The Blackboard

Lucia

If your graphs don’t do it, mixing Cialis with Rogain will make the modellers’ hair stand straight up…

When we moved to the US in the mid-90s, we spent quite a while watching Rogain adverts on the TV and wondering what this mysterious substance could be. Eventually my wife asked someone at work and all was revealed: a product so embarrassing that the advertisers couldn’t bring themselves to reveal what it was!

On topic, that twenty year trend comparison is a great graph. I wonder what is going to happen next!

Chris–
If you like the 20 year graphs, thank Deep Climate for suggesting these as especially meaningful.

Oddly enough, because I’d read some of these discussions about the importance of longer term trends, I had looked at them before. But… now I’m even more curious, and I have one more thing I need to add!

Lucia,

I hope it is the 95% confidence intervals. The ‘comparing a single realization to a ensemble mean’ thing always gets people worked up.

Yes. I want to compare how the observed trends fit into the ±95 range of “all trends for all weather in all models”. For now I’ll stick with the volcano models. I’ll do that tomorrow. With any luck, HadCrut will report, and I can show it with March Data. NOAA reported today.

Lucia,
Not to step on your intention to compare ±95% CIs for the data and models, but I’ve already done it.

See here.

The two data sets begin to diverge at about mid-2006. I haven’t done any real deep analysis. I saw your post and was inspired to kill a lazy Wednesday afternoon with Matlab making this graph.

Ugh. Was such vulgarity really necessary? But thanks. My speculation was pretty close to right.

Chad: Thanks!
Andrew_FL: Hey, what do you expect of a former Catholic school girl?

A question about figure 2.

“Here are the 20 year trends as a function of end year:”
Does this mean you are regressing (x(t),y(t)) on the interval [t:Feb-2009]? I thought it would look extremely variable as you get closer to the end date and smooth out as you get farther. I tried replicating in Matlab and that’s what I found. Is that figure showing a moving 20-Year trend line?

RE Chad #12,800:

Just a couple of questions on your 95 percent confidence interval-
1. How is it that the error bars would be wider on a trend computed from physical observations than the error bars for model outputs derived from number crunching hypothetical forcings?

2. There seems to be something unphysical/unnatural about the long period (2001-2006) that the mean model trend rides exactly on the upper boundary of the 95 percentile confidence interval from observational trend. Any thoughts or speculations?

hswiseman,
To answer question 1: I think it’s because for HadCrut, there are the following sources of error:
1. station and grid-box sampling uncertainties
2. coverage uncertainties
3. bias uncertainties (urbanisation, bucket correction etc.)
From the error estimates they’ve published, I’ve created a graph showing the monthly standard error. It’s pretty big with a strong seasonal component.

The standard error estimates from the models however are calculated from the spread in the monthly values. There are no coverage uncertainties. No bias uncertainties like that found in HadCrut. I would suspect the the error estimate in the model ensemble is a function primarily of the different physics implementations and the different initial conditions applied from the end of the 20th century experiment.

To answer your second question: I have no idea.

Chad:
One graphs shows 20 year trends. However, the beginning and end months slide along. So, for example, one ending in dec 2008 begins in Jan 1988. The one ending in dec 2007 begins in Jan 1987 and so on.

The the other graph shows trends all beginning in 1979. I picked that date because the post that inspired it discussed RSS.

Thanks. I figured it had to be a 20-year sliding window.

[...] second graph showing 20 year trends is more pronounced.Lucia Liljegren of The Blackboard did both of these, and she writes: Note: I show models with volcanic forcings partly out of [...]

[...] global, Cambio Climático | No Comments  Liljegren, de The Blackboard, ha preparado un post [-->] con este interesante caudro. Una comparación entre tendencias de la temperatura de veinte años. [...]

The party’s over sorry AGW’ers ice is also back to near normal even NH imagine that! Antarctic again going way over anomaly…
http://arctic.atmos.uiuc.edu/c.....nt.365.jpg by the way…. AMSR NH ice… more up to date an’ going through the roof (just joking)
http://www.ijis.iarc.uaf.edu/s.....Extent.png. I think we should all realize that at a millenium level NONE of the pro-AGW or ANTI-AGW data has any meaning whatsoever.. but it was fun while it lasted.. LOL

Really VG?

Willing to wager some money on arctic ice this summer? I’d give you 70-30 odds on arctic sea ice being at least at the third lowest level ever recorded. There is also sketchier data before the satellite era (http://tamino.wordpress.com/20.....n-and-now/) that helps put things in perspective.

