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

denver100degreedays145yearsnwsboulder

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.”

    Clear Creek Watershed Festival recap

    From The Clear Creek Courant (Corinne Westeman):

    Saturday’s eighth annual Clear Creek Watershed Festival was a fun and educational experience for children and their parents. More than 20 local businesses, government agencies and nonprofits put together booths and stations for families to visit. For each station visited, the attendee would have her “passport” stamped. A full passport book earned a prize.

    The event was started as a way to celebrate and educate the community, specifically children, on the importance of the watershed and how best to keep it clean…

    Organizers Chris Crouse and Dave Holm said the festival is a way to teach attendees about watershed use and cleanliness factors, including wildlife/urban balance, high altitude, land-use impacts. The Clear Creek watershed not only supplies water for several communities, they said, it also supplies several breweries and Water World in Federal Heights.

    This year, Crouse and Holm said, they tried to promote the event at schools as much as possible, as an opportunity to stimulate learning outside the classroom. And, overall, they anticipated about 500 people to visit the festival throughout the day…

    Cannon said the festival is a great way to “get people exposed to what’s going on” in terms of water cleanliness. Cannon displayed various types of bugs from Clear Creek. He said the presence of certain bugs is “used as an indicator of healthy water,” and that it’s important to keep Clear Creek clean and safe.

    “Anything that keeps kids connected to the environment is a good, healthy thing,” he said.

    Rocky Mountain NP glacier loss a threat to water supply — the Fort Collins Coloradoan

    Tyndall Glacier Rocky Mountain National Park via the SummitPost.org.
    Tyndall Glacier Rocky Mountain National Park via the SummitPost.org.

    From the Fort Collins Coloradoan (Jacey Marmaduke):

    Rocky Mountain National Park’s glaciers are shrinking away.

    And that’s a big problem — not only for the park’s scenic splendor, but also for Colorado communities that rely on water from the Poudre, Colorado and Big Thompson rivers, which are fed by meltwater from dozens of glaciers and glacierlike features strewn about the park.

    For decades, Mother Nature has protected them from unfavorable conditions, but as the park’s temperatures climb and the promise of heavy winter snowfall grows more uncertain, the park’s glaciers and glacierlike features have slowly and unsteadily started to shrink.

    A single decade of prolonged drought and warm summers could spell the beginning of the end for RMNP’s glaciers, according to one park ecologist. It’s already happened in California, where about a decade of drought and warming temperatures have pushed Yosemite National Park’s glaciers to near extinction.

    “It’s sad to say, but most mountain glaciers are predicted to be gone by the end of the century,” said Dan McGrath, a Colorado State University research scientist. “I find it hard to believe (Rocky Mountain’s glaciers) could survive given the predicted warming and likely changes in precipitation.”

    RMNP glaciers have always yo-yoed in size, partially melting in summer heat and regaining mass from winter flakes. The park has 30 glaciers, according to USGS topographic maps, but some of them technically aren’t glaciers anymore. Between the 1990s and 2005, the glaciers started to shrink at an increasing rate — perhaps faster than “at any other time in the historic record,” according to a 2007 Portland State University study.

    And the park’s glaciers don’t have a lot of wiggle room. Its glaciers are tiny compared to well-known glaciers in Alaska, Greenland and elsewhere. RMNP’s biggest glacier is about 31 acres, the size of six Old Town Squares, and the smallest is smaller than two football fields, according to the 2007 study.

    Scientists have no idea how the park’s glaciers have changed in volume over time and have only a limited record of how they’ve changed in area. McGrath wants to fix that.

    He’s conducting a two-year study to find out how the glaciers have changed in area and volume since 2005 using historic maps, climate records, photographs and present-day measurements to fill the gaps in scientific understanding of the glaciers.

