Global Warming Debate: Refuting Common Arguments

[Skyhunter]

Maybe the problem is that the whole hypothetical Earth is treated as been in it's average temperature - radiation state of the black body assumption. However a large part of the Earth receives enough solar radiation all the time to have an average temperature well above freezing, generating it's own water vapor feedback effect without help of other greenhouse gasses.

Where is your evidence?

255K is -18.15C. Water freezes at 0C.

And you are proposing that water vapor is the only GHG? How do you explain the snowball Earth events? Or do you deny them as well? How do you explain the glacial interglacial epochs?

The truth is that neither current climate nor paleo climate can be explained without the contribution from the known radiative forcing of the various GHG, all of them, not just the convenient ones to support your denial.


Here is the absorption spectrum.

http://www.te-software.co.nz/blog/auer_files/image001.gif

You throw out a statistical analysis that demonstrates antipersistent process in climate sensitivity as a refutation of WV and albedo feedbacks, without any explanation of a physical mechanism to support that conclusion. When the simple fact is that the primary feedback is thermal emission, and yes it is negative. Therefore Karner's paper does nothing more than prove the obvious, and says nothing about climate sensitivity in regards to absolute humidity or albedo.

And then you have the gall to insinuate that others are being unscientific.

 

[Skyhunter]

It's true that water vapor dominates at lower elevations. However, CO2 does influence temperatures at lower elevations by increasing the total height of the active atmosphere.

If you look at the absorption spectrum for water vapor you will notice that CO₂ fills in a gap in the water vapor spectrum around 15 microns. Therefore CO₂ does have an effect at lower elevations.

 

[Andre]

Where is your evidence?

255K is -18.15C. Water freezes at 0C.

That's again once more the average, while I have shown twice here that you cannot treath the Earth for it's average. What is the black body temperature on the equator? Is that 255K too? Maybe peek here.

Therefore Karner's paper does nothing more than prove the obvious, and says nothing about climate sensitivity in regards to absolute humidity or albedo.

No Karner shows that the total measured output of all the series that he investigated show non-persistency. Total means for me, including all feedbacks, none excluded. And there is no need to explain what you measure. It doesn't change what you measure.

And then you have the gall to insinuate that others are being unscientific.

That's a strawman I never said that. Others may perhaps judge in which posts here the fallacies dominate the science, for instance:

And you are proposing that water vapor is the only GHG?

Strawman,

How do you explain the snowball Earth events? Or do you deny them as well? How do you explain the glacial interglacial epochs?

three times red herring in a nice slippery slope construction but still totally irrelevant

 

[Skyhunter]

Andre,

Your water vapor feedback hypothesis and experiment in a closed chamber is plain silly. The Earth is not a test tube and the little water vapor that might ablate from the equator would be quickly dissipated and have a negligible effect on LW absorption. Any heating that occurred during the day would be quickly lost overnight.

Yes Karner did analyze the total output and found that negative feedbacks dominate according to his analysis. But as I pointed out, thermal emission is the dominant feedback, and it is negative. Therefore he simply affirmed the obvious and leaped to an illogical conclusion.

You definitely insinuated in this thread and others that those who disagree with your fringe hypothesis are resorting to fallacies over science. Then you go on to wrongly characterize my questions as fallacies.

Why do you not answer the questions?

Because you cannot. You cannot explain current climate, or paleoclimate without greenhouse gasses. Instead you declare the question a fallacy which is itself an ad hominem fallacy.

 

[z0rn dawg]

Isotopic fractionation of the carbon atom is proof that the buildup of CO₂ in the atmosphere is from anthropogenic sources, which is to be expected since humans are adding an additional 7-8 gigatons of carbon a year to the atmosphere.

Over 97% (according to the IPCC's 2001 report) of CO₂ in the atmosphere is from natural sources. I'm not arguing that anthropogenic release of carbon dioxide is in the atmosphere; it just seems so insignificant that making a decision based on that may not be the best course of action.