Can’t be long before… “Arctic is Cold? Yeah, We Knew That”

That’s a tempting bet, ZH, looking at the recent flatness of the melt arc… looks like 2009 will top the 2k+ satellite era for comparable dates in a day or two.

Note: Some comments are causing the blog display to hang up. I don’t know why.However, if your comment is moderated, this may be the reason. (I’ll try to diagnose this when I have time. However, I’m currently trying to write a formal comment on Easterling, and I don’t want to spend the time figuring out what’s up with the comments. For all I know, it’s the ads.)

Zer0th (Comment#12817) April 16th, 2009 at 8:47 am ,

I wouldn’t get too excited yet. There’s about 1Mm2 of sea ice in the Bering Sea and the Sea of Okhotsk that could go away quite rapidly. The extent and area curves do look to be paralleling the 1979 to 2000 averages, but so did 2008 until it fell off a cliff at about this same time (see here).

The ice extent last year collapsed suddenly in aug.

I would not try to draw any conclusions from trends now.

Hm, good point. But I’m set in my ways. I guess.

Lucia,
Your second graph (and Chad’s) will look quite different if you use annual data (which makes more sense anyway). It really cuts down on the noise as I’ve already pointed out.

Deep Climate,

As requested.

Here’s a slightly different version using less color since the other one might be a little hard on the eyes and a bit difficult to interpret.

“There is also sketchier data before the satellite era (http://tamino.wordpress.com/20.....n-and-now/) that helps put things in perspective.”

“Sketchy data”? Have a look at this:

1870 13.37203 15.49576 14.96318 10.91682 12.12467
1871 13.44231 15.44833 15.05777 11.15060 12.12467
1872 13.40097 15.52038 15.00856 10.93797 12.14938
1873 13.55574 15.43840 15.49612 11.17556 12.12467
1874 13.50285 15.50054 15.30021 11.09799 12.12467
1875 13.45613 15.48283 15.21955 11.00970 12.12467
1876 13.43653 15.48176 15.21113 10.94084 12.12467
1877 13.56651 15.56288 15.34898 11.24117 12.12467
1878 13.46723 15.54661 15.38869 10.82099 12.12467
1879 13.44434 15.51596 15.29166 10.85735 12.12467

Being able to give the NH seasonal ice extent with a precision of +- 10 square kilometers for a time period when for example Franz Josephs Land, Severnaya Zemlya and the Sverdrup Archipelago had never even been visited by humans isn’t “sketchy”, it’s bloody miraculous.
Seriously though, out of those seven digits the first is probably significant, but none of the others.

Deep climate–
1) Why do you think using annual data makes more sense? It’s smoothing twice. Is that smoothing optiuum? Or would finding the 20 year trends based on 5 year averages make more sense?

Trends computed based on annual average data have more variability because averaging constitutes throwing away some information, and the end points between the edges are slightly compressed. (Or, at least, I’m pretty sure this is the case.)

In addition, annual average data means we must ignore the most recent three months. I can see why some might prefer ignoring recent data, particularly when engaged in the time consuming process of creating formal journal articles. But in what scientific does the choice “make more sense”?

If you like, when I have my plate cleared, I’ll run some monte-carlo analyses to verify whether or not using annual averages instead of monthly averages inflates the uncertainty intervals unnecessarily. But before I do that, I want to see if it would address the reason you believe using annual averages “makes more sense”.

That way, I won’t waste my time addressing the wrong issue.

Zeke [12815]

Right now Arctic ice extent is on par with 2003 and 2002, above 2008 levels and paralleling the 1979-2000 average. Let’s assume you are right: summer of 2009 becomes third lowest “ever” [your terminology]. All that is required is for ice extent to stay even marginally above 2008 until 2011 and we would have a 10 year data set in which the 2007 ice conditions are clearly the exception.

We know from several papers published last year that the 2007 summer drop in ice extent was predominantly due to wind conditions that forced ice out to warmer waters and not to regional temperatures per se.

I agree with DeWitt Payne [12819], and wait and see how the outlying ice areas are affected by local weather during the summer.

tetris,

Frankly, I think 2007 ice conditions were somewhat of an exception as well, though one exacerbated by a clear downward long-term trend. Remove 2007 (and 2008 if you want) and the arctic trend is still clear.

Zeke-you really should be more careful about throwing around words like “long term” when speaking about trends. They are very vague (and totally meaningless). And we would all do well to remember that trends can change unexpectedly. But pontificate if you must. What exactly do you believe the true “long term trend” is, and why do you think that is more accurate than any estimate, higher or lower? Put another way, do you expect a sea ice free Arctic any time soon, or at all? If so, when? You can give vague answers to these questions, but that would undermine your claim of a “clear long term trend”.

