Global Warming

[polymath]

So less light is reaching the surface, and it's caused by global warming?

No, we have two phenomena - global warming, and global dimming. Nice attempt at not understanding, BTW.

I'll run through it slowly.

a) Less light is reaching the Earth's surface. Fact.

b) The Earth is getting warmer. Fact.

At the bare minimum you must admit that very weird things are happening in the atmosphere and it's 99% likely it's thanks to homo 'sapiens'. If you want to say '...but it's complicated', that's fine by me. I'd be very surprised if climate modellers had an accurate picture of how it works, but we aren't discussing climate modellers, we're discussing the climate itself. I thought that was obvious, but then I thought global warming was obvious too, and I'm rarely wrong.

 

[gene90]

no, @ you!


past temp spikes are usually easily explained, by models, too.

When I am a professor, I am going to make absolutely sure my students know the difference between a model and reality.

Are you also a closest geocentrist?

 

[gene90]

At the bare minimum you must admit that very weird things are happening in the atmosphere

Nope. You have a very short interval at which we've even been collecting data, you have no ground to declare what is 'weird' and what isn't.

but we aren't discussing climate modellers, we're discussing the climate itself.

Everything we allegedly know about global warming is coming from models.

I thought that was obvious, but then I thought global warming was obvious too, and I'm rarely wrong.

Sure, buddy.

I'm preparing to resign from this debate. I have made my case, and all that remains is to question your understandings of science.

 

[polymath]

Hold on to your hat, Gene. You haven't made your case.

20% + drop in solar radiation levels hitting Israel since the 50s.
10% + drop in the US
30% in parts of Russia
15% + in the UK

Not models. Fact. Overall average drop of 1-2% in solar radiation hitting the Earths surface per decade since the 50s. Fact. Still, if you want to stroll around denying facts, there's no helping it.

 

[Pikachu]

And what you don't understand Pikachu, is that the cause of previous fluctuations in climate is irrelevant. What is relevant is what the cause wasn't: industrial CO2 emissions.

It is of course also irrelevant that it wasn’t industrial CO2 emissions last time if that is the case this time.

The argument being that climate has been warming along the same orders of magnitude before there was industrial CO2 emission. Therefore, there is no reason to automatically assume that the current warming is the result of CO2 emission.

Has anybody automatically assumed that the current warming is a result of CO2 emissions?

What can I say, other that in being a "newbie" to this site, I am highly disappointed by the low level of comprehension a lot of you have of the argument...

Is your disappointment specific to our comprehension of your strange arguments about global warming or is it our debating style in general that disappoints you?

Then it would have to be CH4 instead of CO2. And regulating CH4 emission is a completely different ballgame from regulating CO2!!

Why would it have to be CH4 instead of CO2 if it was caused by nature? I thought nature was also capable of releasing huge amounts of CO2 naturally. Maybe you could elaborate a little on why it would have to be like you claim?

In nations like Norway, which if memory serves me, get 25% of their power from hydro

Your memory clearly doesn’t serve you! Electricity production in Norway is almost exclusively based on hydropower. Something like 99% of the electricity produced on the Norwegian main land comes from hydropower!

Besides, you should know as well as anyone that CO2 concentrations are up past 300 ppm, and that this hasn't happened in the last 10,000 years. Therefore, logic would dictate that we should be much warmer than any previous time in the last 10,000 years, assuming GHGs cause global warming.

Yes it would have been a few degrees hotter right now if it weren’t for the steady increase in human production of aerosols that blocks incoming sun rays and thus cancels out most of the increased greenhouse effect. Unfortunately this balance will probably not be maintained much longer. You have to look at more than just one single factor to explain the climate!

No, no, no!

Again you are confusing models with the real world! The geocentric view is invalid because we have direct observational evidence that the Sun is the center of the Solar System! And we have had this evidence for 400 years.

What is that evidence?

Just because you can force a geocentric model to work mathematically does not mean a geocentric model is 'equally correct' with the heliocentric model. The problem with the geocentric model is that it directly contradicts observational evidence (the moons of Jupiter and Saturn, the phases of Venus).

A geocentric model will give the exact same results as a heliocentric model if you convert the coordinates correctly. There are absolutely no fundamental differences. The only difference is that the heliocentric view gives shorter equations that looks nicer, so obviously most people prefer to use that coordinate system, but it is no more correct than any other consistent coordinate system. The choise of reference point only gives cosmetic implications to a model. Personally I prefer to define the moon as the center of the universe.

