If all of the polar ice caps melted

[lisab]

Actually in the video, the interviewer begins by asking about a press release regarding "Arctic ice," and that it will be gone by 2030. The interviewer then transitions to talking about the Greenland ice cap.

This hits directly on why I'm so sceptical...he said, "We had to emotionalize this issue." Once the question was "emotionalized," it became political. Then it's a blue-or-red issue...and science be damned.

 

[Andre]

Anyway here is the stance of Greenpeace.

http://www.greenpeace.org/international/news/urgent-action-needed-as-arctic

Sea ice has dramatically thinned between 2004 and 2008. Old ice (over 2 years old) takes longer to melt, and is also much harder to replace. As permanent ice decreases, we are looking at ice-free summers in the Arctic as early as 2030.

 

[Evo]

Arctic Ice has only been measured since 1979. Years 2008 and 2009 have both seen an increase in Arctic ice coverage since the unusual conditions that caused a decrease in 2007.

During the first half of August, Arctic ice extent declined more slowly than during the same period in 2007 and 2008. The slower decline is primarily due to a recent atmospheric circulation pattern, which transported ice toward the Siberian coast and discouraged export of ice out of the Arctic Ocean. It is now unlikely that 2009 will see a record low extent, but the minimum summer ice extent will still be much lower than the 1979 to 2000 average.

http://nsidc.org/arcticseaicenews/

Antarctic Ice ice has been increasing for 30 years.

http://www.nasa.gov/centers/goddard/news/topstory/2005/sea_ice.html

 

[sylas]

Arctic Ice has only been measured since 1979. Years 2008 and 2009 have both seen an increase in Arctic ice coverage since the unusual conditions that caused a decrease in 2007.

The summer extent in 2008 increased with respect to the exceptional low point of 2007; but not with respect to anything else. 2008 was easily the second lowest summer minimum in sea ice extent since we've had records. It's sometimes called the 2007/2008 minimum, since both years were so low even by comparison with the very strong trends on reducing cover on a scale of decades.

2009 summer minimum is still not here. It is currently very low by comparison with other years on record; though it is unlikely to go as low as 2007/2008. People are watching with interest; but don't get too hung up on individual years.

Like many natural processes, there's a lot of natural variation from year to year. Individual years are an easy focus for a news story, but the trend is really seen by looking at a time series. In this case, the trend is very strong. The Arctic is reducing dramatically in sea ice cover. This trend is very strong indeed. The Arctic is also warming much more strongly than the rest of the globe. This is a regional effect, and must be explained by taking into account regional forcings. It's not just from the greenhouse effect, for example.

http://nsidc.org/arcticseaicenews/

Antarctic Ice ice has been increasing for 30 years.

http://www.nasa.gov/centers/goddard/news/topstory/2005/sea_ice.html

That's a great site, Evo; with lots of good information.

I really recommend their FAQ page. It has nice straightforward non-emotive answers to obvious questions. See http://nsidc.org/arcticseaicenews/faq.html.

Such things as:

• Is it really declining?
• How come 2008 had more ice than 2007?
• What was it like before we had satellites?
• Has there always been sea ice present in summer?
• Why don't we hear as much about the Antarctic?

and lots more.

Cheers -- sylas

 

[Evo]

The summer extent in 2008 increased with respect to the exceptional low point of 2007; but not with respect to anything else. 2008 was easily the second lowest summer minimum in sea ice extent since we've had records.

Too bad we've only had records from 1979, and those older records, not so good. Not long enough to get a real picture of cycles there. But data is getting better. It will be interesting to see more data as years go by.

I guess my greatest concern is what is happening in the oceans. I am not concerned about humans being inconvenienced by having to abandon waterfront property, or the fact that we will see some species go and new species flourish.

Destroying the balance in the oceans could be devastating to a lot of life forms. But as a scientist said the other day that is concerned about human's impact. "You keep hearing about how we need to save the planet. The planet doesn't need saving, the planet will be fine. The issue here is saving ourselves". I guess that's the part I don't care about, so we have to adapt, we've been adapting since we appeared. The difference now is that we don't want to adapt.

