Thursday, May 8, 2014

Northwest Climate Change: Did the 2014 National Climate Assessment Get the Story Right?

This week the media has been full of stories about the release of the 2014 National  Climate Assessment, which examines recent and future climate change around the nation.  At 841 pages, this is a large body of work and in this blog I will examine the portion dealing with the Pacific Northwest.  Did it get the facts correct? Was its handling of the material unbiased, hyped, or too conservative?   Let's take a look.

This section begins with a review of climate change over the past century.  Specifically, they note:

Temperatures increased across the region from 1895 to 2011, with a regionally averaged warming of about 1.3°F.   While precipitation has generally increased, trends are small as compared to natural variability ... Studies of observed changes in extreme precipitation use different time periods and definitions of “extreme,” but none find statistically significant changes in the Northwest.

Fair enough.  Over a more than a century Northwest-averaged temperature has only warmed by about 1.3F and there have been no significant trends in precipitation, including extreme precipitation.  And they note that not all of the 1.3F rise in temperature was due to human influences;  some of that warming was undoubtedly natural since it started in the late 1800's before humans were having much impact.  To illustrate this, the figure below (from the UW Climate Impacts Group) demonstrates that much of the warming occurred before 1940, prior to significant effects of human emissions of greenhouse gases.

So Northwest climate has really not changed much during the past century.

Then the report talks about future projections:

An increase in average annual temperature of 3.3°F to 9.7°F is projected by 2070 to 2099 (compared to the period 1970 to 1999), depending largely on total global emissions of heat-trapping gases. 

So they are suggesting that temperatures over that 100 year period (basically the difference of 1985 and 2085) will warm at 2.5 to 7.5 times the rate it did over the 1895 to 2011 period.  They do not give references for this warming, but we can examine the the co-authors' (Phil Mote and Amy Snover) previous work, which give similar numbers.

 Below is a figure from the recent UW Climate Impact's Group regional climate evaluation (Any Snover is the head of the CIG).  It shows Northwest temperatures predicted by global climate models for various scenarios (increases in greenhouse gases).  8.5 is the most extreme, 2.6 the least.  8.5 is the scenario where we don't make drastic changes in our life style and I believe the most probable assumption. The range of climate model solutions for the 8.5 and 4.5 scenarios are shown and are consistent with the recently released climate assessment report.

You will immediately note a problem with their plot, the temperatures over the NW have been flat since 1985 (see their figure above) and the figure below show a roughly 2F increase.  Furthermore, I believe it is doubtful that the warming will be as much as shown by the 8.5 simulation (7-11F warming by 2085) for two reasons.  First, the climate models appear to be too sensitive to greenhouse gas forcing and secondly they appear to have particular trouble with natural variability of the eastern Pacific.

A number of climate experts at the UW (such as Professor K.K. Tung, paper here) believe that excessive sensitivity of climate models to greenhouse gases results from their "tuning" to match the  warming of the late 20th century.  They believe that the sensitivity of the models was cranked up to compensate for either the failure to handle the cooling effects of atmospheric particles (aerosols) or the models' inability to properly simulate major modes of natural variability like the Atlantic Multidecadal Oscillation (AMO) mode. The tuned models look great over the 20th century (proof you can trust them!), but they overdo things in the future.

In addition, the climate models runs that included the past 40 years have failed to produced the observed cooling of the eastern Pacific (see figure), which obviously is suppressing temperatures around here.

I suspect cutting the RCP 8.5 warming prediction in half would be a far more reasonable prediction of what things will be like in 2085 (as well as starting at the observed level of 2014).  So we are talking 2-4F warming.  The problem is the authors of this section use the larger warming estimates as assumptions in much of the rest of their work (like snowpack changes).

The assessment notes that expected precipitation changes in the region will be modest, with a small increase in precipitation being probable:

Change in annual average precipitation in the Northwest is projected to be within a range of an 11% decrease to a 12% increase for 2030 to 2059 and a 10% decrease to an 18% increase for 2070 to 
2099 for the B1, A1B, and A2 scenarios.