Because those "other factors" are poorly constrained. But go ahead and try if you like. You just need to admit that there are a lot of other variables that could mitigate, even cancel out, global warming.

There sure are, and there are lots of other variables that could amplify it too. It is hard to know which way the feed back mechanisms will go. Maybe some scientists who have worked on this a whole lifetime could give us some answers?

That means that the CO2 imprint on the climate is not very significant.

Or maybe it means that some other factors imprint on the climate also are significant?

 

[Gothmog]

Hey Gothmog,

You can cut down on the arrogance. I can't swing a dead cat in the adjacent hallway without hitting a physicist. There are plenty of geologists and climate people upstairs. I'm not particularly impressed by, or interested in, your opinion on the philosophy of science.

If you want continued correspondence with me, you will behave.

It seems to me that you are the one misbehaving. I have never told you what you think. Just because you rub shoulders with scientists doesn’t mean you know anything about metaphysics. I’ll say it again ‘truth is irrelevant to science’. I happen to believe that accumulated scientific knowledge is as close to truth as humans can achieve, but that is an unsubstantiated belief on my part. It is the predictive nature of science that makes it unique, and that has nothing to do with truth.

And I have removed references to the 1991 paper, but I still am not convinced by your discrediting of it.

What’s to be convinced? The plot showed correlation between recent warming trend and the 11 year sun spot cycle that is related to solar output. This was when the cycle was in an upward trend, now that it is going down we can totally dismiss that earlier plot as irrelevant.

You didn’t even know it was a plot of the sun spot cycle iirc.

Now back to the science.

Can you at least answer this question?
From my last post:

you agree that the insulation has increased significantly due to anthropogenic activities – primarily greenhouse gasses. I’m sure you took Chem and Phys in college. What happens to a gas when it absorbs more radiation?

Oh, and the global dimming is data from ground based sensors, of the type I mentioned.

Look again at this post: http://forums.civfanatics.com/showpost.php?p=2560752&postcount=358

Do you see the negative forcings labled ‘reflective aerosols’ and ‘aerosol indirect’ ? What do you think those represent?

I don’t know why you think that the top scientists in the climate change arena are not aware of the data that they collect. They help design the sensors, they advise as to where money should be spent, etc. etc. They know about these things typically years before the published reports hit the presses.

I said from the very beginning that the indirect effects of aerosols was the biggest remaining uncertainty in anthropogenic climate change. And I mentioned secondary effects (ocean warms, more water vapor, more clouds, increased albedo).

But none of this changes the fact that greenhouse gasses are significantly affecting the radiative balance of the earth system.

Anthropogenic climate change is a fact, ‘global dimming’ is just another reflection of this established consensus.

 

[gene90]

Hold on to your hat, Gene. You haven't made your case.

Go back and read message #184.

Not models. Fact. Overall average drop of 1-2% in solar radiation hitting the Earths surface per decade since the 50s.

Uh huh.

First of all, you should know that, according to Gothmog, truth does not exist. Therefore, this is not "fact".

Second of all, this alleged observation is not included in any of the GW models. Nor did Gothmog's people detect in satellite measurements.

An allegedly major shift in climate went in almost completely under the radar.

That means that either you are wrong about "global dimming", or that the GW proponents don't actually understand climate. I find both possibilities equally credible.

Still, if you want to stroll around denying facts, there's no helping it.

Denying "facts", eh?

Is anybody even going to attempt finding a correlation between CO2 and temperature?

The article also said that it did not quite have a consensus, that the last IPCC report didn't even mention it (kind of like they didn't mention the Little Ice Age )

 

[gene90]

Just because you rub shoulders with scientists doesn’t mean you know anything about metaphysics.

No, but it does mean that your opinion is not particularly credible to me. Especially when making an absurd claim like this one.

It is the predictive nature of science that makes it unique, and that has nothing to do with truth.

Yes, science can be predictive, but even a predictive model is no good when it contradicts observation. (How many times have I repeated this?)

I don’t know why you think that the top scientists in the climate change arena are not aware of the data that they collect.

Umm, because the article in the Guardian said so?? And quoted modelers who said so? Now, if the Guardian got that wrong (wouldn't be the first time they're wrong) you can't exactly blame me for it.

ONCE AGAIN, where is the correlation between CO2 and climate? I have no intention of continuing in this debate (it is a waste of time) without it.

 

[Gothmog]

gene, now I am embarassed for you.

