Anthopogenic Global Warming Myth or Real ?

[AOK Tiger]

I know this is revisiting old territory but I vacillate on this issue so often it deserved another look.

I used to be a strong Anthopogenic (Man Caused) Global Warming (AGW) Skeptic

Sheer weight of numbers of reputable scientists who agreed that AGW was real convinced me there was something to it.

Now I’m not so sure …

Global temperatures have not increased in the past 8 years.. many people are starting to rethink wether AGW does exist.

Here is a good un-hysterical example.

http://xtronics.com/reference/globalwarming.htm

The simple thing is.. we constantly ask for evidence here.. the evidence for AGW is getting thinner and thinner.

Any one here who still believes in AGW ?

 

[jmercer]

Moved from General Skepticism.

Replying to this modbox in thread will be off topic  Posted By: jmercer

 

[a_unique_person]

The global warming folks think that the man's output of CO2 is causing the climate to grow significantly warmer due to a ill named� "green-house" effect. (The glass in a green-house prevents�convection -- obviously� CO2 �does not limit convection and its effect on global temperature should go by a different name.) � This warming is referred to as AGW(Anthropogenic Global Warming). The word 'anthropogenic' meaning 'caused by man'. The warmers think that the slight warming seen in lower troposphere satellite data above is in error and problematic ground station temperature measurements that show a slightly larger warming trend is caused almost entirely by a slight elevation in CO2 levels. The warmers state that solar effects are insignificant.

It is not ill named, it is an attempt to describe something that is highly complex with a simple metaphor. The 'leaky bucket' effect that someone mentioned here the other day would also be a reasonable metaphor, but, once again, there are no big, leaky buckets floating around in the sky.

The 'solar effects' statement is slightly misleading. The sun is primary driver of the planets temperature. What is of interest is what is changing the temperature.

There have been several problems to date with the satellite record, too, since it is not actually a direct measurement, but inferred from readings. The UAH record has had to be updated several times. That's not to say that it's wrong now, but it has been just as problematic as the ground station readings.

 

[Dancing David]

I am on the fence leaning towards AGW, the data is what it is, and it is what we have to work with. It will get better as time goes by and we will get a clearer picture. I think that despite what the shills who work for big oil have to say we should try to switch off the burning of fossil feuls. If the trends of warming continue it could lead to serious drought in the Midwest of the USA. that would be bad for me.

AGW sceptics seems to be playing some strange games to amke their point.

PS One strange game mentioned above, AGW sceptics scream about how the sattelite data supports them, until it doesn't.

Lake sediments seem to show an overall warming trend.

 

[a_unique_person]

First, you have to prove that the increase in CO2 is caused by humans - the venting of CO2 by volcanoes (including those under the ocean) and geysers and other natural sources (and also the natural absorption or sinking of CO2) is a estimate that defies error analysis. To what error band are we certain of the amount of emission of CO2 by natural causes?

That's just wrong. It's quite possible to measure the content of CO2. It's also quite possible to estimate how much we are producing. It's also possible to measure the 'anthropogenic' component using a method similar to carbon dating. Volcanoes and other sources could be adding extra CO2, but volcanic activity doesn't seem to be any different now to what it was, but the amount of CO2 we are producing certainly is. A lot of work has been put into answering this question, and the answer is pretty clear, it's us.

 

[lomiller]

Global temperatures have not increased in the past 8 years.. many people are starting to rethink wether AGW does exist.

The year to year variation in global temperature is 0.5 deg or more, the expected temperature rise per year is only 0.02 deg. Over a short 5-10 year period you can buck the trend simply by starting on a warmer then average year, or ending of a cooler then average one.

There are also a lot of poorly developed trend lines floating around the blogshpere. The correct way to do the trend line is to take a long period of data, 50-100 years, and calculate its trend and then look at just the last few year. This is still subject to the error I mentioned above but it keeps it to a minimum. When you do the trend this way you still get a positive, though slightly flattened trend.

 

[varwoche]

Global temperatures have not increased in the past 8 years

I take it you read an old article and really mean 9? This falsehood is based on using a spike year (1999, unusually warm due to el nino) as a starting point.

many people are starting to rethink wether AGW does exist.

