Climate scientists working on the latest international assessment of rising threats to society say it’s imperative that communities adapt now.
Their warning touches on several fields that Arizona and its neighbors in the Southwest are now attempting to tackle, from drought mitigation and wildfire management to the dangers of urban heat.
As greenhouse gases continue trapping solar radiation and heating the planet, scientists with the United Nations Intergovernmental Panel on Climate Change say society faces two challenges: preparing humans and their surroundings for increasing dangers, and reducing emissions to levels that will allow the adaptations to succeed.
In releasing their latest report, “Climate Change 2022: Impacts, Adaptation and Vulnerability,” the scientists stressed the urgency in protecting against heat, wildfire, food and water insecurity, and more. The report is one in a series of intensive reviews of current scientific literature and knowledge about climate change, and it paints a dire situation today, let alone if the world does change course.
“People are now suffering and dying from climate change,” said Kris Ebi, a University of Washington professor of public health who authored the report’s chapter on community well-being.
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So far, the scientists note, the world has warmed a little more than 1 degree Celsius from the pre-industrial era. Countries are working to curb fossil fuel emissions to prevent rising more than another half of a degree, at which point coping becomes much harder, Ebi and others report. As surrounding ecosystems struggle to keep up with rapid changes, communities face air and water pollution from fires, difficulties in food production, and economic supply chains strained by floods and other hazards.
“We need to remember that we are part of the nature that surrounds us, and not its owners,” said Edwin Castellanos, who wrote the chapter about Latin American and directs the Sustainable Economic Observatory at Universidad del Valle de Guatemala.
Here’s a look at several key adaptation areas in the report, and how Arizona is already facing them.
Water scarcity likely to increase worldwide and in western U.S.
The degree of warming will determine stresses on water supplies, according to fact sheets that the scientists provided journalists on Sunday.
Globally, they wrote, 800 million to 3 billion people will experience chronic water scarcity from droughts at 2 degrees of warming this century, or up to 4 billion people at 4 degrees. For instance, they say, days of scarcity will increase in South America as glaciers and snowcaps in the Andes melt away.
In North America, and especially in the western U.S. and northern Mexico, they conclude that heavy use and limited supplies have increased risks: “Intensified droughts and earlier runoff from diminished snowpack will increase water scarcity during summer peak water demand period especially in regions with extensive irrigated agriculture.”
That would describe Arizona, which already has seen farm losses from mandated cutbacks. A flurry of scientific publications has linked warming to reduced flows in the Colorado River, University of Arizona climatologist Gregg Garfin said.
The state has worked to adapt, especially by convincing water users to accept voluntary reductions through a 2018 Drought Contingency Plan. Water managers followed that with a plan that emerged last fall to compensate users to keep more of the Colorado River in Lake Mead.
Ultimately the state will probably participate in a plan to desalinate water, using either the ocean or salty groundwater, said Garfin, who was not involved in writing the panel's report. A seawater desalting plant could provide water to Mexico or California, which would then share more Colorado River water with Arizona.
That water will be expensive, though, and the region will still face water challenges, Garfin said. On the positive side, Arizona has long faced such challenges and understands the significance.
Wildfire seasons to lengthen
Warming and drying will continue to increase the length and severity of wildfire seasons, the scientists wrote. This compounds other problems, such as air and water pollution, and a reduction in the ability of forests to absorb carbon from the atmosphere to limit further warming.
Simply planting trees, as with a push to plant a trillion worldwide, won’t work when it’s done in areas not suitable for forests, said Camille Parmesan, a University of Plymouth ecologist who wrote the chapter on ecosystems. Still, she said, building resilience into forests and other carbon-absorbing landscapes is critical to arresting climate change.
“Emission reductions are not going to do it,” Parmesan said. “It’s going to take carbon reduction as well.”
In Arizona, partners have worked for years to ramp up a major forest-thinning program in the high country’s ponderosa pine forests. The Four Forest Restoration Initiative seeks to use a re-emerging timber industry to reduce fuels that in this century have fed the state’s largest-ever fires. (Two fires, Rodeo-Chediski and Wallow, together burned about a million acres.)
The thinning program has evolved more slowly than hoped, but this year is receiving support from the new federal infrastructure spending law. If it succeeds, Garfin said, it could protect old-growth pines from disappearing and possibly giving way to shrubbier landscapes.
Besides attending to forest health, he said, the state needs better rules about where and how to build among trees and other fuels.
“We still don’t have good policies about the wildland-urban interface, which increases the risk of people being in harm’s way,” he said. “But also, when structures burn, then you end up with basically a situation where thing can explode and you get embers shooting really far out, and that just spreads the fire.”
Wildfire expert and author Stephen Pyne, an emeritus professor at Arizona State University's School of Life Sciences, agreed there's a need to change.
"We can harden structures against embers, establish defensible space, create enough protection to prevent conflagrations racing through towns," Pyne said in an email.
Rising heat: Cooling centers and early warning systems can reduce deaths
Today, according to the panel, 30% of the world’s population is exposed to potentially deadly heat stress. By 2100, that figure is expected to grow to between 48% and 76%, depending on how much warming occurs. In Europe, for instance, the scientists project that if emissions continue unabated and the planet warms by 3 degrees, the number of people at risk from heat stress would double or triple what would be expected from a 1.5-degree rise.
The “heat dome” that settled over the Pacific Northwest and western Canada last summer would have been virtually impossible without climate change, Ebi said, and it is estimated to have killed more than 1,000 people.
Communities that create cooling centers and early warning systems for extreme heat events can reduce deaths, said University of Alberta public health professor Sherilee Harper, who wrote the report’s chapter on North America. But if warming accelerates, she said, “These strategies will become less effective at protecting health.”
Maricopa County has been a center of heat-related deaths. The county logged 323 of them in 2020, which represented a 15-fold increase from 2001. Preliminary numbers from last year appear similar at the time of the county’s last report, with 252 confirmed as being heat-related and 86 under investigation.
Heat is especially problematic in Phoenix, where Arizona State University climatologist Erinanne Saffell said average warming of 7 degrees Fahrenheit over the last century has more than doubled the statewide average rise.
Phoenix and Tucson have worked to manage this problem, Garfin said, noting that both have heat plans and cooling centers and that Phoenix hired one of the nation’s first heat officers last year. The panel's report emphasizes the need for trees and other cooling environments, which the cities have acknowledged must be priorities.
Planners must ensure these investments are equitable, Garfin said, and may need to provide transportation to cooling centers. “We still need to do better providing that green infrastructure to low-income areas,” he said.
Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook, Twitter and Instagram.
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This article originally appeared on Arizona Republic: Climate change requires action on water, heat, wildfires, panel finds