Hi,
I’m a progressive liberal democrat trying to change the opinions of other progressive liberal democrats about climate change (yeah, I know…)

I commented about this on WUWT and on my fledgling weblog, but since you answer a lot of commenters, Lucia, I’d like your advice on this.

It seems to me that the ‘talking point’ that might actually make some headway on all this is that at least your chart shows that we have time to collect more and better data–that at the very least, the immediacy of any effects is less likely. I think that that is a case that would work–do you think that it’s a good case to make?

Tom–
Actually, I think it’s prudent to begin to do something. The warming we have already seen, combined with a fairly sound theoretical basis that warming will continue is a good enough reason to worry about mitigation and adaptation. The questions is what should we do?

I happen to be for specifically encouraging nuclear energy as a method of obtaining baseload. I like solar too– but I think focusing on solar and wind only will ultimately provide the energy we need to maintain a lifestyle people prefer.

Lucia,
I would be in favor of expanding our nuclear power base as well, although I think nothing will be done in the next few years, sadly. Have you looked much at the possibilities in OTEC or Space Based Solar Power satellites? At least they scale…

lucia (Comment#12836)

“Actually, I think it’s prudent to begin to do something. The warming we have already seen, combined with a fairly sound theoretical basis that warming will continue is a good enough reason to worry about mitigation and adaptation.”

Lucia – could you please respond to the following questions:

(1) When you say “fairly sound theoretical basis” what specifically do you mean?
(2) Why do you believe warming will continue? For how long? Do you think it is equally likely that the global mean temperature (I won’t get into how we define this number) will decrease? If not, why not?
(3) Are your answers to (2) based on computer models?
(4) What do you mean by mitigation? Can humans, by applying this “mitigation” strategy, actually control the climate? Can you assure us that this strategy will work (however we define “work”)?

Thanks,

Frank K.

TomFuller–
I haven’t spent a lot of time investigating alternatives. I support people into them.

FrankK

(1) When you say “fairly sound theoretical basis” what specifically do you mean?

There is a sound theoretical basis that, all other things being equal, increased ghg’s should result in at least some warming. We have been burning fossil fuels, the CO2 has risen since the beginning of the industrial revolution, and the temperature have warmed. So, there is a sound theoretical basis, and some evidence.

(2) Why do you believe warming will continue? For how long? Do you think it is equally likely that the global mean temperature (I won’t get into how we define this number) will decrease? If not, why not?

Because GHG’s should cause warming, and we’ve saw 0.7C warming during the 20th century. I think we’ll have at least that amount of warming in the 21st. Other than that, I cannot say.

(3) Are your answers to (2) based on computer models?

No. It’s based on the spectral properties of ghg’s, the first and second law of thermo and some empirical support.

(4) What do you mean by mitigation? Can humans, by applying this “mitigation” strategy, actually control the climate? Can you assure us that this strategy will work (however we define “work”)?

Mostly generating energy using less CO2 intensive means, and possibly sequestering CO2. No, I cannot assure anyone the method will “work”, by any definition. I favor increased use of nukes to replace carbon based generation in large part because they are a proven technology that would permit us to maintain a mechanized lifestyle while generating less CO2. There are other advantages to nukes.

Lucia (Comment#12836)
April 16th, 2009 at 8:44 pm

“I happen to be for specifically encouraging nuclear energy as a method of obtaining baseload. I like solar too– but I think focusing on solar and wind only will ultimately provide the energy we need to maintain a lifestyle people prefer.”

Lucia, did you happen to omit to omit the word “not” in front of “ultimately” in the second sentence above? I don’t see how focusing on solar and wind only will ever overcome the baseload problem. I agree with you 100% on nuclear, and have had that position for decades. We should have been a world leader in that field.

On the other hand, analyses such as yours suggest to me that watchful waiting, while pursuing alternatives as they become economically viable, may be the best approach. No need to take action with draconian economic effects, when the need for such action is still very questionable.

As of now, 2009 heads the Arctic satellite era pile over 2003 by ~18,000km^2 — let’s see how it goes for the rest of the melt season.

As I largely agree with Lucia on this, maybe I can develop the argument a bit.

1. There are compelling arguments from the national interest on reducing energy usage and improving energy efficiency. (These arguments are applicable to all nations except the largest oil producers and maybe Norway.)

