Climate Change Is Shrinking the Colorado River

Predicted Growth of Drought in the U. S. Southwest

GR: Here’s a helpful article that explains the drought disaster that is spreading across the southwestern U. S. There’s nothing new here, but the discussion clarifies some issues and will help you prepare for the inevitable changes. The article has an optimistic message, but the science is clear, life will become steadily more difficult in the Southwest, people will move away, and most will be gone from Arizona and large areas of surrounding states by 2100. It is inescapably obvious that we need to redirect the energy devoted to development in the Southwest and the corresponding effort to conserve water to forcing an immediate end to fossil fuel use.

Projected Drought Intensity in the U. S.

Though I believe the future for the Southwest is bleak, there is one small hope that the article contains. The Southwest could become a solar power generator that might give some of the people the financial means to survive the drought. Of course, this does nothing to protect nature and wildlife in the region. I’ve posted 43 discussions of climate-change induced drought in this blog. Click here to scroll through stories about the coming megadrought that can no longer be avoided.

“The nation’s two largest reservoirs, Lake Mead on the Arizona/Nevada border and Lake Powell on the Arizona/Utah border, were brim full in the year 2000. Four short years later, they had lost enough water to supply California its legally apportioned share of Colorado River water for more than five years. Now, 17 years later, they still have not recovered.

“This ongoing, unprecedented event threatens water supplies to Los Angeles, San Diego, Phoenix, Tucson, Denver, Salt Lake City, Albuquerque and some of the most productive agricultural lands anywhere in the world. It is critical to understand what is causing it so water managers can make realistic water use and conservation plans.

“While overuse has played a part, a significant portion of the reservoir decline is due to an ongoing drought, which started in 2000 and has led to substantial reductions in river flows. Most droughts are caused by a lack of precipitation. However, our published research shows that about one-third of the flow decline was likely due to higher temperatures in the Colorado River’s Upper Basin, which result from climate change.

“This distinction matters because climate change is causing long-term warming that will continue for centuries. As the current “hot drought” shows, climate change-induced warming has the potential to make all droughts more serious, turning what would have been modest droughts into severe ones, and severe ones into unprecedented ones.

The Colorado River is about 1,400 miles long and flows through seven U.S. states and into Mexico. The Upper Colorado River Basin supplies approximately 90 percent of the water for the entire basin. It originates as rain and snow in the Rocky and Wasatch mountains (Courtesy USGS).


How Climate change reduces river flow

“In our study, we found the period from 2000 to 2014 is the worst 15-year drought since 1906, when official flow measurements began. During these years, annual flows in the Colorado River averaged 19 percent below the 20th-century average.

“During a similar 15-year drought in the 1950s, annual flows declined by 18 percent. But during that drought, the region was drier: rainfall decreased by about 6 percent, compared to 4.5 percent between 2000 and 2014. Why, then, is the recent drought the most severe on record?

“The answer is simple: higher temperatures. From 2000 to 2014, temperatures in the Upper Basin, where most of the runoff that feeds the Colorado River is produced, were 1.6 degrees Fahrenheit higher than the 20th-century average. This is why we call this event a hot drought. High temperatures continued in 2015 and 2016, as did less-than-average flows. Runoff in 2017 is expected to be above average, but this will only modestly improve reservoir volumes.” –Brad Udall and Jonathan Overpeck (Much more: Climate Change Is Shrinking the Colorado River – Indian Country Media Network.)

Average Annual Wildfire Number and Size Increasing in the Great Plains

GR: Large fires occur during periods of high temperature and drought. The fire increase across the North American Great Plains is typical of many other regions undergoing fire regime changes as the Earth warms. Fueled by increasing temperature, drought, and invasive species, the fires will continue increasing. A study appearing in Geophysical Research Papers (GRP) documented dramatic changes since 1985. The study abstract follows the images.

Wildfire grasslands disaster, North American Great Plains, Lon Tonneson

Large wildfire trends in the western United States, 1984–2011
Authors: Philip E. Dennison, Simon C. Brewer, James D. Arnold, Max A. Moritz (Geophysical Research Letters, April 25, 2014)


“Rapid changes in wildfire patterns are documented globally, increasing pressure to identify regions that may experience increases in wildfire in future decades. Temperate grassland and savanna biomes were some of the most frequently burned regions on Earth, however large wildfires have been largely absent from the Great Plains of North America over the last century. In this paper, we conduct an in-depth analysis of changes in large wildfire (>400 ha) regime characteristics over a 30 year period across the Great Plains. For the entire biome, (i) the average number of large wildfires increased from 33.4 + 5.6 per year from 1985-1994 to 116.8 + 28.8 wildfires per year from 2005-2014, (ii) total area burned by large wildfires increased 400%, (iii) over half the ecoregions had greater than a 70% probability of a large wildfire occurring in the last decade, and (iv) seasonality of large wildfires remained relatively similar.” –Victoria M. Donovan, Carissa L. Wonkka, Dirac Twidwell. (Accepted  for publication by GRP)

Warmth will worsen wet and dry extremes – Climate News

GR: This warning is worth repeating. It needs to reach the ears of the climate-change deniers whose willful ignorance is endangering all of us and all the creatures sharing this ride with us. Storms, floods, and droughts will get worse.

