UPDATE: Roger Pielke Jr. alerts us to this:
Last summer the San Francisco Chronicle carried a story about research on fog and climate with a different conclusion:
The Bay Area just had its foggiest May in 50 years. And thanks to global warming, it’s about to get even foggier.
That’s the conclusion of several state researchers, whose soon-to-be-published study predicts that even with average temperatures on the rise, the mercury won’t be soaring everywhere.
“There’ll be winners and losers,” says Robert Bornstein, a meteorology professor at San Jose State University. “Global warming is warming the interior part of California, but it leads to a reverse reaction of more fog along the coast.”
The study, which will appear in the journal Climate, is the latest to argue that colder summers are indeed in store for parts of the Bay Area.
More fog is consistent with predictions of climate change. Less fog is consistent with predictions of climate change. I wonder if the same amount of fog is also “consistent with” such predictions? I bet so.
From the University of California – Berkeley via Eurekalert:
Fog has declined in past century along California’s redwood coast
Analysis of hourly airport cloud cover reports leads to surprising finding
California’s coastal fog has decreased significantly over the past 100 years, potentially endangering coast redwood trees dependent on cool, humid summers, according to a new study by University of California, Berkeley, scientists.
It is unclear whether this is part of a natural cycle of the result of human activity, but the change could affect not only the redwoods, but the entire redwood ecosystem, the scientists say.
“Since 1901, the average number of hours of fog along the coast in summer has dropped from 56 percent to 42 percent, which is a loss of about three hours per day,” said study leader James A. Johnstone, who recently received his Ph.D. from UC Berkeley’s Department of Geography before becoming a postdoctoral scholar in the campus’s Department of Environmental Science, Policy and Management (ESPM). “A cool coast and warm interior is one of the defining characteristics of California’s coastal climate, but the temperature difference between the coast and interior has declined substantially in the last century, in step with the decline in summer fog.”
The loss of fog and increased temperature mean that “coast redwood and other ecosystems along the U.S. West Coast may be increasingly drought-stressed, with a summer climate of reduced fog frequency and greater evaporative demand,” said coauthor Todd E. Dawson, UC Berkeley professor of integrative biology and of ESPM. “Fog prevents water loss from redwoods in summer, and is really important for both the tree and the forest. If the fog is gone, we might not have the redwood forests we do now.”
The scientists’ report will be posted online during the week of Feb. 15 in advance of publication in the journal Proceedings of the National Academy of Sciences.
The surprising result came from analysis of new records recently made available by the National Climate Data Center. The U.S. Surface Airways data come from airports around the country, which have recorded for more than 60 years hourly information such as cloud cover (cloud ceiling height), visibility, wind and temperature.
Johnstone evaluated the data from airports along the northern California coast and found two airports – Arcata and Monterey – that had consistent fog records going back to 1951. With these data, he was able to show that frequent coastal fog is almost always associated with a large temperature difference between the coast and inland areas.
Using a network of 114 temperature stations along the Pacific Coast, Johnstone and Dawson demonstrated that the coast-inland contrast has decreased substantially, not just in Northern California, but along the entire U.S. coastline from Seattle to San Diego. This change is particularly noticeable in the difference between Ukiah, a warm Coast Range site in Northern California, and Berkeley on San Francisco Bay. At the beginning of the 20th century, the daytime temperature difference between the two sites was 17 degrees Fahrenheit; today, it is just 11 degrees Fahrenheit.
The relationship between temperature gradient and fog frequency implies a 33 percent drop in fog along the coast during this time.
Greater fog frequency is connected to cooler than normal ocean waters from Alaska to Mexico and warm water from the central North Pacific to Japan. This temperature flip-flop is a well-known phenomenon called Pacific Decadal Oscillation – an El Niño-like pattern of the north Pacific that affects salmon populations along the US West Coast. The new results show that this pattern may also have substantial effects on the coastal forest landscape.
In addition, the data show that the coast gets foggier when winds blow from the north along the coast, which fits with observations that northerly winds push surface waters offshore and allow the upwelling of deep, cold, nutrient-rich water.
“This is the first data actually illustrating that upwelling along the Pacific coast and fog over the land are linked,” Johnstone said.
By pulling in data on temperature variation with elevation, Johnstone and Dawson also related their fog data with a temperature inversion that each summer traps the fog between the coast and the coastal mountains. The inversion is caused by a warm, dry, high-pressure cell that sits over Northern California in late summer, bringing hot temperatures to inland areas, including the Central Valley. If the inversion is strong, its lower boundary at about 1,200 feet keeps a lid on the cool marine layer and prevents fog from penetrating over the Coast Ranges. When it is weak, the ocean air and clouds move upward and inland, resulting in a cooler interior and a warmer, drier coast.
