I don’t have much time for a detailed post, a number of people want to discuss sea ice, so here is your chance. We also need to update the ARCUS forecast for August, due Monday August 6th. Poll follows:
Sure there is evidence of AGW. It may be evidence you dont accept, but there is evidence.
==========================
Could you post this evidence please Steven
guys guys guys, cut Mosh a break, There is lots of evidence for AGW and it is annoying to even be asking for it WHEN YOU ARE ALL AWARE OF IT..
The behavior of CO2 in the lab is evidence.
Rising temps are evidence.
Sea ice, sea levels are evidence.
Even really bad evidence like citing Hurricane Katrina is evidence.
Whether or not any of this is conclusive evidence is the question, not whether there is any evidence. There is also lots of counter evidence.
The logical gaps of those arguing with Mosh are painful to read. Please understand the difference between evidence and conclusive and irrefutable evidence. They are not the same thing.
Some of you spewing this tripe are scientists and should know better.
It’s hard to educate a person who maintains that just because in the last 4.5 billion years the earth has seen the extremes of a molten surface and a snowball, anything in between is “natural variability”.
Rob Dekker
August 6, 2012 11:09 pm
Gail,
The animation you present from Environment Canada shows ice concentration (ice extent divided by ice area), not the “age” of the ice. It would be very hard to find any 10 year old ice in the Arctic these days. The majority of ice is FYI (First Year Ice) which is thinner, and more saline (melts at lower temperature) than older ice.
The ice concentration in the area (in the Northern Canadian Archipelago) that you refer to simply reduced from larger than 90 % to smaller than 90 %.
Also note that large area of open water just south of it : that is the North West Passage, which has been open for a few weeks now. For centuries, mankind has attempted to cross that passage, to no avail until Roald Amundsen finally manages to do so in 1906. It took him 3 years.
Nowadays, small vessels attempt races to circumnavigate the Arctic in one season, through BOTH the North West AND the North East passage.
How times have changed…
Rob Dekker
August 6, 2012 11:44 pm
Bill Illis,
Seems that your +60 km^2 ice extent was short-lived.
NSIDC reports a whopping 187,400 km^2 reduction in ice extent today (is that an all-time record daily reduction for August?) :
2012, 08, 02, 6.23881
2012, 08, 03, 6.06293
2012, 08, 04, 6.06299
2012, 08, 05, 5.87559
Thus, as “barry” already suggested, (and despite your assertion that barry does not know what he is talking about) there are huge error bars on these daily numbers.
Let us just follow these numbers for a couple of days and see where the average goes, OK ?
barry
August 6, 2012 11:46 pm
How the interglacial degrades to glacial is the question. Something has to “kickstart” the climate into a colder regime first (if not, we’d already be in a glacial regime since the summer sun in the N hemisphere right now is at a minimum).
The big question that needs answering is how North and South Poles can warm at roughly the same time, while orbital variation (Milankovitch cycles) increases insolation in only one of them. How does the Earth warm all over, instead of getting colder at one pole when the other is receiving more sunlight? GHG increase seems to provide a pretty good answer to that conundrum.
Rob Dekker
August 7, 2012 12:52 am
Spence_UK, thank you for your reference to Funder et al 2011.
Here is the paper without the paywall : http://junksciencecom.files.wordpress.com/2011/08/science-sea-ice-seesaw.pdf
Now, I appreciate the postings by Smokey and Gail and others that the current Arctic summer sea ice decline is not “unprecedented” in the history of this planet, or even over the Holocene, but I would also like to point out that nobody actually claims that.
In fact, the only hard claim regarding “unprecedented” sea ice decline was made by Gneiss, who stated that “This warming is unprecedented over the past 2,000 years”, a statement for which NOBODY here provided any counter evidence .
Funder et al 2011 in fact is a bit more specific :
The general buildup of sea ice from ~6 ky B.P. agrees with the LOVECLIM model, showing that summer sea-ice cover, which reached its Holocene maximum during the LIA, attained its present (~2000) extent at ~ 4 ky B.P. (fig. S3)
IOW, summer ice extent around 2000 matches with summer ice extent at around 4,000 before present.
Since summer ice extent reduced another 25 % or so since 2000, Funder et al supports the assertion that current summer ice extent is unprecedented since at least 4000 years.
Now, we know that the decline in temperatues during the Holocene is caused by orbital variations (I think that Gail mentioned a 9 % increase in insolation during summers of the early Holocene). So does anyone have a physical explanation for why this reduction in insolation over 8-4 thousand years suddenly (over 150 years or so) is irradicated and replaced by a significant warming trend ?
