No 'tipping point' for Arctic sea ice

[skierinvermont]

What don't you understand about the clustering of warm proxy data between 900AD and 1100AD? That time period saw Both the Arctic ann Antarctic Ice Sheet shink smaller than today, treelines globally above those of today, Sea levels rise higher than those of today...all sugesting a period of maximum temperatures well above those of todays. You cannot use ONE outlying study, or even 10, out of 700+ to make a case that does not hold true with a huge clustering of warmth from 700 datapoints across the globe showing extreme warmth between 900AD - 1100AD.

Its not manipultive if the data/quotations being used are legitimate.

I completely agree there is a clustering of warm proxy data between 900 AD and 11000 AD. The question is HOW warm GLOBALLY. Your blog site doesn't attempt to combine them and combining them would be a complex mathematical process. Moreover, it takes warm periods 450 -900AD and pretends they occurred 900-1100AD.

I also have not read any that say the arctic and antarctic ice sheet were smaller than today or that treelines were higher GLOBALLY (perhaps in certain regions in certain centuries they were). I've read a good dozen of them from that site and none of them support these two assertions. Even if it were true, it wouldn't necessarily mean the globe was warmer. Well if GLOBAL treelines were higher it probably would, but I don't see any evidence to back that up.

You are probably correct about the higher sea levels, but that doesn't mean it was warmer. It just means the warm period was much longer than our present one has been so far. The same thing could apply to ice sheets as well. Although I have not seen any evidence to back up that assertion.

[skierinvermont]

Say Whaaaaaaaaa?!

We cannot accurately determine the "net effect", let alone how much of it, will result from 0.038% of the atmosphere with basic, limited, understanding of the mechanisms/effects/variables involved with the Sun, the earths GHE/interprocessing, and the energy profiles and the various unknown interaction within and outside of the atmosphere.

Bethesda vs Physicists and the U.S. Navy... who should I believe?

[BethesdaWX]

I completely agree there is a clustering of warm proxy data between 900 AD and 11000 AD. The question is HOW warm GLOBALLY. Your blog site doesn't attempt to combine them and combining them would be a complex mathematical process. Moreover, it takes warm periods 450 -900AD and pretends they occurred 900-1100AD.

I also have not read any that say the arctic and antarctic ice sheet were smaller than today or that treelines were higher GLOBALLY (perhaps in certain regions in certain centuries they were). I've read a good dozen of them from that site and none of them support these two assertions. Even if it were true, it wouldn't necessarily mean the globe was warmer. Well if GLOBAL treelines were higher it probably would, but I don't see any evidence to back that up.

You are probably correct about the higher sea levels, but that doesn't mean it was warmer. It just means the warm period was much longer than our present one has been so far. The same thing could apply to ice sheets as well. Although I have not seen any evidence to back up that assertion.

I see your point. That is the problem with proxies, you have to infer from them what the actual temperature was, which will never be exact.

This summary of the entire Antarctic region in the MWP should clear things up for you.

(FYI, by "global" treelines, I mean those found in Western N America, Europe and Asia. South American proxies have been very scarce and not effective).

http://www.co2scienc...pantarctica.php

Here is a snippet

At about the same time, Hall and Denton (2002) mapped the distribution and elevation of surficial deposits along the southern Scott Coast of Antarctica in the vicinity of the Wilson Piedmont Glacier, which runs parallel to the coast of the western Ross Sea from McMurdo Sound north to Granite Harbor. The chronology of the raised beaches they studied was determined from more than 60 ¹⁴C dates of incorporated organic materials they had previously collected from hand-dug excavations (Hall and Denton, 1999); and the record the dates helped define demonstrated that near the end of the Medieval Warm Period, "as late as 890 ¹⁴C yr BP," as Hall and Denton describe it, "the Wilson Piedmont Glacier was still less extensive than it is now [our italics]," demonstrating that the climate of that period was in all likelihood considerably warmer than it is currently.

Noon et al. (2003) used oxygen isotopes preserved in authigenic carbonate retrieved from freshwater sediments of Sombre Lake on Signy Island (60°43'S, 45°38'W) in the Southern Ocean to construct a 7000-year history of that region's climate. This work revealed that the general trend of temperature at the study site has been downward. Of most interest to us, however, is the millennial-scale oscillation of climate that is apparent in much of the record. This climate cycle is such that approximately 2000 years ago, after a thousand-year gap in the data, Signy Island experienced the relative warmth of the last vestiges of the Roman Warm Period, as delineated by McDermott et al. (2001) on the basis of a high-resolution speleothem δ¹⁸O record from southwest Ireland. Then comes the Dark Ages Cold period, which is also contemporaneous with what McDermott et al. observe in the Northern Hemisphere, after which the Medieval Warm Period appears at the same point in time and persists for the same length of time that it does in the vicinity of Ireland, whereupon the Little Ice Age sets in just as it does in the Northern Hemisphere. Finally, there is an indication of late 20th-century warming, but with still a long way to go before conditions comparable to those of the Medieval Warm Period are achieved.

Two years later, Castellano et al. (2005) derived a detailed history of Holocene volcanism from the sulfate record of the first 360 meters of the Dome Concordia ice core that covered the period 0-11.5 kyr BP, after which they compared their results for the past millennium with similar results obtained from eight other Antarctic ice cores. Before doing so, however, they normalized the results at each site by dividing its several volcanic-induced sulfate deposition values by the value produced at that site by the AD 1816 Tambora eruption, in order to reduce deposition differences among sites that might have been induced by differences in local site characteristics. This work revealed that most volcanic events in the early last millennium (AD 1000-1500) exhibited greater among-site variability in normalized sulphate deposition than was observed thereafter.

Citing Budner and Cole-Dai (2003) in noting that "the Antarctic polar vortex is involved in the distribution of stratospheric volcanic aerosols over the continent," Castellano et al. say that assuming the intensity and persistence of the polar vortex in both the troposphere and stratosphere "affect the penetration of air masses to inland Antarctica, isolating the continental area during cold periods and facilitating the advection of peripheral air masses during warm periods (Krinner and Genthon, 1998), we support the hypothesis that the pattern of volcanic deposition intensity and geographical variability [higher values at coastal sites] could reflect a warmer climate of Antarctica in the early last millennium," and that "the re-establishment of colder conditions, starting in about AD 1500, reduced the variability of volcanic depositions."

Describing this phenomenon in terms of what it implies, Castellano et al. say "this warm/cold step could be like a Medieval Climate Optimum-like to Little Ice Age-like transition." We agree, noting they additionally cite Goosse et al. (2004) as reporting evidence from Antarctic ice-core δD and δ¹⁸O data "in support of a Medieval Warming-like period in the Southern Hemisphere, delayed by about 150 years with respect to Northern Hemisphere Medieval Warming." Hence, the ten researchers conclude their report by postulating that "changes in the extent and intra-Antarctic variability of volcanic depositional fluxes may have been consequences of the establishment of a Medieval Warming-like period that lasted until about AD 1500."

A year later, Hall et al. (2006) collected skin and hair (and even some whole-body mummified remains) from Holocene raised-beach excavations at various locations along Antarctica's Victoria Land Coast, which they identified by both visual inspection and DNA analysis as coming from southern elephant seals, and which they analyzed for age by radiocarbon dating. By these means they obtained data from fourteen different locations within their study region -- which they describe as being "well south" of the seals' current "core sub-Antarctic breeding and molting grounds" -- that indicate that the period of time they denominate the Seal Optimum began about 600 BC and ended about AD1400, the latter of which dates they describe as being "broadly contemporaneous with the onset of Little Ice Age climatic conditions in the Northern Hemisphere and with glacier advance near [Victoria Land's] Terra Nova Bay."