2. The mechanism by which we anticipate greenhouse gases raising the temperature is not at all controversial–it’s only the postulated positive feedback that is suspect.

3. The cheesy tactics of some alarmists should not play a big part in our deliberations on this.

4. If using alternative sources of energy and improving the efficiency of the current installed plant can be done at a non-catastrophic cost, it satisfies other objectives and buys us insurance against possible global warming.

5. Investing in research and development for alternative generating mechanisms will position our economy to do well in future, either by selling it to developed countries or giving it to lesser developed nations. Or both, obviously.

6. We need to nip the biofuels madness in the bud, and biofuels are one of the alternatives that scale, so we need something that can actually scale as well.

Might be other points that I miss this early in the morning…

Assuming that some mitigation is optimal, which seems to be a consensus among even those who question the severity of projected warming, there is the larger question of the best approach to mitigation. As someone with a background in economics, I tend to be skeptical of centralized command-and-control solutions where the government simply pumps large amounts of money into a chosen solution (e.g. nuclear). Rather, I’d prefer to see the expected social harms of carbon be internalized into the cost of emitting carbon through a revenue-neutral tax (the horror, the horror) so that market forces can have the correct incentives to determine both the optimal level and methods of mitigation.
.
If we raise taxes to pay for massive investments in nuclear, or if we raise energy costs via taxing carbon, its still the same amount of money out of pocket. The benefit of using market mechanisms for mitigation is that the market tends to send the money to those activities that give the maximum return at the minimum cost.
.
There is an excellent paper about developing climate policy under uncertainty by Billy Pizer over at RFF that is worth a read: http://www.rff.org/Publication.....onID=17412

Zeke,

Carbon taxes are of limited use because the incremental cost of adopting non-emitting technologies is too high. This leads to a situation where consumers/businesses absorb the extra costs while making sacrifices elsewhere.

Carbon taxes are also limited by what places like China/India do. If they refuse to price carbon then there is no way the develop world can do much more than they already do.

IMO, it is a waste of time talking about mitigation until we have technologies that are viable without massive subsidies. Obviously we should spend money on R+D and large scale pilot projects but there is no guarantee that this R+D will succeed. In fact, most attempts will fail and politicians making policy based on the assumption that these R+D attempts will succeed are setting us up for big problems in the future.

Thank you for your answers, Lucia.

Some follow-up questions and comments:

“There is a sound theoretical basis that, all other things being equal, increased ghg’s should result in at least some warming.”

So, do you think that if humans emitted no industrial C02 at all, the climate would not warm or cool, on average?

“We have been burning fossil fuels, the CO2 has risen since the beginning of the industrial revolution, and the temperature have warmed.”

There have been other warm periods in the past, before the advent of the industrial revolution. What caused those?

“No. It’s based on the spectral properties of ghg’s, the first and second law of thermo and some empirical support.”

Is the “empirical support” the nebulous “global average temperature” time history derived from ground-based and ocean data?

“No, I cannot assure anyone the method will “work”, by any definition.”

Given that noone can be assured that any mitigation strategy will “work”, how much should we as a society pay in increased energy taxes and related burdens for something which noone knows will work? Can this money be best used elsewhere to, for example, eliminate hunger and disease?

And for those who advocate higher taxes for the “harm” CO2 does to earth (even “revenue-neutral” taxes (ha!) ), how much should they increase? Who gets to decide the rates? Where does this tax money go? Do you really think this new-found revenue will really be spent on “mitigation”? Is this really the free-market at work?

Duane– Yes, that was a typo. I meant “not”.

Zeke– I don’t so much advocate command and control institution of Nuclear. But the government has been know to regulate things out of existence in the past and also fund research to improve methods to achieve goals. I would like to see the government moving forward on developing and implementing solutions to handle nuclear waste and favoring nuclear research when making funding decisions.

I’m not in favor of the government mandating solutions or subsidizing things that make no economic sense.

FrankK

So, do you think that if humans emitted no industrial C02 at all, the climate would not warm or cool, on average?

Could you reword your question so I can understand specifically what you are asking? Temperature do vary. So, if you wish to think the current rise in both GHG’s and temperatures is a coincidence, you are free to do so. However, since order of magnitude computations based on the spectral properties of GHG’s suggests that the earth should have warmed, I lean toward believing the GHG’s were the cause.

Admittely, should the earth really begin to cool, I would change my mind. But the data we have seen so far shows not enough cooling.

As for the rest: You are asking good questions, but too many for me this morning. I’m not going to debate questions like “Is this really the free-market at work?”

