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
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2009- Global Warming Causes Foggy Days in San Francisco… 2010- Global Warming Causes Fog-less Days in San Francisco
http://gatewaypundit.firstthings.com/2010/02/2009-global-warming-causing-more-foggy-days-in-san-francisco-2010-global-warming-causing-fog-less-days-in-san-francisco/
D. King (23:51:16) :
Doug,
We accept your kind offer and will send them straight away,
along with their minders.
No problem about the trees but the minders are declined – we’ve got more than enough of those here thank you very much.
Doug
For those who would like to see a real study of fog in California, there’s a 105 page study here.
From the “Conclusions”, page 75 …
They also say (ibid):
With fog coming in two climatological regimes and three possible scenarios, my opinion is that this makes it extremely unlikely that we can generalize from two stations to the entire coast … but hey, I’m not “an authority”, what do I know.
Finally, as evidence that this is an honest scientific endeavour, they include the following graphic at the end of the report that shows the uncertainty in their results …
Over to you, Robert …
“With fog coming in two climatological regimes and three possible scenarios, my opinion is that this makes it extremely unlikely that we can generalize from two stations to the entire coast”
Which may very well be true, but it is nothing you can calculate a CI from; that’s an entirely separate problem. As I said above:
“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.”
Willis continues:
“Here’s how I see it, Robert. Please explain where you think I’m wrong.”
Happy to. You continue:
“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.”
As long as they have fifty years of records, taken however often they were taken, the CI remains the same. What is being measured in the correlation between fog and delta T. Each point in time where you compare those things affects your confidence interval. More stations will probably add to your knowledge of the distribution of the fog, but at the end of the day, you still have to define a condition of “foggy” or “not foggy,” or “medium foggy” or what have you, and while more stations may allow you to make that distinction more accurately, it’s not going to affect your confidence interval.
You see, the stations are collecting data in parallel, not in series. If you had 200 years of data it would decrease your CI; but 50 years of data from 8 stations instead of 2 does not. Which is not to say 8 stations are not better than two, but it has nothing to do with your chi-square test.
You could treat the stations as if they were independent of one another, which would obliterate the distinction between parallel and series. But that would be a terrible mishandling of the data. It would also have a very small impact on the CI: assuming fog conditions were assessed every six hours, fifty years of records would give you 4 x 365 x 50 data points. I make that 73,000 data points (somebody check my math, please). Your CI is going to be very, very small (which, to reiterate one more time, tells you nothing about other sources of error).
Well, the Save the Redwoods League has long been in the pay of Big Oil: since 1926, in fact, when John D. Rockefeller, Jr., otherwise known as Mr. Standard Oil, gave them $2 million.
Back then the dollar was backed by gold and an ounce of gold was worth $25; today an ounce of gold is about $1000. So, major funding by the original Big Oil.
Hmmm…
Philemon (16:28:15),
Apparently it worked, for my tree was saved! I have a giant Redwood in my back yard, nearly 200 feet tall. And we rarely get any fog in our valley.
It’s the only Redwood tree within several blocks, so it is its own eco system. It’s amazing that it can survive in the middle of a large city. It’s probably healthy due to the extra beneficial CO2 from the nearby freeway. Wait ’till its cousins in the Santa Cruz mountains find out. They’re gonna be jealous, even though they get plenty of fog.
Contrary to Michael Mann’s belief system, the climate changes constantly. So do CO2 levels, and temperature. And natural climate change has been going on forever; it caused the LIA and the MWP.
I don’t recommend planting a Redwood tree to anyone, though. Nothing grows under those suckers, and they rain down little pinecones and debris 24/7/365/2000+.
Smokey, I’m glad your redwood is doing well, even with debris, but, given the Rockefeller M.O., there might well be lots and lots of light sweet crude under the Redwood National Park. Maybe not. Maybe Laurance thought it would be a nice money-making resort.
As a general rule, the more land locked up, the better, as far as the Rockefeller trusts are concerned.