    McGrath and his team are focusing mostly on the well-known Andrews and Tyndall glaciers but will monitor about 10 other glaciers along the Front Range. They’ll use electromagnetic waves to measure snow accumulation and ice thickness of the glaciers. With cutting-edge laser technology, they’ll create unprecedented 3D models of the glaciers. And they’re setting up timelapse cameras near stakes planted in the glaciers to study the timing of their shrinkage.

    McGrath has discovered that Andrews and Tyndall glaciers are roughly the same size they were in 2005. They grew in 2010 and 2011 because of heavy snowfall but shrunk after that.

    To get a better understanding of the glaciers’ timelines, McGrath will pore over climate models to see what’s in store for temperature and precipitation in the park’s higher elevations. It’s clear that warming will continue, but climate models are less certain about how precipitation will change over time in the Rocky Mountains.

    Preliminary results from an ongoing study by Glenn Patterson, a CSU geosciences Ph.D. candidate, and Steven Fassnacht, a CSU snow hydrology professor, suggest that snowfall has decreased more in the park’s higher elevations than its lower areas.

    Warming temperatures will melt more of the glaciers in summer, but warming temperatures’ larger impact could come in autumn and spring. A bump of a few degrees when temperatures are near the freezing point can turn snow into rain.

    “Of all the things I’m worried about for glacier health, it’s that threshold,” McGrath said. “It can be 30 degrees and you get snow, or it can be 34 degrees and you might be getting only rain. That is going to dramatically alter both the behavior of the glacier and the mass balance. That’s universal.”

    The final piece: McGrath’s team will study how glacier melt influences rivers, measuring streamflow and collecting water samples to see how much water glaciers contribute to rivers.

    Downstream impacts are worth studying because the Colorado, Big Thompson and Poudre rivers are fed largely by snowmelt and groundwater. The park’s year-round snowfields have particularly important downstream impacts, and the snowfields behave a lot like glaciers.

    Even a small loss in the snow and ice that feed Northern Colorado rivers would be a huge blow to Fort Collins and other nearby communities that rely on their water. The gradual melting of perennial snowfields bolsters late summer and fall streamflow, said Paul McLaughlin, an ecologist at the park’s Continental Divide Research Learning Center, and our water storage system depends on those established patterns. Changing water volumes and temperatures can irreparably damage delicate river ecosystems.

    The strange thing about these glaciers is they shouldn’t really be here.

    The park gets too warm in summer and not enough snow falls on them naturally, McGrath said. But most of the glaciers live in cirques that protect them from the summer sun, and aggressive winds shuttle snow across the Continental Divide, dumping between 5 and 10 times more snow on the glaciers than they would get from the sky alone.

    “There’s something of a climate disconnect,” McLaughlin said. “In these systems where the glaciers have already retreated to these shady areas, there’s kind of a time lag in which the glaciers may persist even though the temperatures are getting warmer. But at some point in the future, we would expect they’ll reach a tipping point where they would quickly disappear.”

    […]

    McLaughlin said the best-case scenario for the glaciers would be a future with less greenhouse gas emissions.

    “We have the opportunity as humans to manage the amount of carbon dioxide we’re producing and putting into the atmosphere,” he said. “That will have an effect on our climate moving forward, and perhaps on the lifespan of our glaciers.”

    MWH gets $11.9 million contract to design Chimney Hollow Reservoir

    Map from Northern Water via the Fort Collins Coloradan.
    Map from Northern Water via the Fort Collins Coloradan.

    From BizWest (Doug Storum):

    Engineering and consulting firm MWH Global Inc. in Broomfield, a division of Canada-based Stantec Inc., has received an $11.9 million contract to design the Chimney Hollow Reservoir dam that will be located between Loveland and Longmont.

    The Municipal Subdistrict of the Northern Colorado Water Conservancy District hired MWH to design a 360-foot-tall dam, spillway and outlet works for the 90,000-acre-foot reservoir near Loveland.