Politically, I lean toward doing something, and my thinking lines up fairly well with Tom Fuller’s points above.

“Could you reword your question so I can understand specifically what you are asking? Temperature do vary. So, if you wish to think the current rise in both GHG’s and temperatures is a coincidence, you are free to do so. However, since order of magnitude computations based on the spectral properties of GHG’s suggests that the earth should have warmed, I lean toward believing the GHG’s were the cause.”

I don’t think, personally, that it is a coincidence. Like you, I would tend to believe that some component of the recent warming is due to man’s presence on the earth. There are over 6 billion people after all! But, I do wonder how large this component is relative to “natural variations”. There have been warm episodes in the earth’s past which obviously can’t be tied to the industrial revolution. If, hypothetically, our CO2 emissions raised the earth’s average temperature by 0.2 C / century over the natural fluctuations, is that enough to label CO2 a pollutant? If we stopped driving our cars tomorrow, would that eventually stop the warming? I am not convinced that AGW is a problem, and furthermore, I am very wary of those who would use climate science to further their own (unrelated) agendas – through unnecessary and burdensome taxes, for example.

Zeke, you say:
“Assuming that some mitigation is optimal, which seems to be a consensus among even those who question the severity of projected warming…”

What?!? Where on Earth did you get that idea? Unfettered economic growth and focused adaptation can completely deal with the tiny impacts of climate change on human welfare-what’s more, there isn’t any mitigation policy seriously under consideration that could have any significant impact on climate-and they are all hugely expensive. Combine that with the possibility that the changes maybe less severe than thought, and why on Earth would there be a consensus that “some mitigation is optimal”?

[...] of 20 year trends inspired by Deep Climate, recall, that in comments on the previous post, Deep Climate said: Your second graph (and Chad’s) will look quite different if you use annual data (which [...]

If I can jump in again after you’ve all done the heavy lifting on this argument, it seems that there are some things almost everyone involved in this argument can agree on:

1. (I always end up using lists–bad habit) If we could reduce our use of fossil fuels with little consequence, it would overall be good for us. Reductions in pollution, mountains of fly-ash avoided, less money flying out the door to unfriendly regimes–if we could do it today at no additional cost, we’d probably be happy to do so.
2. If we could improve the efficiency of our energy-using devices, from planes, trains and automobiles to refrigerators, computers and yes, even mobile phone chargers, we would again be happy to do so. It would save money and make us feel more virtuous.
3. While we are waiting for the verdict to come in on global climate change, it surely must make sense for us to invest some money in points 1 and 2. I personally feel that investing in nuclear power and other scaleable alternative generating technologies such as OTEC and Space Based Power Satellites is the way to go–but if you’re convinced that solar and windmills are more bang for the buck, let’s talk about that.
4. It also must make sense for us to improve data collection and analysis regarding global temperatures. As WUWT has noted, only 11% of our temperature measurement stations meet specifications. We don’t have enough stations around the world, in the sea, in the troposphere, and we need to work on data collection from space as well.
5. As Roger Pielke Sr. has been pointing out over on his weblog, there is a real chance that we are affecting the climate more severely with deforestation, land-use policies and interruptions of the hydrologic cycle than we do with CO2. This is where mitigation could perhaps kill two birds with one stone. Let’s spend some money doing it.
6. The above is low-hanging fruit that seems worth pursuing to me regardless of whether CO2 is triggering a positive feedback cycle that will raise temperatures dramatically or not. As it is worth doing, let’s do it now and then see what happens ten years down the road.

Is any of the above objectionable? The only argument I see being raised by the alarmists is that it is insufficient–but we would have to start somewhere even if we bought their entire argument hook, line and sinker. The only argument I see from the skeptic side is that it is a waste of money if warming isn’t going to happen–but I think it is fairly clear that is not the case.

Comments?

Tom-

1. Well, replace it with what? There are never absolutely ~no~ consequences of major changes to the economy. Using alternative energy sources is a worthwhile goal. However, at the moment, they are mostly expensive alternatives. Markets pursue what makes sense from a profit perspective. The good news on that front is that technology improves as wealth grows. This helped us eliminate the real nasty pollutants in the past, with no real catastrophic consequences.

