Gorged to bursting point, the vulture watches impassively as the twister whips a column of dust past the sun-parched remains of cattle dotting the barren field. If there were such a thing as a textbook image of drought, then this could well be it.

Wracked by a savage drug conflict that has claimed thousands of lives, the last thing northern Mexico needed was a "natural" disaster to compound its woes. But now the region's beef herds are being ravaged by the worst drought on record – one which scientists are linking to climate change. Eighteen of the country's 32 states are affected.

No rain means no pasture and here in Chihuahua, an estimated 350,000 cows have died in the past 12 months, costing ranchers around 2.4bn pesos (£110m). Only the vultures, it seems, are happy.

Ismael Solorio is the third generation to run his family's ranch, only a few hours' drive from the Texas border. But now, four years after inheriting the herd of 200 cows, the 24-year-old is desperate.

So far this year, 26 of his animals have died from starvation. He estimates he has another six weeks for the rains to come in time to save the rest of his weakened herd. "It's a disaster," he says bitterly. "It never used to be like this. I have already had to sell 10 this year. They were so skinny I had to buy in pasture to put some meat on their bones, but it was that or watch them die. If it doesn't rain in the next month and a half, then the decision is made for me. I will have to cut my losses and sell them all."

Although famous for its desert, much of Chihuahua, the size of Belgium and Mexico's largest state, is covered by vast pine forests and extensive, scrubby savannah, which has been used to rear livestock since the conquering Spaniards first arrived in the mid-16th Century.

Traditionally, it did rain here. Not much, but enough to produce meat as well as corn, beans and even wheat for the rest of Mexico. But not any more. In the seven decades to 2010, average annual precipitation was 39cm in Chihuahua. In 2011, it rained only 26cm and so far this year, it has not rained at all. "Parts of northern Mexico are now in permanent drought. In other words, the climate has already changed," says Carlos Gay, an atmospheric physicist and head of the climate change programme at Latin America's largest university, Mexico City's UNAM.

"There is no doubt that this drought is the result of climate change. When you look at a single event, you cannot say so, but when you look at the bigger pattern it becomes very clear."

The region's arable farmers are also facing ruin. In a normal year, Chihuahua produces 100,000 metric tons of corn. In 2011, the entire state harvested only 500 tons. In the process, farmers have racked up losses of 897m pesos (£41m).

Other crops have also been hit. Chihuahua's 2011 bean harvest was only 20,000 metric tons – one sixth of what farmers would have expected in an average year.

Meanwhile, many of the region's poorest families, including the Rarámuri Indians of the remote Tarahumara mountains, are also on the verge of famine. So far this year, the regional and federal governments have given out food aid to 60,000 families in some of this vast state's most far-flung corners.

The Rarámuri, who maintain a traditional, subsistence lifestyle and are famous for their endurance running across the rugged landscape, are particularly ill-equipped to cope with the famine. Some communities have been classified by the UN's Development Programme as having a lower human development index than Niger, the world's poorest nation. There have been reports of suicides by desperate Rarámuri with nothing to eat.

For many here, climate change is now a more urgent problem than the drug conflict, even with massacres with double-digit death tolls becoming routine and local homicide rates making the region statistically as deadly as some war zones.

"Water is the state's number one problem. We are facing a catastrophic situation," insists Arturo Vigil, 49, president of the farmer's association of El Sauz, a village on the outskirts of the city of Chihuahua. "The federal government needs to declare this an issue of national security."

Ignacio Gutierrez, 58, another El Sauz farmer, adds: "Without water, more and more people will lose their livelihoods. There are no other alternatives here and the violence will just get worse."

The pair were speaking at a village meeting at which they were discussing trials of a new product called "Solid Rain". It looks like granular sugar, is mixed into the soil and absorbs water on contact, swelling up to hundreds of times its original size – preventing the moisture from evaporating.

Now, as the rains fail, farmers are increasingly relying on the state's 61 aquifers, pumping water from deep below the ground to irrigate their crops. Yet that offers no long-term solution, either.

Precipitation is the aquifers' sole source of replenishment. And thanks to Chihuahua's blistering sun, just three per cent of the rain that does fall ever makes it down to the subterranean reservoirs, with most of the rest quickly evaporating.

As a result, farmers now have to dig their wells deeper and deeper to access the aquifers. Where wells of 250ft were once commonplace, many now have to be drilled down to three times that depth. "There are no hydrological studies so we don't even know how much longer we can go on drawing water from our aquifer," says Rafael Armendariz Ortiz, 65, president of the community of Benito Juárez, a two-hour drive north-west of Chihuahua city, where Solorio's struggling ranch is also located. "For all we know, we could run out of water tomorrow."

And even drawing water from the aquifers is not an option for many of the poorer farmers, due to the prohibitive cost of pumping it up to the surface. Alejandro Rodriguez, who owns a 340-acre apple and peach farm outside the city of Chihuahua says his monthly electricity bill for pumping water from 350ft deep can come to £6,500. "It's killing me," he says.

This year Mexico became only the second country, after the UK, to set itself legally-binding carbon emissions targets. A 78-0 vote saw the lower house of congress approve a bill that would, among other things, require Mexico to shrink its carbon footprint by 30 per cent by 2020 compared with "business-as-usual". That is no small step for a country that is the world's fifth-largest producer of crude oil.

But the federal government has also calculated the cost of constructing additional water infrastructure to cope with drier conditions brought on by climate change at 246bn pesos (£11.2 bn).

As Solorio gazes at his underweight herd rummaging for pasture in the dust, that seems like money well spent, even if it comes too late to save the family ranch.

"We need help from the government right now," he says. "As things stand, mine is probably the last generation in Chihuahua to live from ranching."

Travel for this story was funded with a grant from the Pulitzer Center on Crisis Reporting.

Latin America: Climate crisis

From tropical storms battering Central America to melting Andean glaciers, Latin America and the Caribbean are particularly vulnerable to climate change. According to a report released last month by the Inter-American Development Bank and the World Wildlife Fund, the region stands to lose $100bn (£64bn) per year by 2050 in lost crops, flooding, storm damage and other climate change effects. That is if temperatures increase by 2C, a minimum rise now thought almost certain based on current carbon emissions. Latin America and the Caribbean account for just 11 per cent of those emissions.

Between a third and a half of the total losses would come from lost agricultural exports, the report warns. Other costs would also stem from the increased spread of tropical diseases, while coral bleaching in the Caribbean would cost $7bn in lost fisheries and tourism.