Warm
August 7, 2012 1:23 am
Two fundamental recent papers about the history of arctic sea ice:
History of sea ice in the Arctic http://www.cgd.ucar.edu/staff/mholland/papers/Polyak_2010_historyofseaiceArctic.pdf
“The current reduction in Arctic ice cover started in the late 19th century, consistent with the rapidly warming climate, and became very pronounced over the last three decades. This ice loss appears to be unmatched over at least the last few thousand years and unexplainable by any of the known natural variabilities.”
Reconstructed changes in Arctic sea ice over the past 1,450 years http://gizmo.geotop.uqam.ca/devernalA/Kinnard_et_al_nature_2011.pdf
“Until now, the question of whether or not current trends are potentially anomalous5 has therefore remained unanswerable. Here we use a network of high-resolution terrestrial proxies from the circum-Arctic region to reconstruct past extents of summer sea ice, and show that—although extensive uncertainties remain, especially before the sixteenth century—both the duration and magnitude of the current decline in sea ice seem to be unprecedented for the past 1,450 years. “
Rob Dekker
August 7, 2012 1:27 am
Gail said :
The 100,000 year stretch: The orbit of the earth gradually stretches from nearly circular to an elliptical shape and back again in a cycle of approximately 100,000 years. This is called the orbit’s eccentricity. During the cycle, the distance between earth and sun varies by as much as 11.35 million miles. [So distance from the sun and therefore insolation does change for the earth as a whole – G.C.]
Gail, did you calculate the how much the insolation changes for the earth as a whole due to these pertubations ?
kadaka (KD Knoebel)
August 7, 2012 2:28 am
From jeez on August 6, 2012 at 10:38 pm:
guys guys guys, cut Mosh a break, There is lots of evidence for AGW and it is annoying to even be asking for it WHEN YOU ARE ALL AWARE OF IT..
The behavior of CO2 in the lab is evidence.
*snort*
*snort*
Heh heh heh heh…
We have an incredibly complex climate system, with many forces at play, numerous feedbacks, with the distinctions between cause and effect often blurred.
CO₂ in the lab is a known GHG. You wish to extrapolate that is evidence of AGW? You are assuming a LONG chain of causality without sufficient proof, where many things currently unknown and unproven must be assigned values, possible mechanisms assumed to exist as proposed and created as needed to fill gaps…
You fail to acknowledge there is far too much guesswork between CO₂ in the lab and possible AGW in the real world to substantiate your “evidence” claim.
You have also not acknowledged that global temperatures have ceased rising while the atmospheric CO₂ concentrations have kept rising, which is clear evidence that CO₂ alone does not control global temperatures.
And you are complaining about the “logical gaps” of others?
Rob Dekker
August 7, 2012 2:39 am
Gail, let’s be skeptical for a moment, and take a slightly closer look at the Roe analysis In defense of Milankovitch
For starters, there is not a lot of doubt in the scientific world that Milankovitch cycles (orbital pertubations) determine the glacial/inter-glacial cycles. Short of bizarre theories of 100k yr cycles of our solar system through the galaxy and even more unsubstantiated theories about clouds forced by cosmic rays causing glacial/interglacial cycles, Milankovitch theory on orbital pertubations is the most accepted theory around. A ‘consensus’ if you will.
Second, their assertion that “This implies only a secondary role for CO2” is nothing new either. In fact, there is not a single scientific paper that asserts that CO2 is the primary driver of glacial/inter-glacial changes.
So short of their paper’s somewhat “strawman” title, what Roe actually proposes is not directly related to Milankovitch, but more to the process by which ice sheets melt. In their own words :
available records support a direct, zero-lag, antiphased relationship between the rate of change of global ice volume and summertime insolation in the northern high latitudes.
Of course, this relation between rate of change and ice volume makes perfect physical sense, and also the observations they present support their hypothesis. No problem there until they start to quantify the relation. For that, they use two ice volume reconstructions : SPECMAN and HW04.
Here, they point out that SPECMAN “The SPECMAP record [Imbrie et al., 1984] assumes a priori that ice volume and orbital forcing are related” which thus implicitly is tuned to their original hypothesis. They realize this and state “Because of this tuning procedure, it is likely that variability at orbital frequencies is overestimated” and “Huybers and Wunsch have recently developed a record (HW04) that is independent of any such orbital-tuning assumptions.”
Following their hypothesis that insolation and rate of volume are related, they conclude :
Figure 2 compares June 65N insolation to dV/dt from the SPECMAP and HW04 records. The maximum correlations
are 0.8 and 0.4, and occur with no lag and a lag of 1 kyr,r espectively.