2. Well, yeah, if we would really save money by making our tech use less energy. Unfortunately, it isn’t so easy-the efficiency improvements have to be developed first which (surprise!) costs money. (as an aside, in some cases, more efficient is not necessarily better. Higher MPG but smaller, lighter cars (which will come about thanks to Government fuel efficiency standards) are less safe: http://www.comcast.net/article.....ash.Tests). Which brings us to…

3. …Investment. Well, who is doing the investing? Is it up to the individual and the corporation, or is this investment done by the government (as I suspect you mean)? In that case, you are forcing everybody to spend money on alternatives whether they like it or not. But also, what makes the government, with its miles of bureaucratic red tape and self righteous pseudo-intellectuals (idiots), so capable of deciding what to invest in? What if we waste huge gobs of money (perhaps all our money) on the wrong energy track? Well, I would argue that better approach is to let the good ol’ invisible hand decide-I doubt I can convince you, though. But I agree as far as nuclear power goes-it seems to be the most promising road, and it is, by the way, a good example of how government restrictions on energy can hurt everyone-political pressure from environmentalists has kept nuclear back! Another point to make as far as government getting into energy-the ethanol debacle. Which I could go on about, but won’t.

4. I totally agree, but would add that I also add that I think our observing network, at least on the ground level, could be extensively improved without having to spend much money, via a sort of mass effort, very much along the lines of what Anthony and his team have been doing.

5. As far as deforestation goes, the best bet would be genetic engineering to allow greater crop yields on less land-and of course, as the third world countries develop, they will not only have access to technology which will allow them to improve crop yields, they will also have stable populations (it happened here and in Europe, after all). The biggest problem with deforestation right now comes from farmers in Brazil trying to grow crops to be used as…Government subsidized ethanol!

6. There are some low hanging fruit that you don’t mention-many non CO2 greenhouse gases could be reduced simply by improving technology, and we could also take out black carbon soot (which as a forcing now estimated at 60% that of CO2) in the same way. After all, in the US, we used technology to get almost nothing but CO2 and H2O coming out of our exhaust pipes and smokestacks-and we’ll continue improving so long as we keep getting richer.

I also want to add that unfortunately, promoters of alarm are actually suggesting that we slow (or even reverse!) the progress of reducing pollutants to retain the cooling effect of some of them. This is not merely ironic but actually disturbing.

Hi Andrew,

Thanks for your follow-up comments. I don’t think governments are necessarily any good at picking winners–but at building roads and internets they do okay. Building a smart grid is something that only a government could do, don’t you think? Building a successful launch capability for space based power satellites is again, something only a government could do.

A lot of current market choices are shaped by signals governments gave in the past that we may no longer want to give. Tax breaks for oil companies, for example. The government not only funds over half the research in this country, it sets broad directions for much more. I’m glad we’re not sending out the same signals about stem cell research as we were last year. I’d like to send out strong signals about energy efficiency research instead.

Well for the most part I would prefer that government not try to “signal” the market where to go, too. Which is why I complained about some of their signals on energy policy. So I would agree completely about tax breaks for oil companies. Why should anyone get special treatment? You have a good point about roads-it was after all a Republican and generally seen as fiscally conservative president Eisenhower who gave us the interstate system. So government has a place. As far as internet goes, I’m not sure it is necessary for government to build the network, but it does help to get it done more quickly. I would however be against the government taxing or regulating the internet-I mean, why? Similarly, as far as a smart grid goes, it might make sense for the government to build one (with the caveat that there are hazards as well as benefits to a highly interconnected grid run by computers-what if there is a firesale (if you don’t know what that is, you should watch Live Free or Die Hard)?) but not so much run it. As far as the satellite thing goes, I don’t know much about getting energy from them (sounds like sci fi! cool!) but if you mean to suggest that only government can put satellites in space, that is clearly not the case-the private spaceflight industry is just starting to appear, and I for one intend to be a part of it!

[...] the “real” climate compared to the models. (For comparison, look at Lucia’s post here; it shows the model trends way above the [...]

ZH Wrote:
(Comment#12815)
April 16th, 2009 at 8:21 am

Really VG?

Willing to wager some money on arctic ice this summer? I’d give you 70-30 odds on arctic sea ice being at least at the third lowest level ever recorded. There is also sketchier data before the satellite era (http://tamino.wordpress.com/20.....n-and-now/) that helps put things in perspective.
—————————————————————-Endquote

When I look at the start of this Arctic melting season, I note that the current melting rate is lower that most of the 20+ years, It appears even lower than the 1979-2000 mean melting rate.
Do you have a suggestioin for plausible mechanisms for this? – I assume we do agree that the current melt is exclusively of first year ice from the polar periphery.

Cassanders
In Cod we trust

I followed the ping a couple of posts above and want to ask a question.

