Thanks...I hope someday a majority of people could simply ask "what's the hubbub, bub?"

In their rush to oppose they've claimed positions politically that can't be supported scientifically. I wish there was a little more group skepticism.

The issue that you're missing, and which Griffin seems to be missing, is that it is not a matter of BEST or BETTER. It is a matter of how fast things are changing.

We are looking at a change of between 4 and 6 degrees Celsius in about 200 years.

To give you a sense of timescale, when it was 5 degrees colder, we were in the middle of the last glaciation, about 10,000 years ago. So we are looking at a rate of change about 50 times greater.

For another timescale, the information I have seen is that it takes about 1 million years for a new species to develop through evolution. 200 years is not long enough for any kind of evolutionary adaptation to take place. We are going to lose numerous species, flora & fauna, big time. (Estimates today are that we are already losing about 3% every year.)

From an engineering point of view, that's reducing the robustness of your system. Which system? Spaceship Earth.

The Deniers:
http://www.canada.com/nationalpost/financialpost/story.html?id=c47c1209-233b-412c-b6d1-5c755457a8af&p=1

Neal King: what you are missing here is the distinction between science and policy. Science says what is happening; policy says what we do about it. Griffin believes the science -- he's being called "unscientific" because he doesn't support the policy. Mahlman and the NYT are abusing climate science to win points in the policy debate; they're the ones being unscientific here, for true scientists don't claim scientific authority to settle questions that aren't scientific.

Of course the Times can't be expected to follow the rules of scientific integrity; but Mahlman's an actual scientist, and he's supposed to do better than this.

What the global warmenists ignore or deny is that from 650 AD to 1315 AD the earth was about two degrees C warmer than it is now, so we know the effects of a temperature increase: there would be excellent British wine vintages, Mexico City would be under a high pressure zone and not get the summer rains, and you could grow wheat in central Scotland. Whether England would suffer another infestation of Danes is unclear.

John Costello,

What you're referring to is the so-called medieval warm period. The IPCC report has a section describing the history of knowledge concerning that period. Basically, the best modern knowledge is that it didn't happen.

MB:

No, the issue is that he's focusing on the wrong point. The issue, as stated before, is the rate, not the direction. He says, Who knows whether warmer is better or not? That is absolutely not the issue and he should know that.

He's another Bush administrator. Heckuva job, Griffie!

jan,

I saw that series by Solomon. At one point I looked at almost every one of those articles. Strange results:

- At least 3 of the profiles, when you look up their websites, specifically disavow the statements attributed to them by Solomon.

- For many of them, Solomon misrepresents or misunderstands the science that his subjects present.

- And one is just funny: His interview with Shaviv. In this one, he doesn't misrepresent Shaviv's perspective and ideas. But he misrepresents one bizarre thing, which Shaviv himself pointed out on his own website: It's customary, when conducting an interview with someone, to actually have some contact with the interviewee. It's not generally considered sufficient to read his website, copy information, and then claim an interview. Shaviv found out about this "interview" for the first time a few weeks later!

Probably that "methodology" explains the discrepancies, pointed out above, between what some of these scientists say, and what Solomon says they say.

Neal: As an aid to clear thought, I shall list the propositions that form the case for restricting CO2 emissions.

1) The temperature of the Earth at sea level is rising swiftly.
2) The concentration of CO2 in the Earth's atmosphere is rising swiftly.
3) Point 2) is the main cause of point 1).
4) Restricting CO2 emissions from power generation will reverse the trend in 2) (and therefore also 1).)
5) A swift rise in the Earth's temperature at sea level is a very bad thing, and ought to be prevented.

Now, points 1), 2), 3), and 4) are all matters of facts and causes; they are real scientific questions. Griffin didn't say anything against them, and he agreed in part with 1). The point he denied is 5) -- which is the one point on the list that is not a matter of facts or causes. Mahlman et alii are calling Griffin "unscientific" for expressing an opinion other than theirs, on a matter that isn't scientific; and that's an abuse of their position as scientific experts.

"Basically, the best modern knowledge is that [the Medieval Warm Period] didn't happen."

Really? You mean there never was a Viking settlement in Greenland?

MB:

- Your summary is missing a critical point, which is that you have to be evaluating the right point before deciding whether or not it is important. Example: "It all boils down to whether we should flip this switch up or down. I just think the answer should be, up. It's just a matter of opinion." If that approach is taken, without pointing out that the switch being up drops a rock on someone's head, then the wrong issue is being focused upon.

I would accept Griffin's perspective as being valid if he said, "We also know that the rapid change in global average temperature will very probably lead to an impact on our world's genetic diversity. But that is a risk we will have to take." (or words to that effect). Then he would be addressing the real point of interest - and he could still have a different final evaluation.

- Medieval Warm Period: Yes, there was a Viking settlement, but the best evidence so far indicates that this does not mean it was any warmer then than now. From IPCC AR4, Chapter 6, p.468-469.: "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 Briffa, 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 Briffa, 2006)." (This the conclusion of two pages of discussion and references, in a section called "Box 6.4: Hemispheric Temperatures in the 'Medieval Warm Period'.")

