These poor snow conditions in Yellowstone, photographed in February, might reflect the new norm, not merely an aberration, according to snowpack research in the park.
This past winter saw an earlier-than-usual decline in snowpack on Yellowstone National Park roads, one that forced the park to shut down access to some snowmobilers and snowcoaches. While some might write that off to simply an unseasonal winter, record-keeping in the park shows less snow is falling there and that in some parts of Yellowstone the once-typical Rocky Mountain winter is actually much shorter than it used to be.
One can debate whether this is simply a natural cycling of the Earth's climate or human-driven global warming -- Yellowstone researchers point to the latter -- but the bottom line, as they note, is that "(D)espite all these caveats and complications, we are confident in saying the long-term forecast in Yellowstone calls for less snow. There may be a few decades-long bumps and flat places in the trend, but the overall picture of a declining staircase is clear. People who rely on water that begins its life as snow in the mountains of Yellowstone should be aware of this fact and plan accordingly."
The snowfall study was released this week in a special climate change edition of Yellowstone Science. The issue offers a range of articles involving climate change in Yellowstone, from the trends in snowfall to how the park's forests will fare under a changing climate.
Whitebark pine was projected to have the greatest loss in area of suitable habitat in the GYE. The areal extent of adult reproductive aged stands has already declined dramatically across the GYE due to mortality from mountain pine beetles. Will whitebark pine be entirely lost from the GYE? Hope for the persistence of whitebark pine in GYE is bolstered by its history. Pollen records indicate that five-needle pine (whitebark and/or limber pine) remained in the region over the past 10,000 years even during the relatively warm hypsithermal period (Iglesias et al., in revision). More research is needed, but various hypotheses suggest viable populations can remain through the projected harsher climate in 2100.
As for snowfall in the park, the researchers detected a trend the layman might find interesting: "We have seen that the longest snow course records in Yellowstone had no significant gain or loss of April 1 SWE (snow water equivalent) from the early 20th century to present day because they include both low snow eras of the Dust Bowl 1930s and the 2000s."
However, the authors went on to note, if you measured snowpack from 1961-2012 -- the longest continuous period during which researchers could rely on SNOTEL data collections from the same sites -- "...70% (21/30) of the sites had significant declines during this 52-year period."
What was behind the decline in snowpack?
"... taken as an average, sites with declining snowpack during 1961'2012 generally had lower precipitation and higher average daily maximum temperatures during the winter months," the article's authors wrote.
"These patterns suggest increasing temperatures during January, February, March, and April have caused significant snow declines in locations with higher average temperatures by pushing them over the freezing point more often. Other factors contributing to site-to-site differences in snowpack patterns include wind scouring (removes snow) and amount of tree cover (protects snow from sun and wind). Interestingly, the elevations of declining vs. no-trend sites overlapped and were not a good explanation of site-to-site differences."
They go on to say that warmer temperatures are the most likely cause for the decline, and that "(L)ocations that were generally wetter and cooler have not yet demonstrated declines, but with continued climate change will begin to lose their snowpack too."
Strikingly, the researchers found that in recent years some parts of Yellowstone have experienced 80-100 more days of above-freezing temperatures that they did in the mid-1980s. "In other words, the season during which temperatures are above freezing is roughly 3 months longer now than it was 25 years ago at the Northeast Entrance."
Comments
I think Kurt has it right and that trees do 'care' whether precipitation falls as rain or snow. Snowpack accumulation helps extend the period of moister soils into the high sun-angle summer season when most conifer photosynthesis occurs and when their water demand is highest.
In a hard rain, much of the moisture runs off and is not soaked in for the trees. Snow would act more like a long drizzle. So how moisture falls does effect the plants and species that live somewhere.
Beachdump, please speak for yourself. The only people that look foolish in today's world are those that deny that the planet is warming.
But EC, regardless of the amount of precipitation that falls as snow, leading either to a deep or thin snowpack, longer periods of temperatures above freezing will melt that snowpack more quickly.
If you get 2 inches of snow, and the temperature is 20 degrees for weeks, that snow will stick around quite a bit longer, and provide a longer period of moisture for vegetation, than if you get 2 inches of snow and two days later the temperature is 35 degrees and rising fast.
If you look at Figure 8 in the study, the graphs clearly point out the impact rising temperatures have had on the park's snowpack.
Would it be nice if they had annual measurements of moisture that fell as both rain and snow in the study? Sure. But if the temperature trend is to more days above freezing, it doesn't really matter, does it?
True, but is that a greater contributor or is less precipitation the major (predominant) contributor? The tree rings don't know and this study doesn't even address the issue.
Yes it does.
Temperature increase globally will cause some parts of our globe to be wetter, some to be drier, some to be hotter, some parts to be colder. And is important to study to see how it may or may not effect you locally, nationally or globally. Human caused or not.
I think everyone agrees the planet is warming, Gary. They just don't agree what we can do about it--or should do about it. In the words of the human ecologist Garrett Hardin, "We can never do merely one thing." All things are related, and all things have consequences. And even if we do the "right" thing there are no guarantees.
I miss the humility educators had in the 1970s when all of this was first being "studied." On one point, however, scientists seemed to agree. More people on the planet would not making solving its problems easier, no matter what the problem was.
So here we are--now deep into the "Grand Experiment" as to what Mother Earth can absorb. How much plastic? How much carbon? How much CO2? How much land scraped bare for cities and agriculture, when the land itself has always "known" something else? That Yellowstone cannot escape the consequences, either, should not surprise us at this late date.
Then what are we selling? A panacea? Those humorous wind turbines pictured on the top of Half Dome the other day? None of it is going to work the way we want it to work, because we can never do merely one thing.
The only certainty is that someone will get rich making the sale. I say we should be selling birth control, but then, I believed the first book I read on the issue way back in 1968.
I agree 100% with that David. Someone made that point earlier in a guest article and was aggressively attacked.