Please think before you post.

The phenomina of 'global dimming' is in the plot I gave, very clearly; and as I mentioned this was from a preprint of a paper that is due to come out sometime this year. Or early next if it gets stuck in review for a while.

If you want to take a newspaper article as a higher source than a journal article, then you will never be a professor. Look at the link polymath posted again, you will see articles dating back to 2003 or earlier. The Guardian didn't get anything wrong, it is just supposed to be reporting news to laypeople, it is not supposed to be a source of cutting edge science.

I can understand why you would want to end this debate.

 

[gene90]

Ok, fine, I concede the point. Sorry, I forgot that it was a preprint.

Thank you for concern for my career.

I am serious about my demand for statistical correlation. Either one will be posted by somebody, or my participation will end. This is not negotiable.

What you fail to understand is my perspective: until you can test the hypothesis (prove a real-world statistical link) I consider it unsubstantiated.

You can call it ignorance if you want, I consider it a cultural difference between modelers and observationalists.

In fact, I'll toss in a carrot with the stick. I have no problem with conceding defeat to a 'true' idea. If you can generate an r value of 0.7 or higher, that will fit my standard for truth and I will concede the entire debate. However, that correlation is what I need to accept the idea.

 

[Gothmog]

gene90 sent me this PM

I am tired of beating around the bush with that correlation. Without it, I consider GW (and all your models) fully discredited. In fact, my continued participation may be contingent upon it.

gene90. I have tried to be patient with you.

I have tried to describe the science, I have outlined what is meant by a 'forcing' and a 'process model', you are not trying to understand.

We have a very good idea of what the forcings on our current climate are. Greenhouse gasses are a significant factor (CO2 is only one greenhouse gas), as can be seen in the plot I refer to above.

You even agreed to this at one point.

The plot also shows very clearly the negative forcings caused by aerosols. (the global dimming).

You have not put forth any alternative theory, nor have you discredited one thing that I have put forth on this topic.

You have repetedly posted things that you do not understand, and made childish remarks.

At this point you may want to cut your losses, and run off with your tail between your legs.

Edit: As you know, it would be easy for me to produce such a plot. All I would have to do is just look at the last 4 years. Temp has been increasing, and CO2 has been increasing over this time period. This would prove nothing.

 

[gene90]

gene90 sent me this PM gene90. I have tried to be patient with you.

I did indeed send the PM. I sent Carlos one similar.

I fully intend to leave the debate if no one will perform the statistical test that I have asked for. I fail to understand why it is such a big deal. 10Seven, in fact, has repeatedly stated that such a correlation is possible. In fact, I have even agreed that a regression coefficient equal to 0.7 or higher will be grounds for concession. Still, no plot.

Is there a reason you don't want a correlation, Gothmog?

You have not put forth any alternative theory

Fallacy: shifting the burden of truth.

The truth or non-truth of your hypothesis is not contingent on a replacement.

At this point you may want to cut your losses, and run off with your tail between your legs.

If you need that kind of justification, Gothmog, it is fine by me if you believe it.

For one with your arrogance, you spend a lot of time arguing with the unwashed.

What's more interesting to me, Gothmog, is that you, the "expert" has not contributed much of anything of value. You posted some model outputs, and that was it. You have not made the connection to the real world.

Edit: As you know, it would be easy for me to produce such a plot. All I would have to do is just look at the last 4 years. Temp has been increasing, and CO2 has been increasing over this time period.

It would be easy. Why haven't you?

Look! A dataset!

http://vortex.nsstc.uah.edu/data/msu/t2lt/tltglhmam_5.1

And somebody else has already plotted it for you!

Now, who wants to test the hypothesis that 2004 was warmer than 1978?

 

[Pikachu]

It would be easy. Why haven't you?

Why do you ask when Gothmog already has answered:

This would prove nothing.

 

[gene90]

Hey Pikachu;


As usual, I disagree with Gothmog. A significant correlation between CO2 and temperature would imply (not "prove") that one is controlling the other. You would need that correlation if global warming is true. I know we disagree about how much other factors affect that relationship: paradoxically, you believe that aerosols will destroy the correlation in the short term, while at the same time, you insist that natural variants like aerosols will not protect us from anthropogenic global warming! I am intrigued by how global warming can be "massive" and yet "weak" or "statistically undetectable", depending on which would benefit GW proponents at the time!

