Did you know the Warmers overpredicted global warming?

Question

Forecast verification is the process of comparing real data to forecasts. Jim Hansen from NASA's GISS made some predictions back in 1988 that were supposedly based on "first principles" of physics. Of course, at the time he did not know how much atmospheric CO2 would increase so he had three scenarios - A, B, C. Scenario A predicted a huge temperature increase because lots of CO2 was going into the air. Scenario B predicted a somewhat smaller temp increase with less CO2. Scenario C predicted a very small temp increase with much smaller CO2.

A number of people have been doing forecast verifications lately. Dr. Roger Pielke Jr did some on the IPCC forecasts. These showed the IPCC overestimated the warming.

Now lucia has completed forecast verification of Hansen's 1988 forecast. Hansen significantly overpredicted the warming.

http://rankexploits.com/musings/2008/temperature-anomaly-compared-to-hansen-a-b-c-giss-seems-to-overpredict-warming/

What do ya think about AGW now?

Answer 1

Let me get this straight.  Way back In 1984 (shortly after scientists were supposedly warning of an imminent Ice Age), Dr. Hansen submitted a paper that projected a long term warming trend with 3 scenarios (depending on emissions levels).  Now, 23 years later, we see that A) It really did warm-up, and B) His most plausible scenario was accurate to within 5 - 10% (within the error bars) of what actually happened.  And thus, we're supposed to conclude that Hansen doesn't know anything about climate prediction?  I'd give him an A+ for that kind of accuracy over such a short term, given the amount of data and computing power available back in the early 80's.

But the key point you need to acknowledge is that no single model, scientist, or paper is the basis for the AGW consensus as reported in the IPCC.  Even if Hansen were discovered to have been off by 50% (an unlikely event, I think you'd agree) there are still countless other scientists using different models independently concluding the same general point: Anthropogenic Global Warming is happening.

Edit:

Ron C - Sorry but your assertions and attempts to attack actual scientists who disagree with you are silly.  The guys at Realclimate post real biographies, have real degrees, from real Universities and work for real scientific institutions.

Lucia, in her own words, said:

"I have done no statistical analysis of this; the observation is based on eyeballing the graph only"

"It’s also not clear this visual comparison between means very much."

"I can ginn up graphs that make Hansen et al.’s 1988 projections look both better or worse than these."

"As far as I can tell, even with 24 years of data, this exercise appears to be a cherry picker’s dream!".  

I prefer to read analysis done by real qualified scientist who publish in journals vs. amateurs who post on blogs.

Answer 2

First let me get your objection straight.  Are you claiming that the AGW theory is wrong, or that the 20-year-old models simply slightly overestimated the subsequent warming?  You can't have it both ways.

Secondly, somebody's analysis is wrong.  Compare the RealClimate analysis graph (done by NASA climate modeller Gavin Schmidt):

http://www.realclimate.org/images/Hansen...

with the "lucia" (who the heck is that?) graph:

http://rankexploits.com/musings/wp-conte...

This lucia person doesn't even have the shape of the Scenario C plot right.  It levels off after approximately 2000

http://www.realclimate.org/images/Hansen...

and as I have shown several times, the global temperature trend has continued upward since 2000:

http://tamino.files.wordpress.com/2007/0...

So it seems clear to me that the "lucia" analysis is flawed.

What I think about AGW now is that it's good you're accepting the basic science of the theory and picking on minute details.

Don't even get me started on Pielke Jr.'s amateurish analysis of 7 years worth of data.

Ron - I love that you of all people are accusing others of cherrypicking.  You only choose to accept the results of the few scientific papers which have conclusions you like (i.e. Schwartz over every other climate sensitivity study, or Scafetta&West over every other solar forcing study).

Now you're accepting the analysis of a climate model of some random person ('lucia') over that of a NASA climate modeller because it's the one you want to be true.  Even though I clearly illustrated that lucia's analysis is flawed.

Don't throw stones in glass houses, Ron.

Answer 3

You seem to be glossing over the fact that over-predicted or not, the warming is still occurring.

Answer 4

I don't base what I know on a single web site.                          The real facts are far more interesting than any made up science that you believe!

Check this out if you want to know the facts.

Answer 5

In NE US, why does fall come 4 weeks later, winter not come until mid January, and we get waves of 60 degree weather?

I predict in 20 years it will flip and the freezing and snow will be the weather that comes in brief waves; and winter will essentially disappear.  

You can't discount what you see with your own eyes.

edit:  Yeah, It's weather.  Early 60's cold, snow.  Late 60's to late 70's, warm rainy winters and no ice skating.  Late 70's to early 80's cold.  Since then, unpredictable, some warm years some cold, some snowy.  

However, an inexorable trend to warmer and more variable.  I have not ice skated since the early 1980's.  Snow and cold come in waves, some years 60 F in Jan and Feb.  Sept is now a summer month and Oct is always warm.  We don't get fall till after Halloween.    

This year something new, very strange, and was posted in an earlier question.  Fall came 2 weeks late this year.  Not the weather, but the leaves.  I have been cleaning up two properties since I was a teenager in the 70's and it goes like clockwork.  Can't do the last of the leaves until weekend after Thanksgiving, after they are all down.  This year they didn't come down until Dec. 15.  