Neal, if either Mahlman or the NYT had said anything about the diversity of species, your argument in their favor would be valid. But the USA Today article Eric linked to contains no sign that Mahlman did say anything of the sort. In fact, the only statement about the possible consequences of global warming in that article comes from James Hansen, and he was talking about a rise in sea levels -- an event that the IPCC is not predicting in the 2007 report.

The significance of the Medieval Warm Period for the climate change question is, of course, that it shows the Earth can approach its present temperature without any contribution from humans burning coal and oil. Thus, climatologists have to demonstrate that whatever cause warmed the Earth in AD 1000 is not doing so today; if they can't do so, the case that burning fossil fuels is the culprit today remains unproven. And it's either ignorant, or dishonest, to claim that because the peak in AD 1000 wasn't quite as high as the present level, it wasn't there at all.

Gee whiz, everyone's an expert. Glad I am so dumb. I like warm days. You folks will look back at this smugness with embarrasment one day. Are you really so sure that warmth is bad? Where's your evidence?
Here's a suggestion: If warmth is bad, and people cause warmth, then less people will solve the problem. Why don't you all set a fine example and quit breating out all that CO2?

Neal King,

My BA and MA are in Archaeology -- the MA paper was on the uses of Obsidian Hydration DAting in Africa, as a result of which I became very conversant with past climate changes.

The IPCC denial of the Medieval Warming Period is hooey. It is garbage. They HAD to deny it because the 'hockey stick' denies it (which tells you how bad the 'hockey stick' is.)But the facts in the ground, the _excavated_ facts in the ground, as well as historical records, prove them -- James Hansen most especially with his 'hottest year in 1000 year' BS -- to be liars.

Presumably they also deny the Roman Warm Period (500 BC to 200 AD) when Britain and northern Gaul were worth being conquered by Roman armies -- two harvests a year and wine grapes grown in Britain -- and the later Roman Cold Period (200 AD to 650 AD), when temperature ranges were only down to mid-20th century norms, which made the northern tier of the western Roman Empire uneconomic, as well as setting in motion the _hunu_, who had to go west in search of new lands because of the Great Wall of China.

In the western hemisphere the Roman Cold Period coincides with the rise and flourit of Teotihuacan. The decreased temperatures removed a permanent high pressure zone from the Valley of Mexico, allowing the summer rains to pass over Cerro Gordo and break over the Pyramid of the Sun. The later warming returned the high pressure zone the city died in famine, fire, and cannibalism (yes, we have the pots with the cooked human hands.)The city's population moved north into Tula, and became the Toltecs. The start of the Little Ice Age in 1315 (eight weeks after Easter, as recorded by the monks) moved the rains south again, allowing the central Mexican lakes to refill, and in 1325 the decendants of the Teotihuacanos -- the Aztecs (this is obvious from the murals in Teotihuacan, which show the Nahuatal creation myths, etc.) -- made their way south and began chomping on their new neighbors

Details on both periods can be found in "The Long Summer" and "The Little Ice Age" by Brian Fagan. Fagan, by the way, does not deny 'global warming,' as someone who spent 30+ years in a UC academic hothouse he knows better than to put his family jewels in a meat grinder and invite anyone out there to turn the crank. What he does is provide exhaustive evidence -- archaeological and documentary -- that the Medieval Warm Period did indeed exist. I found both books a Borders.

Neal King,

My BA and MA are in Archaeology -- the MA paper was on the uses of Obsidian Hydration DAting in Africa, as a result of which I became very conversant with past climate changes.

The IPCC denial of the Medieval Warming Period is hooey. It is garbage. They HAD to deny it because the 'hockey stick' denies it (which tells you how bad the 'hockey stick' is.)But the facts in the ground, the _excavated_ facts in the ground, as well as historical records, prove them -- James Hansen most especially with his 'hottest year in 1000 year' BS -- to be liars.

Presumably they also deny the Roman Warm Period (500 BC to 200 AD) when Britain and northern Gaul were worth being conquered by Roman armies -- two harvests a year and wine grapes grown in Britain -- and the later Roman Cold Period (200 AD to 650 AD), when temperature ranges were only down to mid-20th century norms, which made the northern tier of the western Roman Empire uneconomic, as well as setting in motion the _hunu_, who had to go west in search of new lands because of the Great Wall of China.

In the western hemisphere the Roman Cold Period coincides with the rise and flourit of Teotihuacan. The decreased temperatures removed a permanent high pressure zone from the Valley of Mexico, allowing the summer rains to pass over Cerro Gordo and break over the Pyramid of the Sun. The later warming returned the high pressure zone the city died in famine, fire, and cannibalism (yes, we have the pots with the cooked human hands.)The city's population moved north into Tula, and became the Toltecs. The start of the Little Ice Age in 1315 (eight weeks after Easter, as recorded by the monks) moved the rains south again, allowing the central Mexican lakes to refill, and in 1325 the decendants of the Teotihuacanos -- the Aztecs (this is obvious from the murals in Teotihuacan, which show the Nahuatal creation myths, etc.) -- made their way south and began chomping on their new neighbors

Details on both periods can be found in "The Long Summer" and "The Little Ice Age" by Brian Fagan. Fagan, by the way, does not deny 'global warming,' as someone who spent 30+ years in a UC academic hothouse he knows better than to put his family jewels in a meat grinder and invite anyone out there to turn the crank. What he does is provide exhaustive evidence -- archaeological and documentary -- that the Medieval Warm Period did indeed exist. I found both books a Borders.

