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Fraser
2005-Aug-16, 04:55 PM
SUMMARY: A new NASA-funded study has discovered that sea ice in the Antarctic might actually be on the increase as global temperatures go up. There has been overwhelming evidence that sea ice is decreasing in the Arctic ocean, but scientists didn't realize there might be a difference between the two poles. As temperatures rise, it seems to create more precipitation around the southern pole, which falls as snow. The weight of the snow pushes sea ice below sea level, and causes the snow to melt and then freeze as additional ice.

View full article (http://www.universetoday.com/am/publish/sea_ice_may_increase_in_antarctic.html)

What do you think about this story? Post your comments below.

om@umr.edu
2005-Aug-16, 05:21 PM
There have long been conflicting news reports on the amount of ice being melted and being formed.

I am pleased that UT is covering both sets of observations.

With kind regards,

Oliver
http://www.umr.edu/~om

Spacemad
2005-Aug-16, 08:08 PM
This article on the increase of sea ice in the Antarctic came as a real surprise to me! Like most people I assumed that the ice at both the North & South Poles was melting & not being replaced by an equivalent amount of snowfall!

What effect will this have on the global weather patterns? Will it help stabilise the temp. increase produced by the warming of the atmosphere? What about the circulation of deep water, will this also help transport the surface heat to greater depths? What effect, if any, will the greater weight of sea ice have on the climate?

cran
2005-Aug-16, 11:55 PM
It is a common misconception that much lower temperatures means much more ice and snow around the place - the same misconception is found in "snowball Earth" theories.

The atmosphere's ability to retain water drops dramatically when the temperature falls below -10C; the valleys in central Antarctica are virtually ice-free because it never gets warm enough for snow! Much of the odd bits of surface ice there are quite rich in carbon dioxide.

The increase in sea ice around Antarctica will have some effect on ocean/atmosphere currents - leading to vastly increased precipitation (rain and snow) in some parts of the world - or it could go the other way entirely!! :blink:

The major ocean/atmosphere circulations have developed with fairly substantial 'feedback' and 'rebound' responses to thermohaline (temperature and salinity) input variations - for instance, massive freshwater inputs from Canada and Greenland ice-sheets do disrupt the Gulf Stream, and the concern is that this in turn may shut down the Atlantic deep water conveyor, leading to colder surface water around Western Europe - and another ice age for them (ice age equates with increasing glaciers in higher latitudes and altitudes, but also drier conditions in the lowlands - droughts and increasing desertification) ... and all of that because the temperature increased :huh:

that's what you call 'counter-intuitive' :blink:

Guest
2005-Aug-17, 04:06 AM
Just to keep things clear for everyone, More ice isn't really ok... this doesn't mean that their is no danger from global Warming..

Most of the scientific community would agree that radical changes is necessary in order to curb global warming and , the renewable energy sources is the something the world nations need to start seriously thinking about..

this is for the public things are not ok... Majority of scientist agree that human activity is responsible for global warming.. despite the diversity of its effects it is still required a threat to human life on this planet as well as a large percentage of other animal and plant life.

cran
2005-Aug-17, 07:56 AM
Simple translation...

"Green is Good" :)
"Runaway Greenhouse is Bad" :(

Eric Vaxxine
2005-Aug-17, 08:32 AM
Global warming and global dimming. I like to think that the Earth enjoys change and although we pollute in our ourn unique and selfish way, when the earth gushes tons of noxious gases through volcanoes...it's normal and natural.

Try plugging those holes.

cran
2005-Aug-17, 09:11 AM
:lol: good point, Eric

sam_lelime
2005-Aug-18, 01:09 AM
Eric,
volcanoes have been active for thousands of years... do you have evidence to support that earth has become more geologically active..

the problem with the human selfish burning is that it is inducing change where it is not time for change... if earth atmosphere was to heat up due to increased volcanic activity.... humans like all other species will be forced to adapt...

however if earth's atmosphere is over polluted due to human activity, the increased geological activity could be the disaster life would not adapt to.

and then you could philosophies that humans are a force of nature and we shouldn't worry all will be sorted out, but in that argument reason is a force of nature that give us the ability to pollute and not to pollute.. so our guests argument stands as a legitimate one.

Eric Vaxxine
2005-Aug-18, 08:38 AM
We live in a relatively stable volcanic period (no major life threatening outpourings) and our contribution to the greenhouse atmosphere has been helped by global dimming. It's a fine line we walk.

I am not sure nature judges where or how noxious gases are produced, but it will react to its environment by heating up or getting cold, all the while trying to find a balance.