In describing the significance of their findings, the US, British and Italian researchers say they are indicative of "warmer-than-present climate conditions" at the times and locations of the identified presence of the southern elephant seal, and that "if, as proposed in the literature, the [Ross] ice shelf survived this period, it would have been exposed to environments substantially warmer than present," which would have included both the Roman Warm Period and Medieval Warm Period.

Most recently, Williams et al. (2007) presented methyl chloride (CH3Cl) measurements of air extracted from a 300-m ice core that was obtained at the South Pole, Antarctica, covering the time period 160 BC to AD 1860. In describing what they found, the researchers say that "CH3Cl levels were elevated from 900-1300 AD by about 50 ppt relative to the previous 1000 years, coincident with the warm Medieval Climate Anomaly (MCA)," and that they "decreased to a minimum during the Little Ice Age cooling (1650-1800 AD), before rising again to the modern atmospheric level of 550 ppt." Noting that "today, more than 90% of the CH3Cl sources and the majority of CH3Cl sinks lie between 30°N and 30°S (Khalil and Rasmussen, 1999; Yoshida et al., 2004)," they say "it is likely that climate-controlled variability in CH3Cl reflects changes in tropical and subtropical conditions." In fact, they go so far as to state that "ice core CH3Cl variability over the last two millennia suggests a positive relationship between atmospheric CH3Cl and global [our italics] mean temperature."

As best we can determine from the graphical representation of their data, the peak CH3Cl concentration measured by Williams et al. during the MCA is approximately 533 ppt, which is within 3% of its current mean value of 550 ppt and well within the range of 520 to 580 ppt that characterizes methyl chloride's current variability. Hence, we may validly conclude that the mean peak temperature of the MCA (which we refer to as the Medieval Warm Period) over the latitude range 30°N to 30°S -- and possibly over the entire globe -- may not have been materially different from the mean peak temperature so far attained during the Current Warm Period. And this conclusion, along with the findings of the other studies we have reviewed, suggests there is nothing that is unusual, unnatural or unprecedented about the current level of earth's warmth, which further suggests that the historical increase in the atmosphere's CO2 concentration may not have had anything to do with concomitant 20th-century global warming

[BethesdaWX]

Bethesda vs Physicists and the U.S. Navy... who should I believe?

This doesn't have to do with Changing/Disproving Physics...

[tacoman25]

I completely agree there is a clustering of warm proxy data between 900 AD and 11000 AD. The question is HOW warm GLOBALLY. Your blog site doesn't attempt to combine them and combining them would be a complex mathematical process. Moreover, it takes warm periods 450 -900AD and pretends they occurred 900-1100AD.

I also have not read any that say the arctic and antarctic ice sheet were smaller than today or that treelines were higher GLOBALLY (perhaps in certain regions in certain centuries they were). I've read a good dozen of them from that site and none of them support these two assertions. Even if it were true, it wouldn't necessarily mean the globe was warmer. Well if GLOBAL treelines were higher it probably would, but I don't see any evidence to back that up.

You are probably correct about the higher sea levels, but that doesn't mean it was warmer. It just means the warm period was much longer than our present one has been so far. The same thing could apply to ice sheets as well. Although I have not seen any evidence to back up that assertion.

That's the thing with the MWP and the LIA....both periods suffer from a lack of truly global data, so we must rely on imprecise proxies to approximate global temperatures and there is actually a decent range that is possible. We know that certain areas certainly warmed/cooled quite significantly, but as we can see today, the trends over certain regions often do not match the global one. Especially high latitudes, which are always susceptible to greater swings in temperature patterns.

[salbers]

The apparent fact that sea level will soon rise above the MWP values suggests we are already getting warmer than the MWP.

[skierinvermont]

I see your point. That is the problem with proxies, you have to infer from them what the actual temperature was, which will never be exact.

This summary of the entire Antarctic region in the MWP should clear things up for you.

(FYI, by "global" treelines, I mean those found in Western N America, Europe and Asia. South American proxies have been very scarce and not effective).

http://www.co2scienc...pantarctica.php

Here is a snippet

At about the same time, Hall and Denton (2002) mapped the distribution and elevation of surficial deposits along the southern Scott Coast of Antarctica in the vicinity of the Wilson Piedmont Glacier, which runs parallel to the coast of the western Ross Sea from McMurdo Sound north to Granite Harbor. The chronology of the raised beaches they studied was determined from more than 60 ¹⁴C dates of incorporated organic materials they had previously collected from hand-dug excavations (Hall and Denton, 1999); and the record the dates helped define demonstrated that near the end of the Medieval Warm Period, "as late as 890 ¹⁴C yr BP," as Hall and Denton describe it, "the Wilson Piedmont Glacier was still less extensive than it is now [our italics]," demonstrating that the climate of that period was in all likelihood considerably warmer than it is currently.

Noon et al. (2003) used oxygen isotopes preserved in authigenic carbonate retrieved from freshwater sediments of Sombre Lake on Signy Island (60°43'S, 45°38'W) in the Southern Ocean to construct a 7000-year history of that region's climate. This work revealed that the general trend of temperature at the study site has been downward. Of most interest to us, however, is the millennial-scale oscillation of climate that is apparent in much of the record. This climate cycle is such that approximately 2000 years ago, after a thousand-year gap in the data, Signy Island experienced the relative warmth of the last vestiges of the Roman Warm Period, as delineated by McDermott et al. (2001) on the basis of a high-resolution speleothem δ¹⁸O record from southwest Ireland. Then comes the Dark Ages Cold period, which is also contemporaneous with what McDermott et al. observe in the Northern Hemisphere, after which the Medieval Warm Period appears at the same point in time and persists for the same length of time that it does in the vicinity of Ireland, whereupon the Little Ice Age sets in just as it does in the Northern Hemisphere. Finally, there is an indication of late 20th-century warming, but with still a long way to go before conditions comparable to those of the Medieval Warm Period are achieved.

Two years later, Castellano et al. (2005) derived a detailed history of Holocene volcanism from the sulfate record of the first 360 meters of the Dome Concordia ice core that covered the period 0-11.5 kyr BP, after which they compared their results for the past millennium with similar results obtained from eight other Antarctic ice cores. Before doing so, however, they normalized the results at each site by dividing its several volcanic-induced sulfate deposition values by the value produced at that site by the AD 1816 Tambora eruption, in order to reduce deposition differences among sites that might have been induced by differences in local site characteristics. This work revealed that most volcanic events in the early last millennium (AD 1000-1500) exhibited greater among-site variability in normalized sulphate deposition than was observed thereafter.

Citing Budner and Cole-Dai (2003) in noting that "the Antarctic polar vortex is involved in the distribution of stratospheric volcanic aerosols over the continent," Castellano et al. say that assuming the intensity and persistence of the polar vortex in both the troposphere and stratosphere "affect the penetration of air masses to inland Antarctica, isolating the continental area during cold periods and facilitating the advection of peripheral air masses during warm periods (Krinner and Genthon, 1998), we support the hypothesis that the pattern of volcanic deposition intensity and geographical variability [higher values at coastal sites] could reflect a warmer climate of Antarctica in the early last millennium," and that "the re-establishment of colder conditions, starting in about AD 1500, reduced the variability of volcanic depositions."

Describing this phenomenon in terms of what it implies, Castellano et al. say "this warm/cold step could be like a Medieval Climate Optimum-like to Little Ice Age-like transition." We agree, noting they additionally cite Goosse et al. (2004) as reporting evidence from Antarctic ice-core δD and δ¹⁸O data "in support of a Medieval Warming-like period in the Southern Hemisphere, delayed by about 150 years with respect to Northern Hemisphere Medieval Warming." Hence, the ten researchers conclude their report by postulating that "changes in the extent and intra-Antarctic variability of volcanic depositional fluxes may have been consequences of the establishment of a Medieval Warming-like period that lasted until about AD 1500."