Neal King,

My BA and MA are in Archaeology -- the MA paper was on the uses of Obsidian Hydration DAting in Africa, as a result of which I became very conversant with past climate changes.

The IPCC denial of the Medieval Warming Period is hooey. It is garbage. They HAD to deny it because the 'hockey stick' denies it (which tells you how bad the 'hockey stick' is.)But the facts in the ground, the _excavated_ facts in the ground, as well as historical records, prove them -- James Hansen most especially with his 'hottest year in 1000 year' BS -- to be liars.

Presumably they also deny the Roman Warm Period (500 BC to 200 AD) when Britain and northern Gaul were worth being conquered by Roman armies -- two harvests a year and wine grapes grown in Britain -- and the later Roman Cold Period (200 AD to 650 AD), when temperature ranges were only down to mid-20th century norms, which made the northern tier of the western Roman Empire uneconomic, as well as setting in motion the _hunu_, who had to go west in search of new lands because of the Great Wall of China.

In the western hemisphere the Roman Cold Period coincides with the rise and flourit of Teotihuacan. The decreased temperatures removed a permanent high pressure zone from the Valley of Mexico, allowing the summer rains to pass over Cerro Gordo and break over the Pyramid of the Sun. The later warming returned the high pressure zone the city died in famine, fire, and cannibalism (yes, we have the pots with the cooked human hands.)The city's population moved north into Tula, and became the Toltecs. The start of the Little Ice Age in 1315 (eight weeks after Easter, as recorded by the monks) moved the rains south again, allowing the central Mexican lakes to refill, and in 1325 the decendants of the Teotihuacanos -- the Aztecs (this is obvious from the murals in Teotihuacan, which show the Nahuatal creation myths, etc.) -- made their way south and began chomping on their new neighbors

Details on both periods can be found in "The Long Summer" and "The Little Ice Age" by Brian Fagan. Fagan, by the way, does not deny 'global warming,' as someone who spent 30+ years in a UC academic hothouse he knows better than to put his family jewels in a meat grinder and invite anyone out there to turn the crank. What he does is provide exhaustive evidence -- archaeological and documentary -- that the Medieval Warm Period did indeed exist. I found both books a Borders.

I only meant to post once. Sorry.

And I should have noted that Greenland's glaciers were far less prominent when the Vikings settled there. Can any of _you_ imagine putting a settlement dependant of animal husbandry in Greenland TODAY?

John Costello,

Have you actually READ the 2 pages in the IPCC report, and the references therein? They go over the entire history of the concept of the MWP, who started the idea, what data inspired it, what other people did to try to check the idea, the problems that came up, and so on, from 1965 until 2006. On what basis of expertise or analysis do you call this "hooey"? I'm afraid that I trust the published and peer-reviewed work of climatologists, over the last 40 years, more than the point of view of an archaeologist.

With respect to Greenland:
This article, an investigation into why the Vikings abandoned the Greenland settlements, mentions that the land has been tundra-free for thousands of years: in contradiction to many who think that it's frosted over since the Vikings.

Here's a photo of Erik the Red's farm. Yes, I could imagine a settlement here.

MB,

- The difference between what NYT and Mahlman are saying and what I am saying is that they are simply saying he is an idiot, whereas I am explaining why he is an idiot.

The point is that he is pretending that he thinks it's only a matter of whether you wear a hawaiian shirt or a long-sleeve. Does it really need to be said that anyone exposed to the science of the issue must realize that there are consequences that go beyond where you want to go for vacation?

- You don't need to look for a MWP to show that Earth can approach its present temperature without fossil fuels: C-O2 is only one of a number of factors that affect temperature, as has been known for ages among climatologists. The proof (or evidence) that this is the cause now is:
- The 33% increase in C-O2 over last 100 years, and the easily calculable radiative forcing due to that;
- The carbon-14 evidence that this must be due to carbon that has not recently been involved in the carbon cycle; and hence, not due to out-gassing from the oceans or thawing from the tundras, or heavy breathing from critters;
- The fact that the other conceivable source of carbon, volcanic C-O2, is less significant by a factor of 150 on an annual basis;
- The calculated increase in temperature, when taking into account the effects of volcanic, solar variation, and sulfate aerosols (from unscrubbed burning of coal), matches very well the observed temperature over the last 100 years;
- Other sources of potential explanation, like cosmic-ray flux (CFR) and variation in solar luminosity, simply haven't panned out: the CRF shows no trend, and luminosity has stayed within a 0.1% bound since 1988. Such non-changes cannot explain a change in global average temperature.

contribution from humans burning coal and oil. Thus, climatologists have to demonstrate that whatever cause warmed the Earth in AD 1000 is not doing so today; if they can't do so, the case that burning fossil fuels is the culprit today remains unproven. And it's either ignorant, or dishonest, to claim that because the peak in AD 1000 wasn't quite as high as the present level, it wasn't there at all.

