Accuracy of An Inconvenient Truth

[SkepticLance]

Phanerozoic

 

doG.

Thank you for this data. Most interesting.

Michaels points out the high Carbon dioxide in eras gone by, as well. Carbon dioxide in the Cretaceous once reached ten times the recent historical average. Temperatures reached a maximum of 10 Deg. Celsius more than the present. If you put that on a graph of carbon dioxide versus global temperature, compared to carbon dioxide versus temperature for the last couple of decades, you will see that the relationship cannot be linear. If carbon dioxide levels rise in a linear fashion versus time, temperature rise will fall off.

 

bascule and Swansont.

I might have guessed that you would distort the Hansen abstract. He says, clearly, that the most probable warming, according to his model is 0.15 Deg. Celsius per decade plus or minus 0.05 Deg. This equates to 0.75 in 50 years.

You cannot cut it any other way.

 

Of course, Hansen could be wrong. As could you, or I, or anyone. Which is what I have said all along.

[SkepticLance]

A piece of data for those who do not believe solar forcings can influence global climate.

 

http://www.pnas.org/cgi/content/short/0603118103v1?rss=1

 

Glaciers in the Andes advance by amounts calculated to be caused by a 2 Degree Celsius drop in temperature, which coincides with a drop in solar forcing. All this during the Little Ice Age.

 

If the effect of the sun's radiance was so potent then, why do people believe it cannot happen today? Bear in mind that sunspot activity, and therefore solar activity, increased throughout the warming period of the 1990's.

[SkepticLance]

Another reference for those who do not believe in solar forcings.

 

http://pubs.giss.nasa.gov/docs/1998/1998_LeanRind.pdf

 

Lean and Rind ascribe 30% of all warmings since 1970 to sunspot activity alone. This does not mean that greenhouse gases are 70%, since climate systems have many forcings.

[swansont]

bascule and Swansont.

I might have guessed that you would distort the Hansen abstract. He says' date=' clearly, that the most probable warming, according to his model is 0.15 Deg. Celsius per decade plus or minus 0.05 Deg. This equates to 0.75 in 50 years.

You cannot cut it any other way.

 

[/quote']

 

Yes. IF we continue to reduce emissions, not if we maintain the status quo (what Hansen says as "business as usual" in the paper), as I stated in my previous post. This is the part that has been conveniently omitted. IOW, he's supporting the need to further reduce emissions, and his model assumes that's what happens.

[Dr. Dalek]

Seems like all the scientists here take me seriously, and aren't taking you and Dr. Dalek seriously, with your rather distorted views of what science is.

Science is a methodology, it starts with observation, a natural trend or phenomenon is observed. Then it moves onto speculation, you try to figure out what is behind the phenominon. Then it moves on to the experimental design, where you make a hypothesis and make an experiment to test it. You collect data from the course of the experiment, and you come to a conclusion based on the evaluation of your hypothesis in terms of your data. Then if your hypothesis turns out to be incorrect in some way you try to form a new hypothesis that you will then test.

 

I will argue in this case that your observation is that the average temperature has increased in recent years. Your hypothesis is that humans are the predominant cause.

 

My main criticism is that you are basing all your arguments off theoretical calculations and other people's "hypotheses." So you therefore must design an experiment in order to validate or refute your hypothesis.

Because it is very hard to do experiments in a enormous and complex atmosphere and you seem to like to use calculations and trend models, you could start with this.

Now using the source data for this graph; Petit et al., 1999 Vostok, Antarctica ice core; you could calculate the average increase in temperature from Ice ages to warm periods, based on graph slope (rise over run) , and then do an ANOVA test to see if there is any significant difference between the warming since the industrial revolution and the equivalent times of past warming in the graph.

 

Oh! and Stop Throwing out INSULTS!!!! My veiw of science is sound!!!!!

 

This is a great example of someone slicing the data to support their viewpoint instead of looking at the whole picture. Here the writer tries to compare a 20 year span to a 100 year average' date=' apples and oranges really. Why not compare a 20 year span to another 20 year span, say 1980-2000 to 1916-1936. Then we find that the earlier span had 175% greater warming trend than the current span that the author wants us to look at. Picking and choosing the data to fit a hypothesis while disregarding the rest of it is not science and this is evidence of the type of distorted analysis global warming proponents are using to prove their point. Perhaps some of our man-made problems-proponents can explain that earlier trend and how it was caused by man too.