The tuareg and eskimos reflect our abilities to survive extremes on a small scale.

om@umr.edu
2005-Aug-18, 11:56 AM
Hi, Eric.

I appreciate your well thought out comments on global warming/cooling, etc.

On this issue, I have long been in the uncomfortable position of:

a.) Being appreciative that some scientists are concerned over mankind's selfish, short-sighted ways and their possible disasterous influences on Earth's climate, but

b.) Being appalled at the poor quality of the science being used to support their claims of global warming.

Thanks for being a voice of reason in this debate.

With kind regards,

Oliver
http://www.umr.edu/~om

Dylan Powell
2005-Aug-18, 01:18 PM
This is an interesting and immensley important discussion and I am flattered that our article may have contributed.

Our study focused on the thermodynamic effects of increased precipitation on Antarctic sea ice. We found that with present day precipitation rates (which are increasing) the snow load is great enough to "push" the sea ice below sea level thereby increasing sea ice thickness and thus sea ice volume. Recent trend analysis has shown Antarctic ice extent (total area that the ice encloses) to be increasing slightly in the Antarctic. Increased sea ice extent results in decreased solar absorption in the ocean and thus a downward forcing of air temps. Lower air temps lead to increased oceanic heat flux through the ice and to the atmosphere, cooling ocean temps. However, if the sea ice thickness is increasing then this will dampen the heat loss from the ocean to the atmosphere. Despite the downward forcing of temps due to increased sea ice volume, studies (insitu and modeled) show that Antarctic air temps are increasing (also supported by the fact that precipitation is increasing and that large icebergs are breaking off the Western Antarctic ice shelf).

The moral of the story is that Antarctic sea ice and climate are extremely complicated and (compared to the Arctic) very little is understood. There is a lot of work yet to be done! What is clear is that human behavior is influencing the far flung Antarctic environment and it is no doubt reciprocating. I feel caution is the best approach in anything that is poorly or misunderstood.

Thanks very much for allowing me to join!

Cheers,
Dylan

Eric Vaxxine
2005-Aug-18, 03:39 PM
Thank you for the science Dylan.

Spacemad
2005-Aug-18, 09:22 PM
Originally posted by Eric Vaxxine@Aug 18 2005, 03:39 PM
Thank you for the science Dylan.

Like, Eric, Dylan, I would like to say thanks for your scientific input into this thread, it's greatly appreciated! :)

I found the original article very interesting & informative & it came as a huge surprise to me to discover that in Antarctica sea ice was on the increase! Although, as you point out, so little is known at present about the dynamics of the climate there that it is all to easy to generalise - in some parts more sea ice is being lost than is being laid down & in other parts just the opposite is true!

cran
2005-Aug-19, 12:21 AM
Yes, Dylan, thank you.... and welcome!

If the growth and extent of the Antarctic sea ice is more than an ephemeral response to higher atmospheric temperatures, will there be further studies on possible changes to the Circumpolar Current and the rise of Atlantic Deep Water? :unsure:

Ola D.
2005-Aug-19, 01:01 PM
Thanks a lot for your input Dr. Powell! ;-)

giacarr
2005-Aug-20, 07:51 PM
Very interesting Dylan.

I hope that the doomsday preachers who predict that the world is coming to an end due to global warming are correct.

However if it has been found that there is more ice packing together over the Antarctic - and we know that this ice is always being pressed out towards the ocean from the interior - maybe this is a fluctuation in a very steady source of ice formation in this area.

If this is so (go and ask the pinguins), then it doesn't matter much what weather reports have to say. As wetness from humid clouds move in over the interior from the ocean it builds more ice which cools the polar cap. Temperatures during the dark half of the year can therefore plummet. This is the time when the pinguin males decide to begin their walk into the interior of the pole where they are safe from predators. However, as the warmer winds continue to bring in dampness from the seas this will succumb to the cold and fall as large, warm snowflakes that freeze into the ice sheet. Since this warms the surface as well as the air during mid-winter when it is the coldest the pinguin males manage to survive until the spring so that the eggs can hatch.

Since the pinguins have developed a relationship with the weather patterns of the Antarctic, one must assume that these have been pretty much the same for a very long time, and that the increase in the thickness of the ice sheet is nothing new. Thus it is not only variable, but it also prevents any major warming of the planet. After all when the ice is pressed into the sea at a higher rate than usual because of the increase in the thickness of the ice-sheet, the water that melts off is very cold. This causes it to sinks to the bottom of the ocean where it curves around the polar cap where it forms into deep sea streams that move up towards the equator, where it consequently cools off the seas, preveting these from warming too much.