Human emissions are ~5% of the natural carbon cycle. The cycle is generally in equilibrium, humans are adding more to the positive side of the equilibrium. Natural sinks can only take up about half of these emissions, while the rest builds up in the atmosphere. Additionally, the ocean is becoming more acidic due to the higher rate of absorption.

IPCC's 2001 report stated that upwards of 98% of CO₂ is absorbed, nowhere near the 50% you cited. I'd suspect it's a bit lower now, but not 48% lower.

What are your qualifications? What orifice are you talking out of?

My whole point is that Al Gore isn't an expert. From what I've read (and from what he's said), I really don't think this guy should be considered an "authority" on the topic. Obviously, not everyone thinks he's an expert, but too many Americans take what he says as fact. The fact is he lied in his "documentary", was sued by 30,000 scientists, and was found guilty of fraud in the UK. He's been torn apart in Congress and all he's done IMO is spread propaganda. Even IPCC scientists think he's lying. As for me, I'm a natural science major (I can go bio, chem, or biochem...haven't officially declared yet). I've spoken to post-baccs and doctors about it. I've studied both sides of the research and made my decisions based on that. I think Gore has his own agenda, and it's dangerous what he's doing.

Water vapor accounts for ~66% of the greenhouse effect, Clouds and water vapor ~85%, and CO₂ ~12%. Water vapor is not a forcing, it is a feedback since specific humidity is dependent on atmospheric temperature and a source for evaporation. The warmer the Earth is the more water vapor that is present in the atmosphere.

So is carbon dioxide. As Earth's temperatures rise, the solubility for gas in the ocean decreases and they release CO₂ in the atmosphere. So, they both are dependent on the temperature.

From what I've read, many scientists don't believe that CO₂ is the major cause of global warming.

 

[Skyhunter]

Over 97% (according to the IPCC's 2001 report) of CO₂ in the atmosphere is from natural sources. I'm not arguing that anthropogenic release of carbon dioxide is in the atmosphere; it just seems so insignificant that making a decision based on that may not be the best course of action.

Could you provide a citation to the page where this is stated?

IPCC's 2001 report stated that upwards of 98% of CO₂ is absorbed, nowhere near the 50% you cited. I'd suspect it's a bit lower now, but not 48% lower.

I said ~5% not 50.

Here is the carbon cycle.

http://worldenergyblog.com/wp-content/uploads/2009/09/carbon_cycle_NASA.jpg

My whole point is that Al Gore isn't an expert. From what I've read (and from what he's said), I really don't think this guy should be considered an "authority" on the topic. Obviously, not everyone thinks he's an expert, but too many Americans take what he says as fact. The fact is he lied in his "documentary", was sued by 30,000 scientists, and was found guilty of fraud in the UK. He's been torn apart in Congress and all he's done IMO is spread propaganda. Even IPCC scientists think he's lying. As for me, I'm a natural science major (I can go bio, chem, or biochem...haven't officially declared yet). I've spoken to post-baccs and doctors about it. I've studied both sides of the research and made my decisions based on that. I think Gore has his own agenda, and it's dangerous what he's doing.

I get your point. You don't like Al Gore or his politics. That has absolutely no bearing on his film. And BTW he was not sued by 30,000 scientists. He was threatened with a lawsuit by deniers, but that was more a publicity stunt on their part that never amounted to actual court action. He was not found guilty of fraud in the UK. His film is still being shown to students in the UK with caveats, so that students don't confuse advocacy with science.

It is against forum rules to make false assertions. If you have any evidence to prove otherwise please link it.

So is carbon dioxide. As Earth's temperatures rise, the solubility for gas in the ocean decreases and they release CO₂ in the atmosphere. So, they both are dependent on the temperature.

Whether CO₂ is from ocean off gassing or human emissions is irrelevant to it's radiative properties in the atmosphere.

From what I've read, many scientists don't believe that CO₂ is the major cause of global warming.

Then I suggest you broaden your list of literary selections.

