Antarctic Sea Ice Increasing

[Gravitymaster 0]

Just goes to show the science isn't as simple as some would believe.


http://www.gsfc.nasa.gov/topstory/20020820southseaice.html

SATELLITES SHOW OVERALL INCREASES IN ANTARCTIC SEA ICE COVER



While recent studies have shown that on the whole Arctic sea ice has decreased since the late 1970s, satellite records of sea ice around Antarctica reveal an overall increase in the southern hemisphere ice over the same period. Continued decreases or increases could have substantial impacts on polar climates, because sea ice spreads over a vast area, reflects solar radiation away from the Earth’s surface, and insulates the oceans from the atmosphere.

In a study just published in the Annals of Glaciology, Claire Parkinson of NASA’s Goddard Space Flight Center analyzed the length of the sea ice season throughout the Southern Ocean to obtain trends in sea ice coverage. Parkinson examined 21 years (1979-1999) of Antarctic sea ice satellite records and discovered that, on average, the area where southern sea ice seasons have lengthened by at least one day per year is roughly twice as large as the area where sea ice seasons have shortened by at least one day per year. One day per year equals three weeks over the 21-year period.


“You can see with this dataset that what is happening in the Antarctic is not what would be expected from a straightforward global warming scenario, but a much more complicated set of events,” Parkinson said.

The length of the sea ice season in any particular region or area refers to the number of days per year when at least 15 percent of that area is covered by sea ice. Some areas close to the Antarctic continent have sea ice all year long, but a much larger region of the Southern Ocean has sea ice for a smaller portion of the year, and in those regions the length of the sea ice season can vary significantly from one year to another.

To calculate the lengths of the sea ice seasons, Parkinson used satellite data gridded to 25 by 25 kilometer grid cells for the Southern Ocean region. For each grid cell, the satellite data were used to determine the concentration, or percent area, of the sea ice cover. Whenever the percentage was at least 15 percent, the grid cell was considered to have ice. Using this method, Parkinson went through the entire data set and for each grid cell had a computer count how many days of each year had ice, then calculated trends over the 21-year record.

Overall, the area of the Antarctic with trends indicating a lengthening of the sea ice season by at least one day per year was 5.6 million square kilometers (2.16 million square miles), about 60 percent the size of the United States. At the same time, the area with sea ice seasons shortening by at least one day per year was 3 million square kilometers (1.16 million square miles).

Regionally, the Ross Sea, on average, had its sea ice seasons getting longer, while most of the Amundsen Sea and almost the entire Bellingshausen Sea had their sea ice seasons getting shorter.

“The Antarctic sea ice changes match up well with regional temperature changes,” Parkinson said. “The one region in the Antarctic where the temperature records have shown prominent warming over this period is the Antarctic Peninsula, and indeed it’s immediately to the west and east of the Antarctic Peninsula, in the Bellingshausen/Amundsen and western Weddell seas, respectively, that the sea ice seasons have been shortening rather than lengthening.”

The Arctic also shows a mixed pattern of sea ice trends over the 1979-1999 period, but in contrast to the Antarctic, the area with shortening seasons in the Arctic is far greater than the area with lengthening seasons. The Arctic patterns suggest some connections with major oscillations in large-scale atmospheric pressures, called the Arctic Oscillation and the North Atlantic Oscillation, and it is possible the ice covers of both hemispheres could be influenced by oscillations that are still not fully identified, Parkinson said.

The study used data from NASA’s Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) and the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imagers (SSMIs) and in the future will be extended with data from the National Space Development Agency of Japan's Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) recently launched on board NASA's Aqua satellite.

[billvon 3,116]

Followup to this:

Actually it's decreasing. The study you quoted show that it's covering more _area_, not that the amount of ice is increasing. (As an example, if you shattered an iceberg with explosives, it would spread out over a wider area, but there would be less overall ice.) The area covered by ice is significant because it reflects sunlight and thus _might_ cause a cooling effect, if everything else was equal.

