Arctic Ice May Melt By 2040

Dekortage writes in with a new study by the National Center for Atmospheric Research suggesting that the North Pole may be clear of ice in summer as soon as 2040, decades earlier than previously thought. From the article: "'As the ice retreats, the ocean transports more heat to the Arctic and the open water absorbs more sunlight, further accelerating the rate of warming and leading to the loss of more ice,' Holland said in the statement. 'This is a positive feedback loop with dramatic implications for the entire Arctic.'"

Re:Sea Level?

[AP2k]

Except ice is less dense than water...

No change in sea level.

[RingDev]

Yes, which means the same mass takes more volume. When submerged ice (the majority of the ice in question) melts, it becomes more dense (same mass, less volume) which means it actually LOWERS the water level. Add in the amount of ice that is above water in the Artic channel, and the total change in water levels will be negligible.

-Rick

Re:Sea Level?

[Chris Burke]

Because of bouyancy, melting the ice which is floating in water will not raise sea level. The ice is less dense than water, ergo it floats on the water, but it displaces an amount of water equal to its mass. So when it melts into water, the level will stay the same.

You can try this yourself with a glass of water and ice cubes. Mark the water line with the ice cubes floating, then let the ice melt and notice that it hasn't moved. This is elementary school physics.

There are two things that will raise sea level: First, any ice that is on land (not displacing sea water) that melts and flows into the ocean. Thus why Antarctica is a much bigger concern as far as rising sea levels are concerned. Second, thermal expansion of the ocean as it becomes warmer. I believe that the latter will actually end up being the dominant effect.

Re:No change in sea level.

[hal2814]

"it actually LOWERS the water level."

Wrong again. The volume of the ice submerged in the water is equal to the volume of the ice if it were water. The only difference between the water and the ice is density. Ice is less dense. Because of that, it floats. But the only part of the ice that floats above the water line is the difference in volume between it's forzen and melted states. Submerged ice melting in water leaves the water level at exactly the same place. It's not a centimeter, millimeter, or even nanometer different. It physically can't be different.

Re:Sea Level?

[Derek Pomery]

The ice in the arctic is fresh water, the ocean it is floating in is salt.
http://www.physorg.com/news5619.html [physorg.com]

Re:No change in sea level.

[MustardMan]

How does this get modded insightful? Have you EVER heard how buoyancy works? This is high school physics stuff, people - a floating object displaces exactly the same amount of liquid as it weighs - a floating ice cube that weighs a gram, displaces exactly one gram of water. It sticks up out of the water however much it needs to make this happen. When it melts, the gram of ice cube becomes a gram of water, which now changes the water level by exactly ZERO.

Of course, in real life there are very subtle points about salinity to take into question - but the way the parent post was worded shows a clear and simple misunderstanding of the physics involved, and it always makes me cringe to see such crap modded up.

Then again, the real world question is not the ice that's floating, but the ice that's supported by land - this is the stuff that's going to run off into the oceans and change the water levels. I'll leave it to the climatologists to argue how much.

Re:Sea Level?

[Qzukk]

You can try this yourself with a glass of water and ice cubes. Mark the water line with the ice cubes floating, then let the ice melt and notice that it hasn't moved. This is elementary school physics.

And by the time you get to college, you should have learned that the experiment does not work with saltwater [physorg.com].

Re:Skeptical.

[malsdavis]

There is a slight difference in the academic and scientific quality between the reports appearing in major scientific journals that note the correlation between record high levels of CO2 in the atmosphere and increasing global temperatures, compared to the sort of "research" that appears on Fox news.

The story appeared on "Fox news" in the USA, and references a story appearing in the British newspaper "Daily Telegraph", both of those news organisations are known to be the main global warming deniers in each of those countries. They both love running sensationalist, unscientific articles in order to discredit the real scientific research going on.

Re:No change in sea level.

[RingDev]

My ability to work formulas and functions far exceeds my ability to express those formulas in the english language. ;) So here's a picture of what I was attempting to express.

Ice
~~~ = No change in sea level (or extremely small change)
Ice

Ice
~~~ = Increase in sea level
Land

-Rick

Re:No change in sea level.