 

[Andre]

This thread is going in circles and is pointless when peer reviewed articles by experts can simply be declared void here without any substantiation.

 

[Skyhunter]

This thread is going in circles and is pointless when peer reviewed articles by experts can simply be declared void here without any substantiation.

What are you talking about?

I agreed with Karner, antipersistency in climate sensitivity does support negative feedbacks being dominant.

I disagree with his conclusion that his analysis changes the accepted 2C - 4.5C per doubling of CO₂.

Thermal emission is the dominant feedback and it is negative. The positive feedbacks are not going to overcome it.

 

[Xnn]

Over 97% (according to the IPCC's 2001 report) of CO₂ in the atmosphere is from natural sources. I'm not arguing that anthropogenic release of carbon dioxide is in the atmosphere; it just seems so insignificant that making a decision based on that may not be the best course of action.

IPCC's 2001 report stated that upwards of 98% of CO₂ is absorbed, nowhere near the 50% you cited.

I doubt these claims regarding the 2001 IPCC report are true.
Besides, the most current IPCC report is 2007.
Why reference and out of date version?

Please provide a link and reference to the page number on which it appears.

 

[Xnn]

If you look at the absorption spectrum for water vapor you will notice that CO₂ fills in a gap in the water vapor spectrum around 15 microns. Therefore CO₂ does have an effect at lower elevations.

Thanks Skyhunter;

I appreciate your post and corrections!

 

[mheslep]

If you look at the absorption spectrum for water vapor you will notice that CO₂ fills in a gap in the water vapor spectrum around 15 microns. Therefore CO₂ does have an effect at lower elevations.

Good point, though I think you mean from 1 to 5 microns? Of the predicted total heat gain from CO2, I wonder how much of it is attributed to action at various elevations?

 

[Xnn]

This thread is going in circles and is pointless when peer reviewed articles by experts can simply be declared void here without any substantiation.

What peer reviewed articles are you referring to?

Anyhow, getting back to climate models.

Consider 2 planets covered with ice at the same distance as the Earth is from the sun.
They are frozen solid.
The albedo is so great that there is not enough warmth to melt the ice.
Some ice sublimates during the day, but the water vapor in the atmosphere is very low and condenses every night.

Planet A has a atmosphere of Nitrogen and Oxygen.
Planet B has a similar atmosphere, but we are allowed to vary the level of CO2.

Which planet will be warmer?

Most people realize that Earth was at one time much warmer than it is now.
It was also much colder during the ice ages.
In each extreme case, the level of CO2 was either lower or higher than it is now.

Proof positive!

 

[Skyhunter]

Good point, though I think you mean from 1 to 5 microns?

There is little emission at the 1-5 micron wavelength.

http://www.te-software.co.nz/blog/auer_files/image001.gif

Notice the arrow on the right. It is pointing at peak Earth emission and where water vapor drops off precipitously. You'll note that the CO₂ absorption band peaks right where water vapor begins to drop. There is some overlap, but without CO₂ that portion of the spectrum would not be saturated.

Of the predicted total heat gain from CO2, I wonder how much of it is attributed to action at various elevations?

That is computed by a line by line analysis of the radiation code at different pressures.

 

[mheslep]

There is little emission at the 1-5 micron wavelength..

Yes, sorry I was clumsy there looking back and forth\ between pages.

 

[Vals509]

New estimates have been coming out that show there's more oil than once thought. We're developing the technologies to actually get this oil. OPEC can just say there's xxxx oil left when there's actually yyyy oil left.

Even if that is true, there is still the fact that oil is not something that is produced over a short time. In addition to this, human populations are exploding and also demand for oil is bound increase greatly. Even if there is 'yyyy' oil left, eventually it WILL GET OVER and as i have mentioned before, we will be in great trouble.

 

[Andre]

Which sounds absolutely logical. No problem with that all.

The problem however is if you try to coerce the world to change habits with something that is not true. Eventually, sooner or later, may it be next week or in fifty years, the truth will have its boots on.

