Saturday, April 7, 2018

Plight of Phoenix: How long can the world’s 'least sustainable' city survive?

From our community:
“There are plans for substantial further growth and there just isn’t the water to support that. The Phoenix metro area is on the cusp of being dangerously overextended. It’s the urban bullseye for global warming in north America.”  Jonathan Overpeck, climate researcher 

If we do not eliminate our current greenhouse gas emissions upward trend, we could cross the 1.5°C threshold in “10 to 15 years, somewhere between the years 2025-2030, compared to 2045-2050 when a 1985-2005 baseline is used”. The 2015 Paris Agreement’s goal of “holding the increase in the global average temperature to well below 2°C above pre-industrial levels ( A rise of 2.0°C is considered the most the Earth could tolerate without risking catastrophic changes to food production, sea levels, fishing, wildlife, deserts and water reserves) is not going to happen even if we stopped emissions today. Climate change is feeding off itself at this point in time. As a result, Phoenix, Arizona is projected to be first in line where rising temperatures will make the city uninhabitable. 

The Guardian reports:
That river is drying up. This winter, snow in the Rocky Mountains, which feeds the Colorado, was 70% lower than average. Last month, the US government calculated that two thirds of Arizona is currently facing severe to extreme drought; last summer 50 flights were grounded at Phoenix airport because the heat – which hit 47C (116F) – made the air too thin to take off safely. The “heat island” effect keeps temperatures in Phoenix above 37C (98F) at night in summer.
Phoenix and its surrounding area is known as the Valley of the Sun, and downtown Phoenix – which in 2017 overtook Philadelphia as America’s fifth-largest city – is easily walkable, with restaurants, bars and an evening buzz. But it is a modern shrine to towering concrete, and gives way to endless sprawl that stretches up to 35 miles away to places like Anthem. The area is still growing – and is dangerously overstretched, experts warn.
What these cities want is water. The Phoenix area draws from groundwater, from small rivers to the east, and from the mighty Colorado. The Hoover Dam holds much of the Colorado’s flow in the vast Lake Mead reservoir, but the river itself is sorely depleted. That water has now dropped to within a few feet of levels that California, Nevada and Arizona, which all rely on it, count as official shortages. Lake Powell, the reservoir at the other end of the Grand Canyon, similarly averages half its historic levels
And yet despite the federal Bureau of Reclamation reporting in 2012 that droughts of five or more years would happen every decade over the next 50 years, greater Phoenix has not declared any water restrictions. Nor has the state government decided its official drought contingency proposal.
"It's currently the fastest warming big city in the US," meteorologist and former Arizonan Eric Holthaus told me in an email. A study from Climate Central last year projects that Phoenix's summer weather will be on average three to five degrees hotter by 2050. Meanwhile, that average number of 100-degree days will have skyrocketed by almost 40, to 132, according to another 2016 Climate Central study. (For reference, over a comparable period, New York City is expected to go from two to 15 100-degree days.) 

But Hondula told me that mystery just means that as the city heats up over the next few decades, there are other issues that deserve urgent public attention in the interest of saving people from getting cooked alive. These include"social service programs, homeless shelters, the opioid epidemic, [and] all these other intermediating factors," he said, adding, "If we're not paying attention to those at the same time we're keeping an eye on the thermometers, we might really miss some drivers and some threat magnifiers." 

According to Quay, the first time the river level gets extremely low, the shortage will really only be felt by Arizona's farmers—meaning they'll start getting water from wells. "Going to groundwater and mining groundwater is not sustainable, because groundwater is not like some giant Lake Michigan under Arizona," he told me. "There will be impacts within that 2050 timeframe, but it's going to be spotty, and it's going to be in areas where the aquifers aren't as large. That's rural Arizona—particularly agriculture. You'll see some parts of rural Arizona where some people have to pick up and move."

"When the second shortage occurs, urban areas will feel that," Quay added.

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