Report - Major Shifts In Temperature, Salinity In Southern Ocean - AFP

[hatrack]

Scientists have discovered dramatic changes in the temperature and salinity of deep waters in the Southern Ocean that they warned Thursday could have a major impact on global climate. Expedition leader Steve Rintoul of Australia said his multinational team of researchers had found that waters at the bottom of the Southern Ocean were significantly cooler and less salty than they were 10 years ago.

He said the size and speed of the changes surprised scientists, who have long believed deep ocean waters underwent little temperature change, and could indicate a slowdown in the flow of deep water currents.

"Ocean circulation is a big influence on global climate, so it is critical that we understand why this is happening and why it is happening so quickly," Rintoul said after he and his team docked at Hobart on the Australian island state of Tasmania.

"The surprise was just how rapidly the deepest parts of the ocean are changing, at depths of four or five kilometers (13,200-16,500 feet) below the sea surface," Rintoul said. "Whether its a natural cycle that takes place over many decades, or it's climate change, it's an indication that the deep ocean can respond much more rapidly to changes that are happening near the surface than we believed possible," he said.

EDIT

http://www.terradaily.com/2005/050217070124.jyd3ded9.html

[NMDemDist2]

1. gee could it be because large chunks of Antarctica are melting

and it makes it colder?

[XemaSab]

2. Does anyone know

if sea ice readily melts when totally submerged? I just had a picture of Antarctic ice sheets not sloughing off the side, which is visible and obvious, but rotting from below....

[hatrack]

3. Apparently that's a big part of it

I don't know about total submersion (can you submerge ice, which is less dense than seawater?) but sea ice melt is a process which takes place from above and below.

There's an article or two on this I posted a while back - let me see if I can dig them up.

[XemaSab]

4. Sea ice submerges quite well

As the captain for the Titanic learned. It's only a small percent of the ice that's above the water line.

[jpak]

5. In polar oceans, cold water overlays warmer deep water.

Large bergs generally melt at their base and either turn-turtle or break apart (which are pretty spectacular events).

Annual sea ice generally melts laterally and from the surface in the summer months.

[XemaSab]

6. Thanks

I was thinking that wave action might play a role.

[jpak]

7. Wave action does play a role

Smaller bergs often end up mushroom-shaped and wave action forms cave-like structures in the larger older bergs. The larger bergs (in open water anyway) usually have a trail of bergy bits where waves have nipped off small parts of the parent berg.

I was in the the Ross Sea last month (research cruise). The ship sailed up to the gap between Iceberg B-15 and the the Drygalski Ice Tongue on the day they were suppose to collide (they were 3.89 nm apart according to the ship's radar).

The older terminus of the Drygalski was pocked with caves and was severely eroded by wave action whereas the younger B-15 was relatively smooth (at least at its business end).

I have pictures but they aren't that spectacular (digital telephoto shots ain't that great).

[XemaSab]

8. So how do you

scam a spot on a research cruise to the Ross Sea?

I'm a soil scientist/biologist. :-)

[jpak]

9. Being a Co-PI on the grant always helps

:)

Actually, it's easier for non-scientists to get to Antarctica than "beakers".

NSF sponsors school teachers to spend time at research stations and on research vessels. We've had a couple participate on on past cruises.

Raytheon has the current contract to support the US Antarctic Program - and there's lots of jobs for blue collar types down there. If you're a REAL glutton for punishment you can always sign on as a general assistant at Palmer, Pole or McMurdo (that's the only way I would ever get to the South Pole - not much oceanography going on there). It would at least get you on the Ice...

Or - you could always Roll Them Bones and submit a proposal to NSF. Soils studies in the Dry Valleys might be worth a shot...

cheers

[XemaSab]

10. Thanks

Antarctica actually has interesting soils, from what I've heard. Many of the soils there are ornithogenic (caused by penguins!).