The problem becomes - how to measure the total amount of ice? One way is with a gravity probe. More ice=more mass above sea level. And a study like that has just been performed:

-----------------------------------------------------
The first-ever gravity survey of the entire Antarctic ice sheet, conducted using data from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment (Grace), concludes the ice sheet's mass has decreased significantly from 2002 to 2005. . . .
The researchers found Antarctica's ice sheet decreased by 152 (plus or minus 80) cubic kilometers of ice annually between April 2002 and August 2005.
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(that's a cube of ice about 3.5 miles on a side. Would make for some great BASE jumps.)

http://www.jpl.nasa.gov/news/news.cfm?release=2006-028

[rhys 0]

Quote

Actually it's decreasing. The study you quoted show that it's covering more _area_, not that the amount of ice is increasing. (As an example, if you shattered an iceberg with explosives, it would spread out over a wider area, but there would be less overall ice.)
The problem becomes - how to measure the total amount of ice? One way is with a gravity probe. More ice=more mass above sea level. And a study like that has just been performed:

if the percentage in the first study was changed from 15% to be considered ice cover to say 70% then maybe the information gathered would be more correct. but the stats on the %15 percent study definately show a dissapating ice shelf rather than an increasing one.

"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

[Gravitymaster 0]

Quote

Followup to this:

Actually it's decreasing. The study you quoted show that it's covering more _area_, not that the amount of ice is increasing. (As an example, if you shattered an iceberg with explosives, it would spread out over a wider area, but there would be less overall ice.) The area covered by ice is significant because it reflects sunlight and thus _might_ cause a cooling effect, if everything else was equal.

The problem becomes - how to measure the total amount of ice? One way is with a gravity probe. More ice=more mass above sea level. And a study like that has just been performed:

-----------------------------------------------------
The first-ever gravity survey of the entire Antarctic ice sheet, conducted using data from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment (Grace), concludes the ice sheet's mass has decreased significantly from 2002 to 2005. . . .
The researchers found Antarctica's ice sheet decreased by 152 (plus or minus 80) cubic kilometers of ice annually between April 2002 and August 2005.
--------------------------------------------------

(that's a cube of ice about 3.5 miles on a side. Would make for some great BASE jumps.)

http://www.jpl.nasa.gov/news/news.cfm?release=2006-028

The science is still not exact. Using the figures indicated in the report you cite. At the current sea-level-equivalent ice-loss rate of 0.05 millimeters per year, it would take a full millennium to raise global sea level by just 5 cm, and it would take fully 20,000 years to raise it a single meter. In addition, Zwally et al. report that "the contribution of the ice sheets is also small compared to the most recent estimate of current sea-level rise of 2.8 ± 0.4 mm a-1 from satellite altimetry (Leuliette et al., 2004)," which in their words, "further confounds possible explanations of the causes of contemporary sea-level rise."

In conclusion, the real-world findings of Zwally et al. suggest that the climate-alarmist hype about global warming causing sea levels to rapidly rise to dangerous heights due to the mass wasting of earth's great ice sheets is simply false. This outrageous claim is nothing more than a scare tactic designed to persuade the public to accept the bitter pill they prescribe for the solving of a patently obvious non-problem.

Edited to add: Additional reading here.

http://www.co2science.org/scripts/CO2ScienceB2C/articles/V9/N10/C1.jsp

http://www.sciencemag.org/cgi/content/full/281/5381/1251a

I'm not saying the ice isn't melting, although there is still some credible dispute about that.

[rhys 0]

I was under the impression that more ice = more/higher ocean?

The colums of rock that make up southern thailand were formed during the last 'ice age' when the ocean levels were many metres higher? or so i was told.

"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

[warpedskydiver 0]

George Bush has ordered the ice fields to be diminished by 18% globally...grrrrrrr those damn right wingers!!! and all their damn Margaritas!

actually couldn't an ice density study be dome via IR wavelength scans since the ice is over an ocean of consititent temperatures over a given time period?

also the density of the ice itself is a factor, the more dense ice (blue ice) will occupy less volume than softer ice mass...correct?

