FRISCO, Colo. — We probably didn’t need another glossy government climate report to tell us we may be on the brink of a climate cliff.
Watching for a decade as Colorado forests turned red and died, smelling wildfire smoke for weeks on end and seeing drought and deluge in the same season feels epochal, and scientists already have a name for it — it’s the Anthropocene age, the era when human activities start to become a significant factor in the Earth’s natural cycles. That’s become pretty clear watching greenhouse gases rapidly transforming the basic makeup of the atmosphere. The last time there was this much heat-trapping carbon dioxide in the atmosphere — about 2.6 million years ago — sea level was 30 feet higher and there were no humans.
Never mind what’s ahead, scientists seemed to say recently as they published the federally mandated National Climate Assessment. Climate change isn’t just knocking at the door — it’s in the house, and things are likely to get worse before they get better. For Colorado, the probably means more floods, more fires, more heat waves and less water.
“My biggest concern regarding Colorado over the next 50 years is water resources,” said Mark Serreze, director of the Boulder-based National Snow and Ice Data Center, which is at the heart of global climate change research. “Even with no change in precipitation, a warmer Colorado means less available water,” Serreze said via email. “If we strongly alter the winter snowpack (e.g., alter how much of the precipitation is snow vs. rain) we put our water storage systems at risk. I don’t see ‘more snow’ as as very likely.”
By some measures, Colorado may be warming faster than anywhere else in the Lower 48, according to the most recent update of the official 30-year “climatic normals” maintained by the National Oceanic and Atmospheric Administration. According to the 2011 mapping, Colorado average maximum daily temps jumped faster than any other state — between .7 and .9 degrees — from the old normals, compiled between 1971 and 2000, and the new normals, which are based on temperature readings between 1981 and 2010. On average across the U.S., the new average temperatures are about .5 degrees warmer.
The 10-year span between 2000 and 2010 was the warmest decade in the 110-year instrumental temperature record with temperatures almost 2 degrees Fahrenheit higher than historic averages, with fewer cold air outbreaks and more heat waves.
That trend left Colorado as the bright red buckle on a western belt of orange-colored states where average daily maximum temperatures soared by half a degree or more in the blink of a geological eye. No wonder the mountain snowpack is melting away much earlier than just a few decades ago — by as much as six weeks in years when windstorms dump tons of desert dust on the Rockies, with drought in the Southwest intensifying the impacts of global warming in even the highest reaches of the Rockies.
The climate assessment groups Colorado into the Southwest region, but it’s a little more complicated. The state has always been on the cusp of several different climate and geographic regions, and because global warming doesn’t play out evenly on different fields, the impacts will vary across Colorado.
Northeastern Colorado is part of the Great Plains and Northern High Plains ecoregion, where several studies strongly suggest that intense rainfall events will jump. Southeastern Colorado is part of the Southern Plains ecoregion extending to eastern New Mexico, Oklahoma and Texas. The state’s northern mountains are linked more closely with the rest of the northern Rockies, extending all the way up to Idaho and Montana, but if you get south and west of Aspen, you’re suddenly into Colorado Plateau Country.
That makes it hard to generalize statewide impacts for Colorado, but the report makes it clear that forests across the state will see some of the biggest changes. The decade-long run of exceptionally high temperatures brought huge changes to Colorado forests, and that trend is far from over, according to the assessment, which explains that the absence of cold snaps has enabled bug populations to skyrocket. Aspens took a huge hit after just a couple of years of drought in the early 2000s. At the same time, pine beetles decimated millions of acres of lodgepole forests and in parts of Southwest Colorado, forest scientists say they doubt that the iconic piñon pines will ever grow back in some of the region’s lower-elevation habitat.
“Water, drought, floods and wildfire are the big issues here,” said Kevin Trenberth, a leading climate expert with the National Center for Atmospheric Research.
“There are real prospects for more snow in mid winter, because it is warmer and air holds more moisture when it is warmer. This year may be a case in point,” Trenberth said. “We have seen this already. This is the opposite of, ‘it is too cold to snow,’ where the air gets freeze dried. But the snow season gets shorter at each end and snowmelt occurs sooner and quicker, drying things out more by late May and in the summer, increasing risk of wildfire.”
Like most scientists, Trenberth stopped short of linking any single weather catastrophe to global warming, but said a warmer and moister atmosphere increases the chance of extreme events like last summer’s northeast Colorado floods.
“The flood last year was a very rare event: a lot of things came together to produce it, but the odds go up that similar kinds of things can happen. Again this relates to warmer air holding more moisture and when the weather situation sets up right it can be converged into the mountains and produce prodigious amounts of rain and flooding,” Trenberth said.
“More generally we expect longer dry spells in between more intense rains. Hard to say specifically about droughts, but when natural droughts occur, they are apt to set in quicker, and become more intense because there is more heat from the increased greenhouse gases, and so things dry out quicker, heat waves develop, and risk of wildfire skyrockets. We saw this in 2012,” Trenberth concluded, referring to year that saw Colorado’s snowpack literally evaporate rather than run off because of record warmth in March.
Most of the scientific evidence for the assessment’s conclusions isn’t new. Forest, fire and water experts have been warning of the same consequences for several years, but this latest push to create more climate awareness is backed by the political capital of President Obama, who has roused himself to try and make climate policy a pillar of his political legacy, and that has spurred environmental activists to renewed vigor.
Maybe, just maybe, the effort will pay off with a critical mass of social and political momentum that could speed the inevitable shift from a dirty fossil-fuel-based economy to a more sustainable future based on more conservation, less consumption and a full commitment to a renewable energy path. The assessment spells out one more time what the consequences of our current path are. The question is, can we collectively kick ourselves into gear to make the needed changes?
[ Photo by Bob Berwyn.Firefighters in Summit County stand on a snowbank while battling a small wildfire near Keystone, Colorado in March 2012, a year when fire officials issued unprecedented red flag fire warnings as early as January. ]