That’s interesting, since the the difference between these two correlations is a factor 2.
Where would that come from ? Why is it that the HW04 record of ice volume reconstruction is a factor 2 less sensitive than the SPECMAN record which has a built-in assumption about volume-loss versus insolation, and why does HW02 have approximately a 1 ky delay in response ?
In other words, which physical effect has a factor 2 amplification effect on warming and shows about 1 ky delay in response to orbital temperature changes ? Mmmmm. The CO2 record between glacial/interglacial temperature changes caused by Milankovitch cycles does show that 1 ky delay, and basic physics estimate that the amplificantion effect of temperature-induced CO2 variations observed is about a factor 2, in full compliance with theory and paleo-climate analysis.
Another indication that Roe overestimates the effect of orbital pertubations is in this statement :
The concentration of CO2 varied between about 200 and 280 ppmv over the last several ice age cycles, and
caused approximately 2 W/m^2 variations in surface longwave radiation forcing [e.g., Ramaswamy et al., 2001]. Comparisons of the impacts of shortwave and longwave radiative forcing appropriate over the ice sheets are not straightforward, but taking summer half-year insolation variations in shortwave (Figure 3), and assuming an albedo of 0.5 for melting ice, variations in summertime shortwave forcing exceed the direct CO2 radiative forcing by about a factor of five.
This statement would be correct under clear skies. However, the Arctic in summer is under an 80% cloud cover (albedo similar to snow), which reduces the influence of insolation pertubations over the Arctic by a factor of 5. Thus, CO2 influence of 100-280 ppmv is in the same ballpark as orbital pertubation, which explains the factor 2 I mentioned earlier that we need to explain the temperature swings between glacials and inter-glacials.
Darn. Maybe CO2 DOES conform to the laws of physics, and maybe it DOES comply with Milankovitch.
And in fact, it would be very hard to explain the extremes in temperature between glacials and inter-glacials without CO2, as is confirmed by pretty much every paleo-climate analysis of glacial/inter-glacial temperature swings.
I feel the need to expound on my above rant.
Skeptics are always crying out for rational debate.
Rational debate happens when both sides’ evidence is presented, weighed, evaluated, and the preponderance of evidence favors one side.
For so-called AGW skeptics to keep spewing “what evidence? there is no evidence?” while at the same time calling for debate is both inane and insane.
I feel the preponderance of evidence is for negative feedbacks in the climate system and we have little to fear from increased CO2 from fossil fuel use.
HOWEVER, there are massive amounts of EVIDENCE for AGW and even CAGW. Much of this evidence is flawed, inconsistent, and self-contradictory, BUT there is LOTS and LOTS of evidence.
You folks insisting Mosh provide “the evidence” are personifying the denier label. Seriously, get a grip, Grow up. Do something to stop me from being embarrassed for being on the same side as you. It’s extremely disheartening. It keeps me from participating and helping.
Kadaka,
You missed the point completely. Try a reading comprehension course.
Venter
August 7, 2012 3:16 am
Jeez, yelling about ” lots of evidence ” does not make evidence or fact. Please provide empirical testable evidence that human emitted CO2 has caused unprecedented warming with catastrophic consequences. Hint, model outputs are neither data or evidence.
climatereason
Editor
August 7, 2012 4:34 am
Mosh said to me
‘Tony? do you see me calling this unprecedeneted? Nope you dont.
Did dramatic events happen before 1979. You BET !’
err mosh….I didn’t mention that you said this was ‘unprecedeneted’ (or even unprecedented) I said it has happened frequently in the past, so todays events are not that unusual
tonyb
Gneiss
August 7, 2012 4:45 am
Rob Dekker writes,
“In fact, the only hard claim regarding “unprecedented” sea ice decline was made by Gneiss, who stated that “This warming is unprecedented over the past 2,000 years”, a statement for which NOBODY here provided any counter evidence.”
And just to clarify where my 2,000-year figure came from, I was referring specifically to warming water:
“Second, much of the sea ice is melting from below, because of warmer water. This warming is unprecedented over the past 2,000 years, and linked to Arctic amplification of global warming.”
I have the papers by Polyak, Kinnard and others, but based this statement about water temperatures on Speilhagen et al (2011, Science):
“We find that early–21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming.” http://www.sciencemag.org/content/331/6016/450.abstract
That inspired a flurry of smoke on this thread about much earlier times.