Gothmog is partially correct. A strong regression coefficient would not prove that CO2 drives temperature up. However, no correlation would "disprove" (actually strongly undermine) global warming. That's what I am interested in, not what such an analysis would prove, but what it could potentially disprove. (This is why performing my test would not be in Gothmog's best interests. He has nothing to gain, and potentially everything to lose. Perhaps by offering the possibility of concession, I can increase interest in the test?)

Or in other words, if global warming is real, then more CO2 should cause temperatures to go up. And we are pumping more CO2 into the environment right now...therefore there should be an observed increase in surface temperature. This would not "prove" global warming because there is a possibility of coincidence, though unlikely. However, for global warming to be true, as long as CO2 concentrations increase temperature must increase. If there is a known and quantifiable reason for temps not to increase, then I will soften the demand and allow its inclusion into the plot. But there will be consequences. If we have to include other variables to make it work, there should be a concession that there are other climatic factors that could potentially overpower GW. Also, I require that models not be used in this analysis. All data must be derived from observations of the real world.

It is my opinion that the consistent refusal to comply with this test constitutes ideological protectionism, and is evidence that GW is non-falsifiable. I've learned more about the debate since I got here, the remote sensing data tempts me over to the GW side. (When you move Gothmog away from models, the science he presents is quite good.) But until this observational issue is dealt with, I cannot concede the debate with a clear conscience.

Now, the plot above is from a politically biased site and probably should not be trusted at face value. But the data that is plotted is linked to above, and is from US government sources that tend to be sympathetic to global warming. If anyone happens to have a stats packages like SAS they could generate an expression of how confident we are that 2004 is warmer than 1978. Scuffer pointed out that I won't get a 99% or 95% CI. At this point, though, I've given up on that request and would be happy to just to know what CI we can get for the hypothesis, and whether the hypothesis, when tested statistically, is accepted or rejected. This would be a good start, I think, to fulfilling my concerns about GW in the real world, and would actually bring more data into this debate, the quality of which is in steady decline (and I take a lot of the responsibility for that).

Anyway, here is a global temperature anomaly dataset:
http://vortex.nsstc.uah.edu/data/msu/t2lt/tltglhmam_5.1

Along with some other links:

Here's a 2003 article about solar forcing:
http://www.csmonitor.com/2003/0717/p12s02-stss.html

A paper in Proceedings of the National Academy of Sciences
http://www.pnas.org/cgi/content/full/97/23/12433

Geophysical, archaeological, and historical evidence support a solar-output model for climate change
Charles A. Perry* and Kenneth J. Hsu
* U.S. Geological Survey, Lawrence, KS 66049; and Tarim Associates, Frohburgstrasse 96, Zurich, Switzerland 8006

Contributed by Kenneth J. Hsu, September 5, 2000

From the abstract: Extrapolation of the model into the future suggests a gradual cooling during the next few centuries with intermittent minor warmups and a return to near little-ice-age conditions within the next 500 years. This cool period then may be followed approximately 1,500 years from now by a return to altithermal conditions similar to the previous Holocene Maximum.


From the paper:

Current global warming commonly is attributed to increased CO2 concentrations in the atmosphere (3). However, geophysical, archaeological, and historical evidence is consistent with warming and cooling periods during the Holocene as indicated by the solar-output model. The current warm period is thought to have not reached the level of warmth of the previous warm period (A.D. 800-1200), when the Vikings raised wheat and livestock in Greenland. Therefore, the magnitude of the modern temperature increase being caused solely by an increase in CO2 concentrations appears questionable. The contribution of solar-output variations to climate change may be significant.

Emphasis mine.

Hmm, looks like their model is different from GothMog's.

 

[Gothmog]

It is irrelivant to the issue at hand. One would need to decide which data to use, which to discard, what time period to use, what smoothing algorithm to apply, etc. etc. This is done by experts who spend their lives at it.

Then we could argue over those details.

If you want to look at the data (from a better source than 'junkscience', http://www.cru.uea.ac.uk is a repository for temp data and http://cdiac.esd.ornl.gov/trends/co2/sio-mlo.htm for CO2 data

If you can't see that I have posted anything of value, then you have not been following.

I did discredit the one mechanism that you claimed could explain all climate variability, leaving no room for anything else, if you will remember. You haven't responded to my most recent explanation of why your plot was a silly thing to have posted.

I posted a chart of all the forcings believed to be important to climate. This is where the science is, it shows greenhouse gasses along with many other important forcings.