A year later, Hall et al. (2006) collected skin and hair (and even some whole-body mummified remains) from Holocene raised-beach excavations at various locations along Antarctica's Victoria Land Coast, which they identified by both visual inspection and DNA analysis as coming from southern elephant seals, and which they analyzed for age by radiocarbon dating. By these means they obtained data from fourteen different locations within their study region -- which they describe as being "well south" of the seals' current "core sub-Antarctic breeding and molting grounds" -- that indicate that the period of time they denominate the Seal Optimum began about 600 BC and ended about AD1400, the latter of which dates they describe as being "broadly contemporaneous with the onset of Little Ice Age climatic conditions in the Northern Hemisphere and with glacier advance near [Victoria Land's] Terra Nova Bay."

In describing the significance of their findings, the US, British and Italian researchers say they are indicative of "warmer-than-present climate conditions" at the times and locations of the identified presence of the southern elephant seal, and that "if, as proposed in the literature, the [Ross] ice shelf survived this period, it would have been exposed to environments substantially warmer than present," which would have included both the Roman Warm Period and Medieval Warm Period.

Most recently, Williams et al. (2007) presented methyl chloride (CH3Cl) measurements of air extracted from a 300-m ice core that was obtained at the South Pole, Antarctica, covering the time period 160 BC to AD 1860. In describing what they found, the researchers say that "CH3Cl levels were elevated from 900-1300 AD by about 50 ppt relative to the previous 1000 years, coincident with the warm Medieval Climate Anomaly (MCA)," and that they "decreased to a minimum during the Little Ice Age cooling (1650-1800 AD), before rising again to the modern atmospheric level of 550 ppt." Noting that "today, more than 90% of the CH3Cl sources and the majority of CH3Cl sinks lie between 30°N and 30°S (Khalil and Rasmussen, 1999; Yoshida et al., 2004)," they say "it is likely that climate-controlled variability in CH3Cl reflects changes in tropical and subtropical conditions." In fact, they go so far as to state that "ice core CH3Cl variability over the last two millennia suggests a positive relationship between atmospheric CH3Cl and global [our italics] mean temperature."

As best we can determine from the graphical representation of their data, the peak CH3Cl concentration measured by Williams et al. during the MCA is approximately 533 ppt, which is within 3% of its current mean value of 550 ppt and well within the range of 520 to 580 ppt that characterizes methyl chloride's current variability. Hence, we may validly conclude that the mean peak temperature of the MCA (which we refer to as the Medieval Warm Period) over the latitude range 30°N to 30°S -- and possibly over the entire globe -- may not have been materially different from the mean peak temperature so far attained during the Current Warm Period. And this conclusion, along with the findings of the other studies we have reviewed, suggests there is nothing that is unusual, unnatural or unprecedented about the current level of earth's warmth, which further suggests that the historical increase in the atmosphere's CO2 concentration may not have had anything to do with concomitant 20th-century global warming

It may very well be that there was less ice in the antarctic during the MWP. That would explain the higher sea levels. I would like to see a more complete analysis than the one above which only contains a study from one glacier (it mentions another one in passing).

There are still some manipulative things going on in the above. For example it says "Finally, there is an indication of late 20th-century warming, but with still a long way to go before conditions comparable to those of the Medieval Warm Period are achieved." However, this is based on the proxy data. It would take a while for the present warming to start showing up in the proxy data. Whereas because the MWP was much longer, it shows up quite clearly in the proxy data. So to conclude based on this that current temperatures are cooler, is simply incorrect.

It played the same trick in several other "descriptions" as well. The author concludes that the MWP is warmer because the proxies show it as warmer.. but he completely ignores the fact that our present warming is just too short to show up in the proxies while the MWP was much longer.

And you still have the problem of combining many different proxies from different areas.

When this is done correctly, using many different methodologies not just tree rings, one finds that current temperatures are equal to or warmer than the MWP.

[skierinvermont]

That's the thing with the MWP and the LIA....both periods suffer from a lack of truly global data, so we must rely on imprecise proxies to approximate global temperatures and there is actually a decent range that is possible. We know that certain areas certainly warmed/cooled quite significantly, but as we can see today, the trends over certain regions often do not match the global one. Especially high latitudes, which are always susceptible to greater swings in temperature patterns.

To the bolded: Yes that is why we can't say definitively current temperatures are warmer than the MWP. Although the actual reconstructions do not show the MWP being as warm as present, the error bars are pretty large. That's partially because of error associated with the actual reconstruction, but mostly as you know just because the proxies don't show year-year fluctuations and are limited even decade-decade. Although even the McShane and Wyner paper which dealt with this problem a bit concluded the current decade was probably the warmest.

[skierinvermont]

The apparent fact that sea level will soon rise above the MWP values suggests we are already getting warmer than the MWP.

Yep - sea level probably doesn't have he precision to create an actual reconstruction due to the lags involved which is probably why I have never seen it used as one (maybe it is I don't know). But it probably can give a pretty good ballpark figure and constrain the reconstructions very strongly within certain parameters.

[BethesdaWX]

It may very well be that there was less ice in the antarctic during the MWP. That would explain the higher sea levels. I would like to see a more complete analysis than the one above which only contains a study from one glacier (it mentions another one in passing).

There are still some manipulative things going on in the above. For example it says "Finally, there is an indication of late 20th-century warming, but with still a long way to go before conditions comparable to those of the Medieval Warm Period are achieved." However, this is based on the proxy data. It would take a while for the present warming to start showing up in the proxy data. Whereas because the MWP was much longer, it shows up quite clearly in the proxy data. So to conclude based on this that current temperatures are cooler, is simply incorrect.

It played the same trick in several other "descriptions" as well. The author concludes that the MWP is warmer because the proxies show it as warmer.. but he completely ignores the fact that our present warming is just too short to show up in the proxies while the MWP was much longer.

And you still have the problem of combining many different proxies from different areas.

When this is done correctly, using many different methodologies not just tree rings, one finds that current temperatures are equal to or warmer than the MWP.

Can you find me a link explaining this "lag" in the proxies? Higher sea levels, less ice on Greenland/Antarctica and higher treelines in the Northern Hemisphere (SH is vague) would suggest the MWP was warmer than today during that time. (Southern hemispheric tree data is too vague and inconclusive, and is the reason why we cannot truly call the MWP "global" yet)

Also,

Tree rings are deceptive to use....because there is more CO2 in the atmosphere right now than there has been for a long time...there is something called "photosynthesis", and higher CO2 has already been speeding up plant growth.

What "other methodologies" are you speaking of?

[BethesdaWX]

Yep - sea level probably doesn't have he precision to create an actual reconstruction due to the lags involved which is probably why I have never seen it used as one (maybe it is I don't know). But it probably can give a pretty good ballpark figure and constrain the reconstructions very strongly within certain parameters.

We have not surpassed the MWP in temperatures.......Yet. We'll have alot of questions answered in 30yrs.

As for your other post...... (re-writing it for page change)

Can you find me a link explaining this "lag" in the proxies? Higher sea levels, less ice on Greenland/Antarctica and higher treelines in the Northern Hemisphere (SH is vague) would suggest the MWP was warmer than today during that time. (Southern hemispheric tree data is too vague and inconclusive, and is the reason why we cannot truly call the MWP "global" yet)

Also,

Tree rings are deceptive to use....because there is more CO2 in the atmosphere right now than there has been for a long time...there is something called "photosynthesis", and higher CO2 has already been speeding up plant growth.

What "other methodologies" are you speaking of?