“The data support the idea that Northern California coastal fog has decreased in connection with a decline in the coast-inland temperature gradient and weakening of the summer temperature inversion,” Johnstone said.
“As fog decreases, the mature redwoods along the coast are not likely to die outright, but there may be less recruitment of new trees; they will look elsewhere for water, high humidity and cooler temperatures,” Dawson said. “What does that mean for the current redwood range and that of the plants and animals with them?”
Eventually, Dawson and Johnstone hope to correlate fog frequency with redwood tree ring data in order to estimate climate trends going back hundreds of years.
“While people have used tree ring data from White Mountain bristlecone pines and stumps in Mono Lake to infer climate change in California, redwoods have always been thought problematic,” Dawson said, mainly because it’s hard to determine whether the width of a tree ring reflects winter rain, summer fog, temperature, nutrient supply or other factors. “Stable isotope analyses of wood cellulose allows you to pull this data out of the tree ring.”
Dawson has established that the isotopes of oxygen in a tree reflect whether the water comes in via the leaves from fog, or via the roots from rainwater. “Redwoods live for more than 2,000 years, so they could be a very important indicator of climate patterns and change along the coast,” he said.
The new fog data will allow Dawson and Johnstone to calibrate their tree ring isotope data with actual coastal fog conditions in the past century, and then extrapolate back for 1,000 years or more to estimate climate conditions.
The work was supported by the Save the Redwoods League and the Berkeley Atmospheric Sciences Center.
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Further reading: Fog in California from UCSB
Can I just be mesmorized by the arial photo and not read or get into the substance? I flew into that airport at Arcata. I almost had a job processing redwood chips at the last Pulp Mill in California … probably the last Pulp Mill in the West with a pipe out into the ocean as an ‘effluent system’. Man (or is that ‘Dude’ now), I just missed being bulldozed by ARM’s and precipitously falling real estate values.
There are two kinds of redwoods–the coastal redwoods and the sequoias, which are inland trees in the Sierra Nevada foothills. The inland species lives in a drier, warmer habitat. Just for clarification, it is the coastal redwoods they are talking about. I suspect, but don’t know, it was coastal redwoods planted in Scotland.
I found the fog. Someone parked it outside my window during the night.
Robert (21:54:04) : edit
Dang, I guess we’ll just be forced to discuss the science, hate it when that happens … so what do you think of the claim that we can predict fog on the California coast from:
a) Taking 2 fifty year fog records, one each from Arcata and Monterrey airports, and comparing coastal versus inland temperatures and hours of fog, and
b) Using those two results (N=2), plus other coastal and inland temperature records, to estimate the change in coastal fog over 100 years.
Let’s start with a softball question … if using this procedure we estimate a change in fog of three hours per day as per the study, what would you guess the 95% confidence interval on that would be?
Me, I’d say the 95% CI would be at least ± three hours, but what would I know, I’m a “non-specialist” … what’s your guess?
Bonus question 1 – we haven’t seen the study yet. What are the odds that it won’t contain error estimates on the “three hours per day” at all? I’d say damn high, but again, I’m a n-s …
Doug in Dunedin (21:40:48) :
…In fact I’m sure we could adopt them all if they are really threatened in California. You know – ’support our American cousins an’ all that!
Doug,
We accept your kind offer and will send them straight away,
along with their minders.
Paul Vaughan (15:07:26) – yes, I’m well aware of that. My point was to point out the absurdity of having one claim that global warming causes more fog and another that it causes less. Perhaps you don’t get irony.
I see airport records were used to identify these long term trends in fog. We know that airport traffic has increased dramatically and can continue operating in worse conditions than in the 50’s. Could the warming effect from all those aircraft have had a localized effect.
@ur momisugly Willis Eschenbach
I’ll be interested to see the paper when it comes out. I feel no need to defend its findings, given I look at the science as a tool to improve our understanding, and not as a contest where the objective is to discredit the other side.
The use of two stations does not have anything to due with the confidence interval, and you wouldn’t calculate your p value using n=2. The number of stations speaks to whether the results of the study are generalizable or not, which has nothing to due with the confidence interval.
Here’s a protip for you: if you want to pass yourself off as scientifically literate, learn to use the terminology correctly.
crosspatch (22:58:37) :
If you were around in the 70’s, it seemed like every year someone would pipe off with ‘Something’ is bad for you. So everyone ate something else, until someone said ‘oh no, that’s not bad for you, this is’. So everyone ate what they were eating before.
Salt is bad for you, eat Sea Salt.
Oh, no, Sea Salt is bad for you, eat Salt.
Eggs are full of cholesterol and will kill you. Don’t eat eggs.
Oh, no, eggs have the good cholesterol, meat has the bad stuff. Eat eggs.
Global warming melting is bad for Earth.
Oh, no, Global warming snowing is bad for Earth.
Global warming no-fog is bad for Earth.