[sadtrev]

A few reasons why this is significant

1. not all the ice that could melt is supported by water buoyancy.
2. temperature changes of liquid water will cause change in density.
3. polar bears will drown

The first is what could inhibit the Atlantic Conveyor by weakening its motive force : the downward flow of cooled salty water would be disrupted by large quantities of freshwater runoff from Greenland. Consequence - European weather becomes more like that on Newfoundland.
The second mechanism is what will cause sea levels to rise - the average temperature of the ocean is more than 4C so an uniform increase in water temperature will cause expansion. As the ocean is quite deep in places, a small expansion could lead to a significant rise in water level.
Admittedly not everybody cares about polar bears drowning or European climate becoming too cold to make Champagne or low-lying island states in the Indian Ocean being obliterated. Selfish gits.

Re:No change in sea level.

[Skippy_kangaroo]

If you melt only the ice that is above the waterline there will be less ice below the waterline as the whole iceberg now weighs less and displaces less water to make it buoyant. You can't meaningfully melt only the ice above the waterline (or below the waterline). Your thought experiment is like saying: cut the top off the iceberg and hold the remaining portion of it down in the water using exactly the same force as the top of the iceberg used to exert, then melt the top of the iceberg and look at what happens - just silly.

In fact, the ice above the waterline that melts will cause the whole iceberg to displace a weight of water that is smaller by exactly the weight of whatever melted - whose volume exactly equals the volume of water that melted off the iceberg above the waterline and then, presumably, fell into the ocean to replace the volume that was no longer displaced by the weight of ice. It seems you get this but your talk about melting only the water above or below the waterline makes me wonder.

Re:Oh please

[LionMage]

And it's also well documented that ice is increasing in areas like Greenland.

No it is not, according to RealClimate [realclimate.org]. Snowfall may be increasing at the interior of Greenland, but it's offset by an accelerated dumping of ice into the ocean at the periphery.

From RealClimate:

The critical point for Greenland is whether the increased rate of glacier motion more than compensates for the greater accumulation on the surface. While the broad picture of what is happening is consistent between these papers, the bottom-line value for Greenland's mass balance is different in all three cases. Looking just at the dynamical changes observed by Rignot & Kanagaratnam, there is an increased discharge of about 0.28 mm/year SLE from 1996 to 2005, well outside the range of error bars. This is substantially more than the opposing changes in accumulation estimated by Johannessen et al and Zwally et al, and is unlikely to have been included in their assessments. Thus, the probability is that Greenland has been losing ice in the last decade. We should be careful to point out though that this is only for one decade, and doesn't prove anything about the longer term. As many of the studies make clear, there is a significant degree of interannual variability (related to the North Atlantic Oscillation, or the response to the cooling associated with Mt. Pinatubo) such that discerning longer term trends is hard.

Emphasis added by me.

Re:No change in sea level.

[FriendlyPrimate]

That's not entirely true either. Fresh water is slightly less dense than salt water. So when the ice cap melts, the oceans will become fresher and less dense. Since the overall mass of the water+ice does not change, the sea level will rise slightly.

Pwnt by english

[RingDev]

uhg, my inability to express this analogy is frustrating me. Your first paragraph is what I was posting about. If the only change enacted on the environment is to melt either the submerged, or non-submerged ice, and no other effect is allowed.

While I was writing it, I was applying the logic such that you could replace the submerged half of the formula with dry land. If you break it out into two sperate formulas (submerged ice melting reduced total volume, non-submerged ice melting increases total volume) and you can assume that the volume of water displaced equals the total volume of the ice above and below the water line, then you can state that: ice that is not submerged will increase the volume of water by the same amount as what it would have displaced if it were partially submerged, and the inverse of that for finding the volume of water displace by the submerged ice. When dealing with the two formulas together, the net change in a controled environment is 0.

Since you can then figure out water volume of non-submerged ice, you can then figure out how much volume you are adding to the water body by melting ice that is on dry land.