Also, as to global dimming you will see an older version of this type of forcing plot in the 1991 IPCC report (which I already suggested you read). The 'global dimming' is there too, it just has much larger error bars. It's best not to get your science from newspapers.

I've described the science behind most of the important process models that make up a climate model. You have not even disputed a thing, any one of these could be falsified. You don't even want to discuss the science.

I can't tell why you disbelieve anthropogenic climate change.

As to why I post here. I like to debate, I miss the back and forth of college. I also like to find out if there is 'smoke' behind the 'fire', it helps me refine my ideas, in this case I have found none.

If you want to talk about what science is then here:

In climate science model results are compared to data (I've already described both), and if there is a mismatch, both the data and the models are re-examined. Sometimes the models need to be improved, sometimes the data was mis-interpreted. Then work is done to improve the model, and collect more and better data. Then we again compare model results to data. This process leads to an improved match between the model and the data. That is in fact pretty close to the textbook definition of science, wouldn't you agree?

 

[Gothmog]

Didn't we go over this solar hypothesis before?

You will notice that that paper is from 2000, which means the work was done in 1999 or so. Right before the solar trend turned over, as represented in the forcings I gave earlier.

Also, no one is saying that recent warming is soley due to CO2, I gave the forcings already. Please deal with that.

Just for fun (and because it's lunch time). I made you a plot of temperature anomalies vs. CO2 level.

The data came from the web sites I link to above, and I used data from 1976 onward (annual average for CO2). I could have fudged things (like removing that first point that is quite a bit off the line), but I didn't have to.

Here's the plot with the correlation coefficient:

and here's an even better plot if I apply a running average to the temperature anomalies, as is typically done in plots of this type.

Still doesn't prove a thing though. The science is in the process models and detailed data sets.

 

[gene90]

It is irrelivant to the issue at hand. One would need to decide which data to use, which to discard, what time period to use, what smoothing algorithm to apply, etc. etc. This is done by experts who spend their lives at it.

If Global Warming is as serious as is commonly implied, then the signal should be strong enough that the above concerns wouldn't be an issue.

You're basically saying that we have do a lot of weird things (cooking, processing) the data before we can test GW. That's not what I like to hear when evaluating a hypothesis. It is a bad sign, and worthy of raising suspicion.

If you want to look at the data (from a better source than 'junkscience', http://www.cru.uea.ac.uk is a repository for temp data and http://cdiac.esd.ornl.gov/trends/co2/sio-mlo.htm for CO2 data

The data did not come from Junkscience, it was plotted by Junkscience. I posted the chart, mentioned a warning about the bias of the site, and included a link to the source of that data, a government website. Which, I think, should be trustworthy. But if the above is the same thing, a data repository, so be it. We can use that if you'd prefer.

I did discredit the one mechanism that you claimed could explain all climate variability

Not to my satisfaction. There is a similar figure in the AAPG Bulletin article. While you don't approve of the venue through which the graph was distributed, the data it is derived from was attributed to Bond, who I seem to remember is the author of the infamous Cosmic Rays and Climate. The author (in the AAPG plot) used 10Be as a proxy for solar input over the last 150 years. And got an interesting result. So, even if you have a problem with the Lanssen paper, the solar forcing argument still refuses to die.

Have you seen this?

http://www.pnas.org/cgi/content/full/97/23/12433#SEC4

I quoted it extensively above. You apparently need institutional access, the top of the page I have says it recognizes the institution behind my IP, apparently we subscribe.

Since you're good at this sort of thing, can you confirm if PNAS is peer-reviewed? (Seems to be by the submission guidelines, though I have been burned by this already in this thread.) And the ISI rating?

leaving no room for anything else, if you will remember.

Yes, Gothmog, I remember. See, that is the only thing I regret saying. If I had left in the Lanssen paper I wouldn't be embarrassed. But you seem to have a fascination with that comment.

The 'global dimming' is there too, it just has much larger error bars. It's best not to get your science from newspapers.

I prefer newspapers to political orgs like the one Polymath used in the original post. (You didn't comment on that. In fact, I'm sure you disagree with the other GW proponents on some things and aren't attacking them) Though I will take what is convenient.

I can't tell why you disbelieve anthropogenic climate change.

I'm cynical. If you look at Betazed's poll, I actually gave anthropogenic climate change a 5 (on a scale of 1 to 10) as to whether or not it was good science. The problem is that you're not convincing me. What I find convincing is more in the way of real-world observation. Such as this statistical analysis all of you refuse to have any part of. Now, that remote sensing data was good, but incomplete.

it helps me refine my ideas, in this case I have found none.