This is an area where the assessment is probably too conservative.  Although annual precipitation will not change much, some research (including that of my group), suggests substantial enhancement of the heaviest precipitation events (pineapple express).  Furthermore, with less snow pack on the slopes during early winter, enhanced rainfall could result in more serious flooding (snow actually soaks up some rain, reducing flood risk).

In the next section, the assessment states that the snowpack has declined about 20% since 1950.  I co-authored a peer reviewed paper on the subject and found a reduction of 23% since 1930.  But what is not said in the Climate Assessment Report is that most of this 23% has nothing to do with global warming, but rather was forced by natural variability.  They claim that spring snowmelt has occurred 0 to 30 days earlier since 1950 depending on location, while we found snow melt occurs only 5 days early since 1930. Strangely, they don't even cite our paper in their section, which suggests either a biased viewpoint or a very incomplete search of the literature, neither of which is good.

 The report talks about increases in Northwest wildfires:

Although wildfires are a natural part of most Northwest forest ecosystems, warmer and drier conditions have helped increase the number and extent of wildfires in western U.S. forests since the 1970s

Reading through the wildfire literature the last few days and talking to experts in the USDA Forest Service, I could find no research that shows a significant increase in wildfires in the Northwest over the three decades.   And even if they did increase, it would be nearly impossible to separate climate impacts from the influence of increasing population, changes in forestry practices, and major shifts in wildfire management.  Wildfires are a natural aspect of NW ecology, and the suppression of fires has resulted in the potential for catastrophic conflagrations.  Quite possibly, more fires would be a good thing for the environment.

But most significantly, this regional climate report fails to mention the central and most important fact about climate change in the Northwest:  the impacts of global warming will be weaker and more delayed in the Northwest than nearly any location in the U.S.   The reason:  the Pacific Ocean.

Virtually all climate models indicate the arctic will warm up the most and the continents will warm up more than the oceans (see figure).  Furthermore, the eastern oceans will warm more slowly than the western

oceans.  The weather of the Pacific Northwest is controlled by the Pacific Ocean to our west, and if the Pacific warms more slowly so will we.  In fact, the lack of east Pacific warming of the past 30 years explains why our temperatures and snow pack has remained essentially constant during that period.  Furthermore, most Northwest climate change of the last century has been natural in origin.

The bottom line of my analysis is that the impacts of increased greenhouse gases has been very small here in the Northwest so far.  Global warming will impact our region, but the changes here will be modest and slow. The biggest impacts will be reduced snow pack later in the century and increased risk of heavier precipitation and floods.   Less snow pack will reduce the amount of snow melt available during the summer and early fall. Thus, to ensure sufficient water supplies we will need larger or additional reservoirs or dams.


Big Wave said...

Dear Dr. Mass:

Different subject:

Seattle's school math selection committee has chosen EnVision. A horrible choice. The selection now goes to Superintendent Blanda and the School Board for approval. I feel their reasoning was gravely flawed, see their conclusions here:

Please blog about this - I feel the selection of the proven Singapore math system is slipping away from the concerned parents of this city. Thanks Cliff.

Unknown said...

I think the biggest impact in the NW will be the resource demands of all the people moving here from other parts of the US. People in the SW and along the Atlantic coast in particular will increasingly look to the NW as a kind of climate refuge.

- Douglas

Tom said...

I'm not sure how the connection is with climate change, but I have really noticed a decline in clear night skies over the last 5 or so years. I'm an amateur astronomer and the hobby has become extremely frustrating. About 6 years ago, we had plenty of clear night - all year around. The last few years have really gotten worse. Either it's cloudy, or when it's clear, it's not very clear due to high haze in the sky. I have only seen a small handful of really clear nights a year now.
Our astronomy club has pretty much given up on planning public telescope viewings since it just never works anymore! Years ago, we would plan telescope viewing nights even in the winter - and it would work. Not anymore.
I should take up stamp collecting as a new hobby. Anyone want to buy a telescope? :-P


Michael said...

