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September 25, 2021

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Nevada caves illuminate past climate, future challenges in the Southwest

Nevada Climate History

Steve Marcus

In September, UNLV geoscience professor Matt Lachniet, left, and graduate student Chad Crotty made a trip to the Lehman Caves in Northern Nevada’s Great Basin National Park. By analyzing the layers of stalagmites that naturally break from cavern floors, Lachniet is able to map regional trends over 175,000 years.

On a trip to Great Basin National Park, UNLV geoscience professor Matt Lachniet says that rainfall many millennia ago formed lakes in the desolate basins lining this strip of rural highway. Between the towns of Pioche and Panaca, we stop at Cathedral Gorge, where a multimillion-year dance of erosion and tectonics forged a slender canyon fringed with clay-colored spires.

Closer to Great Basin, Lachniet’s grad student cuts left off an access road, down a 20-foot slope to an unspectacular oval-shaped depression in the land. This thirsty patch of earth was a lake 12,000 years ago, its ridges still marked by the force of ancient waves.

“This is like a van Gogh painting to me,” Lachniet says.

Water’s past forms the foundation of his research, including his climate studies inside Nevada caves. On a hot September day at his UNLV lab, he’d explained why, pointing to a table holding dozens of bisected stalagmites, the spikes that ascend against gravity from a cave’s floor. The delicate lines in the stone resemble tree rings. Cut a stalagmite in half, Lachniet said, and you find layers dating thousands of years, the echo of minerals left behind by water.

Click to enlarge photo

UNLV geoscience professor Matthew Lachniet points to growth layers on a section of a stalagmite at the Las Vegas Isotope Science Laboratory on UNLV campus Monday, Sept. 19, 2016.

For a climate scientist, these imprints are invaluable. Lachniet can track regional trends over 175,000 years, and researchers elsewhere have worked with much older samples. His focus is the long-term, looking at natural controls like gradual shifts in Earth’s orbit. On a time scale of years and decades, climate also is determined by sea-surface temperature, including El Niño patterns.

That dynamic is changing with a modern variable: the politically thorny issue of global warming. While lawmakers debate, scientists agree that human activity exerts a strong force on the planet, a force so strong that when it comes to temperature, the natural climate machinery is often superseded by human-caused change, which has contributed to drought, rising sea levels and glacial retreat.

Climate is a natural, cyclical process, skeptics say. True, but that scientific reality falls flat as an argument when you consider that humans can affect all sorts of natural processes. Just as the U.S. Geological Survey has shown human activity can induce earthquakes, NASA has shown that humans have rapidly affected the climate, with heat-trapping carbon at its highest level in 400,000 years.

Using the cave records, Lachniet found that Nevada’s climate fluctuates between dry and wet in one cycle of about 21,000 years. Around 1,600 years ago, we entered a warming period and will continue trending drier. Add human activity, and Lachniet warns of a potential double-whammy. “There’s going to be the natural trend of warming plus the human trend on top of it. We could potentially expect faster rates of what will be normal due to human influence.”

Snowmelt from Wheeler Peak has sustained generations of Northern Nevada cattle ranchers. The creation of Great Basin National Park in 1986 protected grazing rights and farming claims on the water to grow lush alfalfa crops.

Snowmelt from Wheeler Peak has sustained generations of Northern Nevada cattle ranchers. The creation of Great Basin National Park in 1986 protected grazing rights and farming claims on the water to grow lush alfalfa crops.

Water worries in the desert

Pushing up against the Utah border about four hours north of Las Vegas, we arrive at Great Basin National Park. There’s no thriving tourism economy outside, no fake Western storefronts advertising geodes and panning for “gold.” The village at the park’s base, Baker, registered a population of 68 during the 2010 census. There’s a motel and RV park, a few restaurants, a U.S. Post Office, a church and about a half-dozen irrigation plots.

There also are water worries.

Turning off a local street to enter the park, we see an enormous water bucket with signs protesting the Southern Nevada Water Authority. The SNWA’s plan to develop a $3.2 billion pipeline to pump groundwater south has been controversial for years. In this pocket of Northern Nevada, protest pamphlets are a common sight in gas stations.

The issue is in litigation, as a coalition of local governments and conservation groups argue the water transfer would endanger ecosystems and farmland. On its website, the Great Basin Water Network calls the roughly 300-mile pipeline “unprecedented in ambition and scope. … If implemented, the proposal will cause disastrous impacts to the human and natural environment.”

At the same time, Las Vegas will need water.

Through the ’90s into the early 2000s, the Las Vegas Valley saw rapid growth. While it brought prosperity, it also fueled heat-trapping gas emissions. According to the Environmental Protection Agency’s website, the state’s gas emissions increased almost four times faster than the national rate.