Cloudburst, North Vancouver: Wet or dry, extremes will become more intense. Image: Terence Thomas via Wikimedia Commons

“Wet and dry extremes across the world will become more marked as the planet heats up, evidence from past climates shows.”

“Two US scientists have once again confirmed one of the oldest predictions of climate change: that those regions already wet will become wetter, while the arid zones will become drier.

“This time the reasoning comes not just from computer models of future climate, but also from the evidence of the past.

“Because the northern hemisphere will warm faster than the southern, the temperature difference will drive the planet’s rainbelts northwards, at least during the winter months. The tropics will become wetter, while the subtropics and the mid-latitudes will become drier, and this will be most noticeable in June, July and August.

“The predictions – made in the journal Science Advances – come from two researchers. Aaron Putnam is a glaciologist who studies ancient climates at the University of Maine. Wallace Broecker is an oceanographer at the Lamont-Doherty Earth Observatory of Columbia University, and one of the pioneers of climate research.” –Tim Radford (Learn more: Warmth will worsen wet and dry extremes – Climate News NetworkClimate News Network.)

How a Warming Planet Drives Human Migration

GR:  Thoughts on Climate Change

The climate news today (and really every day now) is not good. The Times article below focuses on just one of the bad bits. Global warming and consequent shifts in weather patterns are stressing everyone, but especially those people living in equatorial regions. Droughts, fires, and floods are becoming intolerable. The emerging climate-change-driven diaspora will carry the stress north and south into temperate latitudes. Projections made by many scientists in the U. S., European Union, and Asia portray a dismal future for Earth and humanity.

A Glimpse of Future Earth

Climate-change emigrants and their descendents moving north will not escape the ravages of a warming planet for very long. Stresses in northern latitudes have already begun. As the human population squeezes north to find food and water, resources will dwindle and conflicts will intensify. Nature in even the diminished form that we see now will sink toward unsustainable levels where wild plants and animals, then watersheds, then soils, and then fresh water are lost.

As I look out across my fields of invasive weeds and my ponds and small stream choked with artificially fertilized algae and filled with invasive animals, I remember the sunflowered fields and sparkling creek of my history. As the pace of climate change accelerates, “the good old days” will become a meaningful phrase for younger and younger people facing a constant need to adapt to more difficult times.

Want to keep up with the changes? The Daily Climate carries the best selection of current stories I’ve found. The Daily Climate included a link to the story below along with dozens of others. (Header image:  A farmer tries to revive his unconscious cow. Photo by CNN.)

Illustration by La Tigre.

“Climate change is not equal across the globe, and neither are its longer term consequences. This map overlays human turmoil — represented here by United Nations data on nearly 64 million “persons of concern,” whose numbers have tripled since 2005 — with climate turmoil, represented by data from NASA’s Common Sense Climate Index. The correlation is striking. Climate change is a threat multiplier: It contributes to economic and political instability and also worsens the effects. It propels sudden-onset disasters like floods and storms and slow-onset disasters like drought and desertification; those disasters contribute to failed crops, famine and overcrowded urban centers; those crises inflame political unrest and worsen the impacts of war, which leads to even more displacement. There is no internationally recognized legal definition for “environmental migrants” or “climate refugees,” so there is no formal reckoning of how many have left their homes because climate change has made their lives or livelihoods untenable. In a 2010 Gallup World Poll, though, about 12 percent of respondents — representing a total of 500 million adults — said severe environmental problems would require them to move within the next five years.

  1. ‘Amazon Basin: As glacial melting reduces freshwater reserves for the Andean plain, tensions are growing between locals and the mining and agribusiness operations that consume much of what remains. Researchers predict that this resource conflict will drive more migrants to the Amazon Basin where many have already turned to informal mining and coca cultivation, fueling the rise of criminal syndicates.

  2. “Lake Chad, 3. Syria, 4. China, 5. Philippines” –Jessica Benko (New York Times: Continue reading.)