 

For those that think the end is near, search on phanerozoic carbon dioxide levels. While current charts indeed show CO2 levels as high as they've been in the last 20 million years you'll see that they are also some of the lowest levels in time when we look back 50 million years or more.

 

Exactly, I havn't heard any numerical compairisons to past warming cycles in any of my opponants on this issue.

[SkepticLance]

Dr. Dalek's views of computer models are very sound.

Look at what the climate experts say.

 

1. Dr. Stephen Schneider, climatologist who is aligned to the catastrophist view. In his book "Laboratory Earth" he says : " ...computer climate models are over complex, and the results fragile."

 

2. Prof. Michaels, in "Meltdown". says : " climate models are simply strings of computer code that attempt to simulate the atmosphere. The key word is 'attempt'. If their output does not correspond to reality, they require modification. In the parlance of the scientific method, a climate model is a hypothesis in search of validation by observed data."

[bascule]

Dr. Dalek's views of computer models are very sound.

Look at what the climate experts say.

 

1. Dr. Stephen Schneider' date=' climatologist who is aligned to the catastrophist view. In his book "Laboratory Earth" he says : " ...computer climate models are over complex, and the results fragile."[/quote']

 

That book is from 1997. Any opinions on atmospheric models from that time, particularly GCMs, are no longer valid. GCMs have improved dramatically in the last decade.

 

2. Prof. Michaels, in "Meltdown". says : " climate models are simply strings of computer code that attempt to simulate the atmosphere. The key word is 'attempt'. If their output does not correspond to reality, they require modification. In the parlance of the scientific method, a climate model is a hypothesis in search of validation by observed data."

 

I spent the last 5 years helping climate scientists develop, use, and debug a mesoscale atmospheric model, the Regional Atmospheric Modelling System, which DrCloud helped develop.

 

And indeed, the process you describe is exactly how models are developed. Empirically derived model inputs are used to produce model output which can also be compared to empirically derived observations. Failures of the model to replicate the empirically derived observations in the model output are progressively solved through tuning the existing model and adding additional modules which simulate components of the atmospheric/climate system which aren't accounted for in the present model. For example, I helped some of the scientists in my research group couple the General Energy and Momentum Transfer plant model with RAMS. I helped another scientist add NASA's Earth Systems Modelling Framework to a GCM.

 

So if you're wondering why I take your outright dismissal of the scientific applicability of atmospheric and climate models, it's because it's personal...

[SkepticLance]

bascule. I do not outright dismiss models - just treat them with scepticism. Models that accord with reality, when the prediction is made before the event, deserve respect. So far, it hasn't happened. Temperature rise has not accorded with models. On average, models exaggerate temperature increases, sometimes by 300 %.

 

I do not believe, however, models will ever be totally accurate, for the simple reason that some aspects of global warming are not predictable. Specifically I refer to such things as solar forcings.

 

An international convention on global warming and computer models of the same in 2003 was disturbed by the revelation that cloud formation, details of cloud formation, and the consequence of cloud formation, could not be modelled. The global climate is enormously complex. Computer models still have a way to go before they can be accurate predictors of future climate.

Just look at the error bars on current efforts!

[SkepticLance]

bascule,

I am glad you agree that a computer model is a hypothesis which must be tested by empirical data. Something I have been trying to get across for ages.

 

Has this been done? Not really. look at the latest IPCC predictions. The error factor is horrendous. The global climate is an immensely complex system, and we are a long way from being able to model it with reasonable accuracy.

[Dr. Dalek]

Strawman. Nobody here is arguing about climate vulnerabilities. All I've been trying to argue is that anthropogenic forcings are predominant, and neither you nor SkepticLance is yet to admit that.

This is not a valid argument, it is only a futile means to convince people to conform, a form of psedoscientific peer pressure if you will.

So if you're wondering why I take your outright dismissal of the scientific applicability of atmospheric and climate models, it's because it's personal...

Has this been done? Not really. look at the latest IPCC predictions. The error factor is horrendous. The global climate is an immensely complex system, and we are a long way from being able to model it with reasonable accuracy.

He isn't dismissing it, and neither am I. We are just saying they are only appliable when people use them as a means to create a hypothesis to comair with real world observation. However I often notice, news agencies, Greenpeace, IPCC (Climate Change 2001:Working Group I: The Scientific Basis:13.2.3 Scenarios Based on Outputs from Climate Models ), and others have cited the modles as reliable sources of information and prediction as opposed to quite possibly inaccurate testable predictions.

Furthermore, science is not personal.