[salbers]

Somehow you are repeating something that doesn't make sense. Higher sea levels during the MWP only mean a more prolonged period of warming, not necessarily higher temps. More that it's warmer now, since sea levels are soon to exceed the MWP.

[stellarfun]

Antarctica:

In Greenland (Figure 6-2) and coastal Antarctica, ice isotopic ratio records clearly shows 20th century warming, a Little Ice Age, and earlier warmth. In Greenland, this earlier warmth is centered at about A.D. 1000, whereas in Antarctica it was much earlier. Borehole temperature analyses yield the same pattern (see Chapter 8). In Greenland, the 20th century warmth is not higher than that during medieval times (11th century). In the Canadian Arctic, ice isotopic ratio records from the Agassiz Ice Cap on Ellesmere Island show warming over the last 150 years, which is unprecedented for the last millennium (Fisher et al. 1995). As a group, the ice cores from interior Antarctica (Figure 6-2) show nothing anomalous about the 20th century (Masson et al. 2000).

Analyses of stable isotopes in glacial ice provide records of climate changes at high resolution over long time periods. In the low latitudes, this signal is a combination of temperature and hydrologic variables. In the polar ice sheets, the signal is primarily driven by temperature.

Greenland had a pronounced period of warmth around A.D. 1000, a cool period from 1600 through 1900, and a modest 20th century warming. Some coastal sites in Antarctica show 20th century warming but interior sites do not. No Antarctic sites show a warming during medieval times.

Ice sheet boreholes permit longer timescale temperature reconstructions because of the purity of ice, the great depth of the boreholes, and the opportunity for combination with isotopic information from the ice core itself. These analyses can only be conducted in dry cold ice, and so are limited to the polar ice sheets and some high-altitude sites.

A borehole from Law Dome (Dahl-Jensen et al. 1999), in coastal East Antarctica, reveals a warming of approximately 0.7°C from the middle 19th century to present (uncertainty of approximately 0.2°C). This was preceded by a period of comparable warmth centered on 1500–1600, a 1°C cooler period centered on 1300, and consistently warmer conditions prior to this (with temperature at A.D. 1 being approximately 1°C warmer than the late 20th century). There was no apparent warming during medieval times at this site. Uncertainties on these results for earlier time periods are on the order of a few tenths of a degree Celsius for averages over a few centuries.

The majority of glaciers in high mountain ranges outside the polar regions have retreated during the last 150 years, primarily as a consequence of warming. Other evidence from glaciers suggests that the recent warmth is unprecedented on millennial timescales, including melt and retreat of Andean glaciers and disintegration of Antarctic ice shelves.

....

Finally, these [glacial] reconstructions cannot be done for mountain glaciers in Antarctica because it is so cold there that melt is not the dominant mass loss process (it is iceberg production), so the connection to temperature is different.

.....

Over the last few decades, the floating ice shelves along the Antarctic Peninsula have been disintegrating, following a progressively southward pattern (Vaughan and Doake 1996, Cook et al. 2005). This is primarily a result of higher temperatures inducing surface melt (van den Broeke 2005). Analysis of sediment cores from the seafloor (Domack et al. 2005) beneath one of the largest former shelves (the Larsen B, which disintegrated in the late 1990s) indicates that this ice shelf had persisted throughout the previous 10,000 years, providing further evidence that recent decades have been anomalously warm.

[BethesdaWX]

Somehow you are repeating something that doesn't make sense. Higher sea levels during the MWP only mean a more prolonged period of warming, not necessarily higher temps. More that it's warmer now, since sea levels are soon to exceed the MWP.

Yes, you are correct...however, thats not the point I actually had in mind. Maybe make an inference? (Below)

Where we have proxy data/physical evidence, we need to correlate what is seen then to what we see now in a given timeframe. The "current sea level rise" on these graphs actually is measurement data applied into the proxy data, thus the spike. If we had measurement data in the MWP, we'd see a large Jump after the DACP, and probably...the peak would be even higher.

My inference comment should come to mind when reviewing my past posts, in what I would attribute to such changes is not the RESULT ( higher sea level), but more of what we observe through proxy data during that timeframe that led be to believe there is a correlation.

1) As mentioned, Penguin Seals & their breeding grounds & habitat in the Antarctic during the MWP was significantly further south than currently. This also coincided with a swift rate in melting of the WAIS. Glaciers referenced, even towards the end of the MWP, were smaller at the time than they are currently

2) Where there are now glaciers in the Arctic, there were trees, and animals, during the MWP. We are finding the remains of trees, animals, viking burial grounds, grasses, etc under todays melting glaciers. These species could not live there now.

3) Treelines were significantly higher, they work upward with the temperature in perfect correlation....given that the overall treeline fluctuates on a long term basis...the correlation would be pretty exact...winds carry seeds near the level of limit, animals eat the seeds, and deposit them elsewhere. You would see small trees beginning to grow less than a decade after conditions allow...at longest.

[BethesdaWX]

Antarctica:

Whats your point here?

You picked out a study without reading the earlier summary I posted?

[stellarfun]

Whats your point here?

You picked out a study without reading the earlier summary I posted?

I had read the CO2 Science 'study' of Antarctica before you posted it, and I was well-familiar with the garbage that it is..

Here are the abstracts of the first six journal articles cited by CO2 Science for their 'study' of Antarctic warming associated with the MWP.

The number and magnitude of large explosive volcanic eruptions between 904 and 1865 A.D.: Quantitative evidence from a new South Pole ice core

A new volcanic record covering the period of 904 to 1865 A.D. was produced from continuous chemical analysis of a 2001 South Pole ice core. This new record is consistent with previous records in the number and dates of large volcanic events. The relative magnitudes of several prominent events in this new record were compared to the same events in previous records from South Pole and Plateau Remote (East Antarctica) ice cores. The comparison demonstrates that the discrepancies in reported magnitudes of these events are probably a result of the glaciological complications at Plateau Remote, and that volcanic deposit or flux measurements from South Pole ice cores are therefore more reliable parameters of the atmospheric mass loadings of volcanic aerosols. The new record also confirms the previous finding that five large or moderately large volcanic eruptions occurred in the 13^th century. The total atmospheric aerosol mass loadings, inferred from volcanic sulfate flux in this new ice core, from these five eruptions appear to be 3 to 20 times those in other centuries during the last millennium, suggesting a significant role by explosive volcanism in the climatic transition from the Medieval Warm Period to the Little Ice Age.

This paper deals with volcanism and its effects, and is not a temperature record for the MWP.

Holocene volcanic history as recorded in the sulfate stratigraphy of the European Project for Ice Coring in Antarctica Dome

A detailed history of Holocene volcanism was reconstructed using the sulfate record of the European Project for Ice Coring in Antarctica Dome C (EDC96) ice core. This first complete Holocene volcanic record from an Antarctic core provides a reliable database to compare with long records from Antarctic and Greenland ice cores. A threshold method based on statistical treatment of the lognormal sulfate flux distribution was used to differentiate volcanic sulfate spikes from sulfate background concentrations. Ninety-six eruptions were identified in the EDC96 ice core during the Holocene, with a mean of 7.9 events per millennium. The frequency distribution (events per millennium) showed that the last 2000 years were a period of enhanced volcanic activity. EDC96 volcanic signatures for the last millennium are in good agreement with those recorded in other Antarctic ice cores. For older periods, comparison is in some cases less reliable, mainly because of dating uncertainties. Sulfate depositional fluxes of individual volcanic events vary greatly among the different cores. A volcanic flux normalization (volcanic flux/Tambora flux ratio) was used to evaluate the relative intensity of the same event recorded at different sites in the last millennium. Normalized flux variability for the same event showed the highest value in the 1100–1500 AD period. This pattern could mirror changes in regional transport linked to climatic variations such as slight warming stages in the Southern Hemisphere.

