Saturday, November 28, 2015

The River Used to Freeze Over! Rally Sunday on Climate Change

Can you imagine ice skating on the Willamette River?

The historic photo record is clear that the river iced up a whole lot more, and more often, than it does today. We used to experience more intense and more extended periods of real cold.

Ice skating and play on the Willamette River in Salem
late 19th century, via Oregon State Library
But our winters are warmer now, and they're getting even warmer still. We see it in changes in vegetation on mountain meadows, we see it in the recession of glaciers, we see it in snowpack depth.

Even ski operators also say
"climate change is real"
In support of the Paris UN climate meetings the local group is having a rally tomorrow on Sunday. From Salem Weekly:
In Salem please join 350 Salem OR on Sunday November 29 at 1:00 pm at High and Court Streets downtown to walk to Riverfront Park for a short rally at 1:30 pm with speakers, music and art.
It's time for a tax on carbon, really.


Anonymous said...

The river not freezing over has nothing to do with climate change, it’s due to the dams on Willamette tributaries keeping the water warmer than it otherwise would be. That’s a widely known fact.

Salem Breakfast on Bikes said...

Ah. well, you could be right. Happy to correct errors of fact - But, citations?

Anonymous said...

See pages 39-42

Anonymous said...

Actually, make that pages 37-42

Salem Breakfast on Bikes said...

Thanks! That is Interesting and certainly does complicate the narrative. Though I'm not sure this quite yet rises to the level of "widely known fact." To say "The river not freezing over has nothing to do with climate change" may be an overstatement and oversimplification in the other direction.

The data and modeling in the study focused on one June-October stretch and a second April-October stretch. The main thrust looks to be more about summer and fall maximum temperatures rather than about winter low temperatures. As we saw this past summer with salmon and other fish mortality, those summer temps are important.

But as regards winter temps, they didn't investigate or model the winter season in the river system, and so notice the qualifier "likely" here in the conclusion:

"Annual minimum temperatures also are likely to be cooler without the dams because it is far easier to cool a river in winter than it is to cool the bottom of a reservoir, which in the Willamette River basin is never likely to be colder than 4°C. Given these patterns at the dam sites, and coupled with lower flows during mid-summer without the dams, it is logical to expect that annual maximum temperatures downstream of the dam sites would be warmer without the dams."

You are probably right that the dam system makes it less likely the river would totally freeze over today - but so does climate change. I stand by the general claim that winters were colder, that the old photos testify to this, and that climate change is an important ingredient in the lack of river ice in recent winters.

Additionally, many (maybe most) of the old photos also show people skating on the slough, and this mostly still body of water would be less influenced by the dams, reservoir flows, and their water temperatures.

Thanks for the information.

It is a useful reminder that systems are complex, and simplifying down to one master variable is fraught with explanatory danger.