Extreme Heat Is Making U.S-Mexico Border Crossings Even More Dangerous

Extreme Heat Is Making U.S-Mexico Border Crossings Even More Dangerous
Two migrant families from Brazil pass through a gap in the border wall to seek asylum in the the United States on June 20, 2021 (Photo: Eugene Garcia, AP)

Dehydration is already a leading cause of death among migrants crossing the border from Mexico to the U.S., and conditions will become worse as the climate continues to warm, according to new research published earlier this month in Science.

The study looks at a stretch of land commonly used by migrants crossing the border between Nogales, Mexico and Three Point, Arizona. The researchers compiled a database of deaths in this region over a nearly 40-year span and narrowed it down to the hottest months of the year between May and September. They then used a biophysical model of human dehydration to calculate which points along that stretch would be the most deadly, comparing them to the map of the 93 deaths in their dataset; the majority of those deaths, the researchers found, correlated with the areas of the map where people would experience the most dehydration.

“We provide the first empirical evidence that the physiological stresses experienced by humans attempting to cross the Sonoran Desert into the U.S. are sufficient to cause severe dehydration and associated conditions that can lead to death,” Ryan Long, associate professor of wildlife sciences at the University of Idaho and senior author of the study, said in a news release. “[A] disproportionately large percentage of migrant deaths occur in areas where the predicted rates of water loss are highest.”

While people making the crossing usually carry water, the average amount they bring is not enough to prevent the most serious cases of dehydration, the study found.

“Access to sufficient amounts of drinking water to support the high rates of water loss experienced during the journey likely makes the difference between life and death for many migrants,” Long said.

To better illustrate conditions people may face when making the dangerous crossing, the study quotes people who emigrated from Mexico to the U.S., who describe the challenges of their journeys.

“We were dying of thirst,” Lucho, a 47-year-old migrant from Jalisco, Mexico, said in a 2009 interview. “I was hallucinating at that point. We were surrounded by dirt but I kept seeing water everywhere in the desert.”

Heat conditions at the border are only set to worsen with climate change. Arizona is the fourth-fastest warming state in the U.S. and already sees 50 dangerous heat days a year, which are set to become 80 days by 2050. To get a better handle on how much more dangerous border crossings will become, researchers plugged models for future warming in the region, based on a middle-of-the-road climate forecast, into a model of water loss over walking scenarios along the route.

“We find that migrants’ journey will become significantly more dangerous over the next 30 years,” Reena Walker, graduate student at U of I and co-lead author of the study, said in the release. Their calculations suggest that, by 2050, people crossing the border on foot will have at least a 30% increase in their water loss during the journey due to higher temperatures.

The research comes during a particularly turbulent time at the border; in August, the U.S. Border Patrol reported almost 200,000 encounters with migrants along the border in July alone, a 20-year high. CBP also reported 470 migrant deaths at the border between January and October of this year, the highest number since 2005; 43 bodies were recovered following an excruciating heatwave in Arizona in June.

While migration between the U.S. and Mexico is complex and influenced by many factors, climate change is definitely driving migration, including the influence of extreme weather, like two back-to-back hurricanes last year, as well as displacement due to crop failures and drought. The crisis at the U.S. border isn’t the only one being worsened by climate. The UN last year defined climate change as an emerging threat that is already displacing people all over the world, which will only get worse as the world warms.

More: Wealthy Countries Are Spending More on Border Security Than Climate Aid


Editor’s Note: Release dates within this article are based in the U.S., but will be updated with local Australian dates as soon as we know more.