Volcanism again.

A late medieval warm period in the Southern Ocean as a delayed response to external forcing

On the basis of long simulations performed with a three-dimensional climate model, we propose an interhemispheric climate lag mechanism, involving the long-term memory of deepwater masses. Warm anomalies, formed in the North Atlantic when warm conditions prevail at surface, are transported by the deep ocean circulation towards the Southern Ocean. There, the heat is released because of large scale upwelling, maintaining warm conditions and inducing a lagged response of about 150 years compared to the Northern Hemisphere. Model results and observations covering the first half of the second millenium suggest a delay between the temperature evolution in the Northern Hemisphere and in the Southern Ocean. The mechanism described here provides a reasonable hypothesis to explain such an interhemipsheric lag.

This is running a simulation model, no recording or analyzing field data.

New relative sea-level curves for the southern Scott Coast, Antarctica: evidence for Holocene deglaciation of the western Ross Sea

More than 130 radiocarbon dates of penguin remains and guano, sealskin, shells, and seaweed from raised beach ridges afford relative sea-level information for southern Victoria Land. A new relative sea-level curve suggests that the final unloading of grounded ice from the coast took place about 6600 ¹⁴C years BP, in keeping with previous estimates of the timing of deglaciation. Since this time, the coast has experienced 32 m of relative sea-level fall at rates ranging from 2 to 15 mm/year, consistent with glacioisostatic rebound.

You do understand how many centuries this data preceded the MWP, don't you? BP is not an oil company, it means Before Present.

(At this point, I skipped a study by the same lead author related to the study above.)

Holocene elephant seal distribution implies warmer-than-present climate in the Ross Sea.

We show that southern elephant seal (Mirounga leonina) colonies existed proximate to the Ross Ice Shelf during the Holocene, well south of their core sub-Antarctic breeding and molting grounds. We propose that this was due to warming (including a previously unrecognized period from ≈1,100 to 2,300 ¹⁴C yr B.P.) that decreased coastal sea ice and allowed penetration of warmer-than-present climate conditions into the Ross Embayment. If, as proposed in the literature, the ice shelf survived this period, it would have been exposed to environments substantially warmer than present.

Antecedes the MWP

Sediment core from beneath the Amery Ice Shelf, East Antarctica, suggests mid-Holocene ice-shelf retreat.

The stability of floating ice shelves is an important indicatorof ocean circulation and ice-shelf mass balance. A sub–ice-shelfsediment core collected during the Austral summer of 2000–2001from site AM02 (69°42.8'S, 72°38.4'E) on the Amery IceShelf, East Antarctica, contains a full and continuous recordof glacial retreat. The AM02 core site is 80 km south of thefloating ice shelf edge and contains a 0.5-m-thick Holocenesurface layer of siliceous mud and diatom ooze of marine origin.Core data are supportive of sub–ice-shelf circulationmodels that predict the landward flow of oceanic water, andprove that the landward transport of hemipelagic sediments occursbeneath floating ice shelves over distances of at least 80 km.An increase in sea-ice–associated diatom deposition inthe upper part of the Holocene suggests that a major retreatof the Amery Ice Shelf to at least 80 km landward of its presentlocation may have occurred during the mid-Holocene climaticoptimum.

The mid-point of the HCO was 7,000 years ago.

______________________________________

What's the point of wasting more bandwidth on this board by going through the entire CO2 Science list when it should be obvious how fraudulent the CO2 Science 'study' of Antarctic warming during the MWP is.

[BethesdaWX]

I had read the CO2 Science 'study' of Antarctica before you posted it, and I was well-familiar with the garbage that it is..

Here are the abstracts of the first six journal articles cited by CO2 Science for their 'study' of Antarctic warming associated with the MWP.

The number and magnitude of large explosive volcanic eruptions between 904 and 1865 A.D.: Quantitative evidence from a new South Pole ice core

This paper deals with volcanism and its effects, and is not a temperature record for the MWP.

Holocene volcanic history as recorded in the sulfate stratigraphy of the European Project for Ice Coring in Antarctica Dome

Volcanism again.

A late medieval warm period in the Southern Ocean as a delayed response to external forcing

This is running a simulation model, no recording or analyzing field data.

New relative sea-level curves for the southern Scott Coast, Antarctica: evidence for Holocene deglaciation of the western Ross Sea

You do understand how many centuries this data preceded the MWP, don't you? BP is not an oil company, it means Before Present.

(At this point, I skipped a study by the same lead author related to the study above.)

Holocene elephant seal distribution implies warmer-than-present climate in the Ross Sea.

Antecedes the MWP

Sediment core from beneath the Amery Ice Shelf, East Antarctica, suggests mid-Holocene ice-shelf retreat.

The mid-point of the HCO was 7,000 years ago.

______________________________________

What's the point of wasting more bandwidth on this board by going through the entire CO2 Science list when it should be obvious how fraudulent the CO2 Science 'study' of Antarctic warming during the MWP is.

What the f**k?

The Antarctic Study mentions data from the LIA, RWP, DACP, CWP And Any other time period to which data can be attained from......so what?

This doesn't change the fact that proxies/physical evidence from this timeframe reflect warmer temperatures, regardless if other time periods had warmer temps. Globally, the MWP was most likely warmer than the CWP.....at this time.

You are clearly dipsh*tting yourself.

[skierinvermont]

1) As mentioned, Penguin Seals & their breeding grounds & habitat in the Antarctic during the MWP was significantly further south than currently. This also coincided with a swift rate in melting of the WAIS. Glaciers referenced, even towards the end of the MWP, were smaller at the time than they are currently

As stellarfun pointed out, it was actually BEFORE the MWP.

Again, this is the whole problem the regional warm periods don't overlap.

[BethesdaWX]

As stellarfun pointed out, it was actually BEFORE the MWP.

Yes, maybe in the section he chose to look at! He fails to realize that the study he referred to was not honed in on the MWP!

Read the red!

Here

This work revealed that the general trend of temperature at the study site has been downward. Of most interest to us, however, is the millennial-scale oscillation of climate that is apparent in much of the record. This climate cycle is such that approximately 2000 years ago, after a thousand-year gap in the data, Signy Island experienced the relative warmth of the last vestiges of the Roman Warm Period, as delineated by McDermott et al. (2001) on the basis of a high-resolution speleothem δ¹⁸O record from southwest Ireland. Then comes the Dark Ages Cold period, which is also contemporaneous with what McDermott et al. observe in the Northern Hemisphere, after which the Medieval Warm Period appears at the same point in time and persists for the same length of time that it does in the vicinity of Ireland, whereupon the Little Ice Age sets in just as it does in the Northern Hemisphere. Finally, there is an indication of late 20th-century warming, but with still a long way to go before conditions comparable to those of the Medieval Warm Period are achieved.

Two years later, Castellano et al. (2005) derived a detailed history of Holocene volcanism from the sulfate record of the first 360 meters of the Dome Concordia ice core that covered the period 0-11.5 kyr BP, after which they compared their results for the past millennium with similar results obtained from eight other Antarctic ice cores. Before doing so, however, they normalized the results at each site by dividing its several volcanic-induced sulfate deposition values by the value produced at that site by the AD 1816 Tambora eruption, in order to reduce deposition differences among sites that might have been induced by differences in local site characteristics. This work revealed that most volcanic events in the early last millennium (AD 1000-1500) exhibited greater among-site variability in normalized sulphate deposition than was observed thereafter.