That's a great site, Evo; with lots of good information.

I really recommend their FAQ page.

Just so as to not confuse members, the FAQ is about the Arctic, not the Antarctic.

 

[mgb_phys]

Water also expands when heated. In fact, thermal expansion of the oceans is, according to the IPCC, the largest single contributor to sea level rise.

Fortunately the expansion of water near it's maximum density is very small 0.01%/c

 

[Jimmy Snyder]

Last Sunday my wife and I staked out a nice place on the beach in Seaside Heights, NJ. We planted the umbrella in the sand, unfolded the folding chairs, spread the tarp and placed books on the corners to keep the flapping down. Then we went wading in the ocean, took a promenade on the boardwalk, and rode the ski lift to nowhere. What a blast. But while we weren't paying attention, there must have been some global warming. Whether man-made or woman-made is yet to be determined. Then one of the ice caps melted and the waterline came and wetted the tarp. Poor books. We picked up and drove inland just ahead of the melting of the other cap. This helped but little as one of the polar ice caps on Mars melted next. We went home exhausted, but happy.

 

[sylas]

Too bad we've only had records from 1979, and those older records, not so good. Not long enough to get a real picture of cycles there. But data is getting better. It will be interesting to see more data as years go by.

This is discussed in the FAQ. There's really no doubt at all about the rate of sea ice reduction in the Arctic being massively out of the normal, by comparison with at least the last several thousand years. This is not a cycle, and the data is certainly good enough to establish that.

I guess my greatest concern is what is happening in the oceans. I am not concerned about humans being inconvenienced by having to abandon waterfront property, or the fact that we will see some species go and new species flourish.

Me also. But for the record, sea ice reduction in the Arctic has very little to do with water levels. Water level change is from thermal expansion, and loss of ice from the land.

I'm mostly interested in the science aspects. Impacts and so on is not really my baliwick. But as far as impact goes, I think the largest impact from water level is not going to be for folks interested in "waterfront property", but in places like Bangla Desh. Biggest ocean change is probably in chemistry and falling pH; but that's got nothing much to do with ice.

Just so as to not confuse members, the FAQ is about the Arctic, not the Antarctic.

It mentions both; though the Arctic is the main focus, as the FAQ title suggests. The FAQ also explains why this focus is appropriate, with reference to what is going on both in the Antarctic and Arctic. It's at a very accessible level, and can really help clear up the nature of the differences.

Cheers -- sylas

PS. The site has lots more pages. For anyone interested in the differences between the Arctic and Antarctic, there's a good summary at another page linked from the Arctic ice FAQ: see http://nsidc.org/seaice/characteristics/difference.html .

 

[lisab]

Last Sunday my wife and I staked out a nice place on the beach in Seaside Heights, NJ. We planted the umbrella in the sand, unfolded the folding chairs, spread the tarp and placed books on the corners to keep the flapping down. Then we went wading in the ocean, took a promenade on the boardwalk, and rode the ski lift to nowhere. What a blast. But while we weren't paying attention, there must have been some global warming. Whether man-made or woman-made is yet to be determined. Then one of the ice caps melted and the waterline came and wetted the tarp. Poor books. We picked up and drove inland just ahead of the melting of the other cap. This helped but little as one of the polar ice caps on Mars melted next. We went home exhausted, but happy.

Aahhh...nice. Sounds like the perfect outing with the one you're legally licensed to fight with.

 

[Evo]

I'm mostly interested in the science aspects. Impacts and so on is not really my baliwick.

It's really quite frightening.

If you are interested in taking a look, I will see what I can find. The methane levels in permafrost is horrific. Digging two feet down into the snow and lighting a match and having a methane torch come from the ice.

If you are interested, let me know.

 

[kldickson]

There's not a lot of Antarctic rock above sea level.http://www.physorg.com/newman/gfx/news/hires/RonneFichner.jpg

 

[kldickson]

There's bigger problems from the loss of sea ice than just water level increase.