Gneiss
August 7, 2012 4:49 am
climatereason writes,
“I am working on historic variations in arctic ice part two and was at the met office today collecting archive material for it. It will join the hundreds of papers I have already read. The only conclusion that can be dawn is that arctic ice melts with astonishing frequency and the modern era is by no means unprecedented- just ask any Viking”
Since you’re working so hard on historical research, I gotta ask … Which Viking did you ask?
And what did he tell you, about the Arctic Ocean?
Bill Illis
August 7, 2012 5:10 am
This new low pressure system is called a “Polar Low” or polar “Cyclone”.
The occur most frequently in the winter but also in the summer. http://en.wikipedia.org/wiki/Polar_low
There was even a “European Polar Low Working Group” at one time.
The NSIDC says that up to 6 can occur in the Western Arctic in July alone. http://nsidc.org/arcticmet/patterns/cyclones.html
So let’s have more research from now on before people start calling a low pressure system something special.
Venter says:
August 7, 2012 at 3:16 am
Jeez, yelling about ” lots of evidence ” does not make evidence or fact. Please provide empirical testable evidence that human emitted CO2 has caused unprecedented warming with catastrophic consequences. Hint, model outputs are neither data or evidence.
===================
Seconded. Please do.
No debate required.
kadaka (KD Knoebel)
August 7, 2012 6:29 am
From Rob Dekker on August 6, 2012 at 11:44 pm:
Bill Illis,
Seems that your +60 km^2 ice extent was short-lived.
NSIDC reports a whopping 187,400 km^2 reduction in ice extent today (is that an all-time record daily reduction for August?) :
2012, 08, 02, 6.23881
2012, 08, 03, 6.06293
2012, 08, 04, 6.06299
2012, 08, 05, 5.87559
The near-real-time data files (hh_seaice_extent_nrt.csv) have extent numbers derived from the Near-Real-Time DMSP SSM/I-SSMIS Daily Polar Gridded Sea Ice Concentrations (NRTSI product). These daily fields do not have missing data filled by interpolation; grid cells missing data are simply flagged with a value for missing. Before we compute extent from these daily fields, the Sea Ice Index processing code fills missing data in a way similar to that used for the GSFC product — by interpolating data from the day before and day after. The exception is at the beginning and end of the time series, when only the day after or the day before, respectively, are available.
Basically your “astonishing announcement” is coming from incomplete data.
Search that page for “masie” and see why that’s a superior product for tracking day-to-day variations.
Spence_UK
August 7, 2012 6:41 am
Rob Dekker,
Your claim that the present conditions have prevailed for the last 4,000 years is wrong. From the paper:
This period comprises half of our driftwood finds, but the high frequencies are punctuated by woodless periods at 2.5 to 2 ky B.P., 1.7 to 0.9 ky B.P., 0.5 to 0.3 ky B.P., and probably since ~1950.
This para shows that within the last 4,000 years, these sub-periods were particularly cold and ice-locked the beaches; note the medieval warm period and roman warm period visible in the “gaps”. During this time, there was less ice than at present. (Note the “woodless periods” are exceptionally cold, as the beaches are too frozen for driftwood to land)
This is not a story of consistent sea ice over the last 4,000 years. Even within that time frame, there have been several century-scale periods with considerably less ice than the last 60 years or so. Also, it is quite inappropriate to compare annual- and decadal- scale measurements directly to centennial and millenial proxies, for obvious reasons. Proxy-to-proxy and measurement-to-measurement comparisons are safest without VERY careful calibration specifically for the task of comparison.
The point of my post was to underline the magnitude of natural variability on longer timescales, which need to be understood before any type of assessment can be made as to whether this is anomalous with respect to natural variability or not. Without understanding these things – that nature’s variability is greater on longer timescales – it is easy to arrive at a wrong conclusion about the causes of the present changes in arctic sea ice (and the consequences, too).
Spence_UK
August 7, 2012 6:44 am
Just to clarify on my last comment to Rob Dekker:
Since summer ice extent reduced another 25 % or so since 2000, Funder et al supports the assertion that current summer ice extent is unprecedented since at least 4000 years.
Absolutely no, Funder et al does not support this. Funder et al can tell us nothing about changes at the 1-2 year scale AT ALL because their data would not support it. On the longer scale, they show there were many periods in the last 3,000 years that had considerably LESS ice than the last 60 years (a measure for which they can provide reasonable estimates). For the reasons above.
Bill Illis
August 7, 2012 7:41 am
kadaka (KD Knoebel) says:
August 7, 2012 at 6:29 am
————————————
I’ve been tracking the Masie sea ice data since day 82 (it only shows the last 30 days but I’ve got the last 138 days).