Citing Budner and Cole-Dai (2003) in noting that "the Antarctic polar vortex is involved in the distribution of stratospheric volcanic aerosols over the continent," Castellano et al. say that assuming the intensity and persistence of the polar vortex in both the troposphere and stratosphere "affect the penetration of air masses to inland Antarctica, isolating the continental area during cold periods and facilitating the advection of peripheral air masses during warm periods (Krinner and Genthon, 1998), we support the hypothesis that the pattern of volcanic deposition intensity and geographical variability [higher values at coastal sites] could reflect a warmer climate of Antarctica in the early last millennium," and that "the re-establishment of colder conditions, starting in about AD 1500, reduced the variability of volcanic depositions."

We agree, noting they additionally cite Goosse et al. (2004) as reporting evidence from Antarctic ice-core δD and δ¹⁸O data "in support of a Medieval Warming-like period in the Southern Hemisphere, delayed by about 150 years with respect to Northern Hemisphere Medieval Warming."

Seal Optimum began about 600 BC and ended about AD1400, the latter of which dates they describe as being "broadly contemporaneous with the onset of Little Ice Age climatic conditions in the Northern Hemisphere and with glacier advance near [Victoria Land's] Terra Nova Bay."In describing the significance of their findings, the US, British and Italian researchers say they are indicative of "warmer-than-present climate conditions" at the times and locations of the identified presence of the southern elephant seal, and that "if, as proposed in the literature, the [Ross] ice shelf survived this period, it would have been exposed to environments substantially warmer than present," which would have included both the Roman Warm Period and Medieval Warm Period

Most recently, Williams et al. (2007) presented methyl chloride (CH3Cl) measurements of air extracted from a 300-m ice core that was obtained at the South Pole, Antarctica, covering the time period 160 BC to AD 1860. In describing what they found, the researchers say that "CH3Cl levels were elevated from 900-1300 AD by about 50 ppt relative to the previous 1000 years, coincident with the warm Medieval Climate Anomaly (MCA)," and that they "decreased to a minimum during the Little Ice Age cooling (1650-1800 AD), before rising again to the modern atmospheric level of 550 ppt." Noting that "today, more than 90% of the CH3Cl sources and the majority of CH3Cl sinks lie between 30°N and 30°S (Khalil and Rasmussen, 1999; Yoshida et al., 2004)," they say "it is likely that climate-controlled variability in CH3Cl reflects changes in tropical and subtropical conditions." In fact, they go so far as to state that "ice core CH3Cl variability over the last two millennia suggests a positive relationship between atmospheric CH3Cl and global [our italics] mean temperature."

As best we can determine from the graphical representation of their data, the peak CH3Cl concentration measured by Williams et al. during the MCA is approximately 533 ppt, which is within 3% of its current mean value of 550 ppt and well within the range of 520 to 580 ppt that characterizes methyl chloride's current variability. Hence, we may validly conclude that the mean peak temperature of the MCA (which we refer to as the Medieval Warm Period) over the latitude range 30°N to 30°S -- and possibly over the entire globe -- may not have been materially different from the mean peak temperature so far attained during the Current Warm Period. And this conclusion, along with the findings of the other studies we have reviewed, suggests there is nothing that is unusual, unnatural or unprecedented about the current level of earth's warmth

[skierinvermont]

Again some of those descriptions do not match the actual studies themselves. Saying there was a warm period, none of this proves the MWP was warmer than present. If we are talking about the MWP we need to restrict our view to 900-1100AD.

This conversation is over until 1) you cite the actual abstracts of the studies themselves not these faulty descriptions of them

2) we restrict our view to the period 900-1100 AD

3) we make actual temperature comparisons instead of just saying "it was warm" .. exactly how warm and when?

[stellarfun]

Yes, maybe in the section he chose to look at! He fails to realize that the study he referred to was not honed in on the MWP!

Read the red!

Here

This work revealed that the general trend of temperature at the study site has been downward. Of most interest to us, however, is the millennial-scale oscillation of climate that is apparent in much of the record. This climate cycle is such that approximately 2000 years ago, after a thousand-year gap in the data, Signy Island experienced the relative warmth of the last vestiges of the Roman Warm Period, as delineated by McDermott et al. (2001) on the basis of a high-resolution speleothem δ¹⁸O record from southwest Ireland. Then comes the Dark Ages Cold period, which is also contemporaneous with what McDermott et al. observe in the Northern Hemisphere, after which the Medieval Warm Period appears at the same point in time and persists for the same length of time that it does in the vicinity of Ireland, whereupon the Little Ice Age sets in just as it does in the Northern Hemisphere. Finally, there is an indication of late 20th-century warming, but with still a long way to go before conditions comparable to those of the Medieval Warm Period are achieved.

.............

Why do you persist in parroting what the agronomists at CO2 Science write?

Here is a very recent study of shelf ice in the Antarctic. I would be interested in reading what you think this study says.

A record of Holocene glacial and oceanographic variability in Neny Fjord, Antarctic Peninsula

C. S. Allen, L. Oakes-Fretwell, J. B. Anderson, and D. A. Hodgson

The Holocene, June 1, 2010; 20(4): 551 - 564.

Analyses of a 12 m marine sediment core from Neny Fjord, Marguerite Bay, Antarctic Peninsula (68.2571°S, 66.9617°W), yield a high-resolution record of Holocene climate variability. The sediments preserve signals of past glacial and marine environments and offer a unique insight into atmospheric and oceanic forcings on the western Antarctic Peninsula climate. Dating of basal material reveals that deglaciation of the fjord occurred prior to 9040 cal. yr BP and provides a minimum constraint on the timing of deglaciation close to the southern Antarctic Peninsula ice-divide. Continuous deposition of ice-distal sediments and seasonally open-water diatoms indicates that the site has not been over-ridden by glacier ice during the Holocene. A facies of sand-rich material offers the only evidence of a localized glacier advance, during the mid Holocene. Statistical analysis of diatom assemblage data reveals several climatic episodes of varying magnitude and duration. These include an early-Holocene warm period (~9000 and ~7000 cal. yr BP), potentially associated with influx of Circumpolar Deep Water onto the continental shelf and coinciding with widespread glacial retreat and Holocene collapse of the George VI Ice Shelf. The mid-Holocene (~7000 to ~2800 cal. yr BP) sediments are characterized by diatom assemblages indicative of less pervasive sea-ice cover and prolonged growing seasons with evidence of increased meltwater discharge from ~4000 cal. yr BP. The youngest sediments (~2800 cal. yr BP to present) contain a record that is consistent with the widely documented ‘neoglacial’ period followed by an abrupt reversal and climate amelioration from sometime after ~200 cal. yr BP.

What about this recent article below. What do you think it concludes?

High-resolution Holocene climate record from Maxwell Bay, South Shetland Islands, Antarctica

K.T. Milliken¹, J.B. Anderson^1,, J.S. Wellner², S.M. Bohaty³ and P.L. Manley⁴

Geological Society of America Bulletin, November 1, 2009; 121(11-12): 1711 - 1725.

The highest resolution Holocene sediment core from the AntarcticPeninsula to date was collected during the first SHALDRIL cruise(NBP0502). Drilling yielded a 108.2-m-long core (87% recovery;site NBP0502–1B) from Maxwell Bay, South Shetland Islands.This high-resolution sediment record comes from a region thatis currently experiencing dramatic climate change and associatedglacial retreat. Such records can help to constrain the natureof past climate change and causal mechanisms, and to providea context for evaluating current climate change and its impacts.

The base of the drill site sampled till and/or proximal glacimarinesediments resting directly on bedrock. Glacimarine suspensiondeposits composed of dark greenish gray silty mud with variablediatom abundance and scattered very fine sand laminations makeup the majority of the sedimentary section. Detailed sedimentologicaland geochemical analyses, including magnetic susceptibility,total organic carbon (TOC) content, carbon and nitrogen isotopiccomposition, pebble content, and biogenic silica content, allowsubdivision of the glacimarine section into nine units, andseismic facies analyses resulted in the identification of sixdistinct seismic units. We used 29 radiocarbon ages to constructan age model and calculate sedimentation rates that vary bytwo orders of magnitude, from 0.7 mm/a to ~30 mm/a.