If you want to claim there is another cause for GW, please point to it. Or at least to a plausible candidate.

Neal King:

I just looked at the section of the IPCC report you cited. John Costello probably won't need to, since he's read the literature on which it's based. However, now I doubt whether you actually read that section -- read it, that is, with a critical eye and a proper attention to its meaning. For what it says, in plain English, is this:

"Yes, we have to admit the Earth was nearly as warm in AD 1000 as it is now. But 'nearly' isn't 'more than'! It's still hotter now than it has ever been, so there!"

In other words, the Medieval Warm Period did exist, and however inconvenient that is for the AGW thesis, it can't be ignored.

Oh, and archeology has been a proper, organized scientific inquiry for a lot longer than 40 years; it's had peer reviewed publications, formal conferences, university departments, and all the other trimmings long before the IPCC was even thought of. I'd put much more faith in an archeologist's methods of judging evidence than I would in climatology's simulations. They've had much more testing in the field.

MB:

- From what he's written, Costello has read two books by an archaeologist. That doesn't constitute "the literature", anymore than a popular book on relativity constitutes "the literature" on gravitational theory.

- Archaeology is a fine & respectable field, and I admire the subject. But an expert in archaeology has no claim to being an expert on climatology. Does an archaeologist know anything about radiative transfer theory? It's critical to the theory of global warming. Unlike money, expertise is not fungible.

- The real point is, there is no evidence at all that any other proposed cause is playing any significant role for GW besides greenhouse gases. Solar luminosity increases: too small. Cosmic-ray flux: not increasing.

So what physical explanation are you proposing? "Memories of the good old days in the MWP" won't do: What actual phenomenon that produces changes in degrees Kelvin do you suggest?

To quote Sherlock Holmes, "When you have eliminated the impossible, what remains must be true - however unlikely."

And in this case, it ain't even unlikely. It fits perfectly into textbook atmospheric physics. Have you ever studied the subject?

We are looking at a change of between 4 and 6 degrees Celsius in about 200 years.
Says who?
I look at the global surface temperature record compared to the satellite tropospheric temperature record and I see urban heat sinks given extraordinary weight by ideologs macarading as scientists. No trend in sight.
Now tell me why didn't the CO2 take effect until after it was at 375 ppm?

"From what he's written, Costello has read two books by an archaeologist."

You didn't notice where he said he has a Master's in archeology? You have to read a lot more than two books on a subject to earn a postgraduate degree in it.

"Does an archaeologist know anything about radiative transfer theory?"

An archeologist doesn't have to know anything about thermodynamics to work out whether there was a Medieval Warm Period, which is the issue at hand.

"So what physical explanation are you proposing?"

I don't see that I'm obliged to provide any causal explanation to answer a historical question. You said distinctly there never was a Medieval Warm Period; the historical record says it happened; even the sacred IPCC says it happened. Why don't you admit you said something indefensible?

That said, I'd be happy to throw possible causal explanations into the air, and let you try and shoot them down.

"Other sources of potential explanation, like cosmic-ray flux (CFR) and variation in solar luminosity, simply haven't panned out: the CRF shows no trend, and luminosity has stayed within a 0.1% bound since 1988."

How about solar variation since 1750 -- as in the end of the Little Ice Age? As I recall the solar flux theory is that the present moment is close to a peak in a long cycle of variation, while 1750 was a trough in that cycle; thus our most detailed observations of climate, and the rise in fossil fuel use, occurred during a trend of rising solar luminosity, and the Earth's temperature would be nearly what it now is even if CO2 emissions had remained flat since 1750. The trend since 1988 isn't a good test of this theory.

"Solar luminosity increases: too small."

Has it occurred to you that variations in solar flux can increase the greenhouse effect, as well as raising the base temperature? Since the atmosphere reflects a fraction of the heat the Earth emits, not a constant amount of energy, its effect on the Earth's surface temperature should be multiplicative, not additive. (Yes, yes, the IPCC has certainly taken that into account -- that doesn't mean you have. We've already seen you can mistake what the IPCC Report says ...)

I cited the two books by Brian Fagan because they are accesible to non-archaeologists, such as yourself. They are both popularizations intended for an educated audience not familiar with the specialized literature. The literature I am familiar with is heavy into palynology (the use of the changes in seeds and pollen percentages taken from cores in bogs to determine long term climatic trends); archaeoloigcal site reports from the South-west, Mid-west,Britain, Europe, etc.

