Hazier days in the high country, Western U.S. due to drought and forest fires, scientists find
By Bruce Finley | This email address is being protected from spambots. You need JavaScript enabled to view it. | The Denver Post
PUBLISHED: January 8, 2017 at 7:12 pm | UPDATED: January 8, 2017 at 8:38 pm

The climate shift favoring droughts and more wildfires in the Western United States is leading to hazier days with reduced visibility in the high country, especially wilderness areas, where visitors seek endless blue skies.
A haze made of dust, soot, ash and smoke — tiny particles that float in the air, not settling — increasingly impairs views, according to government-backed scientists from the universities of Colorado and Utah. They drew on data by Colorado State University and others and deployed shadow band radiometer instruments to measure visibility from once-pristine points around the West, starting with a station at an elevation of 10,525 feet atop the Steamboat Springs ski area.

“You won’t be able to see as far,” said Gannet Hallar, the Utah atmospheric scientist who led the project.

“Your views will decrease. There will be a lot of variability, but on average we’re showing decreases. … In general, we are feeling the impacts of climate change throughout the West.”

The peer-reviewed research results have been published in the science journal Environmental Research Letters.

Scientists first looked at  climate and drought records from across the inter-mountain West. Then they measured the particulate pollution levels in air. They determined there was a strong correlation between drought and the amount of particulates.

The scientists also looked at records showing numbers of acres burned by wildfires each year. In current climate models, scientists anticipate the average number of acres burned may double by 2050. They concluded there’s an even stronger correlation between the number of acres burned and the amount of particulates in air during summer.

Forest fires are expected to drive the increased particulates and haze obscuring views from once-pristine wilderness. The Zirkel mountains will be harder to see from atop Steamboat, and the Sangre de Cristo Mountains will be harder to see from the floor of the San Luis Valley, they said.

Atmospheric scientists collaborated with University of Colorado land surface hydrologist Noah Molotch, a co-author of the published report.

Beyond visibility, the increasing haze from particulate air pollution in Western states likely will have other effects — perhaps including a cooling effect on what are widely expected to be rising temperatures, Molotch said.
“The amount of heating you have at the land surface is dictated by the strength of the sun. And when the sky is hazier, the strength of the sun is reduced. So you could actually cool the surface of the Earth by making the atmosphere hazier,” he said.

Around the West, forest managers in recent years have raised concerns about the thickening of forests because of aggressive wildfire suppression. To improve the health of ailing forests, some managers favor letting fires burn whenever possible, especially in wilderness where wildfire plays essential ecological roles.

These polices, too, may contribute to increased particulate haze wafting through the Western high country depending on the frequency and intensity of the fires, Molotch said.

“As we manage the forest landscapes, it will have an impact on other parts of the Western United States.”