Climate change is real, and it’s here, so Denver Water recently tried to determine how increasing temperatures would affect stream flows and water supplies. With a temperature increase of two degrees over a 50-year stretch — assuming no change in precipitation — streamflows and water supplies would decrease by 7 percent. A second scenario plugged a 5 degree temperature increase into the model. Streamflows would drop by 19 percent, with a 14 percent impact to Denver Water’s supply. Both temperature scenarios are “modest” compared to what many climate change models are predicting. The point of the studies is to develop a long-term water plan that will work in different climate change scenarios. Some recent climate change models are actually predicting an increase in winter precipitation in Colorado. Under those scenarios, the northern Rockies could see a snowfall regime similar to the Sierra Nevada, with more wet and heavy snow. Future snowpack seasons will be shorter and runoff will occur earlier. Up to now, planners have based their planning on past streamflows, for example using the worst recorded droughts as a baseline. “We need to go beyond that.” Global warming could result in more severe droughts. Denver Water’s long-range planning effort is trying to factor those unknowns into the equation in preparing for long-term climate change.
Adapting to the damaging effects of climate change, plants are gradually moving to where temperatures are cooler, rainfall is greater, f...