Oh, no, global warming fog is bad for Earth.
See the game?
.
Its the Clean Air Act wot dunnit 😉
Seriously, fogs are also driven by condensation nuclei (pollution, to you and me), and without them it is much harder to produce a good fog. The London pea-soupers (2-yard fogs) are thankfully a thing of the past, but this must affect climate/weather to some extent.
Another reduction was caused by the banning of field burning in the autumn, which used to produce some spectacular fogs underneath high pressure systems. Again, all of this has gone – allowing more warming of the ground, and more evaporation of the ground.
How this Wiki report on pan evaporation rates fits into this, I don’t know. But I can assure you that NW Europe used to have much worse anticyclonic fogs than it does now.
http://en.wikipedia.org/wiki/Pan_evaporation
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>>Could the warming effect from all those aircraft have
>>had a localized effect.
Yes indeed – depending on the type of fog involved. A well known way of clearing the fog is to run the aircraft down the runway, and presto, a clear gap for a few minutes. But this probably won’t work with advection fog.
Conversely, on a still and humid night, you can create a fog simply by turning on the runway lights. A little thermic mixing, and away she goes.
.
Robert (00:17:39)
Quick description of science. It is not a tool, it is a method. You know, the “scientific method”. That method works like this:
1. Somebody makes a scientific claim, and publishes it with the data, methods, math, and logic that supports it.
2. Other people try to find fault with the data, methods, math, or logic.
3. If nobody can find fault with the claim or the things that support it, the claim is (provisionally) accepted as scientifically valid. If not, if someone can find fault with it, it is not accepted.
Science is about falsification, what you incorrectly describe as “discrediting the other side”. You don’t want to defend the paper, you just want to credulously believe what it says.
On the other hand, those of us who are scientists want to test it, to check it, to make sure it solid, that the math is correct, that the logic is valid. Only then can we use it to further our understanding. That’s the scientific method.
Your claim that there is no reason to try to test or falsify or discredit or defend papers like this is why we are up to our ears in IPCC-approved pseudoscience and bogus claims … because as long as the claims agree with your preconceptions, folks like you aren’t interested in testing them to see if they are true.
I don’t follow you here. Are you saying that if they determined the relationship between fog and coastal/inland temperatures by studying 100 fifty-year coastal fog records, that the 95% CI on the final result would be the same as in this study, where they only used two fifty-year records? Really? Is that your final answer, or would you like to use one of your lifelines and phone a friend?
PS – As you have brought up the issue of terminology, it is “nothing to do”, not “nothing to due” …
Ralph (02:44:30)
While this is true in some parts of the planet, here on the Left Coast of the US we are looking at sea fogs. For these, the typical condensation nuclei are tiny crystals of NaCl, good old sea salt. Makes for a very corrosive fog, of course, but there’s generally no shortage of condensation nucleii around here …
>>Willis Eschenbach (15:01:57) :
>>From the UC Berkeley press release:
>> he was able to show that frequent coastal fog is almost
>>always associated with a large temperature difference
>>between the coast and inland areas.
Yes, but also associated with a high humidity. The Freemantle Doctor (a sea breeze) comes streaming in at mid-morning in W Australia and can produce a 15oc temperature difference, let alone a paltry 17of difference – but you won’t see any fog.
Why? Because the hot air over the land that is cooled is too dry. I might suggest that a change of land use may also reduce fogs in the situation given here. A coastline full of forests will be a lot more humid than a coastline full of condos and parking lots.
Except for Al Gore’s new condo, of course, that is probably permanently covered in snow.
.
Good point by Daniel H that nearby chardonnay vines are more sensitive than Redwoods to fog reduction. Somebody needs to point out to those Berkely professors that they should get on their bikes and visit their local viticulturist for some realworld information.
Beth Cooper (05:00:50) :
Good point by Daniel H that nearby chardonnay vines are more sensitive than Redwoods to fog reduction. Somebody needs to point out to those Berkely professors that they should get on their bikes and visit their local viticulturist for some realworld information.
Beth, they are not being paid by the viticulturists!!!
Quote: “Using a network of 114 temperature stations along the Pacific Coast, Johnstone and Dawson demonstrated that the coast-inland contrast has decreased substantially …”
Isn’t this just another example of the Urban Heat Island Effect? Couple this with the fact that the temp in the interior of the state could be falling due to the current cooling phase.
As the resident observational expert on fog because I’m a Newfoundlander: http://en.wikipedia.org/wiki/Fog, home of some of the foggiest places in the world, I suggest that when you get warm wet air coming off warm water meeting cold land or land based cold arctic currents you get fog.
