Climate scientists share forecast for Bitterroot

Climate scientists share forecast for Bitterroot

News Type: State Source: Ravalli Republic
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Larger wildfires and a longer fire season, less water for agriculture uses and an extended growing season are just of few of the changes Bitterroot Valley residents are expected to experience due to the changing climate in Montana, according to a presentation this week in Hamilton.

Eight people associated with the 2017 Montana Climate Assessment painted a largely bleak picture of the future for the Bitterroot. Kevin Hyde with the Montana Climate Office told about 75 people gathered in Hamilton Wednesday that they can expect an increase in winter, spring and fall precipitation, and a decrease in the summer.

The area can expect moderate increases in precipitation, but that might not fall at the times best suited for current agricultural uses, Hyde added, noting that they’re forecasting more rain or snow in the fall, winter and spring, but less in the summer — quite similar to what occurred last year.

“The 2017-18 winter forecast by state climatologists is calling for a La Niña, where we anticipate reasonably high precipitation and lower than normal temperatures,” Hyde said.

But when and where that snow falls makes a difference. He said it’s higher in the mountains, with the snowline receding up the slopes over time and melting earlier and faster — two or three weeks earlier than it was 20 to 30 years ago.

The upside of that, according to Alex Leone with the Clark Fork Coalition, is that between a stable aquifer and the Painted Rocks Dam, the Bitterroot is in a better position than most areas in Montana to store and release water when needed.

“In the Clark Fork, we don’t have a high-elevation dam,” Leone said. “I know dams are not really a popular thing, but maybe they need to be.”

Bruce Maxwell, a professor of earth sciences at Montana State University, said the unfortunate part of the predictions is that while the agricultural growing season will be longer, the lack of water in the future may be an issue.

And that could be particularly problematic in eastern Montana.

“We’re forecasting we’ll run out of irrigation water, so there are certain crops that will be at risk in eastern Montana: sugar beets, corn and soybeans in the irrigated valleys like the Mussellshell and Yellowstone,” Maxwell said. “The change in the number of days with temperatures over 90 degrees will have a huge impact in Montana because of how that could impact grasses.

“… We had 22 days of over 90 degrees as the state average last summer. That will stretch into June, through August and in some cases into October. That will bring radical changes.”

He expects the wetter springs and dry summers will lower yields for wheat, and that the warmer winters will be beneficial for weeds like cheat grass.

“You’ll need more and more water to produce the same amount of hay. I’ve already had a lot of ranchers saying that’s consistent with what they’re seeing,” Maxwell said. “They’re not getting the same production as they used to with the same amount of irrigation.”

He added that with wetter springs, farmers may find they can’t get into the fields in a timely fashion to plant spring wheat, and it could flower in the middle of the hottest days. They won’t be able to plant earlier, because of the frost in the fields.

“Durum wheat seems to do better,” Maxwell said.

Those hotter days and nights also will prove stressful for cattle, Maxwell said, noting that they need cool temperatures at night to recover from the hot days, and they’re seeing less of that

“That’s become a big issue,” Maxwell said.

In the Bitterroot, an increase in carbon emissions also may affect orchards, vineyards and vegetable farms, according to Zach Miller, superintendent of the Western Agricultural Research Center in Corvallis. While these plants show a brief and promising growth spurt upon initial exposure to carbon dioxide, it limits their ability to pick up other needed nutrients.

“Greenhouses add CO2 all the time … but it also impacts pests. The weeds grow better and the insect damage often increases,” Miller said. “We also can get more bugs here that we don’t have in the state as the winters warm.”

Alisa Wade, a researcher at the University of Montana, said the climate changes also will increase the frequency and severity of wildfires, regardless of the water situation. But she noted that the forests have evolved, adapted and transformed over time, so it’s not like the trees don’t have the capacity to respond.

“However, the rate of change is such that there’s the potential that some species will not be able to keep up and have serious declines,” Wade said.

To read the full 308-page report or the executive summary, go online to http://montanaclimate.org/