 

[sylas]

There's not a lot of Antarctic rock above sea level.

It doesn't need to be. All you need is for the ice to be resting on rock. If so, then melting ice will raise sea level, because the ice surface is above sea level, and it isn't floating.

 

[ideasrule]

There's not a lot of Antarctic rock above sea level.http://www.physorg.com/newman/gfx/news/hires/RonneFichner.jpg

[/URL]

Keep in mind that much of Antarctica has a few kilometers of ice pressing down on it. Once some of that ice is gone, the land would rise, displacing sea water and forcing sea level to rise.

 

[Jimmy Snyder]

Keep in mind that much of Antarctica has a few kilometers of ice pressing down on it. Once some of that ice is gone, the land would rise, displacing sea water and forcing sea level to rise.

That sounds dubious to me. If the land is already above sea level and then rises, it would have no effect whatever on sea level. Would the land really rise? Last year some workers drove a truck on my lawn to cut down a tree and the ruts are still there.

 

[sylas]

That sounds dubious to me. If the land is already above sea level and then rises, it would have no effect whatever on sea level. Would the land really rise? Last year some workers drove a truck on my lawn to cut down a tree and the ruts are still there.

It's called "isostatic rebound", and it is certainly real. It makes a big difference for the water line on a land mass that rises after having a large ice mass removed, but that is because the land is moving, rather than the ocean. I don't think it would have much effect for sea level on other continents; what is more significant is simply the extra water from the ice going into the ocean.

Cheers -- sylas

 

[Andre]

The melting of the arctic has been of concern before.

‘It will, without doubt, have come to your Lordship's knowledge that a considerable change of climate, inexplicable at present to us, must have taken place in the Circumpolar Regions, by which the severity of the cold that has for centuries past enclosed the seas in the high northern latitudes in an impenetrable barrier of ice, has been during the last two years greatly abated. This affords ample proof that new sources of warmth have been opened, and give us leave to hope that the Arctic Seas may at this time be more accessible than they have been for centuries past, and that discoveries may now be made in them, not only interesting to the advancement of science, but also to the future intercourse of mankind and the commerce of distant nations.’

President of the Royal Society, Minutes of Council, Volume 8. pp.149-153, Royal Society, London. 20th November, 1817.

 

[Andre]

I have been wondering about available long term data of arctic temperatures comparing the warmer spell in the 1940s with those of nowadays. So I went to GISS

http://data.giss.nasa.gov/gistemp/station_data/

and clicked on Northernmost Siberia, Greenland and the NWT in Canada, then I selected the first series of stations that were providing data as of at least 1930 until now. Now what would be the difference between the 1930-40s warming and the current warming?


http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222208910006&data_set=1&num_neighbors=1
[URL][PLAIN]http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.222208910006.1.1/station.gif
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222230740000&data_set=1&num_neighbors=1
[URL][PLAIN]http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.222230740000.1.1/station.gif
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222245070006&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.222245070006.1.1/station.gif
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222234720005&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.222234720005.1.1/station.gif

http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222206740006&data_set=1&num_neighbors=1
[URL][PLAIN]http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.222206740006.1.1/station.gif
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222242660006&data_set=1&num_neighbors=1
[URL][PLAIN]http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.222242660006.1.1/station.gif
-----
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=403719250005&data_set=1&num_neighbors=1
[URL][PLAIN]http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.403719250005.1.1/station.gif
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=403719380005&data_set=1&num_neighbors=1
[URL][PLAIN]http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.403719380005.1.1/station.gif
Jan Mayen
[URL][PLAIN]http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.634010010003.1.1/station.gif

http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=431043600000&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.431043600000.1.1/station.gif

http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=620040630003&data_set=1&num_neighbors=1
[URL][PLAIN]http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp.620040630003.1.1/station.gif

 

[kldickson]

It doesn't need to be. All you need is for the ice to be resting on rock. If so, then melting ice will raise sea level, because the ice surface is above sea level, and it isn't floating.