Try to convince the world then, to change habits: "but this time it is really really true, cross my heart"; "Right that's what you say all the time".

The need to change things should be based on facts and that damage to science will be very very hard to repair.

Therefore, the sooner the straying is corrected, the better. However anybody who attempts to do so is automatically a folk devil (the deniers) as has been demonstrated in this thread once more.

 

[Skyhunter]

Andre,

You are projecting. You https://www.physicsforums.com/showpost.php?p=2383401&postcount=15" that is easily debunked.

Instead of defending your position you accuse others of being dishonest.

Not very scientific.

 

[Andre]

Well, one could not wish for better demonstration of what I'm trying to say.

Note the density of strawmans.

 

[Skyhunter]

So why don't you defend your argument instead of attacking others?

 

[z0rn dawg]

Could you provide a citation to the page where this is stated?

Page 188, Figure 3.1.

I get your point. You don't like Al Gore or his politics. That has absolutely no bearing on his film. And BTW he was not sued by 30,000 scientists. He was threatened with a lawsuit by deniers, but that was more a publicity stunt on their part that never amounted to actual court action. He was not found guilty of fraud in the UK. His film is still being shown to students in the UK with caveats, so that students don't confuse advocacy with science.

I'm pretty sure they sued, whether it amounted to anything I'm not sure of. It may have been a publicity stunt, but so was "An Inconvenient Truth." I was mistaken: Gore was not found guilty of fraud. The judge just found nine significant errors, proving Gore's "documentary" is not a documentary. The only thing that bothers me about the guy is that he lied to get his point across. If he had so many scientists working with him on it, how could they make nine significant mistakes? Seems too high to be mistakes.

Then I suggest you broaden your list of literary selections.

So some scientists don't believe that CO₂ is causing global warming? There's no way you can just not listen to what they have to say. They're part of the scientific community. I've looked at both sides, and there does not seem to be a consensus. The media talks about man-made global warming due to CO₂, but many scientists don't agree. I've read parts of the IPCC's 2001 and 2007 reports (I'm citing the 2001 report because that's what I have on hand). I'm pretty sure that's one valid, respected source that blames human activity.

 

[Count Iblis]

There's no way you can just not listen to what they have to say

If they don't publish what they say in peer reviewed journals, then what they say has no more value than what my grandmother has to say about this issue.

 

[Skyhunter]

Thanks for the citation Zorn.

I would point out however that the same figure shows the cycle in balance before the human contribution. It is not the size of the carbon cycle but the differential between emission and sequestration that is creating the problem.

Nothing wrong with being skeptical. But the errors in the documentary were not significant, besides, the film was meant to educate people to the broader public problem, not to answer open scientific questions. I don't remember all the errors found, I assume one was that you could see the clean air act in the ice cores, and another was an incomplete explanation of the correlation between carbon dioxide and temperature, leaving the insinuation that temperature would follow carbon dioxide levels, when the truth is that the temperature rise would be about 1/3 the carbon dioxide rise. Generally the film does a good job of education and was therefore approved for use in public schools with caveats.

 

[Bored Wombat]

When the first hokey stick graph was debunked, I began to take an interest in global warming.

I'm not sure that this is the scientific view.

Probably the most respected scientific journal in the world is Nature. (Certainly the most respected would be Science, Nature or Cell)

Their take on the National Academies review of the Hockey stick is that http://www.nature.com/nature/journal/v441/n7097/full/4411032a.html". Which is approximately the reading that scientists gave the report.

It was critical of how the data was used, and there were statistical methodological errors, but these made no material difference.

Probably your view that it was "debunked" has its origins in the counterscientific blogs and opinion pieces that proliferate on the internet, rather than an unbiased scientific source.

I read different arguments surrounding many of the graphs and models used to predict temperatures. When I saw them I was shocked by how inaccurate they were and their inability to even predict temperature as of now.

Again, it seems like you are not reading scientific sources.

