U Manitoba Researcher - Summer Arctic Sea Ice May Be Gone As Early As 2030 - AFP

[hatrack]

Oh, and the Arctic Ocean's acidifying, too. Have a nice day.

The Arctic Ocean's pack ice is expected to disappear entirely in the coming decades and will bring unforeseeable changes to the region, international experts meeting this week in Norway said. For many participants at the Arctic Frontiers conference held in the northern Norwegian town of Tromsoe, 2,000 kilometres (1,200 miles) south of the North Pole, the pace of global warming is staggering.

"Climate change in the Arctic is not coming. It is here," said Canadian researcher at the University of Manitoba, David Barber. Barber predicts that between 2030 and 2050, the Arctic's sea ice will have disappeared completely during the summer months. "Last time something like that happened was a million years ago. It is a tremendous change," Barber added.

Climate models presented by speakers at the conference all tell the same story. Melting ice sheets -- equivalent to some 70,000 square kilometres (27,000 square miles) a year -- as well as sharp rises in temperatures since the end of the 1990s and the failure of sea ice to recover ground lost during the summer months all characterise changes in the region.

"It is very likely that the ecology of the Arctic will change dramatically over the next decades. These changes will occur and are occurring to an ecosystem that we know very little about," said Richard Bellerby, a researcher at Norway's University of Bergen. Bellerby studies the increasing acidity of the Arctic Ocean, a relatively new area of research. The waters of the ocean have become more acidic in line with increasing emissions of greenhouse gases. A development that could, according to Bellerby, lead to the extinction of certain marine organisms, especially plankton, altering the ocean's entire ecosystem.

EDIT

http://www.terradaily.com/2006/070125025600.zgu360p1.html

[ruiner4u]

1. Hey, does anyone have a link to the maps,,,

of what areas will flood when the ice packs melt? like the computer animations from inconvenient truth

[dtotire]

2. Arctic Ice

There will be no rise in sea level when the sea ice melts, since it is floating ice. What it will do is accelerate the melting of the Greenland ice pack. This would cause the seas to rise.

[phantom power]

3. I can't wait to find out what changing the arctic's albedo from .9 to .1 will do...

to our climate. So exciting.

I bet it happens in 2020.

[hatrack]

4. It will probably look something like this (from AGU)

Citation: Winton, M. (2006), Does the Arctic sea ice have a tipping point?, Geophys. Res. Lett., 33, L23504, doi:10.1029/2006GL028017.



Figure 1. Polar region albedo as a function of (top) time and (bottom) annual mean polar region surface temperature for the MPI ECHAM5 (circles) and NCAR CCSM3.0 (plusses) models. All data have been 5-year boxcar filtered. Enhanced EPS <1.9 MB>




Figure 2. (top) Polar surface albedo feedback in three temperature eras. (bottom) Monthly contribution to polar surface albedo feedback for surface temperatures from −5 to 0C (solid), from −10 to −5C (dashed) and from −15 to −10C (dash-dotted) for the NCAR CCSM3.0 (black) and MPI ECHAM5 (gray) models. All data have been 5-year boxcar filtered. Enhanced EPS <578 KB>



Figure 3. Polar atmosphere heat balance changes over three temperature eras: (top left) top-of-atmosphere absorbed shortwave, (top right) outgoing longwave radiation, (bottom left) atmospheric heating from sides, and (bottom right) heating from the surface. Enhanced EPS <379 KB>



Figure 4. (top) Polar vs. Arctic temperature and (bottom) Arctic vs. global temperature for MPI ECHAM5 (circles) and NCAR CCSM3.0 (plusses). All data have been 5-year boxcar filtered. Enhanced EPS <755 KB>

[phantom power]

5. A couple questions....

what is year zero in those plots?

when they say "positive feedback" are they referring to decreasing albedo increasing the rate of ice melting, or is it some other thing they are referring to?

[hatrack]

6. I believe it's today, since the modeling assumption is 1%/yr CO2 increase

. . . which is slightly above where it is now.

They're referring (as I understand the paper) to two kinds of related albedo feedbacks. One is the albedo change itself, and the other is SICI - small ice-cap instability. There's a certain area threshold below which ice caps can no longer exist in a warming environment, and once this threshold is breached, they can quickly disappear, because of heat diffusion rates and radiative damping.

Here's an applicable paragraph from the article:

<2> If a glass is slowly tipped with a finger, it eventually reaches a point where its upright equilibrium becomes unstable and it proceeds rapidly to a new stable equilibrium on its side. Although climate models show that global temperature change is mainly linear in climate forcings over a broad range , nonlinear or abrupt change may be more prevalent at regional scales. The nonlinear relationship between ice albedo and temperature has been shown to be a potential source for abrupt climate change in ice-covered regions. Simple diffusive energy balance models, that represent this relationship with a step function, produce an abrupt disappearance of polar ice as the global climate gradually warms . Cooling from this ice-free state must proceed well beyond the point where the small ice cap was removed before polar ice abruptly reestablishes. The phenomenon is known as the small ice cap instability (SICI) as it disallows polar ice caps smaller than a certain critical size determined by heat diffusion and radiative damping parameters. Roughly, this scale is the scale below which the ice cap is incapable of determining its own climate which then becomes dominated, instead, by heat transport from surrounding regions . For typical parameters this critical scale corresponds to about 18° of latitude from the pole – a region somewhere between today's minimum and maximum Arctic sea ice in area. Although a number of aspects of these simple models are subject to criticism, a similar kind of instability was found in an atmospheric GCM by Crowley et al. <1994> in a study of Carboniferous period glaciation.

[phantom power]

7. Well. then we are already "at" the SCSI critical point, on average.

I'm going to hurl.
:puke:

[hatrack]

8. I'm still kind of mentally gearing up to track next summer's ice area

If this year was any indication, it's going to be a barn-burner.