If all of the polar ice caps melted

[gravenewworld]

the sea level shouldn't rise? Water takes up more volume as a solid than a liquid right. So why all the fear that we will all be run over by the sea from melting polar ice cap? The sea levels shouldn't change at all right? What am I missing here?

 

[Ivan Seeking]

The South pole is a continent, not just floating ice, and there is a tremendous amount of ice in the north on land, such as in Greenland.

I forget the greatest depth of the ice in Antactica, but I think it is something like a mile thick in places.

 

[gravenewworld]

The South pole is a continent, not just floating ice, and there is a tremendous amount of ice in the north on land, such as in Greenland.

I forget the greatest depth of the ice in Antactica, but I think it is something like a mile thick in places.

But again it is just a big chunk of floating ice right? If the entire thing melted, sea levels shouldn't rise 1 bit.


I can understand if all of the snow and ice on land actually melted, then the sea levels would rise, but if all of the chunks of ice in the ocean were to melt, sea levels shouldn't rise at all.

 

[waht]

Antarctica has about 5 million square miles of 1 mile (average) in depth of solid ice above sea level.

 

[Ivan Seeking]

It also appears that during melting, the water can carve the ice into layers and lubricate its path, so that the ice will move in large sheets rather than slowly melting, which could significantly increase the rate of loss.

 

[Ivan Seeking]

But again it is just a big chunk of floating ice right? If the entire thing melted, sea levels shouldn't rise 1 bit.

No, it is sitting on land, not floating. Antarctica is a ice-covered land mass.

 

[gravenewworld]

Antarctica has about 5 million square miles of 1 mile (average) in depth of solid ice above sea level.

So what? It is still just like an ice cube in a glass of water right? I could fill a bucket a quarter up with some water and then fill it to the brim with ice, once all of the ice melted, none of the water would spill out of the bucket.

 

[gravenewworld]

No, it is sitting on land, not floating. Antarctica is a ice-covered land mass.

Ok, but how much of the land is actually above sea level? Do we even know? I could see how sea levels could rise if all of the ice melts that is on land above sea level.

 

[NoTime]

No. It's like a funnel full of ice sitting over the glass.
The ice is not sitting in the water.

 

[Ivan Seeking]

http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/ICESat_AntElevation.jpg
http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=16758

 

[waht]

So what? It is still just like an ice cube in a glass of water right? I could fill a bucket a quarter up with some water and then fill it to the brim with ice, once all of the ice melted, none of the water would spill out of the bucket.

Antarctica is a continent. All that ice is sitting on a mass of land above sea level. Antarctica even has a mountain range with some peaks over 16,000 ft above sea level.

 

[gravenewworld]

No. It's like a funnel full of ice sitting over the glass.
The ice is not sitting in the water.

OK so if Antartica melts, sea levels rise, but since the North Pole isn't a continent there is no land underneath. Therefore if the entire ice mass of the North Pole melted, sea level wouldn't change.

 

[Cyrus]

http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/ICESat_AntElevation.jpg
http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=16758

Oooo, ahhhhh pretty.

 

[loseyourname]

Water World won't happen, but the sea level will rise.

 

[Evo]

Don't forget that as ice melts, the land beneath it rises. It's a *very* slow process, but one that is happening right now from the retreat of the last ice age.

 

[rootX]

the sea level shouldn't rise? Water takes up more volume as a solid than a liquid right. So why all the fear that we will all be run over by the sea from melting polar ice cap? The sea levels shouldn't change at all right? What am I missing here?

So that we don't run out of issues

But, I think the sea level would increase (and is increasing right now; heard about this somewhere - but don't have any source).

 

[Evo]

But, I think the sea level would increase (and is increasing right now; heard about this somewhere - but don't have any source).

The sea level is rising in some places and dropping in others. I've previously posted the link.

 

[Ivan Seeking]

Here you go

Sea level is rising along most of the U.S. coast, and around the world. In the last century, sea level rose 5 to 6 inches more than the global average along the Mid-Atlantic and Gulf Coasts, because coastal lands there are subsiding.

Higher temperatures are expected to further raise sea level by expanding ocean water, melting mountain glaciers and small ice caps, and causing portions of Greenland and the Antarctic ice sheets to melt. The IPCC estimates that the global average sea level will rise between 0.6 and 2 feet (0.18 to 0.59 meters) in the next century (IPCC, 2007).

...Rising sea levels inundate wetlands and other low-lying lands, erode beaches, intensify flooding, and increase the salinity of rivers, bays, and groundwater tables. Some of these effects may be further compounded by other effects of a changing climate. Additionally, measures that people take to protect private property from rising sea level may have adverse effects on the environment and on public uses of beaches and waterways. Some property owners and state and local governments are already starting to take measures to prepare for the consequences of rising sea level. [continued]

http://www.epa.gov/climatechange/effects/coastal/index.html

Sea levels are rising worldwide and along much of the U.S. coast. (IPCC, 2007) Tide gauge measurements and satellite altimetry suggest that sea level has risen worldwide approximately 4.8-8.8 inches (12-22 cm) during the last century (IPCC, 2007). A significant amount of sea level rise has likely resulted from the observed warming of the atmosphere and the oceans.

