State climatologist warns Colorado is warmer, runoff shifting earlier and summer water stress may increase
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Summary
Colorado State Climatologist Russ Schumacher told the Water Resources and Agriculture Review Committee that the state has experienced notable warming, leading to earlier snowmelt and increased evaporative demand; he said La Niña and natural variability complicate precipitation forecasts but add drought risk for parts of the state.
Dr. Russ Schumacher, state climatologist and director of the Colorado Climate Center at Colorado State University, told the Water Resources and Agriculture Review Committee that Colorado is experiencing a clear warming trend and that the consequences for water supply are already apparent.
"We've seen more warming that's happened. It's been observed," Schumacher said, summarizing decades of state temperature records and model projections. He said the Oct–July period this water year ranked among the state's warmest on record and that much of Colorado fell into the top‑10 warmest category for that period.
Schumacher reviewed regional contrasts: high‑mountain basins can still show above‑average snowpack while southern basins (Rio Grande, Southwestern basins and the Dolores) declined rapidly after April 1. He noted an example: some Southwestern basins fell from near‑average April 1 snowpack to well below average by mid‑May, and streamflow in certain basins (Dolores) ran substantially below historic averages in the April–July window.
On seasonal outlooks, Schumacher said climate drivers matter: "La Niña is on its way back," and the NOAA outlooks tilt toward drier falls on the Eastern Plains and increased confidence of warmer‑than‑average fall temperatures in parts of the state. He cautioned that Colorado sits between strong northern and southern signals and that forecast skill falls off further into winter.
Looking decades ahead, Schumacher reviewed climate model compilations under a moderate emissions scenario and put median warming in the range of several degrees Fahrenheit by mid‑century relative to late‑20th‑century averages. He said there is high confidence in continued warming but low confidence in a single statewide precipitation outcome. "There's some question marks" about precipitation trends, he said.
Schumacher focused on impacts to water managers: increased evaporative demand from higher temperatures, shifts to earlier spring runoff and lower summer streamflow, greater year‑to‑year variability, and amplified wildfire and flash‑flood risks following burned landscapes. He said the timing shift is particularly consequential for irrigators: "When you really need the water is in July and August when it's the hottest. But if it's not there at that point and if it's not being stored, then there's some issues at work there."
He closed with a note on data services: the Colorado Agricultural Meteorological Network (COAGNET) continues to expand sensor coverage and has added taller towers to better measure winds at crop heights. He encouraged committee members to request region‑specific products and said the Climate Center recently updated its public website (coagnet.colostate.edu) and an updated climate report was released in January.
The committee asked for follow‑up materials, including runoff‑timing graphs and regional breakdowns; Schumacher agreed to provide those products.