I know. I was responding to whoever insinuated that the rest of Antarctica was above sea level.

 

[sylas]

I have been wondering about available long term data of arctic temperatures comparing the warmer spell in the 1940s with those of nowadays. So I went to GISS

http://data.giss.nasa.gov/gistemp/station_data/

and clicked on Northernmost Siberia, Greenland and the NWT in Canada, then I selected the first series of stations that were providing data as of at least 1930 until now. Now what would be the difference between the 1930-40s warming and the current warming?

You are looking at regional data, and so you need to be considering regional causes and effects. There's a good discussion of the trends in the Arctic and their credible causes given in the thread [thread=306202]Only dirty coal can safe the Earth[/thread]. (The thread title is a poor attempt at humour; the content of the thread and of the research being discussed is more sensible.)

As I noted previously, this is not the same as the global trend; it is at present much stronger, and so there are additional factors at work in this region which don't apply across the whole globe, and which apply on top of the larger overall global trend to increasing temperatures.

The NCSI site that Evo introduced also has a http://nsidc.org/arcticmet/, which walks through some of the particular factors that pertain to the Arctic, though it doesn't specifically go into the timeline of the 20th century, like the Drew Shindell paper discussed in the thread cited above.

You mentioned also reports from 1817 of Arctic observations; which may relate to movement out of the so-called "little ice age". But there's little doubt that the ice levels then were much greater than now; the period of 1700 to 1800 seems to have been a period of maximum ice; and so that report is about right for moving out of that period.

Recent attempts to look at a history over the last 800 years have been published in "Climate Dynamics". See:

• Macias Fauria, M, A. Grinsted, S. Helama, J. C. Moore, M. Timonen, E. Isaksson, and M. Eronen (2009) Unprecedented 20th century low values of sea ice extent in the Western Nordic Seas since A.D. 1200. Climate Dynamics doi: 10.1007/s00382-009-0610-z. (pdf available http://www.ulapland.fi/home/hkunta/jmoore/pdfs/Macias-Fauria_2009_ClimDyn.pdf ).

From the abstract:

The twentieth century sustained the lowest sea ice extent values since A.D. 1200: low sea ice extent also occurred before (mid-seventeenth and mid-eighteenth centuries, early fifteenth and late thirteenth centuries), but these periods were in no case as persistent as in the twentieth century. Largest sea ice extent values occurred from the seventeenth to the nineteenth centuries, during the Little Ice Age (LIA), with relatively smaller sea ice-covered area during the sixteenth century. Moderate sea ice extent occurred during thirteenth–fifteenth centuries. Reconstructed sea ice extent variability is dominated by decadal oscillations, frequently associated with decadal components of the North Atlantic Oscillation/Arctic Oscillation (NAO/AO), and multi-decadal lower frequency oscillations operating at *50–120 year. Sea ice extent and NAO showed a non-stationary relationship during the observational period. The present low sea ice extent is unique over the last 800 years, and results from a decline started in late-nineteenth century after the LIA.​

So there certainly are cycles and variations in the Arctic; but the current reduction in ice cover is exceptional, and not part of a regular short term cycle. Note that the research is not saying 800 years ago is like today. It isn't. The 800 years is rather the bound of time considered.

There's also some useful but less technical information in the NSIDC FAQ, on http://nsidc.org/arcticseaicenews/faq.html#presatellite, which mentions the warmer period in the 1930s and 1940s, but back to the 1800s the data is indirect. The reports you mention are not comprehensive surveys that in themselves allow an easy comparison with current conditions; for that you need research such as the paper I've cited above.

I suggest we ask this thread be moved into the Earth science forum. Now that we are getting a bit technical, it really belongs there, rather than in "general discussion".

Cheers -- sylas

 

[Count Iblis]

If you have mountains, hills etc. that have been underneath ice for a long time and all that ice suddenly melts, they can be unstable and just crumble and fall into the sea, triggering tsunamis.

I think that Britain was hit by such a tsunami 8000 years ago caused by a landslide in Norway.