Not people who matter, namely expert scientists.

The simple thing is.. we constantly ask for evidence here.. the evidence for AGW is getting thinner and thinner.

Maybe in the alternate universe you occupy, but not in the real one.

 

[mhaze]

....a good un-hysterical example.

http://xtronics.com/reference/globalwarming.htm

The simple thing is.. we constantly ask for evidence here.. the evidence for AGW is getting thinner and thinner.

Any one here who still believes in AGW ?

Warmers Believe in the Great Warming To Come, the Sliding Ten Year Forecast of Doom.

Cognitive Dissonance at work, likely.

 

[Piggy]

Warmers Believe in the Great Warming To Come, the Sliding Ten Year Forecast of Doom.

Cognitive Dissonance at work, likely.

[qimg]http://www.internationalskeptics.com/forums/imagehosting/thum_14224486460913405e.png[/qimg]

mhaze, glad you're here. If anyone can convince folks that the anti-AGW argument is without merit, you can.

You'll be doing the pro-AGW posters a great favor by providing them with a shooting gallery of erroneous arguments to knock down.

 

[lomiller]

I can only speculate what the source of the information in mhaze’s plot is, but it looks like the same rehashed and debunked argument that Hansen’s model must have been flawed because when it's fed incorrect CO2 emissions it doesn't produce accurate results. The problem with this particular line of reasoning should be obvious…

 

[sol invictus]

Any one here who still believes in AGW ?

It often helps to separate two issues:

1) are global temperatures increasing (and/or is the climate changing in some other unusually rapid way), and, if the answer is yes,

2) is the change caused by human activity.


I'm not an expert in this topic, but from what I know it seems very unlikely that the answer to 1) is negative. Arctic sea ice, the opening of a northwest passage, glaciers retreating, and other highly visible evidence is alone nearly enough to convince me, and then there is satellite data, average ground-based measurements, etc., all of which indicate increasing temperatures.

As for 2), there are many good physics reasons to expect human activity and increasing CO2 concentrations to affect the climate. In my opinion (based on what limited knowledge of the topic I have) one can be reasonably confident in the theory and simulations, with the caveat that the system is highly complex and non-linear. So while I don't think the results are rock solid, I do think they are largely correct. Given that the climate is indeed changing and that our best simulations indicate that the reason is anthropomorphic, the burden of proof lies very heavily on skeptics.

How to apply this conclusion to public policy is another question, but that's not what you asked.

 

[mhaze]

I know this is revisiting old territory but I vacillate on this issue so often it deserved another look.

I used to be a strong Anthopogenic (Man Caused) Global Warming (AGW) Skeptic

Sheer weight of numbers of reputable scientists who agreed that AGW was real convinced me there was something to it.

Now I’m not so sure …

Global temperatures have not increased in the past 8 years.. many people are starting to rethink wether AGW does exist.

Here is a good un-hysterical example.

http://xtronics.com/reference/globalwarming.htm

The simple thing is.. we constantly ask for evidence here.. the evidence for AGW is getting thinner and thinner.

Any one here who still believes in AGW ?

D. KOUTSOYIANNIS, A. EFSTRATIADIS, N. MAMASSIS & A. CHRISTOFIDES “On the credibility of climate predictions” Hydrological Sciences–Journal–des Sciences Hydrologiques, 53 (2008).

Abstract “Geographically distributed predictions of future climate, obtained through climate models, are widely used in hydrology and many other disciplines, typically without assessing their reliability. Here we compare the output of various models to temperature and precipitation observations from eight stations with long (over 100 years) records from around the globe. The results show that models perform poorly, even at a climatic (30-year) scale. Thus local model projections cannot be credible, whereas a common argument that models can perform better at larger spatial scales is unsupported.”

Climate models have no predictive value.

 

[sol invictus]

D. KOUTSOYIANNIS, A. EFSTRATIADIS, N. MAMASSIS & A. CHRISTOFIDES “On the credibility of climate predictions” Hydrological Sciences–Journal–des Sciences Hydrologiques, 53 (2008).