Well, Gothmog, since you're an "expert" in this issue, maybe you should go find other "experts" to argue with. I immediately admitted that you know more about climate change than I do. In something my second or third post in this thread. Maybe instead of deriding my "ignorance", you should reinvest your time elsewhere. Or else don't complain about the current quality of conversation. You have nothing to prove, nothing to gain with a "victory" against someone who admits being less informed, nobody is forcing your participation, and I don't particularly appreciate your arrogance.

This process leads to an improved match between the model and the data. That is in fact pretty close to the textbook definition of science, wouldn't you agree?

Yes, except that while it is ok to be skeptical of interpretations of data, when models and data contradict, it is the models that are wrong. The purpose of science is more or less to explain the natural world, correct? Models are abstractions of the natural world, correct? How do we know anything about the natural world? Observation, right?

Observations are always a step closer to the natural world than models, which are a secondary means of obtaining information. And without good observation, models are invalid. Therefore, observation takes priority.

 

[gene90]

Didn't we go over this solar hypothesis before?

Well, then, I concede that anthropogenic CO2 appears to have a strong effect on climate. That is the kind of data I listen to, not models. More of this please.

The problem is how it is to be reconciled with the AAPG article, which I still find credible. But that burden of proof is not on you.

 

[gene90]

You will notice that that paper is from 2000, which means the work was done in 1999 or so. Right before the solar trend turned over, as represented in the forcings I gave earlier.

You didn't read the paper, did you?

About the methodology, taken from the abstract:

Reported cycles in various climate-proxy data show a tendency to emulate a fundamental harmonic sequence of a basic solar-cycle length (11 years) multiplied by 2N (where N equals a positive or negative integer). A simple additive model for total solar-output variations was developed by superimposing a progression of fundamental harmonic cycles with slightly increasing amplitudes. The timeline of the model was calibrated to the Pleistocene/Holocene boundary at 9,000 years before present. The calibrated model was compared with geophysical, archaeological, and historical evidence of warm or cold climates during the Holocene. The evidence of periods of several centuries of cooler climates worldwide called "little ice ages," similar to the period anno Domini (A.D.) 1280-1860 and reoccurring approximately every 1,300 years, corresponds well with fluctuations in modeled solar output. A more detailed examination of the climate sensitive history of the last 1,000 years further supports the model. Extrapolation of the model into the future suggests a gradual cooling during the next few centuries with intermittent minor warmups and a return to near little-ice-age conditions within the next 500 years.

Not exactly dealing with solar cycles in real time, therefore unaffected by the turnover. In fact, this work was cited in December of 2004 in Astronomy and Astrophysics Review (12 (4): 273-320 DEC 2004) by Frohlich C and Lean J, who came to a similar conclusion about the magnitude of solar variation:

Electromagnetic radiation from the Sun is Earth's primary energy source. Space-based radiometric measurements in the past two decades have begun to establish the nature, magnitude and origins of its variability. An 11-year cycle with peak-to-peak amplitude of order 0.1 % is now well established in recent total solar irradiance observations, as are larger variations of order 0.2 % associated with the Sun's 27-day rotation period. The ultraviolet, visible and infrared spectral regions all participate in these variations, with larger changes at shorter wavelengths. Linkages of solar radiative output variations with solar magnetism are clearly identified.

Come to think of it, you haven't actually read any source I gave you, except Lanssen?

And, while I'm at it, there is another interesting article (a review, itself cited 8 times) that cited the one in Proceedings:

Proxy climatic and environmental changes of the past 1000 years. Soon W, Baliunas S. CLIMATE RESEARCH 23 (2): 89-110 JAN 31 2003

From the Abstract:Furthermore, the individual proxies can be used to address the question of whether the 20th century is the warmest of the 2nd millennium locally. Across the world, many records reveal that the 20th century is probably not the warmest nor a uniquely extreme climatic period of the last millennium.

My emphasis.

Hey Carlos and Gothmog, has the natural CO2 level ever previously pushed 370 ppm in the last 1000 years? I don't think so. So why is the 20th century not known for either warmth or extremes?

 

[gene90]

No, we have two phenomena - global warming, and global dimming. Nice attempt at not understanding, BTW.

The article in The Guardian, which I linked to, tried to pin it on GW.

You would know this had you actually read the link.