Since this is most likely a part of a long-term equalization of the earth's temperature and it is therefore a part of the earth's cooling-system, this should also influence the weather pattern in the northern hemisphere. I don't believe that it will create a new ice age anywhere, anywhere soon though. I think the earth is passed this part of its evolution. By the way the ice that melts off the Antarctic does not contain any salt, as was said somewhere in there.

Cheers, GIA

cran
2005-Aug-21, 01:01 AM
By the way the ice that melts off the Antarctic does not contain any salt, as was said somewhere in there. Actually, it does contain some... the salt is from windborne spray, and over time it accumulates and is buried as more ice accumulates over it ...
in warmer latitudes, the same kind of sea salt residue can be found in most soils... and is chemically distinct from evaporites that form in situ... :)

sam_lelime
2005-Aug-22, 03:22 AM
[I hope that the doomsday preachers who predict that the world is coming to an end due to global warming are correct]

lol, and smoking tobacco is good for your lungs,

Alpha and Gamma radiation is good for your skin

and finally


wait for it


PCP is a great way to go on holiday from the confort of your own home.

Jerry
2005-Aug-22, 05:32 PM
Originally posted by Spacemad@Aug 16 2005, 08:08 PM

This article on the increase of sea ice in the Antarctic came as a real surprise to me! Like most people I assumed that the ice at both the North & South Poles was melting & not being replaced by an equivalent amount of snowfall!

What effect will this have on the global weather patterns? Will it help stabilise the temp. increase produced by the warming of the atmosphere? What about the circulation of deep water, will this also help transport the surface heat to greater depths? What effect, if any, will the greater weight of sea ice have on the climate?
Careful,

This article is about a MODEL that predicts more sea ice, not an observational fact...

...Although as the author pointed out, there is limited short term evidence rain/snowfall is increasing on Antartica.

It is also an observational fact ice shelves in Antartica that have been stable for centuries are breaking up, and there is at least one MODEL that predicts this may disrupt tropical flow into the North Atlantic, causing much lower temperatures in Europe.

We don't know exactly what is happening, but we do know that long before the greenhouse effect kicked in, man started making the Earth less hospitable.

We really should stop doing that.

cran
2005-Aug-23, 02:02 AM
Ah, The Messenger (mind if I call you 'Mess'?) ... the voice of reason... :D
Yes indeed; it is but a model, generated by a computer, based on who-knows-what algorithms, and some of the variables may well be guesses... ;) ... but some of the key variables are observed data... including, but not restricted to, increases of snow depth on sea ice... <_<
Other observed data which have been fed into models affecting the northern hemisphere include weakening thermohaline gradients in key parts of the ocean circulation currents - including, but not restricted to, the Gulf Stream System and the effects of increased freshwater from the Subpolar Gyre via the West Greenland and Labrador Currents (the freshwater runoff has been traced back to Greenland, Baffin Island, and northern Canada) contributing to some rather spectacular cold-core eddies in the western boundary current ... but also weakening the North Atlantic Current (an extension of the Gulf Stream System) which feeds into the Norwegian Current, where it cools and contributes to the formation of Arctic Bottom Water (Tomczac 2000, pers comm; Tomczak and Godfrey 1994, Regional Oceanography) ... the overflow of Arctic Bottom Water across the Greenland-Iceland-Scotland ridge is one of the two main water masses that form North Atlantic Deep Water (NADW), the flow of which drives the overturning of the &#39;global conveyor&#39; (the other water mass within the 2 layered NADW is traceable to the Labrador Sea deep convection) ... surface buoy and CTD surveys since 1971 have measured annual variances in temperature, salinities, and current strengths, which have preceded annual variations in Western European climate indicators (average temps and max-min temp ranges; precipitation rates, etc) ... more recent satellite IR surveys have added even more detail ... it is these data which have been fed into models that forecast potentially nasty times ahead for Western Europe... <_<
And what does all that have to do with increased sea ice in the Antarctic Circumpolar Current? :blink: Apart from potentially restricting the flow across Drake Passage/ Scotia Ridge - which would lead to a potential increase in upwelling of NADW into the Circumpolar Current (and the excess flow would have to be accomodated by the Pacific eastern boundary current (the Peru/Chile Current), which might then affect the ENSO (El Nino/Southern Oscillation) cycle.... who knows? :huh:
That&#39;s why we look at models... :blink:

And you are right when you suggest that we humans haven&#39;t exactly been &#39;models&#39; of good stewardship when it comes to our environment... :(