It is quite a bit different than the Near Real Time data that the NSIDC also uses. I think all their charts and quoted data are the Near Real Time ones (even though Masie could be superior). They are diverging by a large amount in recent days.
Charted here. http://s13.postimage.org/6mrt7fzgn/NSIDC_Masie_NRT_Daily_SIE_Aug_6_2012.png
kadaka (KD Knoebel)
August 7, 2012 8:30 am
From Gneiss on August 7, 2012 at 4:45 am:
I have the papers by Polyak, Kinnard and others, but based this statement about water temperatures on Speilhagen et al (2011, Science):
“We find that early–21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming.” http://www.sciencemag.org/content/331/6016/450.abstract
A high-resolution sedimentary record from the subarctic Malangen fjord in northern Norway, northeastern North Atlantic has been investigated in order to reconstruct variations in influx of Atlantic Water for the last 2000 years. The fjord provides a regional oceanographic climatic signal reflecting changes in the North Atlantic heat flux at this latitude because of its deep sill and the relatively narrow adjoining continental shelf. The reconstructions are based on oxygen and carbon isotopic studies of benthic foraminifera from a high accumulation basin in the Malangen fjord, providing subdecadal time resolution. A comparison between instrumental measurements of bottom water temperatures at the core location and the reconstructed temperatures from benthic foraminiferal δ¹⁸O for the same time period demonstrates that the stable isotope values reflect the bottom water temperatures very well. The reconstructed temperature record shows an overall decline in temperature of c. 1°C from c. 40 bc to ad 1350. This cooling trend is assumed to be driven by an orbital forced reduction in insolation. Superimposed on the general cooling trend are several periods of warmer or colder temperatures. The long-term fluctuations in the Malangen fjord are concurrent with fluctuations of Atlantic Water in the northern North Atlantic. Although they are not directly comparable, comparisons of atmospheric temperatures and marine records, indicate a close coupling between the climate systems. After ad 1800 the record shows an unprecedented warming within the last 2000 years.
What’s not to like? There’s unprecedented warming. Sure, there is a long cooling trend attributed to insolation changes, just natural variation.
But there is that alarming “Arctic amplification of global warming” you’re so worried about.
Around 200 years of sudden alarming Arctic amplification, apparently.
Sure there is evidence of AGW. It may be evidence you dont accept, but there is evidence.
==========================
Could you post this evidence please Steven
guys guys guys, cut Mosh a break, There is lots of evidence for AGW and it is annoying to even be asking for it WHEN YOU ARE ALL AWARE OF IT..
The behavior of CO2 in the lab is evidence.
Rising temps are evidence.
Sea ice, sea levels are evidence.
Even really bad evidence like citing Hurricane Katrina is evidence.
Whether or not any of this is conclusive evidence is the question, not whether there is any evidence. There is also lots of counter evidence.
The logical gaps of those arguing with Mosh are painful to read. Please understand the difference between evidence and conclusive and irrefutable evidence. They are not the same thing.
Some of you spewing this tripe are scientists and should know better.
But I still want to bet.
It’s hard to educate a person who maintains that just because in the last 4.5 billion years the earth has seen the extremes of a molten surface and a snowball, anything in between is “natural variability”.
Gail,
The animation you present from Environment Canada shows ice concentration (ice extent divided by ice area), not the “age” of the ice. It would be very hard to find any 10 year old ice in the Arctic these days. The majority of ice is FYI (First Year Ice) which is thinner, and more saline (melts at lower temperature) than older ice.
The ice concentration in the area (in the Northern Canadian Archipelago) that you refer to simply reduced from larger than 90 % to smaller than 90 %.
Also note that large area of open water just south of it : that is the North West Passage, which has been open for a few weeks now. For centuries, mankind has attempted to cross that passage, to no avail until Roald Amundsen finally manages to do so in 1906. It took him 3 years.
Nowadays, small vessels attempt races to circumnavigate the Arctic in one season, through BOTH the North West AND the North East passage.
How times have changed…
Bill Illis,
Seems that your +60 km^2 ice extent was short-lived.
NSIDC reports a whopping 187,400 km^2 reduction in ice extent today (is that an all-time record daily reduction for August?) :
2012, 08, 02, 6.23881
2012, 08, 03, 6.06293
2012, 08, 04, 6.06299
2012, 08, 05, 5.87559
Thus, as “barry” already suggested, (and despite your assertion that barry does not know what he is talking about) there are huge error bars on these daily numbers.
Let us just follow these numbers for a couple of days and see where the average goes, OK ?