Current climate models hindcast global mean surface temperature within the 90% confidence interval much more than 90% of the time, so the question is actually the opposite. Why are they so accurate? (See:http://www.agu.org/pubs/crossref/2008/2008GL034932.shtml" - Geophys. Res. Lett., 35, L18704, doi:10.1029/2008GL034932)

I was also amazed at the overwhelming number of scientists signatures confirming global warming that had no connection to climate studies what so ever.

The closer a scientist's field is to currently publishing on climate change, the more likely they are to agree with the human influence on climate. (see: http://tigger.uic.edu/~pdoran/012009_Doran_final.pdf"[/URL], Eos Trans. AGU, VOLUME 90 NUMBER 3 20 JANUARY 2009)

[quote="jordanfan20, post: 2382847"]As the years seemed to go by Al Gores movie appeared so incorrect I began to wander why so many people took it literally, and like other things I realized that many people only believed it because they thought all people believed it except the crazy skeptics.

I do not deny global warming or man made global warming I merely believe that global warming is not going to cause enormous catastrophe.[/QUOTE]

The current drop in biodiversity is attributable in part to climate change. And that is about 30% in the last 35 years. That should concern most people.

Analysis of species ranges has been pretty grim. (see: [PLAIN]http://www.gbltrends.com/doc/nature02121.pdf"[/URL], Nature (2004))

Note also that adaptation is very expensive. Bhutan was the first nation to receive UN funds for the underdeveloped nations to deal with climate change. The $3.5 million was supplemented further by other international donors, but has been insufficient to drop the level of the new glacial lakes to avoid floods ... and they are only working on one of over two thousand glacial lakes in the small country. (see:[URL]http://www.nature.com/news/2009/091021/full/4611042a.html"[/URL], nature news.)

I am aware of desert ecological communities, and sub antarctic communities that don't exist any more because of climate change, and I think any ecologist could tell a similar story of whatever system they study. Corals are also under severe stress in many parts of the world, with large areas of bleaching (meaning the symbiote is dead). This will lower the entire productivity of the oceans. As will acidification.

The change from snow to rain in the Himalayas puts about a quarter of the worlds population under fresh water stress for most of the year. (And floods their homes and croplands for the rest of the year)

I think the science shows a lot of expensive consequences, but you have to read about them from scientific sources, because there is a lot of fossil fuel-funded nay-saying on the net. If a site is dedicated to global warming denial, it is pretty safe to not read it.

[URL]http://www.nature.com/climate/index.html"[/URL] is a good way to keep up with the science, without it becoming overly technical, and it is important to read a science based site on this subject occasionally, because the signal to noise ratio in the popular press and the blogs and forum sites is very low on this subject.

 

[DrClapeyron]

http://www.youtube.com/watch?v=eScDfYzMEEw&feature=related

People shouldn't be afraid of the future, especially young people such as myself. We should view the potential catastrophic consequence as a very stimulating problem to solve. Why back down and shoot ourselves in the foot?

 

[mheslep]

I'm not sure that this is the scientific view.

Probably the most respected scientific journal in the world is Nature. ...

I think you mean prestigious, not respected, and for its peer review process of submitted papers, and not because of its news articles like the one linked here:

Their take on the National Academies review of the Hockey stick is that http://www.nature.com/nature/journal/v441/n7097/full/4411032a.html". Which is approximately the reading that scientists gave the report.

Probably your view that it was "debunked" has its origins in the counterscientific blogs and opinion pieces that proliferate on the internet, rather than an unbiased scientific source.

How ever one characterizes the Mann et al 1200 year temperature reconstruction, there is the observable point that it appeared http://www.grida.no/climate/ipcc_tar/wg1/005.htm"[/URL]to the paleo section and merged in with several other reconstructions that show the medieval period as warm.

[QUOTE=Bored Wombat]I am aware of desert ecological communities, and sub antarctic communities that don't exist any more because of climate change,[/QUOTE]Could you cite one please (obviously one in the last 30 years to be associate w/ AWG)?

