A midsummer hailstorm that causes millions in damage. Fall wildfires that char thousands of acres. Warm winter winds gusting to more than 100 mph.

It'd be natural to assume climate change was at least partly responsible. But scientists and weather experts in Colorado are hesitant to point fingers.

Drawing a line connecting man-made climate change to any of these occurrences is a difficult and complex task, said Jeff Lukas, a climate researcher for the University of Colorado at Boulder's Western Water Assessment.

"You often hear climate change is making weather more extreme. Perhaps in some ways, but not across the board," said Lukas. "You really have to dig a little deeper and say, 'Is this the type of event that's likely to have been influenced by our warming climate?'"

The planet is heating up, and the vast majority of scientists agree that humans are contributing, and the consequences of global warming could be devastating. Last year surpassed 2015 as the hottest year on record, and human-caused climate change was partially to blame, according to data released Wednesday by the National Oceanic and Atmospheric Administration and NASA.

Temperatures are inching upwards locally and statewide. Last year was Colorado Springs' third-warmest year on record, behind 2012 and 1934, and the average temperature was 3 degrees above normal, according to the National Weather Service in Pueblo. In the past 30 years, Colorado weather has warmed by 2 degrees, according to a 2014 study Lukas lead-authored. The report's summary states the increase in temperatures are "plausibly linked" to human causes, although it's hard to say for sure on a large scale.

Across the United States, scientists have associated global warming with increasingly severe and frequent bouts of extreme weather, including heat waves, droughts, wildfires and torrential rainfall. Some researchers suspect a connection between global warming and occurrences like hurricanes and tornadoes, but establishing a definite cause-and-effect relationship is even trickier with such events.

"We can't say that any particular singular weather event, no matter how extreme, was caused by climate change," Lukas said. "It's hard to pin down even a partial influence on an event."

In Colorado, significant effects of climate change are likely to be more visible in future forecasts. Lukas' report predicts temperatures will have risen several degrees again by the mid-21st century, making heat waves, droughts and wildfires more likely and more severe. Winter precipitation is also expected to increase by 2050, although snowpack probably will decrease as the climate warms.

There is some debate among experts about whether human-caused climate change has already had an effect on wildfires, providing warmer, drier conditions that allow them burn more acres for a longer period of time in the Western United States. A recent study, released in October by the University of Idaho and Columbia University, blamed human-caused climate change for the burning of an additional 16,000 square miles of forest lands between 1984 and 2015.

Southern Colorado experienced wildfires later in the year than usual in 2016, which could have been a result of drier conditions and warming temperatures, said Colorado College Professor Mike Taber, who teaches a class on global warming. But, because many of the fires were human started - such as the Beulah Hill fire, which reportedly sparked during maintenance on a drainage swale, or the Junkins fire, which ignited when wind knocked part of a metal building into a power line - the uptick could also be a product of increasing urbanization and population growth, he said.

Records also show that last year's summer hailstorm, as well as the wildfires that raged late into the fall, weren't unique events in Colorado's history, said Jennifer Stark, meteorologist-in-charge at the National Weather Service in Pueblo.

The winds that tore through the Colorado Springs area on Jan. 9, caused by a Pacific storm system that dumped snow on the Western Slope and forced warm air down the eastern side of the mountains, were rare because the gusts were sustained for hours across El Paso County, said Brian Bledsoe, lead meteorologist at Gazette news partner KKTV.

But high-speed gusts caused by the same phenomenon, known as Chinook winds, are "not uncommon" to the area, said Bledsoe, who added that he is reluctant to attribute any weather event to climate change.

"When someone wants to draw that conclusion, it seems to me that they're trying to make something more out of it than there actually is," he said.

Assigning a cause or set of causes to a specific weather event is such a complicated feat that it makes up an entire scientific field known as attribution, said Stephanie Herring, a scientist at NOAA's Boulder labs.

Scientists' ability to identify climate change as a cause of a weather event depends on what Herring calls the "three pillars of attribution": observational records of past similar events, knowledge of how the physical processes behind the event could be impacted by changing temperatures, and the capacity of computer-generated models to simulate an event.

While scientific advances and technological improvements have made conclusions about attribution more confident and somewhat easier to reach, the process can still take months or years, Herring said.

"Events are very complicated. It's like a recipe. It has a lot of different ingredients," Herring said. "If you don't look at all the factors, you may be missing something."


Contact Rachel Riley: 636-0108

County Government Reporter

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