In the following decade, temperatures were nearly 2 degrees higher than the historical average. Sounds harmless, but it’s significant for all the reasons we imagine: heat waves, changes in weather patterns, harsher drought, less water. Across the Southwest, we’re seeing the consequences. Drought and a human-caused rise in temperature could have contributed to tree mortality, more fires, insect outbreaks and early snowmelt, according to the most recent National Climate Assessment by a consortium of more than 300 experts and a dozen federal agencies.

In this July 17, 2014, photo, recreational boaters ride by a bathtub ring that delineates the high water mark at Lake Mead.

In this July 17, 2014, photo, recreational boaters ride by a bathtub ring that delineates the high water mark at Lake Mead.

In Nevada, higher temperatures mean more severe droughts and stress on the Colorado River network. They mean more evaporation of the water. They mean heat-related health problems, reduced air quality and an ecosystem shift affecting agriculture and wildlife.

“The future for much of the West, including Nevada, is going to be warmer and drier,” said Benjamin Cook, a NASA climate scientist. “The uncertainty is really in the magnitude of those things.”

Las Vegas draws nearly all its water from Lake Mead, where bathtub rings on the surrounding stone show how far and fast levels have dropped in recent years. Within the next several decades, the Southern Nevada Water Authority is likely to accept a 10 percent shortage in its annual allocation, part of a multistate deal to preserve the reservoir. Complicating matters, the SNWA expects that amid this shortage and added pressures from climate change, its water needs could nearly double in 50 years.

Since its creation in 1991, SNWA has been successful in steadying demand among residents through incentives and conscience-tapping awareness campaigns, the type of management critical to adapting. But as demand goes up with new neighborhoods in the coming decades, the area will need long-term solutions.

That’s why Southern Nevada is looking North, though pumping groundwater from the Great Basin and others areas is not the only option. SNWA continues to look at partnering with Mexico for a share of the country’s Lake Mead allotment. “For the next half-century, we have a great idea of what our demands are going to be and how we are going to meet those,” said spokesman Bronson Mack. Despite resistance, he said, the pipeline project was moving forward. “We have to remember that the water within the state of Nevada is a state resource.”

SNWA remains confident it can meet demand through 2065. Much of what happens after that depends on our response now. Climate prognosticators must view the future through a keyhole in which the political will to tackle global warming varies. So every projection offers a high and low greenhouse-gas scenario. Under a low-emission scenario, we fare much better. Instead of jumping 5.5 to 9.5 degrees Fahrenheit in the next century, we jump only 3.5 to 5.5 degrees, the Climate Assessment said.

Acting is not futile. Cook’s data show if we shift to a lower-emission scenario, the Southwest could halve the probability of entering into a multidecade mega-drought during this century. That finding, he says, demonstrates that aggressively reducing carbon emissions could make a concrete difference.

Caves are climate record-keepers

Nevada Climate History

UNLV Geoscience professor Matthew Lachniet stands by formations in the Lehman Caves in the Great Basin National Park Thursday, Sept. 15, 2016. STEVE MARCUS Launch slideshow »

We enter the Great Basin’s prize feature, the Lehman Caves, and the air feels heavier and colder. Joined by the park’s chief of natural resources, Ben Roberts, we explore chambers bristling with formations resembling pipe organs made of melting wax. The scientists point out thin strips of rock, or “bacon,” hanging from the ceiling, and “scallops” where water droplets ever so slowly indented the walls. “Moonmilk,” a white mineral deposit, tattoos several rocky knuckles, and the floor is full of “popcorn” outgrowths attached in clusters like barnacles.

According to the National Park Service, the caves were used as a set for a ’60s sci-fi riff on “The Wizard of Oz” called “The Wizard of Mars.” Look too long at their otherworldliness and a lumpy stalactite becomes Fred Flintstone’s bat, or the fusion of floor and ceiling formations forges the droopy jaws of a nightmare. But under every fantastical abstraction, there’s a constant awareness of the cave’s fragility. Watch your step and, of course, don’t touch a thing.

How caves store climate data

Matt Lachniet’s Great Basin data show that the region has entered a natural dry period. At the same time, the climate is heating up due to human-caused warming. For a region like the Southwest, this could create a double-whammy, in which global warming is amplified by natural climate trends.

Cave deposits are one of the most reliable ways to study past climate trends because the data are protected from erosion. Using samples from stalagmite cores, Lachniet found that, historically, Nevada’s climate cycles through a full wet and dry period about every 21,000 years. Here's how it works: 1. Precipitation flows through surface bedrock and soil, collecting minerals and chemical signatures. 2. It seeps down into caves, leaving behind minerals that harden and form columns of rock that grow year after year as water continues to drip. 3. By analyzing each of these hardened mineral layers, scientists can determine past precipitation, temperature and vegetation above ground.