Chris Pearson suggests that the model values in the graphs are too high (0.28C per decade). IPCC postulates a rise of 0.2C per decade (over the next two decades – from 2006 I presume).

I read in the IPCC that the rate has increased. Were the graphs generated (back in time) with this in mind?

Could you help a non-statistician on this, Lucia?

Barry: I think that person may have answered in such a way that demonstrates a deep misunderstanding of climate data.. (please read very carefully… hint… second last word). In his/her own words:
“I’d give you 70-30 odds on arctic sea ice being at least at the third lowest level ever recorded”.
LOL

IPCC postulates a rise of 0.2C per decade (over the next two decades – from 2006 I presume).

20 year trends vary over time. The IPCC projections compare the average surface temperature of two periods. The periods are: 1980-2000 & 2011-2030.

The distance between the center points is 30 years, and the fact that it’s based on center points of two long periods makes it behave sort of like a 40-50 year average.

If I compute the multi-model mean using all models downloaded from The Climate Explorer, , I get the same result the IPCC got.

However, the 20 year trends vary over time. Factors like Pinatubo affect the 20 year trends in both the models and the observations. Because Pinatubo erupted in 1991, and the dip occurs afterwards, that “dip” falls on the 20 year timelines you are seeing in the graph above. It’s currently moving toward the ‘left’ (i.e. back in time) and tends to create a rise the 20 year trends for for both projections and observations.

Because of these known effects, I prefer to compare like-to-like. That means, I compare 20 year trends to 20 year trends with matching end points. I could compare the current trend 20 year trends to IPCC 40-50 year average, but I prefer apples-to-apples whenever possible.

Thanks Lucia, I think I understand that, but if I may press for a simpler reply…

The contention at Deep Climate was that you had selected an upper-estimate group of model runs, resulting in a decadal trend of 0.28C.

Is that actually the rate you gleaned from the 16 model runs to compare to surface records?

If this is so, I don’t see how that gels with IPCC projection of 0.4C over two decades from 2006. As the IPCC says trends have accelerated, presumably the trend would be a little bit less than 0.2C p/dec if the start point was earlier in time (with or without volcanic forcing).

My questions are no doubt naive. Just trying to understand in simple terms.

Barry–
I’ll show more graphs tomorrow.

The graph is the rate from the 16 models I downloaded from The Climate Explorer (except Essence which would mostly drive the rates higher. Essence wasn’t used in the IPCC.)

I did use the volcano runs for reasons stated: i.e. the volcanoes really did erupt on earth. I’ll show both tomorrow.

The IPCC does not projected 0.4C over two decades from 2006. They a) have specific numerical values in a table discussing the changes for two specific time periods, b) provide a graph of projected anomalies over time and c) discuss the projections are based on the multi-model mean from a specific set of models. For the early part of the century the trend is “about 2C/century”, but this is relative to a start point based on the average from 1980-1999. Trends computed using values in tables are all a bit larger than 2C/century.

Lucia, will you state the rate per decade derived from the mean of the 16 model runs you selected? I don’t know how to ask this any more clearly.

The IPCC specifically states a projection of 0.2C per decade for the next two decades – from 2006 (I presume).

“For the next two decades, a warming of about 0.2° per decade is projected for a range of SRES emission scenarios.” – AR4 SPM

Could you reference the table time-lines, please?

Not having the tools and knowledge to run statistics, I have to resort to reasoning from simpler metrics. If your selection of model runs produces a rate that is higher than the projection mentioned by the IPCC (cited above), and the period you’re examining predates the (2006 – 2025?) period, isn’t there something wrong here? Shouldn’t the rate be less than 0.2C?

Would you disagree/disagree with D/C’s contention that you’ve selected high-estimate model runs?

Again, forgive me if the questions seem naive (and repetitive). It’s just that you haven’t answered them directly as yet.

(I know about the volcanic eruptions)

I will check out your new graphs. Cheers.

Barry–
For which years do you want the trends? Do you want 2000-2020? 2000-2001? That’s “About 2 C/decade”, which will show on the graph I post today.

Would you disagree/disagree with D/C’s contention that you’ve selected high-estimate model runs?

Nope. The 20 year lagging trends vary and are currently high. This is due to the volcanoe eruptions, not the models I picked. You’ll also see this in the graphs. The 20 year trends ending in 2030 will match.

Thanks for the reply, Lucia.

The period I’d like the degrees C/decade trend for is the same as the two graphs in your top post. Are we talking about any other periods?

What are the trend rates/periods you gleaned from the mean of the 16 model runs for the two top graphs?

