All the curves that are fit to print

Regarding the latest UAH and RSS global temperature data plots Dave B writes: “…could you post a best-fit, to be fair? I don’t have the technology.”

Sometimes I’m tempted to tell people to do the work themselves, after all, I’m overloaded as it is. But, it is the 4th of July weekend, and I’m stuck here in the smoky toasty Sacramento Valley babysitting a bunch of servers until my chief tech support guy comes back from vacation, so what the heck.

I’m not sure what he’s implying by “fair” but it has been my experience that no matter what you put in a graph, or how you graph it, somebody will find fault with it.  Below are raw data overlaid with 1st order and 5th order curve fits to show long and short term trends.

Click for large plots

And “to be fair”, and to make everyone happy/angry here is the last 11 years, when the warming trend flattened.

Click for a larger image

Have at it lads. 🙂

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Frank Ravizza
July 3, 2008 6:51 pm

You can say it’s fair to say, “the long term trend is up, the short term trend is down”. The short term trend is a leading indicator, the long term will follow, unless we start warming.

Richard deSousa
July 3, 2008 7:03 pm

Now if only the mainstream media will pick up on this…. Hah!

Larry Sheldon
July 3, 2008 7:22 pm

“fair”
Demands a pun, given the vqrious ways it gets used in the daily forecasts and such.
But I’m not up to it.
I do thing science doesn’t have much use for the word except as a way-point between “bad” and “good”.
But it does seem that the the graphs here provide an underpinning for know-nothings like me that say the Earth by definition has been warming since the bottom of the last “ice age” minimum and will continue to do so until it begins (or began) the next cyclic cooling interval.

Bob Zorunkle
July 3, 2008 7:36 pm

For a layman, could you explain the difference between 1st order and 5th order curve fit in a 30 year period? Obvoiuosly, the 1st takes a longer time frame, but is it 5 times longer?

cohenite
July 3, 2008 7:37 pm

Thanks Anthony; sterling work as usual; I’d send money, but I’m from Australia and the greens are in charge here and we are going to show the world the meaning of self-sacrifice in respect of AGW as soon as Garnaut hands down his report; so I’m going to be broke and I’m putting money away for the lean times ahead; I’ve even got 2 mice running on little treadmills powering my light bulbs; but the mice are hopeless; I think it’s their names ; windy and solaris; no base effort.
I’ve often wondered about the long term trend being up and I’m not going to revisit the trend corruption of base periods, the Great Pacific Climate Event, PDO oscillations and historic revision of data; just looking at your graphs though; if you remove ’98 as an outlier the downward trend is pronounced, and this downward trend would be even more pronounced the further back you begin your graph. Which makes any analysis of what caused the ’98 aberration essential; conventional wisdom is that it was an exceptional El Nino year; but that is tautological; no doubt the SOI was -ve and correlated with El Nino, as did the other indices, but what made it so extreme? I’m wondering whether the Pinutabo after-effects were not having a final say. Pinutabo was in 91-92, and your graph shows the traditional post-volcano cooling; but part of the eruption was higher atmosphere particulate which would have intercepted UV and X-rays; once that particulate settled, the UV and X-ray and their heat would have been free to reach the lower atmosphere and surface; just in time to collaborate with the ’98 El Nino. That being the case the ’98 spike should be removed, along with the relatively minor post Pinutabo cooling.

George M
July 3, 2008 7:41 pm

Hansen postulated global cooling first, before big Al sucked him into the warming camp, where his investments are. Now, for the long view, why is no one saying that we are actually in a very long term cooling trend, and warming is just a temporary glitch? The opposite argument sure gets a lot of traction with nothing more than some impenetrable climate models which seem to have less and less connection to reality. The refusal to admit COO rises after warming occurs, and is not the cause of warming is just one problem.
Still no more cycle 24 sunspots. Hope everyone has their warm clothes ready.

neilo
July 3, 2008 7:52 pm

George M,

Do you have a reference for that claim, please?

Dave B
July 3, 2008 8:07 pm

Thanks Anthony,
As I said, I’m a layman to this. I meant no offense by asking you to be “fair”.
This helps me, I appreciate it.
Happy Independance Day!

tarpon
July 3, 2008 8:07 pm

Of course to be fair, you really need to do the curve fit to temperature data in geologic time, with data in increments of say 100 years over maybe a million years :-). Yes, I watched Prof Carter’s lecture series, very good I might add.
Curve fitting, it refers to the order of the polynomial used to give the best fit of a smoothed curve to noisy data, like temperature samples. Most good spreadsheet programs do it automatically for you, some will select the best fit automatically, without the excess oscillation you may get by selecting too high an order polynomial.
Yes it’s true, Hansen was the original ‘cooling guy’ back in the 70s, he just found more money in warming. One of the schemes put forward back then, was to cover the ice caps with black carbon to melt them and stave off the glaciers.

Bill P
July 3, 2008 8:08 pm

“It is the 4th of July weekend, and I’m stuck here in the smoky toasty Sacramento Valley babysitting a bunch of servers until my chief tech support guy comes back from vacation…”
Change it to past tense and add, “when in came a set of the sweetest curves you ever saw…”
And a great sequel is well on its way.