I took a look, but I found myself pretty confused about something. Take a look at figures 4 and 5 in the paper. Why did they only use Albany for their comparisons with the models? I didn't find anywhere in the text where they justify that.

At least superficially it looks like they just picked the data that would give the worst agreement with climate models. There's a very large deviation among the measurements shown in figure 4, and so unless the models are very accurate in both time and space, you're always going to be able to find a bad fit with some of them. The one they picked is the one that's farthest from a gradual increase in temperature (at least by eye).

So as far as I can see, their analysis shows that climate models are very bad at predicting the climate in Albany - no more, and no less. The models might be good or predicting the climate in other locations - the paper doesn't address that (despite having all the data available for at least 7 more) - and they might be good at predicting the spatially averaged climate - the paper doesn't address that either.

Am I missing something? If not, I must say I don't find the paper very interesting.

 

[lomiller]

Climate models have no predictive value.

Wow, such a sweeping conclusion based on *8 stations*

 

[Pipirr]

Wow, such a sweeping conclusion based on *8 stations*

Not to mention, based on just one paper.

 

[Pipirr]

mhaze, glad you're here. If anyone can convince folks that the anti-AGW argument is without merit, you can.

You'll be doing the pro-AGW posters a great favor by providing them with a shooting gallery of erroneous arguments to knock down.

Indeed, every Socratic dialogue had it's dim interlocuter.

 

[sol invictus]

Wow, such a sweeping conclusion based on *8 stations*

But it wasn't - it was based on one! If you look here you can find the rest of their data (which was left out of the paper). It's clear from the plots that Albany is by far the worst fit to the models. Another odd thing is that none of the models agree with data even at the first year shown on the plots. What kind of initial conditions are they using? Normally one would set the initial conditions using data from the first year, and then run the simulation, no?

The fact that they picked the worst fit to show in their paper - without any comment that that's what they were doing - is disturbing to say the least. I would never let something like that go by as a referee. It's either dishonest, or merely strongly seems so - either way, it stinks.

If this is the level at which this kind of science gets done, no wonder it's so hard to determine the facts.

 

[lomiller]

But it wasn't - it was based on one! If you look here you can find the rest of their data (which was left out of the paper). It's clear from the plots that Albany is by far the worst fit to the models. Another odd thing is that none of the models agree with data even at the first year shown on the plots. What kind of initial conditions are they using? Normally one would set the initial conditions using data from the first year, and then run the simulation, no?

 

[Spud1k]

But it wasn't - it was based on one! If you look here you can find the rest of their data (which was left out of the paper). It's clear from the plots that Albany is by far the worst fit to the models. Another odd thing is that none of the models agree with data even at the first year shown on the plots. What kind of initial conditions are they using? Normally one would set the initial conditions using data from the first year, and then run the simulation, no?

The fact that they picked the worst fit to show in their paper - without any comment that that's what they were doing - is disturbing to say the least. I would never let something like that go by as a referee. It's either dishonest, or merely strongly seems so - either way, it stinks.

If this is the level at which this kind of science gets done, no wonder it's so hard to determine the facts.

Stuff like this is really just trying to muddy the waters. The conclusion that human activity is warming the planet is based around one key variable - the mean surface temperature. As soon as you start making the comparisons more and more specific, e.g. by comparing to a discrete site, the models are going to perform less well. There's no news there and it certainly doesn't prove the models don't work.

 

[sol invictus]

mhaze, you brought this up and claimed it meant that "climate models have no predictive value". So you've obviously read the paper and understand why the problem I raised isn't an issue.

Care to comment?

But it wasn't - it was based on one! If you look here you can find the rest of their data (which was left out of the paper). It's clear from the plots that Albany is by far the worst fit to the models. Another odd thing is that none of the models agree with data even at the first year shown on the plots. What kind of initial conditions are they using? Normally one would set the initial conditions using data from the first year, and then run the simulation, no?

The fact that they picked the worst fit to show in their paper - without any comment that that's what they were doing - is disturbing to say the least. I would never let something like that go by as a referee. It's either dishonest, or merely strongly seems so - either way, it stinks.

If this is the level at which this kind of science gets done, no wonder it's so hard to determine the facts.