And please I would like one of you, swanspot, bascule, anyone to please address this. I think it is a valid argument and I feel it deserves more attention then it is getting.

bascule; I'd like to point out that the current warming looks a heck of alot like previous warming cycles. Also who is to say that that CO₂ isn't natural.

My main criticism is that you are basing all your arguments off theoretical calculations and other people's "hypotheses." So you therefore must design an experiment in order to validate or refute your hypothesis.

Because it is very hard to do experiments in a enormous and complex atmosphere and you seem to like to use calculations and trend models' date=' you could start with this.

[img']http://upload.wikimedia.org/wikipedia/en/c/c2/Vostok-ice-core-petit.png[/img]

Now using the source data for this graph; Petit et al., 1999 Vostok, Antarctica ice core; you could calculate the average increase in temperature from Ice ages to warm periods, based on graph slope (rise over run) , and then do an ANOVA test to see if there is any significant difference between the warming since the industrial revolution and the equivalent times of past warming in the graph.

[bascule]

bascule. I do not outright dismiss models - just treat them with scepticism. Models that accord with reality, when the prediction is made before the event, deserve respect. So far, it hasn't happened. Temperature rise has not accorded with models.

 

The hockey stick reconstruction graph shows output from 12 different models which matches empirical data:

 

 

On average, models exaggerate temperature increases, sometimes by 300 %.

 

FUD FUD FUD

 

It's really getting old

[Dr. Dalek]

FUD FUD FUD

Be vawy vawy quiet, I'm hunting wabbits, huhuhuhuhuhu:D

The hockey stick reconstruction graph shows output from 12 different models which matches empirical data

But the modles are already based on past events and therefore can be more easily corrected, what about modles that predict future events?

[SkepticLance]

Since bascule is so fond of computer models, let's take a look at one. Specifically, the Canadian model which was adopted as the centre-piece of the US National Assessment report in 2000.

 

In the reference below, showing a range of model results, the Canadian one is the dark line.

 

http://putfile.com/pic.php?pic=7/18500012879.jpg&s=f10

 

This model predicts a temperature rise of 5.5C for the 21st Century. However, it also predicts a temperature rise of 1.5C for the 20th Century; an exaggeration of 250%.

 

If we apply a correction of 250% to its 21st Century prediction, to bring it into line with its amply demonstrated error factor, then the prediction for the 21st Century becomes 2.2C. This comes reasonably close to James Hansen's prediction of 0.15C per decade for the next few decades.

 

Why would the US National Assessment choose a model that had already been proven wrong? Here's a clue. It reported to Vice President Al. Gore, who has just produced a movie!

[swansont]

Also who is to say that that CO_{2[/sub'] isn't natural.}

 

_{Excuse me? I think it's pretty well established that we dump CO2 into the atmosphere.}

[Dr. Dalek]

Excuse me? I think it's pretty well established that we dump CO_{2[/sub'] into the atmosphere.}

_{The CO2 level has increased since the industrial revolution, but in even the last couple of decades, when the CO2 pumped into the atmosphere is suposidly more than at the begining of the industrial revolution, the amount of man made CO2 in the atmosphere is only about 3%. That implies that the remaing CO2 increase is likly of a natural process. Especially since we are in the middle of a natural warming cycle when CO2 is suposed to increase.}

_{As you can see from this graph (that I must have posted a hundred times!) we are currently in the middle of a warming trend that very closly resembles the natural ones that have preceeded it.}

 

_{Homo Sapiens have only been around (as far as we know) for about 40,000, years, and the current warming trend has clearly started before the industrial revolution!}

[swansont]

Since bascule is so fond of computer models' date=' let's take a look at one. Specifically, the Canadian model which was adopted as the centre-piece of the US National Assessment report in 2000.

 

In the reference below, showing a range of model results, the Canadian one is the dark line.

 

http://putfile.com/pic.php?pic=7/18500012879.jpg&s=f10

 

This model predicts a temperature rise of 5.5C for the 21st Century. However, it also predicts a temperature rise of 1.5C for the 20th Century; an exaggeration of 250%.

 

If we apply a correction of 250% to its 21st Century prediction, to bring it into line with its amply demonstrated error factor, then the prediction for the 21st Century becomes 2.2C. This comes reasonably close to James Hansen's prediction of 0.15C per decade for the next few decades.

