Feb 18

There’s been much hand-wringing going on in the Pacific Northwest over snowpack levels in recent years due to Al Gore’s continual assurance that climate change is happening “faster than we thought”, and this year the tension has been ramped up even more with the mild temperatures and low snowpack levels at the Winter Olympics in Vancouver, BC.

So, The Oregonian wades into the snowpack issue again, and finds that there is no easy answer:

With spotty snow at the Winter Olympics and snowpack down across much of the Northwest, it would be easy to see this balmy winter as the opening act in our warmer-world future.

Don’t.

It turns out the Northwest’s snowpack climbs and drops more than a cross-country skier, making it especially tough to predict.

Snowpack trends are the subject of a continuing scientific snowball fight among climate researchers, underscoring the hazards of jumping to quick conclusions.

Scientists agree that a future drop is likely at some point if global warming proceeds as expected. But they differ on how much snowpack has decreased, whether any of that was due to man-made climate change and how far and fast it’s likely to drop in coming years.

An example:

The researchers who made predictions last year for Washington’s climate change report figured that the state’s April 1 snowpack will drop nearly 10 percent a decade into 2040 because of climate change.

But three other University of Washington researchers just completed a study that puts the potential loss in the Cascades, including Oregon and Washington, at about 2 percent a decade, a far more manageable rate.

Cliff Mass, a UW atmospheric sciences professor and one of the recent study’s co-authors, said there will be a “profound” decrease in snowpack but much later in the century than others predict.

“The scientific community is pretty unanimous this is a serious issue,” Mass said. “But there are a lot of uncertainties in our modeling system that we’ve got to be honest about.”

As of Wednesday, snowpack in the Willamette River basin was 45 percent of normal. Washington snowpack is about three-quarters of normal.

The Northwest’s snowpack is particularly sensitive to temperature changes. The Cascades and Washington’s Olympics include a lot snow that falls at close to freezing temperatures — the highest fraction of “warm snow” in the continental United States.

“In the Cascades, a lot of the snow is on the edge of melting,” said Eric Salathé, a UW professor and senior research scientist with the university’s Climate Impacts Group. “That’s why these numbers are so touch-and-go.”

Climate cycles

Complicating matters for scientists, reliable snowpack numbers go back to only about 1950.

The region also experiences climate cycles that make it tough to cull the effects of man-made global warming from natural variations. The short-term cycle is El Niño, when warmer waters off South America result in drier, warmer Northwest winters.

This year’s El Niño is the strongest since 1998, said Phil Mote, director of the Oregon Climate Change Research Institute at Oregon State University.

Long term, the “Pacific Decadal Oscillation” shifts ocean temperature in the North Pacific about every 20 to 30 years, with corresponding ups and downs in snowpack. No one knows exactly why it happens.

“The noise can make it look like there’s a trend that’s not really there,” said Mark Stoelinga, who co-authored the latest study with Mass and Mark Albright of UW.

The 1950s had high snowpack to begin with. In the latest study, Stoelinga, Mass and Albright took their estimates back to 1930 by tracking stream flows and temperature and correlating it to snowpack.

From 1930 to 2007, snowpack dropped 23 percent, their study for an American Meteorological Society journal estimated.

From 1976 to 2007, when global temperatures were increasing, snowpack actually increased 19 percent, they concluded. That figure is not statistically significant because of the short time frame, but it illustrates that there aren’t “obvious, huge declines related to global warming,”

Many of the changes were due to natural variations in climate. Some — about a 2 percent loss per decade — were unexplained by climate cycles and could be due to man-made global warming, Stoelinga said.

“But if you try to spin it that all of the loss we’re seeing is evidence of what global warming is doing, you really risk undermining your credibility,” he said.

In some cases, he [Salathé] said, “we’ve been pushing too hard,” citing worst cases and not highlighting uncertainties.

Hmmmmmm. Despite scads of research by highly educated scientists (many with the letters Ph.D. after their names), they still cite uncertainties in their modeling system, only sixty years of snowpack records, El Niño, the Pacific Decadal Oscillation, statistical noise, and natural variations all as reasons that the Pacific Northwest snowpack is virtually impossible to predict.

So, the take-away message here is that these guys don’t have a clue! And yet they assure us that “the scientific community is pretty unanimous this is a serious issue”. Yeah, right 😉

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