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Quick Take: What the Fourth National Climate Assessment Means for Nevada and the West

Climate change researcher Matt Lachniet explains the impacts of hotter temperatures.
Research  |  Nov 28, 2018  |  By Natalie Bruzda
Media Contact: Natalie Bruzda (702) 895-5132; natalie.bruzda@unlv.edu

Pictured is the lakebed at Lake Mead National Recreation Area. (Aaron Mayes/UNLV Photo Services)

The latest national climate assessment captures the future impacts of a warming planet more completely than reports that have come before it, UNLV geology professor Matt Lachniet says.

Lachniet studies climate history that extends thousands of years into the past, and what he’s learned from his research can give us an idea of what Nevada is capable of sustaining today, and into the future.

As he puts it, Nevada is moving in only one direction: to a place that will only become hotter and drier.

“There’s nothing that’s going to save us from that,” he said.

But if some changes are made, we can lessen the degree to which that happens, and also stem the loss of our water supply. We caught up with Lachniet to understand what Nevada, and the West, can learn from the Fourth National Climate Assessment.

How much will temperatures rise and what does it mean for Las Vegans? We’ll be experiencing more extremely hot days. We’re looking at potentially 10 to 30 more days each year that exceed 90 degrees. It’s already starting now, and it’s going to become even more prevalent in the next couple of decades.

Certainly it’s going to be a lot hotter so we’ll be spending more energy in the summer for our air conditioning. It’s going to end up costing us more. But I think we’ll be able to adapt in Las Vegas to the increased heat. We’ll just have to spend more time in doors during the summer.

A major takeaway: We’re really looking at reduced flow of water in the Colorado River — a region that sustains 55 million people. Warmer temperatures are causing less of the snowpack from the Rocky Mountains to make it into the river, and we have less water available.

There’s two reasons why the water levels in Lake Mead are receding: we’re using more than nature is giving us, and nature is giving us less. And the decrease in water flow has a lot to do with rising temperatures. There’s less snowfall in the winter because temperatures are higher. When the Spring season comes, there’s less melting snow that goes into the river.

What does a dwindling water supply mean for the West? In the Colorado River Basin, it’s about deciding on how we reallocate water during shortages. We have to share between Colorado, Nevada, California, Utah, Arizona, New Mexico and Wyoming. There’s been a lot of talks already between the states about how to manage drought contingency plans, and they’re working on some plans right now.

The basic idea is that if water levels in Lake Mead go below the critical low-level, the different parties are going to have to reduce their water usage.

We can slow that decrease, or even stop it if we have climate policies that decarbonize. But if we keep going on the same trajectory, there will not be enough water to sustain the economy as we know it in the southwest.

Are there other key takeaways for the West? Yes. As the climate heats up here, we’re going to have more wildfires. Soil can hold onto less water when it’s hot. And more wildfires will negatively impact air quality in Nevada.

And while sea level rise doesn’t directly impact Nevada as the state is not next to an ocean, we’ll experience secondary effects. Parts of the Bay Area, San Diego and Los Angeles will be underwater 100 years from now because of sea level rise. And those people have to go somewhere. It’s likely that some of those people will end up in Las Vegas if they can fight through the traffic on the I-15.

Is there a silver lining? The good news is that Nevada is already doing a good job of conserving water. We’ve been decreasing our per capita usage while also growing our economy.

The Southern Nevada Water Authority’s rebate program — which pays homeowners to take out their grass and other high water-use landscaping — is one reason for this. Outside irrigation is water that we use and lose. Grass sucks up the water and it goes back into the atmosphere.

Currently, we’re staying below our water limit from the Colorado River Basin.

About Lachniet: Lachniet is a climate scientist who focuses on paleoclimatology, which is the study of climate variations over the last few hundred thousand years. His primary focus is speleoclimatology — a field that concentrates on the use of cave deposits to understand past climate variations. Most recently he’s been diving in caves in Central America to bring greater understanding to climate history as it relates to the Maya civilization.