This is why there’s a National Speleological Society, a nonprofit focused on cave stewardship that celebrated its 75th anniversary this summer in Ely, about an hour away. Many members conceal their discoveries, a move the group supports when disclosure could leave a cave vulnerable to vandalism. There’s even a Caver’s Creed: “Take nothing but pictures. Leave nothing but footprints. Kill nothing but time.” Spelunkers follow these rules because caves, beyond their appeal to tourists, are indispensable record-keepers.

Tilting his red helmet, Lachniet floods the floor with light. We’re looking at a graveyard of decapitated stalagmites, victims of natural breakage that are the core of Lachniet’s research. Brought to his campus lab, the samples are sliced in half and used to piece together a timeline of Nevada’s climate.

Geoscientists do this by dating each layer and determining precipitation through the ratio of different oxygen particles. Put both variables together and you get a model of climate over the stalagmite’s life.

Lachniet has taken this one step further. He has identified the underlying cause of the natural cycle between wet and dry in the Southwest, the results of which were published by the journal Nature in 2014. Using cave data, Lachniet worked with collaborators from Cornell College and the University of New Mexico to show that regional climate in the Southwest, over a long period of time, ties to the Earth’s position in relation to the sun. Lachniet’s finding that one cycle — a full period of wet and dry — has historically lasted about 21,000 years is consistent with what we know: that astronomic and earthly changes in the sun’s energy, sea temperatures and volcanic activity control the climate.

While the natural trend might not affect us year by year, its impact can be felt over a century. And Lachniet found a deviation in his data. It had been consistent over nearly 170,000 years, but the last 1,600 showed the region warming earlier in the cycle. He speculates it could be a result of human activity or other weather variances, including changes in El Niño patterns. Whatever the cause, and no matter how incrementally tiny, the shift is significant to how we plan for the future.

The Reid Gardner Station coal-fired power plant in Moapa is set to be closed by 2017.

The Reid Gardner Station coal-fired power plant in Moapa is set to be closed by 2017.

God, Al Gore and the drive to adapt

With an economy often focused on quarterly gains and a political system that resets every four to eight years, setting policies over centuries to address climate change is mind-numbing. That’s especially true given immediate needs such as road repair or education funding. Objections even come from some conservationists, who point to birds zapped by solar arrays and whacked by windmills, and the quirk that “clean” hydropower has been linked to emissions of methane, a gas at least 25 times more potent than carbon dioxide.

Addressing climate change


— In 2008, the Nevada System of Higher Education received a $15 million federal grant to study climate.

— This year, Gov. Brian Sandoval signed onto a multistate agreement to promote clean energy.

— NV Energy is prepared to comply with the Clean Power Plan, a federal rule to reduce emissions.

— Heat-trapping gasses are tracked by the Southern Nevada Regional Planning Coalition.

— Nevada’s portfolio standard requires 25 percent of its energy to come from clean power by 2025.


Congress has struggled to develop a national strategy for curbing carbon emissions. Policymakers have floated a number of ideas, including a direct tax on fossil fuels or a cap-and-trade system, both of which apply market economics. In the latter system, governments cap carbon emissions but allow companies to buy and sell emission allowances, creating financial incentives for low polluters and a burden for high polluters.

The Obama administration has taken steps to address climate change:

— The Clean Power Plan would create pollution standards for power plants, asking states to cut emissions by 32 percent by 2030. The plan is on hold as federal courts hear a challenge.

— The administration created the first fuel economy standards for medium- and heavy-duty trucks.

— The EPA unveiled a rule to curb methane emissions in oil and gas production. Methane makes up a small portion of emissions but is more than 25 times more potent than carbon dioxide. As with the Clean Power Plan, several states are challenging the methane rule in federal court.


In December, around 200 nations pledged to reduce emissions, setting up an international framework to combat climate change with the Paris Climate Accord. More than 50 countries — including the U.S. and China, representing 39 percent of all carbon emissions — have ratified it, meaning the terms will soon go into effect in countries producing at least 55 percent of global emissions. The goal is to stop the rise in temperature at 2.7 degrees above pre-industrial levels, below a 3.6-degree ceiling after which most experts believe the effects of climate change are irreversible. With some forecasts saying we could hit that ceiling by 2030, there is serious incentive.