[QUOTE=Bored Wombat]The change from snow to rain in the Himalayas puts about a quarter of the worlds population under fresh water stress for most of the year. (And floods their homes and croplands for the rest of the year)[/QUOTE]Source?

[QUOTE=Bored Wombat]I think the science shows a lot of expensive consequences, but you have to read about them from scientific sources, because there is a lot of fossil fuel-funded nay-saying on the net. If a site is dedicated to global warming denial, it is pretty safe to not read it.[/QUOTE]Science can show consequences, I don't know that estimating costs is also science, certainly not by climate scientists.

 

[Bored Wombat]

I think you mean prestigious, not respected, and for its peer review process of submitted papers, and not because of its news articles like the one linked here:

Nature News is still respected on the strength of the scientific basis of the organisation.

And given that most people aren't going to read the national academies report, its a good source of the scientific opinion on it.

Other news sources said the same of course:
http://news.bbc.co.uk/2/hi/5109188.stm" .

And the scientific blogosphere had the same analysis. The point is that the national academies report supported the hockey stick graph, and a scientist that read it could tell you that, even the reporters for Nature.

How ever one characterizes the Mann et al 1200 year temperature reconstruction, there is the observable point that it appeared http://www.grida.no/climate/ipcc_tar/wg1/005.htm" to the paleo section and merged in with several other reconstructions that show the medieval period as warm.

The finding of Mann et al, that the little ice age and the medieval warm period where not at the same time over the northern hemisphere is interesting, valid, and still holds now. This is why whole hemisphere reconstructions show it much more weakly than the 1990 IPPC graph from one site in central England. (still used in the denialist literature such as "swindle".)

The national academies said that it was over used, considering at the time it had not yet been reproduced.

Your argument that it "vanished from the summary", therefore it must be considered wrong doesn't follow. The IPCC reports are about the science that has been learned since the last report. The hockey stick was well reported in the 2001 IPCC report. There is no reason to put it in such a prominent place in the 2007 IPCC report.

It is true that it doesn't appear in the summary for policy makers. You are exaggerating your case when you call this the summary. It does appear in the technical summary.

Could you cite one please (obviously one in the last 30 years to be associate w/ AWG)?

I know that from conversations with ecologists, I don't know where or if they have been published. The rainy season in outback east australia has changed time of year. The ecological communities that blossom in the vastly different temperatures are different. (And not the interesting and unique ones). Freshwater communities devastated by the same effect. The rivers are out of water at the wrong time of year.

The damage to the subantarctic is from interviews with those studying it. I'll look one up if you like, but I'll submit this first, as I might not get a chance.

Source?

Common knowledge.

But the first google hit I got was this:
"Dr Claudia Sadoff of The World Bank, said in her
opening address: “The countries in the Himalayan subregion
account for 40% of the world’s population. The
rivers in the region are extreme in terms of population
density, sedimentation and variability. Each river is in
effect many rivers in one; each is an ecosystem in itself. Hence, issues related to
the Himalayan rivers are complicated. These are difficult rivers to understand,
manage and talk about. They are shared rivers, which increases complications.
There has been a lot of talk recently about how these rivers are under threat.
Glaciers are disappearing, rivers are running dry; rivers are overdrawn and
polluted. These rivers are extremely variable in terms of floods and droughts.
They are even more threatened due to climate change. The World Bank has
identified climate change hot-spots. One is over the Himalayas." - http://www.strategicforesight.com/Kathmandu Report.pdf

Will it do? I'm sure I could find something by the IPCC or a NGO about the consequences of climate change in the region if you want.

Science can show consequences, I don't know that estimating costs is also science, certainly not by climate scientists.

I wasn't really meaning financial costs.
But economics is a science of sorts. And an important one for deciding on climate change policy.

 

[mheslep]

Your argument that it "vanished from the summary", therefore it must be considered wrong doesn't follow.