The big question that needs answering is how North and South Poles can warm at roughly the same time, while orbital variation (Milankovitch cycles) increases insolation in only one of them. How does the Earth warm all over, instead of getting colder at one pole when the other is receiving more sunlight? GHG increase seems to provide a pretty good answer to that conundrum.
Spence_UK, thank you for your reference to Funder et al 2011.
Here is the paper without the paywall :
http://junksciencecom.files.wordpress.com/2011/08/science-sea-ice-seesaw.pdf
Now, I appreciate the postings by Smokey and Gail and others that the current Arctic summer sea ice decline is not “unprecedented” in the history of this planet, or even over the Holocene, but I would also like to point out that nobody actually claims that.
In fact, the only hard claim regarding “unprecedented” sea ice decline was made by Gneiss, who stated that “This warming is unprecedented over the past 2,000 years”, a statement for which NOBODY here provided any counter evidence .
Funder et al 2011 in fact is a bit more specific :
IOW, summer ice extent around 2000 matches with summer ice extent at around 4,000 before present.
Since summer ice extent reduced another 25 % or so since 2000, Funder et al supports the assertion that current summer ice extent is unprecedented since at least 4000 years.
Now, we know that the decline in temperatues during the Holocene is caused by orbital variations (I think that Gail mentioned a 9 % increase in insolation during summers of the early Holocene). So does anyone have a physical explanation for why this reduction in insolation over 8-4 thousand years suddenly (over 150 years or so) is irradicated and replaced by a significant warming trend ?
Two fundamental recent papers about the history of arctic sea ice:
History of sea ice in the Arctic
http://www.cgd.ucar.edu/staff/mholland/papers/Polyak_2010_historyofseaiceArctic.pdf
“The current reduction in Arctic ice cover started in the late 19th century, consistent with the rapidly warming climate, and became very pronounced over the last three decades. This ice loss appears to be unmatched over at least the last few thousand years and unexplainable by any of the known natural variabilities.”
Reconstructed changes in Arctic sea ice over the past 1,450 years
http://gizmo.geotop.uqam.ca/devernalA/Kinnard_et_al_nature_2011.pdf
“Until now, the question of whether or not current trends are potentially anomalous5 has therefore remained unanswerable. Here we use a network of high-resolution terrestrial proxies from the circum-Arctic region to reconstruct past extents of summer sea ice, and show that—although extensive uncertainties remain, especially before the sixteenth century—both the duration and magnitude of the current decline in sea ice seem to be unprecedented for the past 1,450 years. “
Gail said :
Gail, did you calculate the how much the insolation changes for the earth as a whole due to these pertubations ?
From jeez on August 6, 2012 at 10:38 pm:
*snort*
*snort*
Heh heh heh heh…
We have an incredibly complex climate system, with many forces at play, numerous feedbacks, with the distinctions between cause and effect often blurred.
CO₂ in the lab is a known GHG. You wish to extrapolate that is evidence of AGW? You are assuming a LONG chain of causality without sufficient proof, where many things currently unknown and unproven must be assigned values, possible mechanisms assumed to exist as proposed and created as needed to fill gaps…
You fail to acknowledge there is far too much guesswork between CO₂ in the lab and possible AGW in the real world to substantiate your “evidence” claim.
You have also not acknowledged that global temperatures have ceased rising while the atmospheric CO₂ concentrations have kept rising, which is clear evidence that CO₂ alone does not control global temperatures.
And you are complaining about the “logical gaps” of others?
Gail, let’s be skeptical for a moment, and take a slightly closer look at the Roe analysis In defense of Milankovitch
For starters, there is not a lot of doubt in the scientific world that Milankovitch cycles (orbital pertubations) determine the glacial/inter-glacial cycles. Short of bizarre theories of 100k yr cycles of our solar system through the galaxy and even more unsubstantiated theories about clouds forced by cosmic rays causing glacial/interglacial cycles, Milankovitch theory on orbital pertubations is the most accepted theory around. A ‘consensus’ if you will.
Second, their assertion that “This implies only a secondary role for CO2” is nothing new either. In fact, there is not a single scientific paper that asserts that CO2 is the primary driver of glacial/inter-glacial changes.
So short of their paper’s somewhat “strawman” title, what Roe actually proposes is not directly related to Milankovitch, but more to the process by which ice sheets melt. In their own words :
Of course, this relation between rate of change and ice volume makes perfect physical sense, and also the observations they present support their hypothesis. No problem there until they start to quantify the relation. For that, they use two ice volume reconstructions : SPECMAN and HW04.