For its part, Nevada has done some work to prepare. In 2008, a state advisory committee recommended development of a climate change action plan and greenhouse gas reductions, which were partially realized when the Legislature approved a plan in 2013 to close the coal-fired Reid Gardner Power Plant by 2017. In September, an energy task force sent Gov. Brian Sandoval nearly 30 recommendations that would revitalize the rooftop solar industry, encourage renewables and promote electric vehicles. “Our public and private sector have collaborated to implement conservation measures that complement our expansive economic development footprint,” Sandoval said in a statement. “Nevada has done all of these things and more in a concerted effort to protect our gorgeous desert landscape, capitalize on our unique renewable resources and preserve our environment for generations to come.”

With most of our emissions stemming from the transportation and energy sectors, clean-energy advocates are crying out for more action. The Sierra Club is pushing legislators on an early closure of Nevada’s last coal plant. Others stress the need to incentivize efficiency programs, incorporate climate change in regional planning and consider policies that make it easy for companies to take advantage of clean energy.

“In terms of the big picture, I don’t think we are very prepared,” said U.S. Rep. Dina Titus, D-Nev. “The water district has tried to find more water every place they could beg, borrow or steal it, and I’ve heard of some research being done at (Desert Research Institute) with the use of drones and cloud seeding. But those are all piecemeal approaches.”

Titus supports a baseline standard for renewables on the federal level and says she hopes local leaders learned from Las Vegas’ boom, when greater consideration should have been given to air quality and other environmental impacts of rapid growth. “You have to pair growth with these other kinds of concerns or it will not benefit everybody in the community,” she said.

The politics are tricky. Though Titus has secured funding to conserve water and combat drought along the Colorado River, she said it was difficult to make progress because of an intransigent national Republican Party whose candidate for president has called manmade climate change a hoax.

Nevada has its scuffles, too. When Attorney General Adam Laxalt submitted a legal brief challenging the legality of carbon-emission caps in President Barack Obama’s controversial Clean Power Plan, it prompted a heated response from state Democrats, and Gov. Sandoval to distance himself.

There’s a danger in over-politicizing the issue. Take the example of rural Nevada. As part of a $15 million federal grant to the Nevada System of Higher Education to study climate, UNLV anthropologist William Smith examined how ranchers and tribes viewed the issue. Both groups have seen the effects of drought. Among ranchers, Smith observed a disconnect between their eyes and their politics. “Oftentimes, they are fighting each other,” he said.

In a survey, ranchers tended to bring up God or Al Gore without being prompted. Smith said in any climate policy discussion, it was important to include ranchers and tribes and respect their interests, their history with the land and their insights about its changing state.

“A lot of things do come down to economics, but we have to decide what kind of world we want to leave,” he argued. “Can you imagine the environmental injustice that exists if we shred our surroundings and turn around and put the burden on people who didn’t do the same?”

UNLV Geoscience professor Matthew Lachniet looks over formations in the Lehman Caves in the Great Basin National Park Thursday, Sept. 15, 2016.

UNLV Geoscience professor Matthew Lachniet looks over formations in the Lehman Caves in the Great Basin National Park Thursday, Sept. 15, 2016.

'There are ethical questions'

In the Lehman Caves’ Grand Palace, thick columns of woven stalagmites and stalactites descend from the center, the high ceilings and countless pale spires earning the dramatic name. There is speculation that a thousand years ago indigenous people knew of the cave’s entrance, from pre-Columbians to the Paiute and Shoshone, whose descendants were among those surveyed by Smith. About a dozen tourists on a guided tour brush past us, and their Park Service guide asks Lachniet to talk for a minute about his work. Of course, someone asks about climate change.

Lachniet’s Great Basin research suggests that, based on the Earth’s orbit, the region should not be in a dry period. But it is. In any scenario, human-caused climate change, amplified over the next few centuries by natural warming, could be troublesome for a place that’s already notoriously dry and hot.

The international consensus is that it will be tremendously difficult and costly trying to avoid a 3.6-degree temperature rise, the knife’s edge after which the effects of global warming are thought to be permanent. Despite around 200 nations pledging to reduce carbon emissions in last year’s historic climate agreement in Paris, a recent study shows we’re likely to surpass that cap.

Even if the risk can’t be eliminated, many climate scientists and economists argue there’s a cost to doing nothing. According to a January poll from Colorado College, 58 percent of Nevadans see climate change as a serious concern. If we innovate and compromise, experts believe we can temper the rising heat and better conserve water flowing in the West. That might mean, for instance, not growing alfalfa in Northern Nevada and restraining growth in the South.

In short, they say we must adapt.

“If we reach those tipping points and they were preventable, then our generation is culpable,” Lachniet says. “It was our fault for not acting sooner and adding cost, uncertainty and major challenges to future generations that are not yet born. So there are ethical questions, to me, that play into climate change.”

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