026
