In a dirt parking lot near Many Farms, Ariz., a Navajo farmer sold me a mutton burrito. He hasn't used his tractor in two years, he told me, and he’s cooking instead of farming because "there isn't any water." He pointed east at the Chuska mountain range, which straddles the New Mexico border. In a normal year, water coming off the mountains reaches his fields, he said.

But this might be the new normal for the American Southwest, writes William deBuys in A Great Aridness. It was published late last year, months after one of the Southwest's driest summers in history, during which fires of unprecedented size scorched hundreds of thousands of forest acres. This summer is worse than the last. When the Whitewater-Baldy fire was only 17 percent contained, it had already eclipsed last year’s record-breaking Las Conchas fire.

The 30-year-old asparagus patch is toast, as are the perennial herbs, garlic and strawberries, along with everything he planted this spring. Even the weeds are dead.

Springs, wells and irrigation ditches are bone-dry. Farms are withering with the surrounding landscape. We've all heard the gloomy scenarios of global warming: extreme weather, drought, famine, breakdown of society, destruction of civilization. Here in New Mexico it feels like we’ve made the switch from esoteric to actual, from computer model to daily life. My perch in Placitas feels like a front-row seat to the apocalypse. Smoke is in the air. Neighbors are fighting over water. Some of my outdoor flower pots have melted in the heat. Wild animals are getting thirsty, hungry and bold.

“When a fire runs through, it really affects the soils. It burns so intensely that it can turn them to glass. When it does rain, the rain just slides off. It loses that absorption, and that filtration process is kind of lost.” Porfirio Chavarria, Santa Fe firefighter

Periodic, decades-long droughts have been relatively common in the last few thousand years, according to analysis of dried lake beds, deBuys writes. Most of the area's famously collapsed civilizations—Chaco Canyon, Mesa Verde, the Galisteo pueblos—are thought to have died out for lack of water in these extended dry periods, which he calls " megadroughts. "

Much of the early population growth in the American Southwest occurred during a relatively wet period in the climactic record, a respite between megadroughts, and sooner or later we were due for another one, deBuys believes. It’s possible, in fact, that this is the start of the next megadrought, but it’s impossible to know right now. "The character of a drought becomes clear only retrospectively,” he writes.

Mr. deBuys does, however, think that global warming could trigger the next megadrought. In fact, he’s afraid that might happen. And dios mío, have we had the warming. Over the past century, average temperatures in New Mexico increased at a rate that’s 50 percent faster than in the world as a whole, according to a 2008 Nature Conservancy report. And daily highs and daily lows have risen throughout the state—winter and summer—by almost 2 degrees since 1976.

The Twitter feed of climate activist and author Bill McKibben is a steady news ticker of the disaster unfolding globally. A standstill in barge traffic from lack of water in the Mississippi, a "year's worth of rain in a weekend" in Kyoto, the worst drought in a century in North Korea, a five-mile Alaskan landslide attributed to melting permafrost. Around the world, different versions of a new normal are surfacing.

A Battle at the Acequia

"Not even the Land of Enchantment can cast a spell strong enough to keep climate change at bay—it's going to take hard, urgent effort, here and around the world." Bill McKibben, author and climate activist

Lynn Montgomery’s farm was part of a thriving community in the ’60s and ’70s. Most of the inhabitants drifted away, or ran away, or got dragged away by the police. Montgomery was the last man standing.

He’s been farming that same Placitas plot for more than 40 years now. And like many farmers in Northern New Mexico, he irrigates his land with water from an acequia, a type of canal system implemented by the Spaniards. (And they adopted the technique from the Moors.) For the second year in a row, Montgomery's acequia has run dry.

In the Sandia Mountains above Placitas, last winter's snowpack was relatively deep. But the spring runoff never came—the snow evaporated straight into the air of the hottest spring on record. Summer rains arrived in time to save his crops last year, but the monsoon has yet to reappear. The ditch is dry. His farm is dying.

First to go were the young Italian prune trees. His more established pear trees were next. Now, his decades-old grape vines are dropping their fruit and clinging to their lives. The 30-year-old asparagus patch is toast, as are the perennial herbs, garlic and strawberries, along with everything he planted this spring. Even the weeds are dead.

Montgomery sold the farm to the local Pueblo Indian tribe on the condition that they assume ownership after his death. Proceeds from the sale were mostly diverted to lawyers and legal fees that he's incurred while enforcing water laws around Placitas. He took a landmark case all the way to the state Supreme Court, where his adversary bailed at the eleventh hour, after more than a decade of bluffing (Montgomery v. Lomos Altos).

