Financial Times, Oct. 13, 2009
The condition of the land on Mike Macauley’s 63,000-acre ranch near Williams in northern Arizona ranges between dry and bone dry.
Water is so scarce that Mr. Macauley has this month been chugging around in his mini-digger ripping out shrubs one by one, in an effort to stop them from sucking up water the patchy grass could use.
“A lot of times you will have decent feed but no water nearby,” Mr. Macauley says, as he reaches an empty water gauge in a dusty paddock. “We have to trap the water, then we pump it through a system of pipelines to where we need it.”
Driving in his pick-up truck for miles through his ranch, he finds empty fields until he reaches a pond where cattle have gathered. A 25-mile pipeline network transports water from entrapment tanks to these ponds but, when the tanks are empty, Mr. Macauley must buy water by the truckload.
Mr. Macauley’s family has run the ranch since 1894, so they have learnt to live with the perpetual water shortage in this desert state. But living off the land is becoming ever more difficult, because of higher temperatures and lower rainfall.
“The environment here is changing at a shocking speed. The summer has been coming a week earlier and staying a week longer,” says Scott Harger, a conservationist near Flagstaff, northern Arizona.
“We are always complaining that we do not get enough rain, but most people are able to sense that it is getting drier, and they are concerned about it.”
Beetles leave trail of destruction
The increasingly warm and dry weather has led to some unwelcome visitors in trees across the south-west, and even well up into the Rocky Mountains. Bark beetles are stripping the trees in Colorado, where it was once too cold for them to live. And in Arizona the warmer weather has added a whole new generation each year to the beetle population.
“They have just overwhelmed the trees out here,” says Scott Harger, a conservationist near Flagstaff in north Arizona. On his property, skeletons of what were once trees litter the landscape.
The beetles are adding to broader forest mortality, which is becoming a serious issue in a region that has traditionally had timber extraction as a main industry, and it is a factor in increasing fire danger, says Gregg Garfin the University of Arizona Institute of the Environment. “Moreover, it has impacts on moisture retention, erosion and aesthetics – in a region that has a strong recreation economy.”
Much of the US south-west has been in a drought since 1999, the most severe in more than a century, but it has been exacerbated by record warming.
The average temperature in the south-west has already increased by about 1.5ºF above the average recorded between 1960-79, the US Global Change Research Program said in a recent paper.
It is projected to rise as much as 10ºF by the end of the century, the programme says, as “human-induced climate change appears to be well under way in the south-west”.
Just as global warming is affecting life in developing countries such as Bangladesh and the Pacific island of Nauru, where rising sea levels are gobbling up land, so too is it affecting the richest country on earth.
Some studies estimate that the “dust bowl” drought conditions of the 1930s will become the norm in the south-west by 2050, and supplying the area with water will cost $950bn (€644bn, £600bn) a year, almost 1 per cent of US gross domestic product.
Certainly, 2009 has been difficult. The winter was drier than usual. Then the monsoons that usually drench the state each summer never arrived, leaving large areas to manage with less than half their average annual rainfall, says Gary Woodall, chief meteorologist in Phoenix.
“Compounding that, we have had very warm temperatures, even by Arizona standards,” Mr. Woodall says. “So we have had a one-two punch of very low precipitation and very warm weather.”
Rising temperatures are reducing the flows in the Colorado river, the south-west’s lifeline, while fast-growing cities such as Phoenix emit ever increasing amounts of carbon while demanding more and more water.
The water shortages affect ranchers the worst. In northern Arizona, a pasture can cover as many as 90,000 acres, and some ranches run to almost 20 pastures, meaning the likes of Mr. Macauley can aim only to fill ponds.
But farmers who are able to irrigate their fields are feeling the heat too.
“The difficulty of irrigating is constant,” says Jim Hanness, who grows cotton, durum wheat and forage for cows on his 710-acre farm near Casa Grande in southern Arizona.
“Am I worried about the drought we’re in? Yes. Am I concerned about the amount of storage space [in dams] not filled? Yes. But I can’t affect this – we live in a perpetual drought and we have gone to great lengths to use water very wisely,” he says.
While conceding that water supplies are becoming more scarce and their state is experiencing increasing desertification, many Arizonans who work the land are climate-change sceptics.
Both Mr. Macauley and Mr. Hanness blame the combination of Arizona’s natural dryness and population growth for their water problems. “I can’t quite buy the idea of global warming in its entirety,” Mr. Hanness says.
Even in academic circles, there is debate on how much the region’s water shortages are the result of climate change and how much the result of unfavourable weather patterns.
“It’s tricky to say that this is caused by greenhouse gases because the natural variability in this region is colossal. But certainly the drying is going to get worse and worse as the global climate warms up,” says Richard Seager, a research scientist at Columbia University’s Lamont Doherty Earth Observatory.