I did not say that.

It is true that it doesn't appear in the summary for policy makers. You are exaggerating your case when you call this the summary. It does appear in the technical summary.

Summary, as in Summary for Policy Makers.

I know that from conversations with ecologists, ...

That's fine, but not appropriate for this forum.
https://www.physicsforums.com/showthread.php?t=280637

 

[Bored Wombat]

I did not say that.

I doubt that I misinterpreted you. If you think that the paraphrase has lost your meaning, could you point out how?

Summary, as in Summary for Policy Makers.

I can see that that's why you must mean, because of the way that it appeared in the Technical Summary. But you should still be specific when claiming something "vanished" from somewhere, and using that to imply that it has lost favour.

That's fine, but not appropriate for this forum.

It's pretty common knowledge, and not at all controversial that ecosystems are being impacted by climate change, and neither that for ecosystems with smaller geographic ranges, (being the unique in especially interesting ones) that impact is more often extinction or increased risk of extinction.

Since its not controversial, its not inappropriate.

 

[heldervelez]

Google for 'Joanne nova' her handbook is very helpfull.
Her 16 pages "The skeptics handbook" can help you.
quoting from her site "Volunteers have translated it into German, French, Norwegian, Finnish, Swedish, Turkish, Portuguese and Danish. (Versions in Dutch, Spanish, and possibly Italian are on the way). "

The translation to pt-br has been done by university teachears that are brasilian climatologists.
Joanne is not a scientist but, as myself and a lot of us, are tracking the inconvenient facts behind all that noise that pervades the media.
And her site has links to helpful sources.

 

[mheslep]

...I can see that that's why you must mean, because of the way that it appeared in the Technical Summary. But you should still be specific when claiming something "vanished" from somewhere, and using that to imply that it has lost favour...

I referred to the exact title in the first part of the sentence; in the same sentence I referenced it again. Sorry for the confusion.

How ever one characterizes the Mann et al 1200 year temperature reconstruction, there is the observable point that it appeared right up front in the 2001 IPCC Summary for Policy Makers almost as an icon, with no medieval warming period, and then in the 2007 third IPCC report after the investigation it vanished from the Summary, was moved to the paleo section and merged in with several other reconstructions that show the medieval period as warm.

And yes I'd say it is fair to say that some of the key ideas reflected in the MBH 98 hockey stick, namely that there was little or no medieval warming period, has indeed lost favour; that this is reflected by its removal from the Summary for Policy Makers and its subsequent embedding in the graph in the Paleo section with several other competing studies that show a substantial medieval warming, comparable with today's warming.

 

[mheslep]

On this other point, I'm referring to this specific claim:

Iam aware of desert ecological communities, and sub antarctic communities that don't exist any more because of climate change

Could you cite one please (obviously one in the last 30 years to be associate w/ AWG)?

I know that from conversations with ecologists, I don't know where or if they have been published.

That's fine, but not appropriate for this forum.
https://www.physicsforums.com/showthread.php?t=280637

It's pretty common knowledge, and not at all controversial that ecosystems are being impacted by climate change, and neither that for ecosystems with smaller geographic ranges, (being the unique in especially interesting ones) that impact is more often extinction or increased risk of extinction...

Perhaps I misunderstood. By 'ecological communities' that 'dont exist anymore' do you mean a species extinction? I took that to mean human communities. This another good reason for cites - in addition to the data, they avoid ambiguity.

 

[Xnn]

The Medieval warm period was only warm in comparison to the 17th century cold.

See Box 6.4 on page 468 to 469 in the following link.

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter6.pdf

The evidence currently available indicates that NH mean temperatures during medieval times (950–1100) were indeed warm in a 2-kyr context and even warmer in relation to the less sparse but still limited evidence of widespread average cool conditions in the 17th century (Osborn and Briff a, 2006). However, the evidence is not sufficient to support a conclusion that hemispheric mean temperatures were as warm, or the extent of warm regions as expansive, as those in the 20th century as a whole, during any period in medieval times (Jones et al., 2001; Bradley et al., 2003a,b; Osborn and Briff a, 2006).

