We’ve run out of time.
The latest assessment of global climate trends suggests that we barely have time to thin the forests and complete water supply projects like the Blue Ridge Reservoir before the inexorable warming trend hits Rim Country with longer, deeper droughts, forest die-offs and a disastrous increase in community-destroying megafires.
The explosive growth of yet another wildfire near Show Low over the weekend just after the anniversaries of both the Dude Fire and the Yarnell Fire underscore the stakes for the region. The Dude Fire killed six firefighters in 1990 and the Yarnell Fire last year killed 19 firefighters. Both fires burned in thick, overgrown forests that hadn’t burned in decades.
The assessment projected a possible 15 percent decrease in the flow of the Colorado River plus a decrease in snowpack and average rainfall throughout a region already in the grip of perhaps the worst drought in centuries. In recent decades, 20 percent of the forests in the region have already died or burned. Most of the largest wildfires in recorded history have occurred in the past 15 years.
The National Climate Assessment offered a rough estimate of the effect of a projected 2.5 to 9.5 degree warming in the Southwest by mid-century. The estimates are based on projecting forward the 2 degree increase in the southwest in recent decades, which the overwhelming majority of climate scientists blame in large measure on the buildup of greenhouse gases in the atmosphere caused by the release of pollutants. Past measurements have shown that some regions of the planet heat up more quickly than others given the overall effect of the buildup of gases that let sunlight through but trap infrared wavelengths radiating off the surface — the same way the glass panes of a greenhouse trap solar radiation.
The Climate Assessment envisions a 2.5 to 5.5 degree warming if we quickly manage a substantial decrease in the release of greenhouse gases like carbon dioxide. The increase would be closer to 10 degrees if the rate of increase in the release of those pollutants continues unabated, according to University of Arizona geoscientist Gregg Garfin, lead author of the section on the Southwest.
The climate assessment drew immediate criticism from industry groups, since it provides the scientific support for the Obama Administration’s latest efforts to reduce carbon emissions from power plants and other sources. That includes requirements that would require an expensive retrofit of the Navajo Generating Plant, which provides the bulk of the power to pump water out of the Colorado River and into the Central Arizona Project, which supplies Phoenix and Tucson.
American Coalition for Clean Coal Electricity spokeswoman Laura Sheehan said, “The Obama administration is busy promoting its politically driven climate-change agenda, instead of addressing the real issues plaguing the nation.”
Rep. Paul Gosar (R-Prescott) and other members of the Arizona congressional delegation have issued press releases harshly critical of the Administration’s efforts to reduce carbon emissions.
Other Rim Country representatives like Sen. Chester Crandell (R-Heber) have also opposed any new regulations of coal fired power plants. In Senate hearings, Crandell has not only said he doesn’t believe most scientists agree on global warming but said a buildup of carbon dioxide in the atmosphere could help farmers by increasing the rates of plant growth.
However, the National Climate Assessment’s panel of 300 climate scientists providing analysis to the 60-scientist federal advisory committee agreed quickly on the trend and the broad and potentially devastating effects of even the minimum likely warming. An array of federal agencies and a panel of the National Academy of Scientists reviewed the assessment.
The scientists concluded that the gradual warming tend will turn much of the late winter and early spring snow into rain. This will not only reduce the snow pack, it will promote early melting of the snow that did accumulate during the winter. That will likely have a major impact on ponderosa pine and pinyon forests, already living at the edge of their drought tolerance in much of the Southwest. That loss of snow pack will reduce the flow of rivers throughout the region, including the Colorado, Salt and Verde.
The warming trend will also increase the threat of wildfires, especially given the already stressed and overgrown condition of the forests, after a century of grazing, logging and fire suppression — followed by a deadlock about a shift in management that had eliminated much of the logging and grazing in the past 20 years. Loggers, environmentalists and forest restoration experts came together in the past decade to recommend large-scale thinning focused on trees smaller than 16 inches in diameter called the Four Forest Restoration Initiative. But the Forest Service has had trouble finding a contractor that can raise the money to build mills able to handle the massive supply of small trees and brush. The Forest Service has also not yet come up with a timber prescription to implement 4FRI.
The report concluded that large-scale thinning projects in the coming decades could reduce flood and fire risks for the Valley and the rest of the state. Another recent study by researchers from Northern Arizona University concluded that a 4FRI style thinning project would increase runoff by 12 percent in a normal year and potentially prevent widespread tree death in a dry year. That could prove increasingly valuable if the projected warming trend reduces average rainfall.