No 'tipping point' for Arctic sea ice

[nzucker]

I'm not saying we have seen a death spiral I'm just saying we have not seen a recovery and the overall condition has deteriorated further.

With the ice pack being much younger and therefore thinner than it was in September 2007, I think a similar weather pattern could produce a minimum up to 1,000,000 sq km less than 2007. That was a highly anomalous weather pattern though so I don't expect to see that any time soon.

We also saw this summer, even though conditions were no where remotely close to as poor as September 2007, the ice extent was only 500k sq km above 2007. You could just watch on the loops this summer how there was absolutely nothing holding back the wind and warmth from pushing the ice around and melting it because it was extremely young and thin.

The ice isn't necessarily thinner though because you do have a pretty high concentration, which means less breaks in the pack ice. That might be an advantage coming into the summer even if the ice isn't "thick" in terms of how deep it extends into the ocean. We'll just have to see how these factors play out over the summer.

But I don't think you can say we've seen deterioration since 2007 when both the maximum and minimum extent have notably improved. You obsess over the multi-year ice, but that's just a small part of the cryosphere health. And after the 2007 meltdown and then a massive +AO/+NAO, you'd expect there to be a lot less multi-year ice, with losses continuing for a while due to the impact of that incredibly unfavorable regime. There's definitely a bit of a domino effect which will take years to recover.

[Clifford]

I've been trying to gather a little information about the Bering Strait.

Lots of data in this source (and source for a couple of the attached images).

http://access.afsc.n...empAndIceBS.pdf

I tried to overlay a couple of maps...

Sorry, I don't see the sea ice extent for 2010...

But, the Bering Strait sea ice extent for 2008 and 2009 appears to be very similar to that of the mid 70's.

I'm trying to understand the flow.

When looking at the M2 monitoring station... Something happened in the mid-2000's which caused the Pacific Ocean to flush a bunch of "warm" water up into the Arctic.

Records are short (and missing 2010).

But the anomaly seems to have corrected itself by 2009.

Looking at the St. Paul Temperature Records. (NASA)

There seems to be little change now from the 20's.

Cold in the 70's (last solar minimum).

Also cold around 1915 (also a solar minimum).

And dropping in temperature again (another solar minimum).

Since 2000, it got hammered with several years in a row of above average temperatures.

St. Paul temperature anomalies seem to be going negative again.

And, so far it looks like it may lead to an extended trend.

I'm thinking that the colder North Pacific (Bering Sea) temps as well as the return to 70's era maximum Bering Sea Ice Extent may be an indicator of a shift to growth in the Arctic Ice Sheet.

[nzucker]

The colder North Pacific probably has a lot to do with the -PDO pattern.

[Clifford]

I found some more interesting diagrams.

Ice Displacement/Thickness/Concentration, 1998 to present.

http://www7320.nrlss...hive/index.html

Here are the Ice thickness diagrams for February 11, 1999, and 2005-2011

While we don't have much ice over 3 meters thick... that is still quite thick!!!!!!!!!

And, it is not clear if we had the thicker ice in 1999.

The "Collapse" in 2007 & 2008 seems to be reversing itself.

So, the paper at the beginning of this topic suggested 2 years to recover from an Arctic with ice-free summers.

That is probably ambitious.

However, if we look at the current collapse/recovery.

Minimum Summer Sea Ice Extent: 2007

Normalizing of the Pacific Conditions in 2008... still low.

Some recovery 2009

A bit more in 2010

The "February" ice looks as healthy as it has all decade by 2011, although perhaps slightly lower on the 2.25m ice (light blue) than in 1999.

That is a recovery period of maybe 4 or 5 years from a summer of loosing 1/3 the summer sea ice 6 million km² beginning of decade to 4 million km² mid-decade (and perhaps 7-8 million km² in 70's).

Will we return to 70's and 80's levels soon?

It is interesting that there is very little 4-5m ice (yellows and reds) on any of the graphs.

Feb 11, 2011

Feb 11, 2010

Feb 11, 2009

Feb 11, 2008

Feb 11, 2007

Feb 11, 2006

Feb 11, 2005

Feb 11, 1999

[skierinvermont]

The ice isn't necessarily thinner though because you do have a pretty high concentration, which means less breaks in the pack ice. That might be an advantage coming into the summer even if the ice isn't "thick" in terms of how deep it extends into the ocean. We'll just have to see how these factors play out over the summer.