There is also my own research. As I said, my specialty was obsidian hydration dating. Obsidian adsorbs hydrogen atoms -- the higher the temperature, the faster the rate of adsorption and the wider the hydration rim that shows up under the microscope. Most of my interest was in sites that were in the 2000-1600 BP range, and I could see that the obsidian dates matched the C14 dates, which led me to conclude that the Medieval Warm Period and the Little Ice Age cancelled each other out. But on sites which were a century or so into the MWP, the artifacts gave a much younger reading. Why? Because there was less of the hotter period to offset the Little Ice Age cooling.

It's tge changing planetary temperatures over time which render the use of OHD problematical. Obsidian acts to measure total heat input, so that if you know the temperature you can determine the age with more or less the same precision as C14 (that is, within the same +/- period. A date may be 1614 BP +/- 150 years. This isr eally the same date as 1500 BP +/- 150 years or 1700 PB +/- 150 years. The only way to tell which is older or younger is by stratigraphic position -- which was above or below the other.) In theory, if you have well (C14 or tree ring dated obsidian)you should be able to determine average temperature from that time period to the present. I belive some people at Oak Ridge were working on that.

Papertiger,

4-6 degrees in about 200 years
IPCC AR4 Summary for Policymakers, p. 13: "...the best estimate for the high scenario (A1FI) is 4.0°C (likely range is 2.4°C to 6.4°C)." OK, I should have said "2.4 to 6.4". I believe scenario A1F1 is the "business as usual" scenario (although they seem to have dropped these terms in AR4), and if so, that's what we're looking at, if there are no changes in policy.

Urban Heat Sinks
Fig. 3.6 on page 65 of the NOAA report
(http://www.climatescience.gov/Library/sap/sap1-1/finalreport/default.htm)
mentioned on the Dyson thread shows temperature trends at all these levels as a function of location on the globe. You can see that it’s heating up a lot over many areas in the northern hemisphere that don’t have any big cities: northern Canada and Alaska, for instance. And also over some ocean areas, too.

"Now tell me why didn't the C-O2 take effect until after it was at 375 ppm?"
It got to 379 ppm in 2005. I don't understand your question.

Medieval Warm Period

Let's look at the history of this discussion.

John Costello brought it up, saying:
"from 650 AD to 1315 AD the earth was about two degrees C warmer than it is now..."

to which my reply was:
"What you're referring to is the so-called medieval warm period. The IPCC report has a section describing the history of knowledge concerning that period. Basically, the best modern knowledge is that it didn't happen."

So what was I denying? I was denying that there was a period (ca.650-1315) when the Earth was 2 degrees warmer than now.

Now, according to the text in Box 6.4 that I cited in the IPCC: "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 Briffa, 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 Briffa, 2006)."

So, I was saying that this period of time was not 2 degrees hotter than now. And Box 6.4 is saying that there's no evidence that it was even as warm then as it is now.

Where's the inconsistency, Michael Brazier?

Which of us is having difficulty reading?

Papertiger,

4-6 degrees in about 200 years
IPCC AR4 Summary for Policymakers, p. 13: "...the best estimate for the high scenario (A1FI) is 4.0°C (likely range is 2.4°C to 6.4°C)." OK, I should have said "2.4 to 6.4". I believe scenario A1F1 is the "business as usual" scenario (although they seem to have dropped these terms in AR4), and if so, that's what we're looking at, if there are no changes in policy.

Urban Heat Sinks
Fig. 3.6 on page 65 of the NOAA report
(http://www.climatescience.gov/Library/sap/sap1-1/finalreport/default.htm)
mentioned on the Dyson thread shows temperature trends at all these levels as a function of location on the globe. You can see that it’s heating up a lot over many areas in the northern hemisphere that don’t have any big cities: northern Canada and Alaska, for instance. And also over some ocean areas, too.

"Now tell me why didn't the C-O2 take effect until after it was at 375 ppm?"
It got to 379 ppm in 2005. I don't understand your question.

Medieval Warm Period - reprise

John Costello,

The substance of the issue is, Where do you get your 2 degrees?

I'm going to quote from Box 6.4, adding emphasis:

"At least as early as the beginning of the 20th century, different authors were already examining the evidence for climate changes
during the last two millennia, particularly in relation to North America, Scandinavia and Eastern Europe (Brooks, 1922). With regard to
Iceland and Greenland, Pettersson (1914) cited evidence for considerable areas of Iceland being cultivated in the 10th century. At the same time, Norse settlers colonised areas of Greenland,..."

"Lamb (1965) seems to have been the first to coin the phrase ‘Medieval Warm Epoch’ or ‘Little Optimum’ to describe the totality of
multiple strands of evidence principally drawn from western Europe, for a period of widespread and generally warmer temperatures
which he put at between AD 1000 and 1200 (Lamb, 1982). It is important to note that Lamb also considered the warmest conditions
to have occurred at different times in different areas: between 950 and 1200 in European Russia and Greenland, but somewhat later, between 1150 and 1300 (though with notable warmth also in the later 900s) in most of Europe (Lamb, 1977)."