[billvon 3,116]

> I was under the impression that more ice = more/higher ocean?

Not usually. Floating icebergs = no change since they displace exactly their weight in liquid water. Glaciers = lower ocean since the water that _could_ be in the ocean is locked up on land.

[billvon 3,116]

>At the current sea-level-equivalent ice-loss rate of 0.05 millimeters
>per year, it would take a full millennium to raise global sea level by just
>5 cm, and it would take fully 20,000 years to raise it a single meter.

The current rate of melting in Antarctica is causing a .4 millimeter rise per year in sea levels. So the contribution from the antarctic ice shelf alone, if it remains constant, will raise sea levels about 1 inch in about 60 years, or 26 feet in that 20,000 years you mention. Of course, you would have to add the melt rate of other ice masses (primarily Greenland) to see what the actual sea level rise due to melting ice is going to be. Since the Greenland ice sheet is shrinking, it will be somewhat faster than that.

The above, of course, also assumes that nothing happens to speed it up or slow it down. Given what we have seen in Siberia and Alaska, and given that open ocean absorbs more heat than ice-covered ocean, odds are it will tend to get faster rather than slower. Also, melting ice is not the only reason the sea is rising. Simple thermal expansion is another big factor. This is going to take a long time since the ocean has such an incredible thermal mass.

Real world measurements indicate that the sea has risen 4 to 10 inches in the past 100 years, which means the antarctic ice sheet melting is a small part of the total increase in sea level.

For a good overview of what this means in terms of property loss in the US, check out http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterPublicationsSeaLevelRiseIndex.html

>In conclusion, the real-world findings of Zwally et al. suggest that
>the climate-alarmist hype . . .

It would be nice to have one discussion here that did not immediately descend into a political slam against someone. I suppose that's unrealistic.

[Gravitymaster 0]

Quote

It would be nice to have one discussion here that did not immediately descend into a political slam against someone. I suppose that's unrealistic.

Sorry heh, heh.

[SpeedRacer 1]

In college I took a course in oceanography that showed that global warming's MAIN effect would be Thermal Expansion of the waters of the ocean, and that glacial melting would be less important in terms of creating WaterWorld.

Speed Racer
--------------------------------------------------

[billvon 3,116]

>actually couldn't an ice density study be dome via IR wavelength
>scans since the ice is over an ocean of consititent temperatures over a
>given time period?

Dense ice is warmer than aerated ice if the surface temp is colder, colder if it is warmer, due to effects of thermal conductivity on the heat of the ice mass. So you'd have to correct for that. You'd also have to correct for IR absorption in the atmosphere; it would be difficult from a satellite to get an accurate far-IR image that would be usable for such a study. (Here's a very basic problem - if there are more greenhouse gases in the atmosphere, they will block IR, the ice will appear cooler, and you'd get exactly the wrong result!)

>also the density of the ice itself is a factor, the more dense ice (blue ice)
>will occupy less volume than softer ice mass...correct?

Right. It's pretty linear with depth in any given place, though, so you can correct for it to some degree. They see that effect in ice cores.

[rhys 0]

Quote

Not usually. Floating icebergs = no change since they displace exactly their weight in liquid water. Glaciers = lower ocean since the water that _could_ be in the ocean is locked up on land.

water expands when cooled/frozen therefore more displacement not only from the ice but all the h20 that is at a cooler temerature.

if a water bottle expands to the point of explosion when frozen imagine a whole ocean?

"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

[billvon 3,116]

>water expands when cooled/frozen therefore more displacement . . .

Nope. As an iceberg freezes, the volume of its water increases but its weight does not. Hence, it displaces, or 'takes up,' the same amount of water. When it melts, the same thing happens in reverse. So _floating_ ice does not change the level of the water it's floating in when it melts.

Ice on land is another story, of course. The land supports its weight, so when it melts, it all drains into the ocean and raises the level of the water.