But I don't think you can say we've seen deterioration since 2007 when both the maximum and minimum extent have notably improved. You obsess over the multi-year ice, but that's just a small part of the cryosphere health. And after the 2007 meltdown and then a massive +AO/+NAO, you'd expect there to be a lot less multi-year ice, with losses continuing for a while due to the impact of that incredibly unfavorable regime. There's definitely a bit of a domino effect which will take years to recover.

The age and therefore thickness of the ice is everything. It has been very well documented that in 2008 a massive volume of ice was spewed out the Fram strait and that ice has not rebuilt itself. There is far less ice than there was following the 2007 melt season because we continued to bleed huge quantities of ice in 2008.

[skierinvermont]

I found some more interesting diagrams.

Ice Displacement/Thickness/Concentration, 1998 to present.

http://www7320.nrlss...hive/index.html

Your entire post is based off PIPS data. Even the DESIGNERS of PIPS say it is NOT climate quality data. PIPS is not DESIGNED to model ice thickness in the middle of the pack it was designed to model the EDGE of the ice for navigation purposes for the Navy.

If you READ the peer-reviewed literature you wouldn't be making such egregious and basic errors. PIPS is just something Anthoony Watts and Steve Goddard stumbled across and decided, given their vast expertise and familiarity with the product (sarcasm), that they would use it to refute PIOMAS. PIOMAS is a model just like PIPS, except PIOMAS is actually designed for the purpose of modeling ice volume. But I can see why skeptics would throw PIOMAS (the model intended to model ice volume) out the window and use PIPS (which wasn't intended for that purpose at all) to refute it.. the fairies told them to!

[nzucker]

The age and therefore thickness of the ice is everything. It has been very well documented that in 2008 a massive volume of ice was spewed out the Fram strait and that ice has not rebuilt itself. There is far less ice than there was following the 2007 melt season because we continued to bleed huge quantities of ice in 2008.

This actually proves that thickness isn't that important; the ice was lost because of the AO/NAO pattern, not because of the volume loss in 2007's meltdown. Why do you say this is everything? How can you refute the idea that extent is both important to albedo and ecosystems, as well as the weather pattern at 500mb?

It's just amazing how obstinate you become once you start to adhere to an idea. At least I'm able to shift my views of climate change to reflect all sides of the argument I've heard.

Your entire post is based off PIPS data. Even the DESIGNERS of PIPS say it is NOT climate quality data. PIPS is not DESIGNED to model ice thickness in the middle of the pack it was designed to model the EDGE of the ice for navigation purposes for the Navy.

If you READ the peer-reviewed literature you wouldn't be making such egregious and basic errors. PIPS is just something Anthoony Watts and Steve Goddard stumbled across and decided, given their vast expertise and familiarity with the product (sarcasm), that they would use it to refute PIOMAS. PIOMAS is a model just like PIPS, except PIOMAS is actually designed for the purpose of modeling ice volume. But I can see why skeptics would throw PIOMAS (the model intended to model ice volume) out the window and use PIPS (which wasn't intended for that purpose at all) to refute it.. the fairies told them to!

PIPS does show a big increase in thickness in 2011, and this may be confirmed by the Cryosphere Today maps showing very high concentrations in the Arctic Ocean...not a direct connection, but could be a sign that the ice pack is healthier and will melt less in the Summer. We'll have to wait for the findings of the new satellite to discover more about conditions up there, should be available soon.

[skierinvermont]

This actually proves that thickness isn't that important; the ice was lost because of the AO/NAO pattern, not because of the volume loss in 2007's meltdown. Why do you say this is everything? How can you refute the idea that extent is both important to albedo and ecosystems, as well as the weather pattern at 500mb?

It's just amazing how obstinate you become once you start to adhere to an idea. At least I'm able to shift my views of climate change to reflect all sides of the argument I've heard.

PIPS does show a big increase in thickness in 2011, and this may be confirmed by the Cryosphere Today maps showing very high concentrations in the Arctic Ocean...not a direct connection, but could be a sign that the ice pack is healthier and will melt less in the Summer. We'll have to wait for the findings of the new satellite to discover more about conditions up there, should be available soon.

Of course extent is important to albedo and ecosystems.. but ultimately the number 1 factor that determines the fate of the arctic is the THICKNESS and VOLUME of ice... not the prior year's extent. We can have all the extent you want and yet if it is paper thin, it will melt during the first unfavorable weather pattern. The arctic is undoubtedly more vulnerable than it was even following the 2007 melt season. If we had a 2007-esque weather pattern again, I have no doubt that the minimum would be at least 500,000 sq km less than in 2007. In 2007, the strong warm cross polar winds were fighting 3+m thick ice.. now in those same regions we have 1.5m thick ice.