"Much of the evidence used by Lamb was drawn from a very diverse mixture of sources such as historical information, evidence of treeline and vegetation changes, or records of the cultivation of cereals and vines. He also drew inferences from very preliminary analyses of some Greenland ice core data and European tree ring records. Much of this evidence was difficult to interpret in terms of accurate quantitative temperature influences. Much was not precisely dated, representing physical or biological systems that involve complex lags between forcing and response, as is the case for vegetation and glacier changes. Lamb’s analyses also predate any formal statistical calibration of much of the evidence he considered. He concluded that ‘High Medieval’ temperatures were probably 1.0°C to 2.0°C above early 20th-century levels at various European locations (Lamb, 1977; Bradley et al., 2003a)..."

"A later study, based on examination of more quantitative evidence, in which efforts were made to control for accurate dating and
specific temperature response, concluded that it was not possible to say anything other than ‘… in some areas of the Globe, for some
part of the year, relatively warm conditions may have prevailed’ (Hughes and Diaz, 1994)."

"A number of studies that have attempted to produce very large spatial-scale reconstructions have come to the same conclusion: that medieval warmth was heterogeneous in terms of its precise timing and regional expression (Crowley and Lowery, 2000; Folland et al., 2001; Esper et al., 2002; Bradley et al., 2003a; Jones and Mann, 2004; D’Arrigo et al., 2006)."

"The uncertainty associated with present palaeoclimate estimates of NH mean temperatures is significant, especially for the period prior to 1600 when data are scarce (Mann et al., 1999; Briffa and Osborn, 2002; Cook et al., 2004a). However, Figure 6.10 shows that the warmest period prior to the 20th century very likely occurred between 950 and 1100, but temperatures were probably between 0.1°C and 0.2°C below the 1961 to 1990 mean and significantly below the level shown by instrumental data after 1980."

"In order to reduce the uncertainty, further work is necessary to update existing records, many of which were assembled up to 20 years ago, and to produce many more, especially early, palaeoclimate series with much wider geographic coverage. There are far from
sufficient data to make any meaningful estimates of global medieval warmth (Figure 6.11). There are very few long records with high temporal resolution data from the oceans, the tropics or the SH."

"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 Briffa, 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 Briffa, 2006)."

So, this is what I am relying on: the team of 1 coordinating lead author, 14 lead authors, and 33 contributing authors (all professionally involved in climate studies, and all signed onto the front page of Chapter 6.)

So, can you explain where your 2 degrees comes from?

Can you explain how Hughes & Diaz (1994), Crowley & Lowery (2000), Folland et al. (2001), Esper et al. (2002), Bradley et al. (2003a), Jones & Mann (2004), D'Arrigo et al (2006), Jones et al. (2001), Bradley et al. (2003b), and Osborn & Biffa (2006) have all gotten it wrong; but Brian Fagan has gotten it right?

Should you care to remind yourself of the contents of these papers, the full citations are given at the end of Chapter 6.

Michael Brazier:

Now that I've clarified what I was saying, and how it accords with the actual text of the IPCC report, let's go back to the issue at hand: plausible explanations for GW.

"Solar variation since 1750" Unfortunately, changes that happened long ago don't act in the present. It gets warm during the daytime, when the sun is shining, not hours later at night. If the sunshine hasn't gained more than 0.1% strength in 19 years, it really doesn't matter what was happening earlier: It's not going to explain the last 19 years. Which have been up, temperature-wise, a lot more than 0.1%.

"Multiplicative effects of solar variation"
The way the enhanced greenhouse effect works, the point at which optical depth = 1 for the IR band of interest gets moved up, and therefore the temperature at which the Earth is effectively radiating for that band is reduced because of the adiabatic lapse rate. As I do the calculation, the decrease in the effective radiating temperature is proportional to the original radiating temperature. So if the temperature starts off higher because of the extra 0.1% luminosity, it does make the change in temperature larger.

But not by much: To steal a result from an earlier calculation at
(http://www.classicalvalues.com/archives/2007/05/the_solar_conve.html)
posting:
Neal J. King·May 21, 2007 01:53 PM
the increase in the Earth's temperature directly due to a 0.1% luminosity increase would be 0.064 degrees. Since T-effective is currently about 267 K, the significance of this factor is less than .064/267 = 0.00024, or an additional 0.024% effect. That's not going to help very much.

"So what was I denying? I was denying that there was a period (ca.650-1315) when the Earth was 2 degrees warmer than now."

I'm willing to believe that's what you intended to say, but it's not what you actually said. In ordinary usage "the Medieval Warm Period didn't happen" asserts that the Earth's temperature in the 10th century AD was not significantly higher than it was in the 17th century.

Since you now agree that the Medieval Warm Period really did happen, I'll let John Costello handle the question of whether it was warmer or cooler than the present.

By the way, while looking for data on trends in CO2 concentration and solar flux, I ran across this fascinating new paper by Ernst-Georg Beck, "180 Years of atmospheric CO2 Gas Analysis by Chemical Methods" (ENERGY & ENVIRONMENT VOLUME 18 No. 2, 2007), stating that CO2 concentration has not been smoothly rising over the 19th and 20th centuries, but has actually spiked to 400 ppm around 1820, 1857 and 1942, falling back to 300 ppm in the intervening years. Did you notice it?