I appreciate your thoughtful examination of the NW section of this study. I believe all of your readers would appreciate your overall take on the entire report. It appears this report will be a key resource for the EPA in the near future. With all the hype from alarmists and deniers it is often difficult to obtain a clear view of the science.

Placeholder said...

Excellent posting, Cliff. Really appreciate it. Add my name to the list of people who'd like your take on the whole report.

Toby Thaler said...

"there have been no significant trends in precipitation"

There is a study that found a significant trend in "storminess" near here: T. Muschinski & J. I. Katz, Nature Climate Change , (2013) | doi:10.1038/nclimate1828

Article at

I believe Katz plans to publish more on the subject.

Cliff Mass said...

The paper you quote says nothing about the intensity of rainfall, but the second moment...the variability over time, which they claim is increasing ONLY at Aberdeen 20 NE and no where else. I suspect there are issues about their data analysis, but in any case it does not deal with the AMOUNT of rainfall, which is what I was talking about..cliff

Placeholder said...

Hey Cliff, I just wanted you to know that I was in Aberdeen on the day after Thanksgiving in the late '90s, and rainfall was 0.5" in Seattle but was coming down in buckets.

Besides immediately understanding both why Kurt Cobain moved away and why he eventually took his own life, I regard that day as proof positive that you are a global climate change denialist, and a mere weather man who doesn't get the bigger picture. :-)

Seriously, please keep on doing what you are doing. The climate change issue desperately needs your voice. It really does. In the maelstrom of increasingly vicious rhetoric, your thorough and workmanlike exposition is truly valuable and trustworthy.

As a Seattle resident whose taxes or tax exemptions one way or the other help support the University of Washington, I deeply appreciate and highly respect your contributions. I'm only one guy out here in cyberspace, but I want you to know that what you are doing has an impact that perhaps in your lonely moments you might doubt.

Finally, I understand about academic politics, at least as much as someone outside that particular "greenhouse" can. I very much salute you for your willingness to critically evaluate a colleague's work.

John Bower said...

Thank you for your analysis. I agree with Douglas - if we accept that the impacts on other parts of the country (the midwest, SW, and California for instance) will be much greater than the impacts here, then the biggest concern we should have is for how changes in other regions affect us. One obvious impact is through increased migration to the NW. Another is destabilization of the U.S. food supply. Still another is the effect on disease, both plant disease and human disease. And these types of impacts go well beyond the U.S. border. One of the biggest questions in my mind (and one hardly ever hears this addressed) is how the impact resulting from serious climate change impacts in many other parts of the world will affect us? The potential for destabilizing global economics and politics could have serious consequences for the U.S., including those of us in Cascadia. I am a scientist, and I have always been amazed at how scientists wear blinders when it comes to the secondary (economic, political) effects of environmental issues. As much as I respect you Cliff, I do think you sometimes commit this error in your blog, both today and previously.

nwwindwatcher said...

Dr. Mass,

When an economist like Patty Glick, with the self appointed title of Senior Global Warming Specialist, lead authors an NC Assessment and declines to cite or discuss your scientific research, bias is the conclusion.

Biased research by non-scientists only intensifies debates.

Snoqualman said...

Interesting stuff, Cliff. I must disagree strongly with your statement that we will need new dams and reservoirs. Ever visited the Yakima valley in summer? Seen the giant sprinklers throwing water everywhere? Everywhere but on the irrigated crops in many instances.

Maybe all the evaporated water helps out rainfall in the mountains to the east, but I doubt it. It does not take a genius to see that most of the irrigation water in this state is wasted. Treated like it's free, which it basically is. Even where it reaches the crops, the crops themselves are often low value, like hay, or other items better grown elsewhere.