Are you seriously using cryosphere today maps to claim the ice is thicker? What a joke. The cryosphere today maps show the same thing in the arctic basin every winter - near 100% concentration. It's no different this year.

[tacoman25]

Your entire post is based off PIPS data. Even the DESIGNERS of PIPS say it is NOT climate quality data. PIPS is not DESIGNED to model ice thickness in the middle of the pack it was designed to model the EDGE of the ice for navigation purposes for the Navy.

If you READ the peer-reviewed literature you wouldn't be making such egregious and basic errors. PIPS is just something Anthoony Watts and Steve Goddard stumbled across and decided, given their vast expertise and familiarity with the product (sarcasm), that they would use it to refute PIOMAS. PIOMAS is a model just like PIPS, except PIOMAS is actually designed for the purpose of modeling ice volume. But I can see why skeptics would throw PIOMAS (the model intended to model ice volume) out the window and use PIPS (which wasn't intended for that purpose at all) to refute it.. the fairies told them to!

Really?

I used to have a much higher opinion of the unbiased, objective nature of your posts, but you have really undermined that in recent weeks.

[skierinvermont]

Really?

I used to have a much higher opinion of the unbiased, objective nature of your posts, but you have really undermined that in recent weeks.

I am sorry, but the use of PIPS to refute PIOMAS is just a complete joke. It really is sad to see skeptics resorting to such poor methodologies.

[tacoman25]

I am sorry, but the use of PIPS to refute PIOMAS is just a complete joke. It really is sad to see skeptics resorting to such poor methodologies.

It's pretty sad that you have resorted to bunching all skeptics together like the other closeminded individuals on here, and that you have resorted to "fairy insults" in that regard.

[Clifford]

Ahhh.

So the thickness is interpolated data.

With relatively few data points.

Sound familiar?

Ever notice the "Global Warming" camp tends to start all their graphs at extremes.

Start the "warming" from the lowest temperature since 1930.

Start the "shrinking ice" from the highest peak ice since the 40's.

http://seaice.alaska...R_20thC_RSI.pdf

The Mahoney paper indicates an over-estimate of the sea ice extent used in the HadISST for historical estimates.

Using 1980 as a "base point" for the calculations seems to inappropriately weight the most recent "high", rather than the more logical comparison of what is likely a "low" to the previous "low" in an oscillation pattern.

Truthfully, it does appear as if the summer sea ice has retreated since the 40's and 50's, but that doesn't seem to be the case for other seasons.

The sea ice thickness/age animations back to the early 80's also seem to be heavily weighted towards modelled data in the 80's and 90's, and do a shift to more observational data after 2000. Thus, the shape and age of the "old ice" seems to be highly speculative, and even potentially misleading.

[skierinvermont]

It's pretty sad that you have resorted to bunching all skeptics together like the other closeminded individuals on here, and that you have resorted to "fairy insults" in that regard.

I'm not bunching them all together - I am specifically referring to Anthony Watts, Steve Goddard and other individuals who would use PIPS data to refute PIOMAS when PIPS is not designed for that purpose and PIOMAS is.

[WeatherRusty]

It's pretty sad that you have resorted to bunching all skeptics together like the other closeminded individuals on here, and that you have resorted to "fairy insults" in that regard.

So you consider those who find AGW science very, very compelling as close minded? We get extremely tired of unsubstantiated claims being thrown against the wall to see what sticks as argumentation by skeptics. There are as many skeptical arguments out there casting doubt on every aspect of science if it happens to support AGW theory as there are sciences in support of the theory. Everything is attacked from all possible angles.

Every possible mechanism is suggested as a viable alternative to CO2 and the enhancement to the greenhouse effect. Science and scientists are not close minded, but they are discriminating. You can't just counter AGW theory with any plausible argument, especially ones that have long ago been debunked.

I don't accept most skeptical arguments for the same reason I don't believe in little fairies. All to many folks appear to believe in fairies however.

[skierinvermont]

Ahhh.

So the thickness is interpolated data.

With relatively few data points.

Is this you admitting that your use of PIPS was incorrect?

[skierinvermont]

The Mahoney paper indicates an over-estimate of the sea ice extent used in the HadISST for historical estimates.

I believe that is a paper I have cited on here multiple times to substantiate my belief that sea ice has been somewhat cyclical.