I think the trees know something we don't.  You and the rest of the deniers that is.

Answer 6

Typical conservative lie. Man-made global warming and tobacco's link to cancer are ridiculous, but creationism should be taught in schools.

Love the way your source changes everything to come up with his conclusions. Change everything and you get a different answer...New scientific reasoning...lol

Answer 7

One of the sad things about this 'Man-did-it' global warming craze is that some of the same so-called climate experts on this 'bandwagon' were suggesting that we cover the Arctic with black soot (1970's) to avoid the 'Man-did-it' Ice Age that was supposedly beginning at that time.

Answer 8

Al Gores powerpoint presentation was complete c**p.  Its funny how his chart showed a straight line, up to where it just skyrockets, in a constant manner.  That is c**p, that is not what the records show.

No one knows what the "normal" temp is supposed to be, so no one can say for sure if anything is really happening or not.

Answer 9

The predictions are based off of models.  Models predict trends.  Climatologists predicted a range of possible scenarios based on observed trends.

They're not psychics.  If you expected the numbers to be absolutely on the dot, then you've a LOT to learn about science.

The trends, however, were generally correct...

In short, you're not asking a question - you're making an argument... one which you don't understand.  If I were you, I'd refrain from doing things like that.

Answer 10

Yes.  They can't identify, nor can they quantify all the variables that determine the average planetary temperature as a function of time.   That is why they they invented 35 different models, each generating a wide range of future predictions.  When operated in reverse to recreate climate history, they failed predict the last ice age, a temperature drop of -10C!!

Answer 11

I wouldn't trust a source that says, and I quote from your linked article, "I have done no statistical analysis of this; the observation is based on eyeballing the graph only."

This just simply doesn't sound very scientific to me. I bet that this guy will go on to misrepresent known science and cherrypick information.

Answer 12

If you over estimate a problem, you do too much to fix the problem, you end up creating another one.  There have also been NWS sensor violations.

I think that it is only a minor increase, not an apocalyptic climate change.

I saw the movie, 3 times (all at school and against my will).  What does losing the election and death of his friend from tobbaco have to do with climate change?  And how does making swipes at the current president help the cause?

Answer 13

Scary isn't it and to think they are showing the Inconvenient lie to our children in the public schools.

Answer 14

That realclimate rebuttal doesn't make any sense at all.  They're saying don't look at the temperature predictions vs actual temperatures - look at something we have absolutely no way of verifying - claimed effective forcing and you will see that the predictions were completely accurate.  

Needless to say climate scientists have since stopped believing in their own ability to predict the future and now only predict things that won't happen in their lifetimes.

gcnp58  what do you mean by physics?  We are talking about numerical models of a physical system - they are always based on an a vast simplification of what actually happens.  Generally a model won't be accepted by the scientific community untill it actually predicts something before it happens.  Climate change models seem to be the exception.

Answer 15

I've only read Pielke's piece (I think you posted a link to it a couple days ago) on the matter so far, which I, even with my meagre knowledge of statistics, found to be very poor. So I'll have to do some more reading on it before commenting.

Have you read the discussion over at RealClimate yet? You might find it interesting:

http://www.realclimate.org/index.php/arc...

Answer 16

'A spokesman for the Royal Society, Britain's leading scientific academy, said: "At present there is a small minority which is seeking to deliberately confuse the public on the causes of climate change.

They are often misrepresenting the science, when the reality is that the evidence is getting stronger every day.'

Answer 17

Whether or not the degree of warming was overpredicted, the fact is that warming is occurring, and that ice melt in the Arctic, Greenland and Antarctica is happening much faster than anyone thought possible. There is news about these things nearly every day, a good science source is livescience.com.

Answer 18

If it justifies your choice in buying the Cadillac vs. the smart car, go for it. However, the smart cars of the future will probably double as life rafts after the floods come. I may still pick up you up thumbing on the highway if gas rationing strands your Cadillac though....

Answer 19

Really... Check out the Al Gore presentation.  U can rent it at any block buster. Besides, I would rather they over estimate it than underestimate it!

Answer 20

I agree with Dana.  None of this calls into question the physics of the problem, which simply state that the increase of CO2 due to man is now causing a 1.6 W/m^2 radiative forcing.  That heat has to go somewhere, and as it redistributes, climate changes.  If you don't believe that, you have to explain where the physics is wrong.  Do you doubt man is affecting atmospheric CO2 levels?  Do you doubt that radiative transfer, which is based on work done by Chandrasakhar in the 50's, is correct?  Do you think 1.6 W/m^2 is too small to effect anything?  Do you think the redistribution of heat won't affect climate?  Where is the fundamental flaw in the physics that causes you to believe there is not a problem?

Aside from a strong bias towards disbelief because you don't like the implications, what are your scientific objections to the physics outlined above?  You need to be specific because at this point, guys like Pielke are just looking like scared kids, raising objection after objection as to why they can't enter a darkened room to turn the light on.