Hence the rapid loss of Arctic sea ice is an issue because of albedo change and habitat loss, but will not cause a higher sea level - because that ice is all floating. The Greenland ice shelf, though, will cause a significant rise in ocean levels if it melts. Sea levels would rise ~22 feet if that happened. If all the ice in Antarctica melted, we'd see a 200 foot increase in sea level. Fortunately that's not likely.

Below is a link that explains the floating ice thing.

http://science.howstuffworks.com/question473.htm

[kallend 2,148]

Quote

> I was under the impression that more ice = more/higher ocean?

Not usually. Floating icebergs = no change since they displace exactly their weight in liquid water. Glaciers = lower ocean since the water that _could_ be in the ocean is locked up on land.

Don't confuse us with physics, Archimedes! This is a political thread.

...

The only sure way to survive a canopy collision is not to have one.

[kelpdiver 2]

how much water can be captured in clouds? Insigificant to the matter in question?

[billvon 3,116]

>Insigificant to the matter in question?

Insignificant in terms of the amount of water they contain vs sea level. Significant in that the hydrologic cycle is what determines how fast sea level rises and falls, and clouds are a big part of that cycle.

[Jasmin 0]

Some guys I know are working on ice cores from Antartica, that seem to be indicating the thickness of the ice is decreasing...

Now if someone wants a physics debate, bring it on...normally I only get such a pleasure at work!

xj

"I wouldn't recommend picking a fight with the earth...but then I wouldn't recommend picking a fight with a car either, and that's having tried both."

[ChrisD 0]

You want to update this thread?

I'll leave it to you guys to do this...

Something like half a million cubic hectares have dissapeard in the last 7 years...??

My math is a little off,...

It's worse....

C

But what do I know, "I only have one tandem jump."

[lawrocket 3]

Global ice: http://www.climatechangefacts.info/Today-Global-Ice-Area-and-Trends.html

Antarctic Ice:

[url]http://nsidc.org/data/seaice_index/[/url

It shows what's going on. Considering the ice loss in the Arctic and the relatively slight decrease in total ice loss,

Methinks that the data in support of your allegation with Antarctic sea ice decreasing is missing. Antarctic sea ice has increased. A lot. To record levels last year.

I know something.

My wife is hotter than your wife.

[quade 4]

lawrocket

Methinks...

What is it with you and the 16th century?

quade -
The World's Most Boring Skydiver

[Gravitymaster 0]

quade

***Methinks...

What is it with you and the 16th century?

Nave!!!

[kallend 2,148]

Gravitymaster

******Methinks...

What is it with you and the 16th century?

Nave!!!

What has the central aisle of a church or cathedral got to do with it?

...

The only sure way to survive a canopy collision is not to have one.

[oldwomanc6 60]

kallend

*********Methinks...

What is it with you and the 16th century?

Nave!!!

What has the central aisle of a church or cathedral got to do with it?

That's the first thing I thought, too.

lisa
WSCR 594
FB 1023
CBDB 9

[kallend 2,148]

lawrocket

Global ice: http://www.climatechangefacts.info/Today-Global-Ice-Area-and-Trends.html

Antarctic Ice:

http://nsidc.org/data/seaice_index/

It shows what's going on. Considering the ice loss in the Arctic and the relatively slight decrease in total ice loss,

Methinks that the data in support of your allegation with Antarctic sea ice decreasing is missing. Antarctic sea ice has increased. A lot. To record levels last year.

I know something.

Antarctic sea ice is increasing because the run-off from melting continental ice is freshwater, and freshwater will freeze at temperatures at which seawater is still liquid. The NET amount of Antarctic ice is decreasing.

www.mortonsalt.com/content/images/chip-images/phase_diagram.jpg?v=1.1 Phase diagram.

...

The only sure way to survive a canopy collision is not to have one.

[lawrocket 3]

It's a fine theory. Problem is: is there data to back it up?

Second, you've got to explain why it's warm enough to melt the fresh water while at the same time being cold enough to freeze it once it mixes with sea water.

So while your theory has some merit, there's something counterintuitive about being warm enough to melt but cold enough to freeze.

My wife is hotter than your wife.