Keep in mind a couple things:

1) It's only Russian ice (the study encompasses something like 60% of the arctic if i recall correctly)

2) HadISST contains massive error bars

[Clifford]

I believe that is a paper I have cited on here multiple times to substantiate my belief that sea ice has been somewhat cyclical.

Keep in mind a couple things:

1) It's only Russian ice (the study encompasses something like 60% of the arctic if i recall correctly)

2) HadISST contains massive error bars

Is there more shrinkage of the Sea Ice on the Russian side of the Arctic or the Canadian side?

[skierinvermont]

Is there more shrinkage of the Sea Ice on the Russian side of the Arctic or the Canadian side?

I don't really know of any good precise data for the Canadian side prior to 1980.. since then I'm not sure I'll check.

[Hambone]

And to be fair, it is unfortunate that we only have about 30 years worth of data...considering the often cyclical nature of the Arctic and nature in general, it gives us little reference for how "gradual" or not the drop has been.

If it is anything like global temperature trends, the trend for Arctic ice over the past 100 years could accurately be described as gradual.

That's not exactly true. We have archeologic records that indicate arctic ice at lower levels during the MWP.

[Clifford]

I don't really know of any good precise data for the Canadian side prior to 1980.. since then I'm not sure I'll check.

When you look at the summer ice loss in the central Arctic

The old ice gets slammed up against the North Coast of Canada.

So, 100% of the loss in the central Arctic Ocean is either on the north coast of Alaska, or the North coast of Russia.

There certainly are additional losses around Sweeden, Norway, Finland, and Greenland.

However, the sea ice extent along the Russian Northern Coast should be representative of the sea ice extent in the central Arctic Ocean.

That isn't, of course, a measurement of thickness. However, perhaps one could even ignore some of the thick multi-year ice along Canada, and still look at the thickness of the ice in the central Arctic, and towards the Russian side that tends to be younger, and thinner.

Here are a couple of other early studies...

I was having troubles orienting myself... until I discovered I was looking at the world upside-down

http://www.ncdc.noaa...mbusAVCSNew.ppt

From: Nimbus satellite data for polar ice survey. J. Sissala et al, Polar Record, 1972

NimbusPhoto1:

July 1966-15.26 10⁶km², 1969-16.83 10⁶km², 1970-17.62 10⁶km² 2010~15.88 10⁶km²

Nimbus Photo2:

August 1966-15.17 10⁶km², 1969-17.19 10⁶km², 1970-18.55 10⁶km²

Anyway, from 1966 to 1970, the Antarctic maximum sea ice extent increased significantly.

Ok...

For all the "Alarmists" out there... the Antarctic Sea ice maximum has actually decreased from the 1970 maximum extent levels of 18.55 10⁶km²

Or the 1972 to 1975 levels in excess of 19 10⁶km² (see below)

However, we are still consistent with the 1966 levels and could likely consider the 1969-1980 levels a "spike" anomaly due to solar activity.

This article provides sea ice level graphs back to 1972, both North and South.

http://www.atmos.umd...e.30yrs.GRL.pdf

North... not much apparent difference between 1972 and 1980.

South. See the "spike" noted above, returned to 1966/current levels by 1980.

While we are lacking previous data, I would attribute the sea ice spike in Antarctica round 1970 to the weak solar cycle during that period.

[BethesdaWX]

I am sorry, but the use of PIPS to refute PIOMAS is just a complete joke. It really is sad to see skeptics resorting to such poor methodologies.

PIOMAS?

[stellarfun]

That's not exactly true. We have archeologic records that indicate arctic ice at lower levels during the MWP.

What are those records? Can you provide a link?

_________________

The Navy did a validation exercise on PIPS 2.0; the mean ice edge error was 210 km.

[BethesdaWX]

What are those records? Can you provide a link?

_________________

The Navy did a validation exercise on PIPS 2.0; the mean ice edge error was 210 km.

I provided links on this several times over, citing peer reviewed sources. Viking expeditions through the arctic were rarely hindered by Ice, Glaciers were half the size of those today, as wee see remains of trees, and viking cemetaries, showing up under our melting glaciers. Heck, trees were growing where there are now ice floes.

This was solar caused. Todays maximum is similar in strength to the medieval maximum, so why is our current WP not solar?

It is

[Clifford]

The Navy did a validation exercise on PIPS 2.0; the mean ice edge error was 210 km.

I wasn't particularly using the Navy system to look at the ice edge as I know that the ice already covers most of the Arctic Ocean. Other resources can provide the "edge" in various outlying areas.

I was looking at a comparative indication of the thickness of the ice.

