From The Colorado Sun (Evan Ochsner):
Much of Colorado continues to suffer through extreme drought, and nearly all of the state is experiencing drought, according to the latest data released by the U.S Drought Monitor, a collaboration between the National Oceanic and Atmospheric Administration, the U.S. Department of Agriculture and others.
Climate change could make droughts more severe and more common and disrupt the state’s economy. And while this year’s drought isn’t the most severe of the past decade, it will take “years and years of heavy rain to get back up to normal,” drought monitor author Richard Heim said.
The red on the map below represents extreme drought, while orange represents severe drought…
A year ago, Colorado was pleasantly, surprisingly moist. The Western corners of the state were “abnormally dry,” shown in yellow, the lowest level of drought classification by the monitor. The rest of the state, shown in white, was drought-free…
But conditions deteriorated over the past year, and a combination of short-term dryness and long-term dryness in the state has led to drought. Heim says Colorado has been in a “persistently dry pattern, in general, for most of the state.”
Colorado has also been suffering from relatively warm temperatures and a high propensity for evaporation. When the air is evaporating water at a higher rate, there is lower humidity and less water in the soil, rivers and reservoirs.
The monsoon late last summer was lackluster, which put the state on the trajectory toward drought. The state was dry going into the winter, and a dry and warm spring contributed to the current conditions…
Another important factor in staving off dryness: snow melt. Colorado’s high country snowpack plays a critical role in maintaining moisture in the state. Alpine snow fields serve as a reservoir, and when the snow melts it feeds rivers and streams and percolates into the soil. The unusually dry spring disrupted this process, and the snow melted too quickly to feed water systems downstream.
The past few months have been particularly dry, with vast portions of the state — shown in red in the map below — suffering from precipitation levels well below average…
Though conditions have worsened in the northwestern corner of the state, they have improved in many other places, particularly in the southern portion of the state…
The improvement is explained at least in part by increasing rainfall in a large part of the state. “So far, the early parts of the monsoon season have been promising,” Colorado State Climatologist Russ Schumacher said.
The drought-stricken southern portion of the state has had more rain in recent weeks, which has made a noticeable impact. Precipitation can temporarily lower fire danger and make a dent in dry conditions, but thunderstorms are not enough to lift a region out of drought…
The long-term outlook for Colorado this summer and early fall suggests the drought will persist. NOAA forecasts predict Colorado will be among the driest parts of the country, relative to its normal levels of precipitation. Most of the state, shown in dark brown, has a 40% chance of seeing lower precipitation than normal. Those are the worst odds in the country, the model shows.
Heat, too, will likely exacerbate the likelihood of sustained drought. Much of Colorado has a 60% likelihood of being hotter than normal in the coming months.
“If it remains warmer than average for an extended period, even if you have normal or above-normal precipitation, it doesn’t really end the drought in that situation,” said Schumacher, the state climatologist.
The heat projection shown above reflects recent trends, as much of the Southwest has become increasingly hot during the summer months in recent years. Experts say the western portion of the U.S. has grown hotter and hotter over the years.
The darker the red in the map below, published by the National Oceanic and Atmospheric Administration, the hotter the area has been trending. According to the model, there is a “clear warming trend,” compared to previous summers.
Climate change is causing serious concern among scientists who study drought, because it could make droughts more severe and more common. The changing climate could stress systems necessary for staving off drought.
Colorado’s critical snowpack could be severely hit by climate change. The warming temperatures could shorten the snow season, lead to quicker melting and turn wintertime snow into rain. The high altitude of Colorado’s mountains insulates the state from some of those effects, but it’s not immune. As droughts this summer and in years past demonstrate, changes in snowpack can affect the climate year-round.
A warming climate could also lead to less overall precipitation and increase the rate of all-important evaporation.
“Climate change is water change,” Schumacher said.
Because Colorado already has an arid climate, changes in precipitation caused by climate change can have a major impact on the economy and people’s livelihoods. And while drought in Colorado is not a new phenomenon, scientists are increasingly confident that climate change is playing a role.
“What’s happening in the West is attributed to climate change,” said Heim, the drought monitor.