    Officials said on Tuesday that the Chimney Hollow Reservoir dam, located on the west side of Carter Lake, will be the largest dam built in Colorado in 50 years. It will provide water storage for growing communities in Northern Colorado, including Broomfield, Longmont, Loveland and Greeley. The subdistrict estimates that its communities could see a water-supply shortage of 64,000 acre feet, or approximately 29 billion gallons, by 2030.

    The design for the Chimney Hollow Reservoir Project is expected to be completed in 2018, with construction completed in 2021. The engineering services provided by MWH will include evaluating alternatives, final design and support during bidding.

    Keystone: Greeley Water wins taste and odor competition at RMSAWWA conference

    LadyDragonflyCC -- Creative Commons, Flickr
    LadyDragonflyCC — Creative Commons, Flickr

    From KDVR.com:

    Nine municipalities from a three state region competed for the title of best drinking water based on taste, odor and appearance.

    The judges at a taste test at the 2016 Rocky Mountain Section of the American Water Works (RMSAWWA) annual conference in Keystone deemed Greeley as the city with the best water in the region.

    Nine municipalities from a three state region competed for the title of best drinking water based on taste, odor and appearance.

    The winner of this competition will represent the RMSAWWA at the national “Best of the Best” taste test at the AWWA Conference in Philadelphia next June.

    Castle Rock Water was named runner-up.

    9/12/2013: Phenomenal rain reports coming in from all over Boulder County — Coyote Gulch

    Storm pattern over Colorado September 2013 -- Graphic/NWS via USA Today
    Storm pattern over Colorado September 2013 — Graphic/NWS via USA Today

    I made the mistake of checking my Twitter feed overnight on the 12th. Couldn’t get back to sleep. What a set of storms. Aurora got almost as much rain as Boulder County. Lots of flooding.

    @OmahaUSACE: Public meetings scheduled to discuss Cherry Creek Dam studies

    Cherry Creek Dam looking south
    Cherry Creek Dam looking south

    Here’s the release from the US Army Corps of Engineers (Eileen Williamson):

    Three public meetings to provide an update on the status of two studies taking place at Cherry Creek Dam are scheduled for the week of September 20.

    The U.S. Army Corps of Engineers will host meetings to provide a status update on alternatives under consideration to address risks from extreme storm events associated with Cherry Creek Dam including a study to modify the dam’s water control plan.
    The meetings will be held at the following times and locations:

  • Tuesday, Sept. 20 from 6 – 8 p.m.
    Cherry Creek Presbyterian Church
    Rooms 112/113 (Main Building)
    10150 E. Belleview Avenue
    Englewood, CO 80111
  • Wednesday, Sept. 21 from 5:30 – 7:30 p.m.
    Virginia Village Library
    1500 S. Dahlia Street
    Denver, CO 80222
  • Thursday, Sept. 22 from 5:30 – 7:30 p.m.
    Aurora Municipal Center
    City Café
    15151 E. Alameda Parkway
    Aurora, CO 80012
  • The public meetings will include a presentation and an open house to provide the public an opportunity to ask questions about Cherry Creek Dam and the alternatives being presented and considered as part of the Dam Safety Modification Study and Water Control Plan Modification Study.

    Meeting materials will be made available online following the meetings at http://go.usa.gov/cQ7hP.

    Background: Cherry Creek Dam and Reservoir is located in the southeast Denver metropolitan area on Cherry Creek, 11.4 miles upstream of its confluence with the South Platte River.

    In 2005, (post-Katrina) USACE began screening its dams (approximately 700 across the U.S.) to determine each dam’s risk level. Cherry Creek Dam received an elevated risk rating primarily because of the large downstream population and the potential for overtopping during an extremely rare precipitation event.

    A dam safety modification study began in 2013 and is being conducted in accordance with USACE policy as described in Engineering Regulation 1110-2-1156 “Safety of Dams – Policy and Procedures.” An Environmental Impact Statement is also being prepared pursuant to the National Environmental Policy Act of 1969, as amended.