 

Why would the US National Assessment choose a model that had already been proven wrong? Here's a clue. It reported to Vice President Al. Gore, who has just produced a movie![/quote']

 

According to the legend it's predicting temperatures for the US alone, which I would guess has to be a harder assessment to make, since it relies on more local factors. It's quite obvious that one area of the world can see different trends than the overall behavior at different times. Do you have a link that explains what the differences are between the models and their inputs?

[swansont]

The CO₂ level has increased since the industrial revolution, but in even the last couple of decades, when the CO₂ pumped into the atmosphere is suposidly more than at the begining of the industrial revolution, the amount of man made CO₂ in the atmosphere is only about 3%. That implies that the remaing CO₂ increase is likly of a natural process. Especially since we are in the middle of a natural warming cycle when CO_{2[/sub'] is suposed to increase.}

 

_{You say that anthropogenic CO2 comprises 3% of the total, but talk about the remaining increase as being natural; this is deceptive. The anthropogenic contribution to the increase is about 15% (roughly 12 ppm out of 80 ppm), and the total variation is 40%. (One thing I haven't seen is how these increases are broken down; are some of the "natural" increases occurring because of destruction of CO2 sinks, for example)}

 

_{As you can see from this graph (that I must have posted a hundred times!) we are currently in the middle of a warming trend that very closly resembles the natural ones that have preceeded it.}

 

_{Homo Sapiens have only been around (as far as we know) for about 40' date='000, years, and the current warming trend has clearly started before the industrial revolution![/quote']}

 

_{I think it's disingenuous to imply that nobody else is aware that there are natural variations to worldwide temperature. The thesis, as I understand it, and I thought others did, is that man has made a noticable contribution on top of natural variations.}

 

_{If we are currently in the middle of a warming trend, then it will be twice as big as any of the previous ones shown. But that's not what the graph shows. We are at a relative peak of temperature, but 3 (possibly 4) of the previous 4 were much narrower. Tough to tell on that first one.}

 

_{Note also that CO2 concentrations are pretty much at an all-time high for the period shown on the graph.}

[SmallIsPower]

Isn't it likely that cutting down trees will result in less carbon sequestration, and higher CO₂ levels. This would occur before the industrial revolution, and trees that no longer exist couldn't reverse the warming trend. This is not the time to wait for proof, being wrong can be devestating.

 

Is there any info on earth's albedo during previous warmings, has this much of the ice ever been melted? Is there evidence of past sea levels?

 

Even if it is checked by vegitation or whatever, The Great Conveyor Belt could stop, desertifying and starving Africans and freezing Europe.

[doG]

Note also that CO_{2[/sub'] concentrations are pretty much at an all-time high for the period shown on the graph.}

_{Does that really mean anything? Search on phanerozoic carbon dioxide levels. You will find that CO2 levels were 1000-2000 ppm through the Triassic and Jurassic eras and 4000-5000 ppm around the Silurian period. Anyone could crop any piece of one of these charts with a rise on it and claim the maximum is an all time high for the era shown...}

[Dr. Dalek]

You say that anthropogenic CO₂ comprises 3% of the total, but talk about the remaining increase as being natural; this is deceptive. The anthropogenic contribution to the increase is about 15% (roughly 12 ppm out of 80 ppm), and the total variation is 40%. (One thing I haven't seen is how these increases are broken down; are some of the "natural" increases occurring because of destruction of CO_{2[/sub'] sinks, for example)}

_{Even so, the ammount of current CO2 is not the highest its ever been, even in the last 400 thousand years. (From the graph)}

_Also:

_{Does that really mean anything? Search on phanerozoic carbon dioxide levels[/url']. You will find that CO2 levels were 1000-2000 ppm through the Triassic and Jurassic eras and 4000-5000 ppm around the Silurian period. Anyone could crop any piece of one of these charts with a rise on it and claim the maximum is an all time high for the era shown...}

 

_{If we are currently in the middle of a warming trend, then it will be twice as big as any of the previous ones shown.}

_{Why would it be such a dramatic peak? From the statistics I've read, (sources including Wikipedia, IPCC, and a few others) the tempeature sice the begining of the 20th century has only increased by about 1.4 degrees.}

_{Relative to the period 1860–1900, global temperatures on both land and sea have increased by 0.75 °C (1.4 °F),}

_{Note also that CO2 concentrations are pretty much at an all-time high for the period shown on the graph.[/Quote]}

_{Reguarding stats on Wikipedia, the CO2 on the graph is lower than recent measurements .}

_{from the initial reading of 315 ppmv, as shown by the Keeling curve, to over 380 ppmv in 2006}