So, the 20th century (1900 to 1999) was warmer than the MWP.

Also, notice the following conclusions:

Centennial-resolution palaeoclimatic records provide
evidence for regional and transient pre-industrial warm
periods over the last 10 kyr, but it is unlikely that any
of these commonly cited periods were globally synchronous.
Similarly, although individual decadal-resolution
interglacial palaeoclimatic records support the existence
of regional quasi-periodic climate variability, it is unlikely
that any of these regional signals were coherent at the
global scale, or are capable of explaining the majority of
global warming of the last 100 years.

• The TAR pointed to the ‘exceptional warmth of the late
20th century, relative to the past 1,000 years’. Subsequent
evidence has strengthened this conclusion. It is very likely
that average Northern Hemisphere temperatures during
the second half of the 20th century were higher than for
any other 50-year period in the last 500 years. It is also
likely that this 50-year period was the warmest Northern
Hemisphere period in the last 1.3 kyr, and that this
warmth was more widespread than during any other 50-
year period in the last 1.3 kyr. These conclusions are most
robust for summer in extratropical land areas, and for
more recent periods because of poor early data coverage.

 

[mheslep]

The Medieval warm period was only warm in comparison to the 17th century cold.

See Box 6.4 on page 468 to 469 in the following link.

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter6.pdf

[my bold] Yes I've been all through it. I think you misread? Your first sentence directly contradicts the box:

The evidence currently available indicates that NH mean temperatures during medieval times (950–1100) were indeed warm in a 2-kyr context and even warmer in relation to the less sparse but still limited evidence of widespread average cool conditions in the 17th century (Osborn and Briff a, 2006).

One can not draw that conclusion from MBH 98, hence its disfavour.

 

[Xnn]

good point mheslep; "only warm" is overstating.

However, the MWP was not as warm as the 19th century, which some people would tend to consider as a baseline.

 

[Bored Wombat]

Google for 'Joanne nova' her handbook is very helpfull.

It looks like a reproduction of some debunked counterscientific fossil fuel pressure group propaganda.

In what was is it "very helpful"?

Off the top of my head, a brief response to her "only four points that matter" are:

1) The greenhouse signature is missing.

No it's not. The greenhouse signature, the cooling of the stratosphere and the exaggerated warming at the poles is unambiguous, measured and real.

The "hot spot" that you are mistaking for a greenhouse signature has nothing to do with the greenhouse effect. It occurs under any warming that causes the air to hold more water vapour, and is caused by the release of the latent heat of vaporisation of that water when it condenses as rising air cools.

2) The strongest evidence was the ice cores, but newer more detailed data turned the theory inside out.

No the strongest evidence is the physics of optics, by which we understand the greenhouse effect, and therefore know that increasing the concentration of greenhouse gasses will make it warmer.

A 600 or 800 year lag in temperature change over 5000 or 6000 years is an 80% co-incidence. The fact that greenhouse feedback drives the switch from a glaciation to interglacial, set of by milankovich cycles, is perfectly in line with all previous theory. The 10 or 12 K temperature change over that time was only ever about 2 or 3 K due to the 50% increase in CO2 that occurs over that time.

The current best estimates for the effect of doubling CO2 is about 3 or 4 K.

3) Temperatures are not rising.

No they're not.

"In a blind test, the AP gave temperature data to four independent statisticians and asked them to look for trends, without telling them what the numbers represented. The experts found no true temperature declines over time." http://news.yahoo.com/s/ap/20091026/ap_on_bi_ge/us_sci_global_cooling"

4) Carbon dioxide is doing almost all the warming it can do.

No. The current best estimates for the effect of doubling CO2 is about 3 or 4 K.

And that's the top four points.

So I'm at a loss as to what help we've got from them, especially on a physics board, where people probably have some basic scientific understanding.