The 99 chart seems to show relatively little ice in excess of 4 meters which may cast some doubt on the specific details on that chart.

However, looking at the 2011 chart, there seems to be an increase in the 3+ meter ice.

I suppose there would be a significant difference between... say 2.5 meter ice, and 3.5 meter ice. But, for the purposes of my comparison, I don't need that much detail.

I can just hope that the values are somewhat reproducible... so whether 3 meter ice is off by 20%, as long as it is equivalent in the last 5 years, that would be sufficient.

As far as the annual sea ice extent:

http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Extent_L.png

We've fallen down to the lowest sea ice extent in the decade again

However, the Arctic Ocean is frozen solid.

All of the areas that are short of sea ice are outside of the Arctic Ocean, in areas that ordinary melt by mid-summer.

http://nsidc.org/data/seaice_index/images/daily_images/N_daily_extent_hires.png

The paper that started this subject indicated that the maximum effect would be an ice cover in the summer, and no ice cover in the winter. While that may not be possible, I am most interested in the minimum sea ice extent mid-summer. And, the signs are that trends with respect to that ice sheet may be reversing towards rebounding.

[stellarfun]

I provided links on this several times over, citing peer reviewed sources. Viking expeditions through the arctic were rarely hindered by Ice, Glaciers were half the size of those today, as wee see remains of trees, and viking cemetaries, showing up under our melting glaciers. Heck, trees were growing where there are now ice floes.

This was solar caused. Todays maximum is similar in strength to the medieval maximum, so why is our current WP not solar?

It is

The Vikings never sailed around the top of Greenland, or got to the Nares Strait did they? Do you have a link that they did?

The Vikings got to the southern tip of Greenland, and no one disputes that southern Greenland was warmer during the MWP than it is today. But southern Greenland isn't even within the Arctic Circle.

Vikings did sail east over the top of what is now Norway and then down into the Kola peninsula. (That's within the Arctic Circle.) But that is not so extraordinary. Convoys by the dozens took that route during WWII -- the run to Murmansk.

None of the Vikings seem to have made it up to Svalbard, which is well within the Arctic Circle. It wasn't discovered until after the MWP was over. And the North Atlantic Current moderates its climate, allowing vessels to get there through open water most of the year. How do you explain Vikings not making it to Svalbard? During the MWP, Svalbard must have been like the French Riviera.

So I am looking for a link that shows the Vikings were sailing way up into Baffin Bay, getting up to Ellesmere etc. That would demonstrate that the Arctic had a lot less summer ice during the MWP than today.

[skierinvermont]

I wasn't particularly using the Navy system to look at the ice edge as I know that the ice already covers most of the Arctic Ocean. Other resources can provide the "edge" in various outlying areas.

I was looking at a comparative indication of the thickness of the ice.

The 99 chart seems to show relatively little ice in excess of 4 meters which may cast some doubt on the specific details on that chart.

However, looking at the 2011 chart, there seems to be an increase in the 3+ meter ice.

I suppose there would be a significant difference between... say 2.5 meter ice, and 3.5 meter ice. But, for the purposes of my comparison, I don't need that much detail.

I can just hope that the values are somewhat reproducible... so whether 3 meter ice is off by 20%, as long as it is equivalent in the last 5 years, that would be sufficient.

As far as the annual sea ice extent:

http://www.ijis.iarc...ce_Extent_L.png

We've fallen down to the lowest sea ice extent in the decade again

However, the Arctic Ocean is frozen solid.

All of the areas that are short of sea ice are outside of the Arctic Ocean, in areas that ordinary melt by mid-summer.

http://nsidc.org/dat...xtent_hires.png

The paper that started this subject indicated that the maximum effect would be an ice cover in the summer, and no ice cover in the winter. While that may not be possible, I am most interested in the minimum sea ice extent mid-summer. And, the signs are that trends with respect to that ice sheet may be reversing towards rebounding.

And as I explained, PIPS is not a valid tool for measuring thickness. It isn't designed for the purpose at all and is likely to be wildly inaccurate year to year. PIOMAS is designed for that purpose, and has had 5 years of validation against IceSat in which it performed well. Now I'm not saying PIOMAS is perfect, but there is no reasonable argument for using PIPS over PIOMAS. PIOMAS shows continued ice volume loss since 2007.

[tacoman25]

So you consider those who find AGW science very, very compelling as close minded? We get extremely tired of unsubstantiated claims being thrown against the wall to see what sticks as argumentation by skeptics. There are as many skeptical arguments out there casting doubt on every aspect of science if it happens to support AGW theory as there are sciences in support of the theory. Everything is attacked from all possible angles.