Here, they point out that SPECMAN “The SPECMAP record [Imbrie et al., 1984] assumes a priori that ice volume and orbital forcing are related” which thus implicitly is tuned to their original hypothesis. They realize this and state “Because of this tuning procedure, it is likely that variability at orbital frequencies is overestimated” and “Huybers and Wunsch have recently developed a record (HW04) that is independent of any such orbital-tuning assumptions.”
Following their hypothesis that insolation and rate of volume are related, they conclude :
That’s interesting, since the the difference between these two correlations is a factor 2.
Where would that come from ? Why is it that the HW04 record of ice volume reconstruction is a factor 2 less sensitive than the SPECMAN record which has a built-in assumption about volume-loss versus insolation, and why does HW02 have approximately a 1 ky delay in response ?
In other words, which physical effect has a factor 2 amplification effect on warming and shows about 1 ky delay in response to orbital temperature changes ? Mmmmm. The CO2 record between glacial/interglacial temperature changes caused by Milankovitch cycles does show that 1 ky delay, and basic physics estimate that the amplificantion effect of temperature-induced CO2 variations observed is about a factor 2, in full compliance with theory and paleo-climate analysis.
Another indication that Roe overestimates the effect of orbital pertubations is in this statement :
This statement would be correct under clear skies. However, the Arctic in summer is under an 80% cloud cover (albedo similar to snow), which reduces the influence of insolation pertubations over the Arctic by a factor of 5. Thus, CO2 influence of 100-280 ppmv is in the same ballpark as orbital pertubation, which explains the factor 2 I mentioned earlier that we need to explain the temperature swings between glacials and inter-glacials.
Darn. Maybe CO2 DOES conform to the laws of physics, and maybe it DOES comply with Milankovitch.
And in fact, it would be very hard to explain the extremes in temperature between glacials and inter-glacials without CO2, as is confirmed by pretty much every paleo-climate analysis of glacial/inter-glacial temperature swings.
I feel the need to expound on my above rant.
Skeptics are always crying out for rational debate.
Rational debate happens when both sides’ evidence is presented, weighed, evaluated, and the preponderance of evidence favors one side.
For so-called AGW skeptics to keep spewing “what evidence? there is no evidence?” while at the same time calling for debate is both inane and insane.
I feel the preponderance of evidence is for negative feedbacks in the climate system and we have little to fear from increased CO2 from fossil fuel use.
HOWEVER, there are massive amounts of EVIDENCE for AGW and even CAGW. Much of this evidence is flawed, inconsistent, and self-contradictory, BUT there is LOTS and LOTS of evidence.
You folks insisting Mosh provide “the evidence” are personifying the denier label. Seriously, get a grip, Grow up. Do something to stop me from being embarrassed for being on the same side as you. It’s extremely disheartening. It keeps me from participating and helping.
Kadaka,
You missed the point completely. Try a reading comprehension course.
Jeez, yelling about ” lots of evidence ” does not make evidence or fact. Please provide empirical testable evidence that human emitted CO2 has caused unprecedented warming with catastrophic consequences. Hint, model outputs are neither data or evidence.
Mosh said to me
‘Tony? do you see me calling this unprecedeneted? Nope you dont.
Did dramatic events happen before 1979. You BET !’
err mosh….I didn’t mention that you said this was ‘unprecedeneted’ (or even unprecedented) I said it has happened frequently in the past, so todays events are not that unusual
tonyb
Rob Dekker writes,
“In fact, the only hard claim regarding “unprecedented” sea ice decline was made by Gneiss, who stated that “This warming is unprecedented over the past 2,000 years”, a statement for which NOBODY here provided any counter evidence.”
And just to clarify where my 2,000-year figure came from, I was referring specifically to warming water:
“Second, much of the sea ice is melting from below, because of warmer water. This warming is unprecedented over the past 2,000 years, and linked to Arctic amplification of global warming.”
I have the papers by Polyak, Kinnard and others, but based this statement about water temperatures on Speilhagen et al (2011, Science):
“We find that early–21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming.”
http://www.sciencemag.org/content/331/6016/450.abstract
That inspired a flurry of smoke on this thread about much earlier times.
climatereason writes,
“I am working on historic variations in arctic ice part two and was at the met office today collecting archive material for it. It will join the hundreds of papers I have already read. The only conclusion that can be dawn is that arctic ice melts with astonishing frequency and the modern era is by no means unprecedented- just ask any Viking”
Since you’re working so hard on historical research, I gotta ask … Which Viking did you ask?
And what did he tell you, about the Arctic Ocean?