-Rick

Global Cooling myth

[benhocking]

Also, it wasn't scientists who were talking about global cooling in the 70's. It was some of the same media types who now think that "both" sides of the global warming "debate" need to be discussed. I.e., journalists who didn't understand science, but want to sell subscriptions. I challenge you to find a single peer-reviewed article supporting global cooling in the 70's. In fact, you'll find that scientists in the 70's were already warning about global warming.

Re:Sea Level?

[jc42]

I was thinking for some dumb reason that the ice cap would be frozen salt water.

Well, taken literally, that is true. The problem is that when salt water freezes, most of the salt is left behind. The explanation is fairly simple: The water starts forming crystals, and the salt (mostly Na and Cl ions) don't fit into the crystal structure very well. So at the surface, the water molecules slowly join the growing crystal, while the dissolved salt ions don't. You do get some salt in the ice, because ice usually consists of a lot of crystals that grew together, trapping salt in the pores. But usually there's not enough salt for the ice to taste salty.

This phenomenon is used sometimes. It's often called "freeze distillation". One way it has been used is to concentrate wine. For instance, people used to leave jugs of apple cider out on below-freezing nights. In the morning, they'd remove the layer of ice at the top. The liquid left would be thicker, and would contain most of the alcohol, because ethanol also doesn't join into ice crystals. The resulting concentration is more like alcoholic syrup than brandy, but due to the high alcohol content, it doesn't spoil.

Re:No change in sea level.

[Marxist Hacker 42]

RTFA- Atmospheric CO2 or even methane has NOTHING TO DO WITH THIS FEEDBACK LOOP, except maybe for starting it. You could kill off every cow on the planet, shut down every CO2 producer, and the arctic ice would STILL be gone by 2040- because the cause (ocean absorbing more sunlight than ice) is a positive feedback loop that has already started.

In other words, the argument is over, global warming is happening, and it's far too late to play the blame game.

Re:No change in sea level.

[Climate Shill]

I've been following global warming for a long time now doing a lot research on the side for the last couple of years. Here are some facts about global warming. Some of which you hear and don't hear from the main stream media: 1.) The world appears to be getting warmer with many computer models showing an increase in global temperature.

The word you're looking for here is "thermometers".

3.) Apparently, the Earth magnetic field has decreased by 10% in the last 150 years (source: http://www.space.com/scienceastronomy/earth_magnet [space.com] ic_031212.html). I'm an electrical engineer and during my studies in particle physics, I learned that a particles velocity can be affected by magnetic fields. I believe it's possible that more of the Sun's radiation is penetrating the Earth's magnetic field due to it being weaker. If more radiation hits the Earth, shouldn't that also increase the overall temperature of the Earth and can global warming be attributed to this?

No, obviously not. The temperature was falling throughout those 150 years and has only started rising recently. The only correlated factor is CO2.

4.) Jupitor is experiencing the same climate change that Earth is. (source: http://www.space.com/scienceastronomy/060504_red_j [space.com] r.html [space.com])

5.) Mars is experiencing the same climate change that Earth is. (source: http://www.space.com/scienceastronomy/solarsystem/ [space.com] mars_snow_011206-1.html and http://www.dailymail.co.uk/pages/live/articles/new [dailymail.co.uk] s/news.html?in_article_id=410901&in_page_id=1770)

Complete crap. We have absolutely no idea what the temperature history of the other planets is and so we have no way of drawing any conclusions from any changes we see.

6.) The United Nations found that there is more Methane produced from livestock, which raises global temperature greater than CO2 by a factor of approx. 20, than any human caused CO2 combined (source: http://www.fao.org/newsroom/en/news/2006/1000448/i [fao.org] ndex.html)

The article you linked to says that CH4 only amounts to 18% of CO2-equivalent emissions. Since the lifetime of CH4 is only 12 years, the cumulative effect is smaller still.

How can you explain the recent same climate changes on different planets? I doubt it's all those cars being driven there.

See above. However, since temperatures on Earth have only started rising recently, and we've been monitoring the Sun's output longer than that, we can be sure the reason isn't a change in the Sun.