And, along comes the MSM with one more scary story:
http://www.latimes.com/news/la-na-cyber-attack17-2010feb17,0,803757,full.story
Robert (14:39:11), thanks for your reply:
First, you say:
Absolutely not. They are comparing degrees of temperature difference inland/coastal with HOURS of fog. They are not defining any condition such as “medium foggy”, thats a total misconception.
Instead, they are collecting pairs of individual data points, of the form
Coastal/Inland Difference, Fog Hours
7°C, 11 hours
9°C, 21 hours
4°C, 3 hours
17°C, 24 hours
and the like. Note that it doesn’t matter if these are in temporal order or not. The are just pairs of data points, not ordered pairs. Because these are individual pairs, each one adds information.
Now, what they are trying to do is estimate the function that relates those two variables FOR THE ENTIRE WEST COAST. Not just for one site, not for two sites, but for the whole coast.
To get a function that more closely matches the actual reality FOR THE ENTIRE WEST COAST, there’s two things that they can do:
1. Use longer records from each station, to include data from different temporal climate regimes.
2. Use more stations, to include data from different spatial climate regimes.
Both of these will make the final function more closely represent reality.
If your claim were true, that additional records don’t change the CI, then they could just use one station record to represent the entire coast, and the confidence interval for that record would be the CI no matter which station was chosen … which makes no sense at all.
“If your claim were true, that additional records don’t change the CI, then they could just use one station record to represent the entire coast,”
No. Not every problem with a study shows up in the CI: all the CI tells you is the impact of random variation on the data set. If you had one station, you could have an extremely narrow CI. BUT the results, just as you say, would be impossible to generalize to the whole coast. But the generalizablity of a study is a different issue from the CI. A study can have a p value of 10^-900 and be total crap.
I hope that’s clear.
Thanks, Robert. I think we might be talking about different things. From Eric Weiss’s “Mathworld”, a definition of the confidence interval:
Note that anything that makes the result more uncertain widens the confidence interval. You keep talking about “generalizability”. But if the study is not generalizable, when it is applied to a general situation the results will have a larger error … or in other words, it will have a wider confidence interval.
This study is a good example. There is a confidence interval for the results of a single station. This is how well the function is able to characterise the hours of fog compared to the temperature difference between the coast and the inland for that station.
However, there is another, separate confidence interval for the application of the function to the entire coast. This is a combination of how well the function applies to a single station, and how representative that station is of the coast as a whole.
You call this something like “generalizability”. But it is a confidence interval, just like the one for an individual station, except perforce it is wider. At the end of the day, they say that their method claims a 3 hour/day decrease in fog. But it might really be 2 hours/day, or 4 hours/day. For it to be honest science, we need to be able to say “There is a 95% chance that the true change is between 1 and 4 hours/day decrease”, or something along those lines. That’s the CI of the study as a whole, and that’s the number I’m interested in.
I’m still waiting for this study to come out, not just the press release, so we can see how they’ve handled this question. I doubt very much that you can accurately model the entire coast with any accuracy using a function developed from just two stations …
“You call this something like “generalizability”. But it is a confidence interval, just like the one for an individual station, except perforce it is wider.”
No. Nothing in the characteristics of the standard distribution will tell you whether or not the results at x sites are representative of the whole coast. Imagine if there were. You put a hundred stations within ten miles of the northern border. All done, problem solved? Of course not. Generalizability and being able to reject the null hypothesis are two different things.
Generalizability, of course, is not a concept I made up just now. It’s a basic element in evaluating all scientific research: http://en.wikipedia.org/wiki/External_validity.
I like to return to a claim you made above:
“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.”
That’s not an accurate description of how science works, because people are always going to find fault. People will find fault by saying the claim is contrary to the Bible, or what the voices tell them, or because the universe is made of green cheese. Invalid objections, according to your model, would bring the process of scientific discovery to a halt.
So we have to have a test for objections, as well as for claims. A good objection, like a good claim, is based in evidence, logically consistent, accurately reflects the original claim, and so on. If a claim is addressed in a responsible fashion with good evidence, repeating that objection is not a valid objection. That, essentially, is the scientific consensus: not necessarily a body of beliefs, but a body of objections raised and answered, such that if you want to go over them again, you need something new.
“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.”