Radiocarbon ages from glacimarine sediments just above the tilldate back to between 14.1 and 14.8 ka. Thus, ice was groundedin the fjord during the Last Glacial Maximum and eroded oldersediments from the fjord. Following initial retreat of groundedice from Maxwell Bay, the fjord was covered by a permanent floatingice canopy, probably an ice tongue. The highest sedimentationrate corresponds to an interval that contains abundant sandlaminations and gravelly mud inter vals and likely representsa melt-out phase or period of rapid glacial retreat from 10.1ka to 8.2 ka. There is no evidence for an early Holocene climaticreversal, as recorded farther south at the Palmer Deep drillsite. Minimum sea-ice cover and warm water conditions occurredbetween 8.2 and 5.9 ka. From 5.9 to 2.6 ka, there was a gradualcooling and more extensive sea-ice cover in the bay. After 2.6ka, the climate varied slightly, causing only subtle variationin glacier grounding lines. There is no compelling evidencefor a Little Ice Age readvance in Maxwell Bay. The current warmingand associated glacial response in the northern Antarctic Peninsulaappears to be unprecedented in its synchroneity and widespreadimpact.

Hhhmmmm, I guess CO2 Science happened to miss this study.

[BethesdaWX]

Why do you persist in parroting what the agronomists at CO2 Science write?

Here is a very recent study of shelf ice in the Antarctic. I would be interested in reading what you think this study says.

A record of Holocene glacial and oceanographic variability in Neny Fjord, Antarctic Peninsula

C. S. Allen, L. Oakes-Fretwell, J. B. Anderson, and D. A. Hodgson

The Holocene, June 1, 2010; 20(4): 551 - 564.

What about this recent article below. What do you think it concludes?

High-resolution Holocene climate record from Maxwell Bay, South Shetland Islands, Antarctica

K.T. Milliken¹, J.B. Anderson^1,, J.S. Wellner², S.M. Bohaty³ and P.L. Manley⁴

Geological Society of America Bulletin, November 1, 2009; 121(11-12): 1711 - 1725.

Hhhmmmm, I guess CO2 Science happened to miss this study.

First link me the study so I can read it

Second, I'm not talking about ONE STUDY, These are over 700 studies, with about 500 of them clustered between 900AD to 1100AD.

[BethesdaWX]

Again some of those descriptions do not match the actual studies themselves. Saying there was a warm period, none of this proves the MWP was warmer than present. If we are talking about the MWP we need to restrict our view to 900-1100AD.

This conversation is over until 1) you cite the actual abstracts of the studies themselves not these faulty descriptions of them

2) we restrict our view to the period 900-1100 AD

3) we make actual temperature comparisons instead of just saying "it was warm" .. exactly how warm and when?

1) The actual abstracts are included in Co2 science if you bothered to read it

2) We restrict our view from 850AD to 1150AD when discussing the GLOBAL mean at its peak.

3) Well, the proxies are how we will determine this....sure, there are places that probably are warmer now than they ever were in the MWP, its to be expected. However, the vast majority clustered between 850AD to 1150AD , especially from 900AD to 1100AD, present the high likelyhood that the MWP was as warm, or warmer, than today. Can we say this for sure? Absolutely not, nothing is certain here.

[stellarfun]

First link me the study so I can read it

Second, I'm not talking about ONE STUDY, These are over 700 studies, with about 500 of them clustered between 900AD to 1100AD.

On the first abstract, I asked you to read a single paragraph and tell me what you concluded from the paragraph. You don't need the whole study to understand what is written in a paragraph, unless you don't understand what's written in a paragraph.

Second, the geographic area being discussed is Antarctica, not the entire globe. CO2 Science lists 14 studies for Antarctica that they used to write the paragraphs that you cut and paste in red. I gave you two additional studies that CO2 Science did not use in writing its description, and asked you about them. So, for the second abstract I gave, you refused to describe what you concluded from that, instead you danced away to a recitation of what CO2 Science did. I didn't ask you for that.

You said that you read the National Research Council's study. When I excerpted parts of the study that discussed measuring climate change in Antarctica, you dismissed the findings of the NRC study. You again relied on your primary source for information on climate change: CO2 Science.

_____________

The CO2 Science web site does not provide the abstract. CO2 provides its description and interpretation of what is in a paper.

Here is CO2 Science's description of Level One Studies:

Studies that allow a quantitative comparison to be made between the temperatures of the Medieval Warm Period (MWP) and the Current Warm Period (CWP). These reports are very important, especially those that reveal the MWP to have been warmer than the CWP and that were published after the papers of Mann et al. (1998, 1999) appeared, because the authors of such Level 1 reports likely knew that their findings were not in harmony with the contemporary position of the Intergovernmental Panel on Climate Change, which strongly endorsed the Mann et al. papers that claimed the warmth of the latter part of the 20th century was unprecedented over the entire past millennium. Authors of more recent Level 1 papers have additionally had to contend with the contrary force of the paper of Mann and Jones (2003), which claimed that the warmth of the latter part of the 20th century was unprecedented over the past two millennia. Hence, it can be appreciated that the authors of many Level 1 papers were really "sticking their necks out" when reporting something considered by much of the scientific community to be incorrect, which would tend to give special credence to the sincerity of their belief in the validity of their data.

In other words, Level One studies are only those that disprove Mann's hockey stick.

Level Two Studies

Studies that allow a qualitative comparison to be made between the temperatures of the Medieval and Current Warm Periods. They enable one to determine if peak MWP temperatures were warmer than, equivalent to, or cooler than, peak CWP temperatures, but they do not enable one to determine how much warmer or cooler they may have been. Many of these studies, i.e., those that indicate the MWP was warmer than the CWP, were also published by scientists who likely knew their findings were not in harmony with the position of the scientific establishment, nor, for that matter, with the views of the political establishments of most of the world's nations, which again bears testimony to the strength of their faith in their findings.

In other words, the data in these studies can't be comparatively measured, but the studies supports CO2's view that the MWP was warmer than the CWP.

Level Three Studies

Studies that simply indicate the Medieval Warm Period did indeed occur in the studied regions. They may seem rather innocuous, but many of them may also be considered to be "politically incorrect," in that they contradict the climate-alarmist claim that the MWP, if it occurred at all, was only a regional phenomenon experienced by lands significantly influenced by the North Atlantic Ocean. In this level we include certain studies that are based on data related to parameters other than temperature, such as precipitation. These studies, however, are only used to help define the timeframe of the MWP; they are not employed to infer anything about either its quantitative or qualitative thermal strength.

Of course, there are no studies included in any of these levels that would support that the CWP is warmer than the MWP.

For North America, there are 20 Level One studies; 35 Level 2 studies, and 33 Level 3 studies.

We've already discussed one of their Level One studies, the one on the Chesapeake Bay. Let's take another, the first one of their Level One list for North America.

Boniface River Area, Northern Québec, Canada

Arseneault, D. and Payette, S. 1997. Reconstruction of millennial forest dynamics from tree remains in a subarctic tree line peatland. Ecology 78: 1873-1883.