Several points. This line of thinking is begging for a PDO graph to try to find a relationship and then maybe a graph of water versus land temperature graph. The current situation is an absolute great experiment because cold arctic air traveled over land while the water was extra hot. Did we have a recent spike in fog? Also, the urban heat island effect could reduce fog. Fog requires the land to cool and make water vapor condense. Heat islands seem to have the larger effect at night retaining heat meaning less fog? Less variation in temperatures between day and night could also mean less fog.
Wasn’t there also a drop or in water vapor over the last century. A tough topic for those that belief CO2 and water vapor create a strong feedback loop.
D. King (19:56:57) :
Problem solved….Next!
D. That is one tres sexy fog machine….. ooohhhh yyyeahhhhh baaayyybbby…….
I wonder, will the good folks at GHCN adjust the temps of the four California stations down to adjust for the increase in warmth caused by less fog, which would of create an anomalous increase in the heat signal?
“I don’t follow you here. Are you saying that if they determined the relationship between fog and coastal/inland temperatures by studying 100 fifty-year coastal fog records, that the 95% CI on the final result would be the same as in this study, where they only used two fifty-year records? Really? Is that your final answer, or would you like to use one of your lifelines and phone a friend?”
Yep, exactly. You’re going to determine the CI according the the number of data points you have for fog/no fog as compared with the temperatures. This will give you a p value for the relationship between fog and delta T AT THE AIRPORTS. Whether the conditions at the airport are representative of conditions elsewhere is a problem of generalization.Perfectly valid issue, but you are not going to address it by calculating a 95% CI, which tells you only about the relationship of your data points to the likely chance distribution.
CI specifically address the problem of random fluctuations in the data that may look like patterns. Using one to try and address a problem of the generalizability of your results makes as much sense as trying to fix a broken windscreen by pouring gasoline on it.
I kinda skimmed the rest of your stuff about “science is.” You really don’t seem like an authority on what “science is.” So why don’t we follow your excellent suggestion and confine our discussion to the paper itself?
Sort of ironic that this morning in the SF bay area is extremely foggy. There was a crash this morning of a twin engine Cessna taking off from Palo Alto airport in the fog. It apparently struck some major power lines about a minute after takeoff.
“Quote: “Using a network of 114 temperature stations along the Pacific Coast, Johnstone and Dawson demonstrated that the coast-inland contrast has decreased substantially …”
Isn’t this just another example of the Urban Heat Island Effect? Couple this with the fact that the temp in the interior of the state could be falling due to the current cooling phase.”
Leaving aside the fact that there is no measurable UHI effect (http://www.ncdc.noaa.gov/oa/climate/research/population/article2abstract.pdf), if there were, wouldn’t it tend to increase the coast-inland contrast, not decrease it?
Robert (09:57:48)
Here’s how I see it, Robert. Please explain where you think I’m wrong.
The authors are using two sites (Monterrey and Arcata) to say that fog is related to coastal/inland temperature difference at those two sites by some function “f”, like:
FogHours = f(TempDiff)
However, we know that for those two sites this has an associated confidence interval (CI), so the function is actually
FogHours = f(TempDiff) ± 95%CI
As you say above, this measures the relationship of your data points to the likely chance distribution.
The size of that CI depends on the size of their dataset, which in their case is two fifty year records. If they had more data, of course, the 95%CI would be smaller.
Then they take that formula, and apply it to some other TempDiff data from a new location. However, the CI doesn’t magically disappear. The new formula is
FogHours2 = f(TempDiff2) ± 95%CI
There is, of course, the additional problem that you point out. We don’t know if the function “f” is generalizable to the new TempDiff2 dataset from the new location. The meteorological conditions in the new location may be totally different.
But all that does is to increase the 95%CI of the final result. We now have two sources of error. First, the original formula may not be accurate. Second, the original formula may not be generalizable. Both of these increase the CI of the result (typically in quadrature).
Consider the theoretical case where the result is 100% generalizable, the case where the meteorological conditions are the same in all of the location. Would that make the CI of the final result equal to ± zero?
Of course not, because the final result is only as good as the underlying formula, and it has an inherent 95%CI. Thus, as I started this out by saying, the fact that they only have two fifty-year sites does affect the final CI. It is not the only source of error as you point out, but it is assuredly one source of error.
What am I missing here?
In other words, you couldn’t find anything substantive to say about my ideas, so you make an ad hominem attack by saying that I’m not “an authority” … which perfectly encapsulates the point I’m making in my discussion of what “science is”.
It doesn’t matter if I’m an authority or not. It only matters if I’m right or not. If you think my description is wrong, tell us where, that’s science at work.
But don’t bother us with your speculations about who is “an authority” and who is not, that’s a meaningless attempt to avoid the issues.
Finally, my “excellent suggestion” you referred to above was:
So using that as an excuse to avoid discussing the science doesn’t work.
Fortunately the rising CO2 levels may be providing additional nutrient to the fog-deprived redwoods, helping them to survive the stress.
KW