According to the Intergovernmental Panel on Climate Change (IPCC), the primary factors driving current sea level rise include:

the expansion of ocean water caused by warmer ocean temperatures
melting of mountain glaciers and small ice caps
(to a lesser extent) melting of the Greenland Ice Sheet and the Antarctic Ice Sheet
Other factors may also be responsible for part of the historic rise in sea level, including the pumping of ground water for human use, impoundment in reservoirs, wetland drainage, deforestation, and the melting of polar ice sheets in response to the warming that has occurred since the last ice age.

Considering all of these factors, scientists still cannot account for the last century's sea level rise in its entirety. It is possible that some contributors to sea level rise have not been documented or well-quantified.

The rate of sea level rise increased during the 1993-2003 period compared with the longer-term average (1961-2003), although it is unclear whether the faster rate reflects a short-term variation or an increase in the long-term trend. (IPCC, 2007)

While the global average sea level rise of the 20th century was 4.4-8.8 inches, the sea level has not risen uniformly from region to region.[continued]

http://www.epa.gov/climatechange/science/recentslc.html

http://www.epa.gov/climatechange/images/slr_trends_7-apr-2006.gif

 

[Andre]

Meanwhile, the global (eustatic) sea level appears to have stopped rising.

http://icecap.us/images/uploads/SeaLevel_TOPEX.jpg

 

[Ivan Seeking]

It looks to me that the data is still within the existing envelope of about +- 10mm.

There is no way to draw any conclusions based on one simple graph.

 

[turbo]

During the last ice age, glacial subsidence occurred rather quickly in geological terms, while rebound of the land that the glaciers had depressed progressed more slowly. The result is that Skowhegan, ME (~175' above current sea level) was under water, as evidenced by the blue marine clays and silt that can be found almost everywhere. The oceans probably intruded much farther inland, but I have done a lot of soils-work in that area and it is pretty amazing to think about ocean-front property so far from the (current) ocean.

 

[vociferous]

On both polls, there is a lot of ice sitting on land. The Arctic may be an ocean, but there is still plenty of ice in the area (Siberia, Alaska, Canada, et cetera) that it will greatly increase sea levels.

I seem to remember an estimate of somewhere between ten a thirty five meters if all the landlocked ice melted.

And that is not even taking into account the fact that water expands as it heats up. The warmer the oceans, the greater their volume. The mass of water in the oceans is so great that seawater expansion could have a clearly noticeable effect.

 

[matthyaouw]

OK so if Antartica melts, sea levels rise, but since the North Pole isn't a continent there is no land underneath. Therefore if the entire ice mass of the North Pole melted, sea level wouldn't change.

The Greenland ice sheet is on a landmass too

 

[Ivan Seeking]

Also, there is the water in formally "permanent" glaciers, such as in the Himalayas, that eventually makes it to the oceans. As indicated in the links from earlier, it isn't just the poles.

 

[shamrock5585]

well even if we talk about the north pole... we can picture it as a giant iceburge and true about 90% of that ice is in the water so when it melts the water level will stay the same... but what about the 10% above the water... that will make the the oceans rise won't it? i mean 10% of the whole north pole is a whole damn lot of water!

 

[turbo]

well even if we talk about the north pole... we can picture it as a giant iceburge and true about 90% of that ice is in the water so when it melts the water level will stay the same... but what about the 10% above the water... that will make the the oceans rise won't it? i mean 10% of the whole north pole is a whole damn lot of water!

No. Ice floats because it is less dense than water. The 10% above water is indicative of the density difference. When floating ice melts, it will not change the sea-level. Try it with a glass of water with some ice floating in it. Mark the water level and wait for the ice to melt. You'll see.

 

[vociferous]

well even if we talk about the north pole... we can picture it as a giant iceburge and true about 90% of that ice is in the water so when it melts the water level will stay the same... but what about the 10% above the water... that will make the the oceans rise won't it? i mean 10% of the whole north pole is a whole damn lot of water!

Ice forms a crystal lattice, so it reduces volume quite a bit when it melts.

EDIT: Aw, you beat me to it.

It should also be noted, that it is not as if just the ice in the Arctic Sea is going to melt. A lot of nearby landlocked glacial ice and frozen tundra is going to disappear along with it.