_{So at least in that respect you may have a point,}

_{But that's not what the graph shows. We are at a relative peak of temperature, but 3 (possibly 4) of the previous 4 were much narrower. Tough to tell on that first one.}

_{Uh, not meaning to offend but I think you may be reading the graph the wrong way, 0 (the left side of the graph) is the most recent while the right is 400 thousand years ago.}

 

_{Isn't it likely that cutting down trees will result in less carbon sequestration, and higher CO2[/sub'] levels. This would occur before the industrial revolution, and trees that no longer exist couldn't reverse the warming trend. This is not the time to wait for proof, being wrong can be devestating.}

_{Actually, in my section of north America at least, a lot of trees have grown back since the industrial revolution, and yes albedo does have a definite effect. In fact it is the only major thing I worry about global warming wise. However I don't believe even our massive cities can have a devistating ecological effect, in terms of heat, I only worry that it may effect albedo and indirectly heat water sources, thus it may have an effect on the weather in general and throw off surface measurements of "climate change"}

[SkepticLance]

Swansont said :

 

According to the legend it's predicting temperatures for the US alone, which I would guess has to be a harder assessment to make, since it relies on more local factors. It's quite obvious that one area of the world can see different trends than the overall behavior at different times. Do you have a link that explains what the differences are between the models and their inputs?

 

Whoops! You are right. I should have been more careful. My apologies. The graph does indeed refer to the United States.

 

This does not, of course, change the point I am making. In fact, in a purely quantifiable basis, it strengthens the point. The Canadian model predicted 1.5C increase for the 20th Century, whereas the United States alone had an increase of 0.5C. The exaggeration was 300%, not the 250% I said.

 

Just for comparison, the average temperature increase for the whole world was 0.6 to 0.7C.

 

This means that, for the United States, the prediction of 5.5C increase must be reduced 3 fold, to 1.83C over the next 100 years. Again, I say, why the panic?

[swansont]

Does that really mean anything? Search on phanerozoic carbon dioxide levels[/url']. You will find that CO2 levels were 1000-2000 ppm through the Triassic and Jurassic eras and 4000-5000 ppm around the Silurian period. Anyone could crop any piece of one of these charts with a rise on it and claim the maximum is an all time high for the era shown...

 

 

It wasn't my graph, it was Dr. Dalek's (posted a hundred times), so I'm not the one who did the cropping. I was commenting on DD's interpretation of it.

 

Anyway...so what? Once again, it's not a matter of whether natural fluctuations occur; they do. The question is how much effect are humans having. To say that the concentrations have been that high before, in the remote past, is meaningless, considering that the species that were alive then aren't now; the natural conditions could have been very, very different.

[swansont]

Even so, the ammount of current CO_{2[/sub'] is not the highest its ever been, even in the last 400 thousand years. (From the graph)}

 

_{It looks to be within a few percent of the maximum to me.}

 

 

_{Why would it be such a dramatic peak? From the statistics I've read' date=' (sources including Wikipedia, IPCC, and a few others) the tempeature sice the begining of the 20th century has only increased by about 1.4 degrees.[/quote']}

 

_{Why are you asking me? YOU are the one who claimed that we are currently "in the middle of a warming trend." So, you tell me which position you are really taking here. Either it's a big increase or it's not. If we're in the middle we're not done yet.}

 

_{The graph tells a different story, though, which is what I was pointing out. It has us at a relatively flat temperature over the last few thousand years, (noisy probably because we have more and better data), with peak values slightly below to the previous four, but with a prolonged duration. That does not put in the middle, it puts us at the end, maybe. Why is this peak (plateau, really) lasting longer, and not sharp?}

 

 

_{Uh, not meaning to offend but I think you may be reading the graph the wrong way, 0 (the left side of the graph) is the most recent while the right is 400 thousand years ago.}

 

_{The "first peak" to which I referred is the one that occured ~400kya (first one occurring in time), and is the only one that rivals the current one for duration. The other peaks were much sharper. You can't tell on the first one partly because it's cut off.}

[RichF]

These guys have the average historical global temp being 17C. What is the current average global temperature? Are we positive that we are not in one of the dramatic shifts seen below?

 

Edit: I would like to note that I by no means am an expert. I do believe that man's actions have an impact on the environment but I'm still a little skeptical about how much.

 

http://www.scotese.com/climate.htm

[RichF]

I'm sorry to be whoring but after looking at the above chart...the earth's temp seems to be most happy at 22C. What happenened in the Tertiary period to cause the slow decline as compared with the other dramatic drops?