This new low pressure system is called a “Polar Low” or polar “Cyclone”.
The occur most frequently in the winter but also in the summer.
http://en.wikipedia.org/wiki/Polar_low
There was even a “European Polar Low Working Group” at one time.
The NSIDC says that up to 6 can occur in the Western Arctic in July alone.
http://nsidc.org/arcticmet/patterns/cyclones.html
So let’s have more research from now on before people start calling a low pressure system something special.
Venter says:
August 7, 2012 at 3:16 am
Jeez, yelling about ” lots of evidence ” does not make evidence or fact. Please provide empirical testable evidence that human emitted CO2 has caused unprecedented warming with catastrophic consequences. Hint, model outputs are neither data or evidence.
===================
Seconded. Please do.
No debate required.
From Rob Dekker on August 6, 2012 at 11:44 pm:
You’re using strange numbers for the daily extent. Try the NSIDC-MASIE extent file (last 4 weeks):
http://nsidc.org/data/masie/
ftp://sidads.colorado.edu/DATASETS/NOAA/G02186/masie_extent_sqkm.csv
“Day of year” is used, e.g. 2012218 is August 5, 2012 (218th day of 2012). Northern Hemisphere and individual region figures are in the file.
date, Northern Hemisphere extent, difference from previous day
8/1/2012, 6503888.13
8/2/2012, 6558378.42, +54490.29
8/3/2012, 6499522.69, −58855.73
8/4/2012, 6498851.02, −671.67
8/5/2012, 6471961.20, −26889.82
Nope, no “whopping 187,400 km^2 reduction in ice extent” there.
Ah, found your numbers! You used the Near Real Time (nrt) info:
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/north/daily/data/NH_seaice_extent_nrt.csv
Do you know you have to be careful with those?
http://nsidc.org/data/docs/noaa/g02135_seaice_index/#daily_data_files
Processing Steps
1. Obtain input data
Basically your “astonishing announcement” is coming from incomplete data.
Search that page for “masie” and see why that’s a superior product for tracking day-to-day variations.
Rob Dekker,
Your claim that the present conditions have prevailed for the last 4,000 years is wrong. From the paper:
This para shows that within the last 4,000 years, these sub-periods were particularly cold and ice-locked the beaches; note the medieval warm period and roman warm period visible in the “gaps”. During this time, there was less ice than at present. (Note the “woodless periods” are exceptionally cold, as the beaches are too frozen for driftwood to land)
This is not a story of consistent sea ice over the last 4,000 years. Even within that time frame, there have been several century-scale periods with considerably less ice than the last 60 years or so. Also, it is quite inappropriate to compare annual- and decadal- scale measurements directly to centennial and millenial proxies, for obvious reasons. Proxy-to-proxy and measurement-to-measurement comparisons are safest without VERY careful calibration specifically for the task of comparison.
The point of my post was to underline the magnitude of natural variability on longer timescales, which need to be understood before any type of assessment can be made as to whether this is anomalous with respect to natural variability or not. Without understanding these things – that nature’s variability is greater on longer timescales – it is easy to arrive at a wrong conclusion about the causes of the present changes in arctic sea ice (and the consequences, too).
Just to clarify on my last comment to Rob Dekker:
Absolutely no, Funder et al does not support this. Funder et al can tell us nothing about changes at the 1-2 year scale AT ALL because their data would not support it. On the longer scale, they show there were many periods in the last 3,000 years that had considerably LESS ice than the last 60 years (a measure for which they can provide reasonable estimates). For the reasons above.
kadaka (KD Knoebel) says:
August 7, 2012 at 6:29 am
————————————
I’ve been tracking the Masie sea ice data since day 82 (it only shows the last 30 days but I’ve got the last 138 days).
It is quite a bit different than the Near Real Time data that the NSIDC also uses. I think all their charts and quoted data are the Near Real Time ones (even though Masie could be superior). They are diverging by a large amount in recent days.
Charted here.
http://s13.postimage.org/6mrt7fzgn/NSIDC_Masie_NRT_Daily_SIE_Aug_6_2012.png
From Gneiss on August 7, 2012 at 4:45 am:
Why not toss in Hald et al 2011?
A 2000 year record of Atlantic Water temperature variability from the Malangen Fjord, northeastern North Atlantic
Abstract (bold added):
What’s not to like? There’s unprecedented warming. Sure, there is a long cooling trend attributed to insolation changes, just natural variation.
But there is that alarming “Arctic amplification of global warming” you’re so worried about.
Around 200 years of sudden alarming Arctic amplification, apparently.