CO2 Science description:

The authors obtained tree-ring and growth-form sequences from more than 300 black spruce (Picea mariana) remains buried in a presently treeless peatland located near the tree line in northern Québec (57°44'N, 76°10'W), which they analyzed to produce a proxy record of climate for this region between AD 690 and 1591. Over the course of this 900-year time period, the trees of the region experienced several episodes of suppressed and rapid growth, indicative of both colder and warmer conditions, respectively, than those of the present. The most striking of the warm periods exhibited what they described as "well-defined boundaries" that extended from AD 860 to 1000, which they associated with the Medieval Warm Period (MWP) and which they described as having "exceeded in duration and magnitude" the "20th century warm period." In addition, on the basis of the then-current annual temperatures at their study site and at the northernmost 20th-century location of the forest, which was 130 km south of their study site, they concluded that the Medieval Warm Period was ~1°C warmer than what it was when they conducted their work, which was concluded about the time when 20th-century warming leveled off and reached a plateau from which there has been no further warming over the ensuing years.

The actual abstract

Tree ring and growth form sequences of 319 black spruce (Picea mariana [Mill.] BSP) stems buried in a treeless peatland at the arctic tree line of northern Quebec were used to reconstruct the development of a woodland in response to climate change and fires during the last 2500 years. A high frequency of diagnostic tree rings (light rings and narrow rings) allowed the cross-dating of 142 individuals and the construction of a master chronology spanning AD 690-1591. Three floating chronologies covering 964 (178 BC-AD 785), 349 (587-239 BC) and 210 (1274-1065 BC) years were also developed. The buried stems were classified as arborescent (75%), small fragments of unknown origin (13%), stumps (11%), and portions of stunted stems (1%). The high frequency of arborescent individuals indicates that the buried spruces were the remains of a former forest. The forest bordered the peatland between 600 BC and AD 1568, and successfully regenerated after two fires around 350 BC and 10 BC. Winter-damaged trees dominated during periods of suppressed growth at AD 760-860 and AD 1025-1400, whereas undamaged trees were more frequent during periods of rapid growth around AD 700-750, 860-1000, 1400-1450, and 1500-1570. Fast growth between AD 860-1000, along with the concurrent establishment of symmetrical trees, suggests well-defined boundaries for the Medieval Warm Period in northeastern Canada. The forest abruptly shifted to an open krummholz (stunted spruce) after the last fire in AD 1568, indicating that a climatic threshold inhibiting postfire regeneration was crossed between the second and the last fires. The maintenance of this old growth forest over 1500 yr, in the absence of external disturbances except climate change, was probably due to the buffering effect of aggregated trees on wind-drifted conditions at the snowpack line. With the exclusion of the forest influence on microclimate and local growth conditions, the AD 1568 fire caused the forest vegetation to shift to krummholz. The amplitude of these ecosystem changes at tree line does not mirror that of climate change. Hence, it is concluded that climate and vegetation reconstructions from proxy indicators cannot portray full ecological impact, because vegetation change at tree line is nonlinear relative to climate change.

(Bolding mine.)

Why do you suppose there was suppressed growth of trees during the peak of the MWP, and rapid growth after the MWP had ended?

Now let's go back to CO2's description of papers they've included in Level One: "

These reports are very important, especially those that reveal the MWP to have been warmer than the CWP and that were published after the papers of Mann et al. (1998, 1999) appeared, because the authors of such Level 1 reports likely knew that their findings were not in harmony with the contemporary position of the Intergovernmental Panel on Climate Change,

The paper above on the Boniface River area was published in 1997, one and two years before Mann published his hockey stick stuff.

[BethesdaWX]

On the first abstract, I asked you to read a single paragraph and tell me what you concluded from the paragraph. You don't need the whole study to understand what is written in a paragraph, unless you don't understand what's written in a paragraph

And I asked you to link me the study. Do it.

I cannot "conclude" anything until I have the link to the study with all relevant data.

[stellarfun]

And I asked you to link me the study. Do it.

I cannot "conclude" anything until I have the link to the study with all relevant data.

Dance away. Typical.

All right, here is a journal article

Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica

Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J.-M., Basile, I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pepin, L., Ritz, C., Saltzman, E., and Stievenard, M. 1999

Nature 399: 429-436

Full text. What do you conclude from it?

http://www.clas.ufl....tit_etal_99.pdf

Here's another one. Full text. If the one above is too hard.

Late Holocene cyclic glaciomarine sedimentation in a subpolar fjord of the South Shetland Islands, Antarctica, and its paleoceanographic significance: Sedimentological, geochemical, and paleontological evidence

GSA Bulletin; July 2010; v. 122; no. 7-8; p. 1298-1307;

http://bulletin.geoscienceworld.org/cgi/reprint/122/7-8/1298

[BethesdaWX]

Dance away. Typical.

All right, here is a journal article

Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica

Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J.-M., Basile, I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pepin, L., Ritz, C., Saltzman, E., and Stievenard, M. 1999

Nature 399: 429-436

Full text. What do you conclude from it?

http://www.clas.ufl....tit_etal_99.pdf

Here's another one. Full text. If the one above is too hard.

Late Holocene cyclic glaciomarine sedimentation in a subpolar fjord of the South Shetland Islands, Antarctica, and its paleoceanographic significance: Sedimentological, geochemical, and paleontological evidence

GSA Bulletin; July 2010; v. 122; no. 7-8; p. 1298-1307;

http://bulletin.geos...nt/122/7-8/1298

completely unrelated to the MWP.

reading it anyway as an act of respect.

[Clifford]

Full text. What do you conclude from it?

http://www.clas.ufl....tit_etal_99.pdf

Had modern civilation developed during the Eemian rather than the Holocene, we would be sitting here discussing Anthropogenic Global Cooling.

We would have excellent graphs showing the lowest temperatures on the moon at 26K, and predicting that our current activities would lead the earth into a death spiral ending at 26K (-247°C). :snowman:

[stellarfun]

Had modern civilation developed during the Eemian rather than the Holocene, we would be sitting here discussing Anthropogenic Global Cooling.

We would have excellent graphs showing the lowest temperatures on the moon at 26K, and predicting that our current activities would lead the earth into a death spiral ending at 26K (-247°C). :snowman:

Fail.

Permian instead of Ermian. -10 points for that.

Permian is a period within the Paleozoic; Holocene is an epoch within the Quartenary [Period]. -10 points for mixing classifications..

Earth warmed during the Permian. - 20 points for that.

Temperature of the moon is 250K -20 points for that.

Correct on 26K to Celsius.

Temperature of the earth reaching 25K -20 points for that (Sun will become a red giant and consume earth first)

No points for the graphics.

Sorry, you' have failed the semester. Back to community college for you.

[Clifford]

Fail.

Permian instead of Ermian. -10 points for that.

Permian is a period within the Paleozoic; Holocene is an epoch within the Quartenary [Period]. -10 points for mixing classifications..

Earth warmed during the Permian. - 20 points for that.

Temperature of the moon is 250K -20 points for that.

Correct on 26K to Celsius.

Temperature of the earth reaching 25K -20 points for that (Sun will become a red giant and consume earth first)

No points for the graphics.

Sorry, you' have failed the semester. Back to community college for you.

I said Eemian not Ermian

http://en.wikipedia.org/wiki/Eemian

The Eemian is an excellent comparison to the Holocene, with a higher peak temperature, and a quicker downslope (at least per reconstructions)

And... the "Homo Sapiens" were considered to be alive during the Eemian. Just not as advanced as today.

http://en.wikipedia....Hermite_(crater)

In 2009, it was discovered by NASA's Lunar Reconnaissance Orbiter that Hermite is the coldest place recorded in the solar system, with temperatures at 26 kelvins (−247 degrees Celsius).

http://news.bbc.co.uk/2/hi/science/nature/8416749.stm

And, how many times have I heard Earth compared to Venus with a "runaway greenhouse effect"? Not to mention that Venus is closer to the sun. At least the moon shares the orbit with the Earth. What is the limit on the AGW charts that show exponential temperature growth?

And, I never said 25K

I'd encourage redoing your math!!!!