Philip_B
July 3, 2008 8:20 pm

I used to annoy Warmers by pointing out that Earth’s climate is always warming and it’s always cooling. It just depends on the time frame you are measuring over.
So the argument that you need to measure climate over x versus y years is spurious.
So how do we determine if the Earth’s climate is warming?
One answer to this question is you treat the data as a continuous data stream. Whenever it goes down it’s cooling and whenever it goes up it’s warming. You can then say climate data is noisy* and the data has to go up or down for some period in order to ensure we are not just seeing noise.
How long that period is, is determined by how noisy the data is.
* I would argue there is no reason climate data should be noisy, and there is no real evidence for the claimed noisyness of the data. It looks to me like an ad hoc explanation to save the Forcings Model. Because if the climate really is bouncing around the way the graphs above say it is then the Forcings Model and all the climate models are just junk.
Which is not to say the models aren’t junk for other reasons.

John Andrews
July 3, 2008 8:20 pm

It seems to me that the fitting of a polynomial curve to this data is inappropriate. Although you can get a polynomial to fit almost any data, it has no meaning other than it seems to fit. My preference for this kind of trending is to use an exponential moving mean that weights the most recent data heavily and earlier data less. The result is a curve that tends to follow the current change in the data which is what we want in this case whether it is going up or down.
Love your site. Read it every day.

neilo
July 3, 2008 8:32 pm

George M,
Sorry if the last posting came out terse; I was trying to quote and, well, things didn’t quite work out.
Anwya, you said :”Hansen postulated global cooling first”. Do you have a reference for that, please? Not that it’s any biggie; people are allowed to change their minds.
Thanks,

Brendan
July 3, 2008 8:47 pm

First or fifth order curve fits have nothing to do with time frames. A first order curve fit is one of the form y=mx+b. You need at least two points to make such a fit (which would be a wast of time). A fifth order curve fit is of the form y=ax^5+bx^4+cx^3+dx^2+ex+f. You need at least six data points (ie, xy) to perform that. A first order curve fit is a linear (straight) line. A fifth order fit is useful for making a smooth fit through a lot of data, but has little physical meaning (ie, try to project it beyond the last point in Anthony’s graph and it might project down to -infinity or swing around and go to +positive infinity. Now, Anthony isn’t trying to pull the wool over anyone’s eyes by doing that – its just that making a nice smooth fit using a fifth order is easy and fast in excel.
The other “curve fits” that are often discussed are actually statistical deconstructions of wave forms, and assume that temperature follows a complex combination of long and short waves that are combined. The waves are assumed to have a basis in reality in that they could be caused by sun spots or some other periodic influence, and, unlike a fifth (or even first order curve fit) can be projected into the future. THey are used often in financial and other types of forecasting. Those types of deconstructions and take more time (and a good stats package like “R” – climateaudit.org discusses R quite extensively and is a good place to go if you want to see how stats are applied. The R CRAN site is another…
You can do the same – I believe that a few posts back someone made a link to all the data for the last few decades in excel. THere are a lot of good quickie instructions on the web as to how to do the first and other curve fits using excel. I strongly encourage those who don’t know how to fit data (or even how to graph it!) to learn…
Oh, and Neilo – don’t be lazy. It took me three seconds to find the IBD article that confirms what George M stated. Hanson has apparently been trying to find the limelight since the 70’s….
http://www.investors.com/editorial/editorialcontent.asp?secid=1501&status=article&id=275267681833290
Happy Independence Day!

Diatribical Idiot
July 3, 2008 9:12 pm

“For a layman, could you explain the difference between 1st order and 5th order curve fit in a 30 year period? Obvoiuosly, the 1st takes a longer time frame, but is it 5 times longer?”
It’s simply the best polynomial fit to the data. A linear trend is in the form of y = mx + b (first order polynomial). A second order polynomial has an x-squared term in it, and the curve will have a maximum of one inflection point. A third order will include a cubed term and have up to two inflection points, and so on. The fifth order term will have up to four inflection points. The increased number of inflections allows a curve that will better adapt to changes in trends, though it’s somewhat of a dubious exercise to add too many terms, because at some point all you are doing is duplicating the data. The problem with using things like a fifth order polynomial is demonstrated by the last segment of the graph. While the curve certainly fits recent history well, a logical extension of the curve provides illogical long-term results. Though, to be fair, many would argue that using a linear trend does the same.

Jim
July 3, 2008 9:13 pm

Bob Zorunkle,
If memory serves, first-order and fifth-order refer to the degree of polynomial to which the data has been fitted. Both first-order and fifth-order curves provided by Anthony encompass ALL the data.
A first-order curve fitting is an assumption that the data are following a straight line and that deviations from that line are just random variations. This strikes me as a fantastically stupid assumption on something that is coupled, nonlinear and chaotic, like climate. But hey, most members of the media don’t even understand the concept of slope.
A fifth-order curve is one of the form fx5 + ex4 + dx3 + cx2 + bx + a, and is much more robust for fitting temperature trends.