While Montgomery managed to thwart several developments in Placitas, he couldn’t stop numerous wells from being drilled, especially in the ’80s and ’90s. The water table has dropped so low that many springs in Placitas are starting to run dry, along with the acequias they feed, he says.

Montgomery's neighbors, with the turn of a tap, can water their grass and wash their cars thanks to the wells that killed the spring that feeds his acequia. But it's only a matter of time, he says, until they feel his pain.

“At that point all the bedroom community types will realize that the real estate people have bamboozled them, and most of us too," he says, referring to the area’s recent history of property value booms and subsurface water grabs.

To the north, in New Mexico’s corner of the Rocky Mountains, Harold Trujillo is president of Acequia de la Isla near Mora. He tells me by phone that all of the acequias in his Sangre de Cristo mountain valley, neighboring the headwaters of the Pecos River, are dry. Before this one, the worst year he remembers was 2002. According to the Colorado state engineer's office, that had been the region's driest year in the last three centuries.

"In 2002 there were natural ponds that never dried up. Cows could drink out of them. Now those ponds are dry,” Trujillo says. “People have been digging them deeper with backhoes to get them to fill with water."

Tempers are getting short. Trujillo said he was verbally threatened one weekend in June at Morphy Lake, the reservoir his acequia association helped build.

"We were opening Morphy Lake to get water in the river. These people wanted us to open it more, so more water would flow into the river,” he says. “But we can't. We need to save some water for July and August because we don't know if it's going to rain or not." In the not too distant past, Montgomery—who acts as the manager, or mayordomo, of his acequia—had to use infrared remote sensing cameras to bust abusers of his ditch.

The Changes Downstream

Firefighters are as flummoxed as the farmers and ranchers. Porfirio Chavarria, a Santa Fe firefighter, says that since he started in 1998 he’s seen an increase in fires of more than 100,000 acres in size, which coincidentally enough (or not) he calls “megafires.” Chavarria attributes that to increases in dry and hot air, which optimize the conditions for burning. Las Conchas burned incredibly fast at first, incinerating 40,000 acres in just 15 hours, before growing to 150,000 acres, he says in an online video recorded this May (watch it here: bit.ly/LasConchas).

“When a fire runs through, it really affects the soils. It burns so intensely that it can turn them to glass. It can make them hydrophobic,” he explains. “When it does rain, the rain just slides off. It loses that absorption, and that filtration process is kind of lost.”

The New Mexico State Engineer’s office is expecting climate change to have a wide range of impacts on both suppliers and users of water. Higher freezing altitudes, changes in snowpack elevations and water equivalency will mean less snowpack overall, and essentially no snowpack south of Santa Fe. According to the International Journal of Climatology, increased evaporation from agricultural and riparian microclimates will reduce soil moisture in Northern New Mexico and exacerbate desert conditions in the south. If that sounds like the present, welcome to the new normal.

In A Great Aridness, deBuys writes that "building resilience against drought into the region's water systems and cultural practices would be a wise course, irrespective of the cause or timing of the next emergency." Feast or famine, everyone can benefit from installing water catchment systems, waterwise gardens and sensible irrigation policy (though, admittedly, the last one is much easier said than done).

But while we brace for what's to come, it's important to remember that this may not be a done deal. It's still possible that policy changes could affect the fate of our climate, and that democratic action can create those policies.

Our governor might not fear climate change, but many New Mexicans do. There has never been so much attention drawn to the climate as now, thanks to the crazy weather we've been having nationwide. Now is the time to strike, while the asphalt is hot.

Climate activist Bill McKibben agrees. "Last year's drought and this year's record fires are reminders of the wholesale changes now underway on this planet," he tells me via email. "Not even the Land of Enchantment can cast a spell strong enough to keep climate change at bay—it's going to take hard, urgent effort, here and around the world." If you're interested in doing something about climate change, the New Mexico branch of 350.org, the nonprofit McKibben helped found, would happily put you to work.

Hoping not to have to put his considerable burrito making skills to use, Lynn Montgomery is scraping together resources to retool his farm to be more efficient with water. He's installed a holding tank, in which he'll be able to store precious acequia flow in future years, before the ditch runs dry again. And with that tank he’ll be able to give his garden a good base on which to ride into the monsoons, which will hopefully come.

After decades of doing it the old ways, he’s leaving behind the traditional flood irrigation practices that go hand in hand with a booming acequia, and he’s making the switch to more efficient drip tape. It remains to be seen whether his adaptations, and his resilience, will be enough to help him face the new normal. But the old hippie in the pitch pit house isn’t going out without a fight.