Is it possible that the warmer temperatures that Earth is experiencing are caused by cyclical natural phenomena? What about glaciers in Greenland that have been shrinking for 100 years (source: http://www.breitbart.com/news/2006/08/21/060821191 [breitbart.com] 826.o0mynclv.html [breitbart.com])? Also, how do you explain huge ice ages on Earth? Were thse caused by huge carbon emissions or was it a small natural climate cycle that just happens? Were those climate changes, which are no doubt more extreme than what's going on now, caused by the combustion engine? I don't have answers and everyone seems to have an opinion including a Nobel laureate who says the answer is more pollution (source: http://www.cnn.com/2006/TECH/science/11/16/smog.wa [cnn.com] rming.ap/index.h

It does change sea level... a little

[FhnuZoag]

Actually, no. Sea level will still rise: though only by a little. The water from the ice is less dense than the sea water around it because the sea ice typically contains less salt. Hence, more floats up above the water than bouyancy would suggest, which reduces the water level as it gets frozen, and increases the water level when the ice melts again.

Search for 'salinity' in http://www.radix.net/~bobg/faqs/sea.level.faq.html [radix.net]

And you are wrong also ...

[Evil Pete]

Must admit I accepted this too until the argument was put to me recently. Fact is of course that the ice is fresh water (less dense) than the sea water it floats in. Check out the links posted elsewhere to physorg about this. Archimedes principle is about the force of the ice pushing down and displacing an equal weight of sea water. But since the ice is lower density then the volume of sea water displaced is less than the volume of the fresh water in the ice ... even after melting. So when floating ice melts in sea water the sea level goes up. Check here [physorg.com], not just the reasoning but also the actual experiment to prove it.

Re:Skeptical.

[terrymr]

I don't know, did they ? : Rearing cattle produces more greenhouse gases than driving cars, UN report warns [un.org]. Note the un.org domain in my link.

Once again... hacking the papers

[OUWxGuesser]

Here's the full abstract. Note that 1 of 7 computer models showed total ice melt by 2040... the worst case scenario. Gotta love how the media grabs the flashy stuff. Holland, Marika M.; Bitz, Cecilia M.; Tremblay, Bruno Future abrupt reductions in the summer Arctic sea ice Geophys. Res. Lett., Vol. 33, No. 23, L23503 http://www.agu.org/pubs/crossref/2006/2006GL028024 .shtml [agu.org] Abstract We examine the trajectory of Arctic summer sea ice in seven projections from the Community Climate System Model and find that abrupt reductions are a common feature of these 21st century simulations. These events have decreasing September ice extent trends that are typically 4 times larger than comparable observed trends. One eventexhibits a decrease from 6 million km2 to 2 million km2 in a decade, reaching near ice-free September conditions by 2040. In the simulations, ice retreat accelerates as thinning increases the open water formation efficiency for a given melt rate and the ice-albedo feedback increases shortwave absorption. The retreat is abrupt when ocean heat transport to the Arctic is rapidly increasing. Analysis from multiple climate models and three forcing scenarios indicates that abrupt reductions occur in simulations from over 50% of the models and suggests that reductions in future greenhouse gas emissions moderate the likelihood of these events.

Re:Let me remind you...

[Anonymous Coward]

1975 quote is a lie.

Acid rain has had many negative effects.

The ozone hole DID get worse. As a New Zealander I've grown up with it. We have soaring melanoma rates in our country due to it. It may still be another few decades before it shrinks enough to lessen risk.

Bird Flu is a danger, and there WILL be a flu pandemic in the future. We don't know when, but we do know that many of the flu pandemics of the past occurred due to changes in viruses from jumping between porcine, avian and human populations. But there will definitely be a pandemic in the future.

The debate over climate change never really existed. The so-called "debate" has been a generated controversy of American corporate and right-wing interests.

As for your opinion that concerning anything happening globally "we can't change anyway" I have to say, you're an idiot. Please take an hour or two to look into humanity's effects globally on fishing stocks, the current human-caused mass extinction, pollution etc. Humans have a huge impact on this planet, and this also indicates that we can also take action to prevent global changes of our own making.

(Perhaps you should think before you post)