Warming looms over Colorado River
Vail, CO Colorado
SUMMIT COUNTY ” There’s good news and bad news when it comes to the state of the Colorado River this year, depending on your geographic perspective.
At its Rocky Mountain headwaters, above-average snowfall helped boost the snow pack.
“We’ve had a pretty good water year on the Blue River,” said water commissioner Scott Hummer at the state of the river meeting in Frisco Wednesday evening. “We’re the leader on the West Slope.”
The South Platte Basin is the wettest drainage anywhere west of the Mississippi this year, Hummer said.
The snowpack above Dillon Reservoir is at about 95 percent of average for this date and stream flows in Summit County’s Colorado River tributaries are flowing well above historic means, Hummer said.
Denver Water engineer Marc Waage said he expects Dillon Reservoir to fill early, and there is some concern about the potential for flooding in neighborhoods north of Silverthorne. Green Mountain Reservoir should be filled by early July and stay that way through most of the summer recreation season, said the Bureau of Reclamation’s Ron Thomasson.
But the local watershed is an exception. Zooming out to some maps that showed the entire western half of the U.S., it’s clear that the larger region is still in the grip of a serious and widespread drought.
Whether or not that drought is related to climate change or global warming is not clear. But the Earth has experienced its 12 warmest years ever during the past two decades, said Dr. Andrea Ray, a researcher with the National Oceanic and Atmospheric Administration.
Ray said some of the most recent research coming from the International Panel of Climate Change suggests that the rate of warming is increasing.
“Warmer and fewer cold days are virtually certain,” she said, recapping some of the findings from the international panel’s latest reports. Those temperature trends won’t be spread evenly across the entire planet, and some regions may even become a bit colder, she said
The global data is mirrored closely by studies of temperature records in north-central Colorado. Colorado-based National Oceanic and Atmospheric Administration researcher Klaus Wolter recently studied temperature records from a number of sites in this region and found some unequivocal evidence that a strong warming trend has persisted in the north-central part of Colorado for about 50 years.
In that span, average low temperatures have climbed by about five degrees, and one degree per decade, while average highs have climbed about two degrees.
Wolter said the warming is most pronounced in the winter and spring, and the impacts have already shown up in a trend toward earlier snow melt and runoff, well-documented by the U.S. Geological Survey.
On the global scale, scientists are increasingly confident that greenhouse gases generated by human activities are a significant part of the warming trend.
Based on the projected temperature increases and streamflow changes, it may not be possible to fulfill all present-day water demands in the region, Ray said.
In the bigger regional picture, those shortages could play out in the ongoing battle over water use between the Upper Colorado River Basin states and lower basin states, such as California and Arizona, said Glenwood Springs water attorney Scott Balcomb, who represents Colorado in those talks.
Balcomb warned that the Colorado is already over-allocated and said every future water developer should realize that new claims may not be available for extended periods of time.
“We’ve got to make a plan that sufficiently flexible to deal with potential climate change,” Balcomb said.