MB,

Now that you mention it, I did. RealClimate did a detailed examination of it, to which I refer you: (http://www.realclimate.org/index.php/archives/2007/05/beck-to-the-future/)

I will clip just the key points:
"Beck’s approach is very simple: He decided from the beginning that Keeling and Callendar obviously are ideological fanatics and that finally all chemical measurements in the 19th and early 20th century actually were fine. Great news of course!

"So what does the new CO2 'reconstruction' look like? For example, within 15 years CO2 levels rose from about 290ppm (1925) to about 470ppm (1942). Worse, within only 10 years these huge CO2 levels were absorbed again and came back to boring mainstream values of about 300ppm.

"The list of arguments against such variability in the carbon cycle is too long even for a post on RC but here are a few of the main ones:

* The fluxes necessary to produce such variations are just unbelievably huge. Modern fossil fuel emissions are about 7.5GT (Giga Tons) Carbon per year which would correspond to about 3.5ppm increase per year (except that about half is absorbed by natural sinks in the ocean and the terrestrial biosphere). Beck’s supposed 150ppm source/sink in a decade corresponds therefore to a CO2 production/absorption about ten times stronger than the entire global industrial production of 2007 (putting aside for the moment additional complications since such CO2 levels had to be equilibrated at least partly with the ocean and the real CO2 source must even be larger).

* Such huge biospheric fluxes would leave an enormous 13C signal in the atmosphere. Nothing remotely like that is observed in tree ring cellulose data.

* Beck makes an association of some of the alleged huge CO2 peaks with volcanic eruptions. The Mauna Loa CO2 record started by Charles Keeling 1955 (http://cdiac.ornl.gov/, http://cdiac.ornl.gov/trends/co2/graphics/mlo145e_thrudc04.pdf ) however doesn’t show much variability associated with the big eruptions of El Chichon, Agung or Pinatubo. (Readers should know however that on much longer, geologic, timescales, CO2 levels are heavily influenced by volcanic and tectonic activity, but that is not important on the interannual (or even centennial) timescale).

* The paper suggests that the CO2 peak in the 1940 is forced by the first temperature rise in the 20th century. That would make 150ppm due to a temperature shift of 0.4°C. What happened then with the next rise from the 1970s to today? The observed about 0.5°C rise corresponded to 'only' 70ppm always assuming that fossil fuel combustion does not leave any remains in the atmosphere.... ;)

* And most importantly, we know from ice core analysis the CO2 concentration from the pre-industrial to modern times. The results of three different Antarctic cores broadly confirm the picture of an accelerating rise of CO2 above levels of natural variability over the last 650.000 years.

"The last question to answer is how on earth Beck’s paper could survive a half-decent review process from anyone who knows any of this history. But this is a question best posed to the Editorial board of Energy and Environment and its Editor, Sonja Boehmer-Christiansen."

MB,

I posted a reply a few hours ago, but it hasn't been "cleared" yet.

MB,

It looks as though my reply has gotten stuck in the clearing process. I'll try again, without URLs:

RealClimate have done an extensive and detailed review, with references, of this paper by Beck. I will quote from it:

"“Climate sceptics” do not like this and keep coming up with their own temperature histories. One of the weirdest has been circulated for years by German high-school teacher E.G. Beck (notorious for his equally weird CO2 curve). This history shows a medieval warm phase that is warmer than current climate by more than 1 ºC (see Figure 2). So how did Beck get this curve?"

"The curve is a fake in several respects. It originally is taken from the first IPCC report of 1990: a scan of the original is shown in Figure 3. At that time, no large-scale temperature reconstructions were available yet. To give an indication of past climate variability, the report showed Lamb’s Central England estimate. (Unfortunately this was not stated in the report – an oversight which shows that IPCC review procedures in the early days were not what they are now. We will post in more detail on the history of this curve another time.)"

"But Beck did not stop at simply using this outdated curve, he modified it as highlighted in green in Figure 2. First, he added a wrong temperature scale – the tick marks in the old IPCC report represent 1 ºC, so Beck’s claimed range of 5 ºC exaggerates the past temperature variations by more than a factor of three. Second, the original curve only goes up to the 1970’s. Since then, Northern Hemisphere temperatures have increased by about 0.6 ºC and those in central England even more – so whatever you take this curve for, if it were continued to present, the current temperature would be above the Medieval level, as in the proper reconstructions available today. As this would destroy his message, Beck applied another fakery: he extended the curve flat up to the year 2000, thereby denying the measured warming since the 1970s. With this trick, his curve looks as if it was warmer in Medieval times than now."

"When approached directly about these issues, Beck published a modified curve on a website. He changed the temperature range from 5 ºC to 4.5 ºC – but he shortened the arrow as well, so this was just cosmetics. He also added instrumental temperatures for the 20th Century at the end – but with his wrong temperature scale, they are completely out of proportion. (In fact his version suggests temperatures have warmed by 2 ºC since 1900, more than twice of what is actually observed!)"

