Researchers Find Significant Increase in Freshwater Content of Arctic Ocean
05 July 2009
A team of US researchers has found a significant increase in the amount of fresh water in the Arctic Ocean as well as a significant change in the distribution of fresh water, as compared with average winter values. Fresh water flowing into or out of the Arctic Ocean plays an important role in ocean circulation and may be a factor in the response of the world ocean to climate change. The study appears in the current issue of the AGU journal Geophysical Research Letters.
To study recent changes in freshwater content of the Arctic, a team from McPhee Research; Woods Hole Oceanographic Institute; the Polar Science Center at the University of Washington, Seattle; and Oregon State University analyzed data from an extensive aerial hydrographic survey carried out in March and April 2008.
In particular, the authors find that freshwater volume in the Canada and Makarov basins on the Pacific side of the Lomonosov Ridge increased by about 8,500 cubic kilometers (about 2,000 cubic miles), while the freshwater volume on the Eurasian area decreased by about 1,100 cubic kilometers (about 260 cubic miles).
The freshening of the Arctic occurred in conjunction with the recent dramatic loss of Arctic sea ice, the authors note. They find that these changes have altered Arctic Ocean circulation, with a large increase in northward transport of fresh water in the Canada Basin.
The dramatic reduction in minimum Arctic sea ice extent in recent years has been accompanied by surprising changes in the thermohaline structure of the Arctic Ocean, with potentially important impact on convection in the North Atlantic and the meridional overturning circulation of the world ocean.
—McPhee et al.
Resources
McPhee, M. G., A. Proshutinsky, J. H. Morison, M. Steele, and M. B. Alkire (2009), Rapid change in freshwater content of the Arctic Ocean, Geophys. Res. Lett., 36, L10602, doi: 10.1029/2009GL037525
Per above article, "Fresh water flowing into or out of the Arctic Ocean plays an important role in ocean circulation and may be a factor in the response of the world ocean to climate change."
It makes sense that if Arctic sea ice is diminishing then there is a good chance of more fresh water circulating in the ocean (assuming the ice doesn't simply evaporate off the surface first).
What I'm unclear about in the above excerpt is exactly what "important role in ocean circulation" does fresh water play, or specifically fresh water melting off from Arctic sea ice?
Thanks!
Rob
Posted by: Rob H. | 05 July 2009 at 08:35 AM
The problem is that they don't have a long track of records on this parameters so it is hard to interpret at this point. Not a good sign but not a proof either of long term trends. I think that the global warming will be more visible in trends like blooming of plants shift in time, migration of birds change, signs like this in the first place
Posted by: Treehugger | 05 July 2009 at 09:36 AM
One problem is there is not as much fresh water flowing because there is not as much ice melting:
http://ocean.dmi.dk/arctic/meant80n.uk.php
And the sea ice extent is second highest since 2002:
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
Posted by: Reel$$ | 06 July 2009 at 12:46 PM
From the IARC website.
http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv
07/05 data 2002-2009 from largest to smallest arctic ice extents.
9757344 2002
9719688 2004
9672656 2003
9236250 2008
9237244 2005
9214375 2009
8774219 2006
8704219 2007
Shows that the arctic ice extent is the 3rd smallest since 2002. Not the second highest.
http://nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png
And is lower than the 20 year average.
Posted by: aym | 06 July 2009 at 06:55 PM
Oops 2005 & 2008 should be transposed. Doesn't change 2009's place though for 07/05 date.
Posted by: aym | 06 July 2009 at 06:57 PM
Wouldn't more freshwater there be a good thing? Freshwater has a higher freezing point than saltwater; some cities still put salt on their snowy/icy roads to liquify the snow/ice and create traction. More freshwater in the artic at relatively higher temperatures = more ice.
Posted by: ejj | 06 July 2009 at 07:14 PM
@Rob H.
Current theory states that disrupting the thermohaline circulator, as it's called, would effectively reroute the gulf stream and, as most of the rest of the planet heats up, northern Europe would face a "mini-ice age". The Woods Hole Oceanographic Institute has conducted much research and published a number of articles on this. See http://www.whoi.edu/page.do?pid=12457&tid=282&cid=7115 for example. Lately, it appears as though the recently slowing circulator has sped up again http://www.whoi.edu/page.do?pid=12455&tid=282&cid=54347
Before the denialists jump on this and tell us the original theory is invalid and the new evidence proves it, I'd like to point out that ANY major changes to such a fundamental part of our climate regulation mechanism ought to scare the living daylights out of any thoughtful person.
Posted by: wesmontage | 07 July 2009 at 07:00 AM
"I'd like to point out that ANY major changes to such a fundamental part of our climate regulation mechanism ought to scare the living daylights out of any thoughtful person."
No. Don't think so. Natural variability demonstrates that climate changes all the time. e.g. there is strong evidence that areas of the Arctic averaged 4-5°C WARMER in mid Holocene. But 6,000 years ago there was no one around to demand we pay money to make it cooler. It happened naturally.
There is a difference between extortion and climate change.
Posted by: Reel$$ | 07 July 2009 at 09:27 AM
From NOAA
"In summary, the mid-Holocene, roughly 6,000 years ago, was generally warmer than today, but only in summer and only in the northern hemisphere. More over, we clearly know the cause of this natural warming, and know without doubt that this proven "astronomical" climate forcing mechanism cannot be responsible for the warming over the last 100 years."
http://www.ncdc.noaa.gov/paleo/globalwarming/holocene.html
Posted by: aym | 07 July 2009 at 11:24 AM