 

[shamrock5585]

hmmm... i knew it was less dense and i knew water expands when frozen but i never looked at it in depth... i guess this makes sense because the amount of water the ice displaces is equal to the force holding up the ice due to buoyancy... so when the ice melts it will weigh the same as the water it displaced... hence it will make the same amount of water it displaced in the first place... interesting

 

[mgb_phys]

i guess this makes sense because the amount of water the ice displaces is equal to the force holding up the ice due to buoyancy.

Yes to first order approximation it doesn't make any difference. But the water in the ice is fresh rather than salt and colder then the sea water so it will have other effects when it melts changing the pattern of currents.

One big concern is that it is cold fresh water flowing into the artic that drags wam salt water in the gulf stream so a change in currents in the arctic can have a huge effect on the climate.

 

[Andre]

Apparently there has been a mistake.

 

[Ivan Seeking]

Yes, there has been a mistake. Apparently you posted something completely out of context. That relates to claim made by Greenpeace, not NOAA, or the IPCC, or the Academy of Sciences, or NASA, or anyone else of interest.

 

[Andre]

Not really

http://www.treehugger.com/files/2007/09/no_more_arctic.php

If present trends continue, scientists predict that the Arctic could become ice-free within 23 years. To put that into context, it took the last 30 years for it to lose almost a third of its ice. "It's amazing. It's simply fallen off a cliff and we're still losing ice. If you asked me a couple of years ago when the Arctic could lose all of its ice, then I would have said 2100, or 2070 maybe," said Mark Serreze, an Arctic expert at the University of Denver's National Snow and Ice Data Center (NSIDC).

edit, see also:

http://www.energybulletin.net/node/34363

Experts say they are "stunned" by the loss of ice, with an area almost twice as big as the UK disappearing in the last week alone.

So much ice has melted this summer that the Northwest passage across the top of Canada is fully navigable, and observers say the Northeast passage along Russia's Arctic coast could open later this month.

If the increased rate of melting continues, the summertime Arctic could be totally free of ice by 2030.

Mark Serreze, an Arctic specialist at the US National Snow and Ice Data Centre at Colorado University in Denver, said: "It's amazing. It's simply fallen off a cliff and we're still losing ice."

edit see also:

https://fp.auburn.edu/sfws/sfnmc/web/bet5.html

On June 23, 2008, James Hansen (I offered this $1,000 bet with Dr. Hansen in April) said…."We see a tipping point occurring right before our eyes," Hansen told the AP before a luncheon at the National Press Club. "The Arctic is the first tipping point and it's occurring exactly the way we said it would." Hansen, echoing work by other scientists, said that in five to 10 years, the Arctic will be free of sea ice in the summer.

 

[Moonbear]

Hansen, echoing work by other scientists, said that in five to 10 years, the Arctic will be free of sea ice in the summer.

As usual, trying to distort the misinformation you spread. This is what scientists are talking about, SEA ice in the Arctic Ocean, not, as Greenpeace was trying to claim and the subject of that news clip, the Greenland ice sheet (i.e., ice on LAND). As usual, mixing apples and oranges to make dubious claims.

 

[billiards]

hmmm... i knew it was less dense and i knew water expands when frozen but i never looked at it in depth... i guess this makes sense because the amount of water the ice displaces is equal to the force holding up the ice due to buoyancy... so when the ice melts it will weigh the same as the water it displaced... hence it will make the same amount of water it displaced in the first place... interesting

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.

Don't forget that as ice melts, the land beneath it rises. It's a *very* slow process, but one that is happening right now from the retreat of the last ice age.

Yes that is true, and will cause a local lowering in the apparent sea level. But the rising of land in one location is compensated for the sinking of land elsewhere. An example: the sea level in SE England appears to be rising faster than it should be, this is because the land is sinking in the SE - the mantle beneath is creeping back towards the N from where it was displaced by the last ice sheet.

 

[Andre]

Arctic warming has become so dramatic that the North Pole may melt this summer, report scientists studying the effects of climate change in the field.

"We're actually projecting this year that the North Pole may be free of ice for the first time [in history]," David Barber, of the University of Manitoba, told National Geographic News aboard the C.C.G.S. Amundsen, a Canadian research icebreaker. [continued]

http://news.nationalgeographic.com/news/2008/06/080620-north-pole.html

From the same source:

Recent models suggest that the Arctic won't see its first completely ice-free summer until somewhere between 2013 and 2030.

linking to:

http://news.nationalgeographic.com/news/2007/12/071212-AP-arctic-melt.html

An already relentless melting of the Arctic greatly accelerated this summer—a sign that some scientists worry could mean global warming has passed an ominous tipping point.

One scientist even speculated that summer sea ice could be gone in five years.

Greenland's ice sheet melted nearly 19 billion tons more than the previous high mark, and the volume of Arctic sea ice at summer's end was half what it was just four years ago, according to new NASA satellite data obtained by the Associated Press (AP).

 

[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.