"Beck goes even further: in a recent article (in German), he has the audacity to claim that his manipulated curve is right and the more recent scientific results shown by IPCC are wrong. And for years, he has offered his curve on an internet site (biokurs.de) that distributes teaching materials for schools, with support from German school authorities. It is quite likely that his fake curve has been shown (and will continue to be shown) to many school children."

I have left out the figures, but you can find everything at the original posting. I will see if I can find a way to express this without triggering the URL-review:

---http://www-dot-realclimate-dot-org---
---/index.php/archives/2007/05---
---/the-weirdest-millennium/#more-450

MB,

Darn, I didn't realize that RealClimate had critiqued TWO of Beck's articles. OK, here's the one I posted the first time:

"Recently an article by E-G. Beck has been wafting through the Internet and has now been 'published' by Energy and Environment which challenges all these findings or, more precisely, ignores the last 50 years of carbon cycle research [Curiously, this journal always seems happy to ennoble even the strangest idea with the scientific label: "peer reviewed"]. Beck’s approach is very simple: He decided from the beginning that Keeling and Callendar obviously are ideological fanatics and that finally all chemical measurements in the 19th and early 20th century actually were fine. Great news of course!

So what does the new CO2 “reconstruction” look like? For example, within 15 years CO2 levels rose from about 290ppm (1925) to about 470ppm (1942). Worse, within only 10 years these huge CO2 levels were absorbed again and came back to boring mainstream values of about 300ppm.

The list of arguments against such variability in the carbon cycle is too long even for a post on RC but here are a few of the main ones:

* The fluxes necessary to produce such variations are just unbelievably huge. Modern fossil fuel emissions are about 7.5GT (Giga Tons) Carbon per year which would correspond to about 3.5ppm increase per year (except that about half is absorbed by natural sinks in the ocean and the terrestrial biosphere). Beck’s supposed 150ppm source/sink in a decade corresponds therefore to a CO2 production/absorption about ten times stronger than the entire global industrial production of 2007 (putting aside for the moment additional complications since such CO2 levels had to be equilibrated at least partly with the ocean and the real CO2 source must even be larger).

* Such huge biospheric fluxes would leave an enormous 13C signal in the atmosphere. Nothing remotely like that is observed in tree ring cellulose data.

* Beck makes an association of some of the alleged huge CO2 peaks with volcanic eruptions. The Mauna Loa CO2 record started by Charles Keeling 1955 (CDIA URLs) however doesn’t show much variability associated with the big eruptions of El Chichon, Agung or Pinatubo. (Readers should know however that on much longer, geologic, timescales, CO2 levels are heavily influenced by volcanic and tectonic activity, but that is not important on the interannual (or even centennial) timescale).

* The paper suggests that the CO2 peak in the 1940 is forced by the first temperature rise in the 20th century. That would make 150ppm due to a temperature shift of 0.4°C. What happened then with the next rise from the 1970s to today? The observed about 0.5°C rise corresponded to “only” 70ppm always assuming that fossil fuel combustion does not leave any remains in the atmosphere.... ;)

* And most importantly, we know from ice core analysis the CO2 concentration from the pre-industrial to modern times. The results of three different Antarctic cores broadly confirm the picture of an accelerating rise of CO2 above levels of natural variability over the last 650.000 years."

You can find the original at:

---http://www-dot-realclimate-dot-org---
---/index.php/archives/2007/05---
---/beck-to-the-future/

File this one under Unproven Conspiracy Theories.

In a news release, Global Warming Key Factor in Increase of Cat Population yesterday, Pets Across America President Kathy Warnick said global warming is thought to be a contributing factor to the dramatic increase of stray, owned and feral cats.

Pets Across America, self-described in the release as "the largest umbrella organization for animal shelters serving more than 130 million people" also stated that cats outnumber dogs by 13.5 million and that the number is growing and that animal shelters across the United States are reporting skyrocketing influxes of cats and kittens being brought into their agencies. Most importantly, however, they used their news release to tell the world that "many believe global warming is extending cat-breeding seasons and causing the cat population to swell."

I repeat their claim: "many believe global warming is...causing the cat population to swell!"

WARNING: Below is where the conspiracy-theory angle, though still very much unproven, comes into play. Proceed at your own peril.

After taking into account this earth-shattering news from Pets Across America, can you honestly believe it's a coincidence that this Kansas City, Mo.-based group chose to issue its news release only one week prior to the airing of Bob Barker's last episode of The Price is Right? No way!

I suspect that Barker, arguably the world's most-visible advocate of spaying and neutering pets, opted to retire this year only after coming under immense pressure from a below-the-radar campaign by animal shelter advocate groups like Pets Across America. Their never-made-public argument: Barker's spaying and neutering advocacy was a flop, and we should have been concentrating on stopping Global Warming.

Something to think about from Bob McCarty Writes™

[Editor's Note: The final episode of The Price is Right
featuring Bob Barker airs on CBS June 15 at 11 a.m. Eastern.]