Science is also about reserving judgment until you have all the facts. Nowhere did I say I believed everything (or anything) in the paper. You attribute such a belief purely because you identify both the paper and myself with a pro-AGW “team” and conceive of my role and protecting and advocating for that team. But that’s not science. Science, a wise man said, is not about proving yourself right, it’s a way to become right.
So there’s no reason I should defend this paper. Why don’t you defend it, and I’ll question it? It would be a good exercise for our skeptical faculties. The test of skepticism is questioning things you want to believe are true, not attacking those that you don’t.
This sums up the whole AGW mentality:
1. Climate is not supposed to change. Ever. (Didn’t the Hockey Stick prove that?)
2. Any change is due to human CO2 emissions. *
3. Any increase is bad.
4. Any decrease is bad.
5. The sky is falling. The sky is falling.
6. The planet is going to die.
7. When it dies, we have no one to blame for it but ourselves.
8. The planet would be better off without human activity.
9. Mea culpa, mea culpa… It is all our fault.
10. Humans are evil.
11. If humans are to be allowed to remain, we need to go back to an agrarian society; pre-agrarian would be best.
I adhere to The Tugster, Tug McGraw’s, philosophy:
[Note: He didn’t really say, “So, let’s go have a beer.” I added that to make it sound more homey. But it WAS in keeping with his attitude. The Tugster would have approved the addition.]
* Isn’t it odd that the really negative human activity – land use – is given a pass, and only CO2 is targeted as evil?
Fog is back with a vengeance today. Of course, summer fog is of greater interest; supposedly that’s what keeps the sapling growing during the rain-free months, generally April through October.
Smokey , I have a redwood growing in a very large pot. It’s about 4 years old and about the size of a christmas tree now. I originally found it growing on the edge of the driveway , when it was about 5 inches high. I love walking through redwood forest, but there is concern about whether we really want one of those monsters growing in the yard. So I’ll keep it the pot until it gets too big, then not sure what I’ll do . . .
Robert (08:50:49), I think we are at least approaching agreement.
I return to the definition of a confidence interval:
Note that there is nothing in there about the “characteristics of a standard distribution”. Sometimes we estimate the confidence interval from the math of a standard distribution. But we can just as well estimate it by comparing our results to reality. All it is is an estimate of how accurate our results are. In this case, as you point out, it depends on a variety of things like where our test stations are located. If the hundred stations are within ten miles of the border, our results will be less accurate.
But that does not mean that we cannot estimate the range within which we are say 95% confident that our results are accurate. This can be done by a variety of mathematical methods.
I agree. However, that is a separate issue, one which does not make it impossible to calculate a CI for a study such as the fog study. For example, the citation I gave above shows that we have a host of shorter than fifty year fog records along the coast. It would be trivially easy to compare the results of their whiz-bang formula to those records to determine just how accurate their method is.
Care to guess whether they did that or not? My guess is not, we’ll see when the paper is published.
I assumed the part about the objections being valid and verifiable.
However, you invalidly extend this to the idea of “scientific consensus”, and define that consensus in a way which is not how it is commonly used. In climate science, the claimed “consensus” is like the “consensus” of those who do not believe in evolution … that is to say, a group of people who all refuse to look at the data and the results.
You know, the ‘fog blanket’ needs rising warm air inland to ‘pull it in’ from the ocean. We get some of the best fogs when it’s warmer inland…
So maybe “less fog” is just saying “less inland warmth”.
It also forms over the ocean from a water / air temperature difference, so unless you have the ocean currents thing really well worked out, you don’t know it there is a net heat change, or just a rearrangement.
*******
Smokey (17:07:29) :
Philemon (16:28:15),
Apparently it worked, for my tree was saved! I have a giant Redwood in my back yard, nearly 200 feet tall. And we rarely get any fog in our valley.
*******
A pic of such a giant would be nice. There was a coastal redwood (not an inland sequoia) in one of the wine-country establishments north of San Fran when I was there. Seemed well inland of the natural groves & out of the fog belt. It was open grown — very wide branch-spread w/a huge trunk prb’ly 12′ in dia but just under 200′.