rio grande
Sanjay Gupta assesses climate change impact
04:20 - Source: CNN
CNN  — 

The people of El Paso, Texas, are resilient. Living in the middle of the harsh Chihuahuan Desert, the city has no other choice. On average, 15 days every year spike over 100 degrees Fahrenheit. The city gets little relief with annual rainfall of just about 9 inches. It’s one of the hottest cities in the country.

One of its prime sources of water is the Rio Grande. Typically the river can supply as much as half of the city’s water needs. But climate change is making that increasingly difficult and is pushing the city to look for new sources of water. Now, El Paso is on track to become the first large city in the United States to treat its sewage water and send it directly back into its taps.

Increasing temperatures will make the dry region even more vulnerable to drought, according to the federal government’s most recent national climate assessment. Already challenged with balancing the demands of about 700,000 thirsty El Pasoans along with agriculture and industry needs, El Paso must also face the fact that climate change is literally drying up one of its major sources of water.

Analyzing tree ring records, scientists have been able to reconstruct the climate history of the region as far as the late 1500s and have found that as temperatures have risen, the amount of snow melting and feeding the Rio Grande has dropped.

“We’re getting less runoff now than we would have gotten as recently as the ’80s or ‘90s,” said J. Phillip King, a professor of civil engineering at New Mexico State University. King has tracked the river’s water levels for the past 27 years as an adviser to the Elephant Butte Irrigation District. The district manages the water distribution of some 90,000 acres of farmland along the Rio Grande Valley in New Mexico and Texas.

King told CNN Chief Medical Correspondent Dr. Sanjay Gupta that there is simply less snowmelt coming from northern New Mexico and southern Colorado to feed the river. Since 1958, the amount of early April snowmelt going into the Rio Grande has dropped 25% due to less snowpack and evaporation.

What’s happening in the Rio Grande is not unique. It’s a phenomenon happening throughout the Western United States.

King called the Rio Grande a harbinger of what’s to come. “You know we’ve already gotten critically low here, and you can think of the Colorado as a few years away from a similar fate,” he said.

Drought isn’t anything new for the 1,800-mile long river. The Rio Grande has survived severe and sustained droughts, King said. But an increase in temperature is pushing both a warmer and dryer climate. And that means not only potentially less snowfall but a greater chance for water to evaporate.

The federal government projects that temperatures could rise an additional 8 degrees Fahrenheit in the region by 2100.

The dwindling reserves are apparent at Elephant Butte Reservoir, just outside of Truth or Consequences, New Mexico. The reservoir there sits right on the Rio Grande and forms the largest recreational lake in the state. It holds water for farmers from north of El Paso up to Colorado. It has a capacity of about 2 million acre feet, King said. Currently, it’s hovering around 3% to 4% of its full capacity. Buildings that were built as offices during the dam’s construction in the early part of the 20th century were previously submerged in the 1980s. Now, they serve as lookout points to a nearly e