Every possible mechanism is suggested as a viable alternative to CO2 and the enhancement to the greenhouse effect. Science and scientists are not close minded, but they are discriminating. You can't just counter AGW theory with any plausible argument, especially ones that have long ago been debunked.

I don't accept most skeptical arguments for the same reason I don't believe in little fairies. All to many folks appear to believe in fairies however.

Closeminded individuals prefer to see things in a "us vs. them", black/white scenario...when the truth is that there are a lot of shades of gray out there. Closeminded inviduals also seem to believe their position is absolutely right, no matter what. They stereotype/simplify those with opposing viewpoints and opposing arguments. These individuals exist on both sides of this debate.

But if it makes you feel better, go ahead and equate AGW skepticism with believing in fairies. That makes your "side" of the argument so much more logical and scientific!

[Clifford]

I agree that we need to look at the argument as weighting different "forcing agents" which is what the IPCC is supposed to be doing, but unfortunately seems to get stuck with only a single forcing agent.

And, it may well be that they are considering every possible forcing agent, but leaving them in the background and only discussing a single forcing agent that they think is most "important". However, it comes across as if they are just ignoring everything else.

As far as different ice thickness models. It may well be that the Navy PIPS model is not as complete as other models. It is odd that the shape of the Feb 2011 3m ice resembles the Sept 2010 ice, when we know that everything tends to move around a lot.

As far as the calibration of the PIOMAS model. The initial points on their calibration chart are there because they forced them to be there. And, in fact, the 4th and 5th points seem to be drifting (to the positive in their chart).

http://psc.apl.washi...010.MarNov2.png

In fact, when you read their notes on calibration.

Compared to the submarine data, their model tended to show thicker ice on the Alaska side (by about 2m), and thinner ice on the Greenland side (by about 2m). I suppose it all averaged out.

http://psc.apl.washi...lation_2006.pdf

The idea behind the model is that the "Mass" calculations should be more stable than the area calculations.

There apparently is no 2011 data published, so we have to base our analysis on a 2010 graph, already a month and a half old.

http://psc.apl.washi...malyCurrent.png

What you notice is that in mid-2010 there was a "Flash Crash", beginning sometime in May 2010, and beginning to resolve itself by July 2010 (before the minimum ice extent).

http://nsidc.org/ima...608_Figure5.png

http://neven1.typepa...cbf47970c-800wi

I only see anomalies so I can't tell if their model added ice in the summer, or just stopped loosing ice in the summer. Either one, there was a problem with the flash crash. Other models show a divergence from the mean ice area in the spring, but don't note whether it is ice that would have melted later anyway.

In the 2010 AMSR-E graph, there was no rapid transition in the May/June/July time period, nor any reason to believe that an anomaly should have ended with a point of any sort.

http://www.ijis.iarc...ce_Extent_L.png

I may have some ideas of what caused the instability, but it seems as if the PIOMAS is less predictive of the mid-summer ice than the just tracking the area with out the mass.

[BethesdaWX]

The Vikings never sailed around the top of Greenland, or got to the Nares Strait did they? Do you have a link that they did?

The Vikings got to the southern tip of Greenland, and no one disputes that southern Greenland was warmer during the MWP than it is today. But southern Greenland isn't even within the Arctic Circle.

Vikings did sail east over the top of what is now Norway and then down into the Kola peninsula. (That's within the Arctic Circle.) But that is not so extraordinary. Convoys by the dozens took that route during WWII -- the run to Murmansk.

None of the Vikings seem to have made it up to Svalbard, which is well within the Arctic Circle. It wasn't discovered until after the MWP was over. And the North Atlantic Current moderates its climate, allowing vessels to get there through open water most of the year. How do you explain Vikings not making it to Svalbard? During the MWP, Svalbard must have been like the French Riviera.

So I am looking for a link that shows the Vikings were sailing way up into Baffin Bay, getting up to Ellesmere etc. That would demonstrate that the Arctic had a lot less summer ice during the MWP than today.

When did I say they did? Go back and read the links I posted.

Either way, my point is unscathed in regards to trees growing in areas that are still partially ice covered, viking burial grounds, higher treelines, higher sea levels....etc. This all solar.

next?

[Clifford]

The Northwest Passage, however, has been open a few times in the past, 1906, as well as in 1942.

http://www.norwegianblue.co.uk/history.htm

Then, again in 2007.