Climate change will likely bring stronger storms and more 100-degree days to the Front Range — Denverite

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From Denverite (Ashley Dean):

The Rocky Mountain Climate Organization released reports yesterday predicting a more extreme climate in metro Denver and Boulder and Larimer counties.

Stephen Saunders, president of the RMCO and lead author of the report said that “our current path of steadily increasing heat-trapping emissions” will create a climate that is “fundamentally different from the climate we have known in Colorado.”

In Boulder County, that means temperatures of 100 degrees or more for an average of eight days a year by mid-century, and an average of 35 days a year late in the century.

In Larimer County, they’re predicting those days will come four times a year by mid-century and 23 days a year by the end of the century.

The report for metro Denver is still in the first phase, but early projections are looking at an average of seven days per year over 100 degrees by mid-century and 34 days per year by late century.

Those predictions are for a world in which we continue to release very high emissions. Very low emissions bring the projections down to one or two days a year in which temperatures climb over 100 degrees.

Those reports also project that storms of a half-inch of precipitation or more in one day will be more likely with continued high emissions:

  • 16 percent more frequent by mid-century and 36 percent more frequent by late-century in Boulder County;
  • 12 percent more frequent by mid-century and 33 percent more frequent by late-century in Larimer County;
  • 15 percent more frequent by mid-century and 31 percent more frequent by late-century in metro Denver.
  • From The Denver Post (Bruce Finley):

    “By the middle of the century, summers here will be as hot as summers have been recently in El Paso,” said Stephen Saunders, director of RMCO, who led the research.

    “Half the houses in Denver today do not have air conditioning. We’re going to be facing serious threats to people’s health because of these temperature increases,” Saunders said.

    “Temperature increases also will drive wildfires, increased evaporation from reservoirs, changes in snowpack, and enormous increases in energy use for air conditioning. These temperature changes will affect every aspect of our life,” he said.

    The average number of days with temperatures above 100 degrees in the metro area is 0.3 days.

    But summers are already getting hotter. This year, the average temperature in Denver for June, July and August was 72.7 degrees — 1.5 degrees higher than the annual average of 71.2 dating to 1872, said Kyle Fredin, meteorologist for the National Weather Service in Boulder.

    The reports were done for the purpose of helping Colorado prepare and are based on government temperature data and university consortium climate models. RMCO does advocacy work in favor of limiting greenhouse gas emissions in addition to climate research. Denver environmental health officials commissioned the Denver climate analysis. Boulder and Fort Collins analyses were done as part of a $57,300 project run by the Colorado Department of Local Affairs.

    Denver officials commissioned this study for $9,000 “as a way to frame our actions on climate, both for the mitigation of climate altering greenhouse gas emissions and the adaptation to a warming, altered climate,” city spokeswoman Kerra Jones said. “This study was intended to bring real data into models that could project what that might specifically mean for Denver and the metro area.”

    If current trends in heat-trapping emissions continue, Denver residents by 2050 will face an average of 35 days a year where temperatures hit 95 degrees or hotter, the study found. Right now, the average is five days a year.

    The study also found that storms dropping less than a quarter inch of precipitation will happen about as often as today regardless of emissions levels but that storms dropping more than a quarter inch or rain or snow will become 15 percent more frequent by 2050 and 31 percent more frequent late in the century.

    Boulder by 2050 will have an average 38 days a year with temperatures exceeding 95 degrees and, by the end of the century, an average of 75 such days a year. The studies found Fort Collins by 2050 will have an average 24 days with temperatures exceeding 95 degrees and 58 days on average by the end of the century.

    While RMCO researchers project more extreme precipitation — intense storms dropping rain and snow — these projections are considered more uncertain because they depend on more variables including air currents, terrain and storm patterns.

    Denver officials last year issued a Climate Action Plan calling for citywide cutting of emissions by 80 percent, below 2005 levels, by 2050. But local efforts to reduce emissions from vehicles, factories, the oil and gas industry and other sources in Colorado likely would make a small difference because climate change is driven by global-scale increases in heat-trapping gases.

    “All this depends on global emissions,” Saunders said. “However, people around the world will be looking to see what we do here in response.”

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