Brendan
July 3, 2008 9:20 pm

To give Anthony a devil of a headache this 4th, here’s a link that will have AGW types wailing, with much grinding and gnashing of their teeth. This guy actually explains the physics very much the way I know them, and is very careful in describing how CO2 affects global temperature. So, when someof my buddies get all rightous on me and say “Admit that increased CO2 increases temperature” I have to say that is correct. I even have had to grind my teeth when I’ve been reading Jim Manzi (note to Jim – being rich doesn’t always make you right…) when he says we should just admit that CO2 increases temperature and move the subject onto the economics. I feel we can argue the economics on energy quite well on their own…
Anyway, here’s the link…
http://brneurosci.org/co2.html
And here’s another to make the wind worshipers (I’ve written briefly here before about the false economics of free wind being cheap – it isn’t for a variety of reasons). This article uses very basic data and shows how wind can’t fill the void – its too unreliable. Read it – its brutal…
http://www.theregister.co.uk/2008/07/03/wind_power_needs_dirty_pricey_gas_backup_report/
I will admit that cheap solar may make a difference (see my post from a week or so ago…) but it will need pumped storage to make it effective.

Keith
July 3, 2008 9:27 pm

Bob, in this case, first order and fifth order refer to polynomials of the form:
y=a0 + a1*x**1 + … + an*x**n
which describe a best fit curve to the data. A first order polynomial is a line.

Leon Brozyna
July 3, 2008 9:30 pm

I had a thought {happens from time to time} while looking at these graphs — they show what has happened, not what will happen. So opposing positions can look at the graphs and take solace that their position has been ‘proven’. The graphs don’t explain why there’s been warming and cooling, though the red line suggests that perhaps a cooling period has begun. And in ten or twenty years, should the blue line also go negative, will the AGW proponents start trotting out temperature charts dating to just after the end of the LIA? Of course, should the cooling get really serious with another brief LIA, there are sure to be folk foolish enough to suggest we can ‘do something’ to change the climate. And the beat goes on…

July 3, 2008 9:34 pm

Thanks for the graphs, Anthony. It’s pretty clear that anyone looking at the first two graphs back in 2004 would think things were getting warmer.
I sure hope all the fuss will slack off, and people will start thinking about what they will do long-term to handle climate change, both colder and warmer. It’s a good start that more people are paying attention, and more detail is being developed on the potential effects of both warming and cooling. Long range contingency planning, efforts to better inform our representatives, and acquiring more knowledge on these topics would be a lot more helpful than knee-jerk political bashing.
Tnx again – Tim (www.timprosserfuturing.wordpress.com)

Keith
July 3, 2008 9:41 pm
WWS.
July 3, 2008 9:55 pm

Why not a 200 day moving average? That would show more of the short term moves while smoothing out the peaks and valleys. The 5th order isn’t bad, at least it shows a little bit of the variation. (just eyeballing it, it looks like about 1,000 day moving average, but I’m guessing)
With a little bit of logic, I think I can demonstrate that the first order curve fit is of no analytical value. It appears to be simply a straight line fit through the available data. Here’s the problem: the slope of that line is dependant on the starting point, which was a completely arbitrary decision by the observors. I realize that that is all of the data we have for these measurements, but the underlying temperature function stretches back to time immemorial. The choice of starting point was a human decision that has no relationship to the underlying function. When an arbitrary decision by the obersvor which has no relationship to the underlying function can dramatically skew the results of the curve fit, then that curve fit tells you next to nothing about the underlying function. The fact that the 11 year fit shows a very different slope illustrates this point.
Moving averages may not tell you much about the underlying long term function, but at least they show you relative movement over a defined time period, which seems quite appropriate when dealing with a cyclical phenomena.

mark
July 3, 2008 10:00 pm

which claim neilo?

crosspatch
July 3, 2008 10:14 pm

neilo:

On July 9, 1971, the Post published a story headlined “U.S. Scientist Sees New Ice Age Coming.” It told of a prediction by NASA and Columbia University scientist S.I. Rasool. The culprit: man’s use of fossil fuels.
The Post reported that Rasool, writing in Science, argued that in “the next 50 years” fine dust that humans discharge into the atmosphere by burning fossil fuel will screen out so much of the sun’s rays that the Earth’s average temperature could fall by six degrees.
Sustained emissions over five to 10 years, Rasool claimed, “could be sufficient to trigger an ice age.”
Aiding Rasool’s research, the Post reported, was a “computer program developed by Dr. James Hansen,” who was, according to his resume, a Columbia University research associate at the time.
So what about those greenhouse gases that man pumps into the skies? Weren’t they worried about them causing a greenhouse effect that would heat the planet, as Hansen, Al Gore and a host of others so fervently believe today?
“They found no need to worry about the carbon dioxide fuel-burning puts in the atmosphere,” the Post said in the story, which was spotted last week by Washington resident John Lockwood, who was doing research at the Library of Congress and alerted the Washington Times to his finding.

From this article.

neilo
July 3, 2008 10:23 pm

All: Thank you.

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