Our Governor who claims to be so concerned about climate change is pushing a $5 billion plan to further subsidize the already colossally wasteful irrigators of Yakima. My request to you: please take a look at the whole picture of irrigation in this state before lending your voice to the dam lobby. Go visit the old growth forests surrounding Bumping Lake east of Mt. Rainier and decide if it is worth sacrificing so that Yakima irriogators can avoid making even the most basic efficiency improvements.

DEORTMAN said...

I also cringe at headlines that confuse weather with climate. I tend to agree with your analysis below, but NOT your conclusion (last sentence).

"The bottom line of my analysis is that the impacts of increased greenhouse gases has been very small here in the Northwest so far. Global warming will impact our region, but the changes here will be modest and slow. The biggest impacts will be reduced snow pack later in the century and increased risk of heavier precipitation and floods. Less snow pack will reduce the amount of snow melt available during the summer and early fall. Thus, to ensure sufficient water supplies we will need larger or additional reservoirs or dams."

Just as BPA and the utilities planned on building large numbers of new power plants to "meet" forecasted energy demand, the Bureau of Reclamation has launched a new "WaterSmart" (i.e., Waterdumb) program with proposals to build up to 100 new dams and reservoirs in the west in response to Climate Change.


Please do not climb on the Build More Dams bandwagon without examining the incredible amount of water wastage going on in our cities and in irrigated agriculture, or the incredible insane choices being made (e.g., the Kittitas Reclamation District irrigating timothy hay for export to the Japanese racehorse industry.

A Nissen said...

Seattleite McKenzie Funk's 2014 "Windfall, the Booming Business of Global Warming" is as sobering as it is explanatory on how varied impacts have been and will most likely be. Douglas' comment is in line with anticipated local impacts due to decidedly different situations elsewhere.

A WSJ Opinion piece alerts readers to check out the Report in question's mitigation and adaptation chapters which are far less attention getting (for one thing, they are buried) and much more measured, if not scholarly. I too would appreciate Cliff's take, at least there.

T said...

Prof. Mass polite dissection is rather deeply besides the point.

President Obama is succoring the Big Bucks of activist billionaire Tom Steyer, who's been complained that he won't give Democrats $100 million in campaign funds this election cycle unless they wake up and get on board with the mission of making global warming alarm at top priority by ending CO2 "pollution" and getting the nation to turn down the control knob of the climate's temperature through making serious policy changes in the energy sector.

I know that the report (above) is distinct from the White House's handpicked environmental lobbying scientists - or mouth pieces that was on display for the media last week.

But to Joe Q Citizen, the distinction is one without a difference.

The National Climate Assessment is merely qualifying cover to gin up the base and get rich donors like billionaire Steyer on board with money.
Washington, DC is now the richest per capita city in the New Roman Empire, and it can't stay that way without mulcting more and more from the cows of the hinterlands.

Steyer and his friends pursue a flawed - but well intended - and even possibly destructive lobbying policy end. And by destructive, I mean wasteful, misspent, and generally destructive to poor human lives - but they are only poor black and brown people elsewhere in the world, not the hoi poloi of rich and white California. So, in their minds they can kill with good conscience.

Since I write that as an environmental scientist myself, let me put it another way: many scientists are happy to be tools for industry or fools for nonprofits or both for the state. Others disassociate ourselves with as many of these interests as possible, when we cannot educate them.

And thus, this effort - while commendable in theoretical terms - is rather useless and amoral. Let the Hunger Games go on.

james papsdorf said...

I just found this very interesting and insightful blog through and I commend the latter source for all of your readers who are open to an objective discussion of all climate issues.Whilst most of us would probably fall within the "denialist" camp, our most common position is that the IPCC has wildly exaggerated climate sensitivity for political and economic gains. I am pleased to see that some of the posts here share this view.