Dunno for sure, but if you use the volcanic forcing lower values near the beginning of the computed series, and that pushes the trend up, isn’t the trend then an artifact of an anomalously low start point? Bit like running a trend from 1998 and saying it’s an accurate reflection of a climate trend?

I note that the observed trend for the 25 yrs to 2005 was about 0.177C

(I realize you’re taking on someone else’s suggestion re 20 year time periods in god humour and playing out the results)

20o years must be the absolute minimum to derive a meaningful climate trend. I noticed someone on another thread stating that the WMO 30 year period is ‘arbitrary’, but from what I’ve read it’s selected to weed out noise – weather, ENSO, 11 year solar cycles etc. The PDO oscillation has only been discovered relatively recently, so perhaps the perod should be doubled (PDO is roughly 30 years).

The period I’d like the degrees C/decade trend for is the same as the two graphs in your top post. Are we talking about any other periods?

You & DeepClimate are simultaneously discussing two periods. The final point on my graph represents the 20 year trend from 1989 through 2009. The “about 2″ trend for the the first two decades of the century is either 2000-2020 or 2001-2021. These are two different time periods. We don’t have data for the second period discussed in the IPCC and I don’t show it on the graph above. I’ll show it later today.

Since you want numbers now:

Using the IPCC models, I get these 20 year trends:

Ending March 2009: 0.028 C/year and 0.024 C/year (Volcano only, all respectively.)

Ending Dec 2019: 0.22 C/year, 0.20 C/year (Volc only, all ) respectively.

but if you use the volcanic forcing lower values near the beginning of the computed series, and that pushes the trend up, isn’t the trend then an artifact of an anomalously low start point?

If you compare observed 20 year trends in a volcano dip, you will get an observed trend that is high compared to what you expect when there are no volcanos. It overstates warming due to ghgs because that trend shows combined warming from ghgs and recovering from Pinatubo.

Deep Climate appear to be suggesting that we should compare the observed 20 year trends ending in March 2009 to the projections ending in Dec. 2019.

That comparisons is apples to oranges. We know why the model trend ending in March 2009 are high: They are clearing off Pinatubo!

On looking at smoothed trends: I don’t like this method at all. I prefer to estimate uncertainty intervals for trends of any length and to compare observed simulated and observed trends matching the time periods. No matter what length of trend you pick, there is an uncertainty interval. You can get all sorts of weird things if you don’t match the time period.

Lucia,

If we assume that the models are approximately correct, how would you go about determining the likelihood that we would see a run of 12-13 data points below the projected trends?

I have run some modelling of this, and it appears that such a run is not an unusual occurrence; indeed, runs of below or above projected trends of 15 or higher (the highest in 10 random datasets being 22) occur in pretty much every single run of my model.

So, it seems to me that the above data is not sufficient for us to say that the models are wrong.

Now, I will admit that I am a novice at this and have possibly made errors. But I am willing to learn. I can provide further explanation if you wish – I can even email you the excel set-up I have for my model if you want. The source for my randomly generated data (no surprise: it is random.org).

I will say, however, that the last data point is about at the limit of my model with regards to the size of the difference between the predicted trend and the actual trend.

David,
Re your comment # 13006 isn’t the whole point that the cilmate by AGW theory is not random but trending. So if you can replicate cilmate behaviour with a random number series then you’ve shown no trend just chaos and failed to prove AGW.

Andrew

Andrew Kennett,

The data that I am generating has a built-in trend plus randomness to represent the yearly fluctuations that we see in nature.

And that is the point: if you do not build in a trend, the data generated looks nothing like the real temperature data that we have seen over the last 30 to 40 years in particular. However, if you do build in a trend, it looks very, very similar.

This seems to demonstrate that the world is indeed warming.

Lucia:

There is a sound theoretical basis that, all other things being equal, increased ghg’s should result in at least some warming. We have been burning fossil fuels, the CO2 has risen since the beginning of the industrial revolution, and the temperature have warmed. So, there is a sound theoretical basis, and some evidence.

Except there’s one problem with that (at least if one accepts there’s any validity to climate models at all). That is that when one sums the total anthropogenic forcings (mainly CO2 and sulfates), the cooling effects of the sulfates nearly balanced the increased CO2 until circa 1980. Almost all of the cooling prior to this point in time has to be attributed to changes in natural forcings.

See e.g., this figure.

That said, I basically agree with you. The climate is changing, and humans are partly responsible for it. However, I am really not interested in returning to the hard times of the 17th and 18th centuries. There was nothing “optimal” about that at all.

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