Antarctic Sea Ice Extent

[bluewave]

This looks like a version of the north-south climate-seesaw.

 

 

http://www.nature.com/nature/journal/v457/n7233/edsumm/e090226-02.html

 

The north–south climate seesaw

Theoretical models and observational data have long suggested that the Northern and Southern Hemisphere climates behave in a seesaw-like fashion: when the northern ocean warms, the southern ocean cools and vice versa. So far, however, the data have indicated a much muted response in Antarctic climate compared to the Arctic. An analysis of new records from an ocean core from the South Atlantic — including planktonic foraminifera assemblages, Mg/Ca ratios, temperature and ocean productivity data — shows that the South Atlantic cooled essentially instantaneously with the warming in the North Atlantic during the last deglaciation. This first concrete evidence of an immediate seesaw connection also provides a link between the rapid warming in the North Atlantic and the more gradual Antarctic response, and suggests a mechanism potentially driving rapid Northern Hemisphere deglaciation.

NEWS AND VIEWS:Climate change: Southern see-saw seen

The bipolar see-saw hypothesis provides an explanation for why temperature shifts in the two hemispheres were out of phase at certain times. The hypothesis has now passed a test of one of its predictions.

Jeffrey P. Severinghaus

doi:10.1038/4571093a

Full Text | PDF (1,313K)

ARTICLE:Interhemispheric Atlantic seesaw response during the last deglaciation

Stephen Barker, Paula Diz, Maryline J. Vautravers, Jennifer Pike, Gregor Knorr, Ian R. Hall & Wallace S. Broecker

doi:10.1038/nature07770

Abstract | Full Text | PDF (626K) | Supplementary information

 

http://www.bitsofscience.org/bipolar-seesaw-greenland-antarctica-climate-variability-3124/

 

 

New evidence for bipolar seesaw link between Greenland and Antarctica – and abrupt climate variability

Posted on  September 10, 2011 by Rolf Schuttenhelm

 

 

 

 

[Jonger]

It probably has something to do with wind patterns changing. The Southern Ocean has seem a huge up swing in OHC in the deeper levels.

Looks like OHC has been rising steadily for over a 100 years, without any significant anthropogenic forcing early on. Unless you think the paltry co2 from 1900-1940 was driving the same rate as 400ppm today.

[chubbs]

Looks like OHC has been rising steadily for over a 100 years, without any significant anthropogenic forcing early on. Unless you think the paltry co2 from 1900-1940 was driving the same rate as 400ppm today.

GHG forcing fits that general trend well - slow increase - then more rapid in past 50 years. What natural factor fits that trend?

[CAD_Wedge_NC]

GHG forcing fits that general trend well - slow increase - then more rapid in past 50 years. What natural factor fits that trend?

It was explained well in an earlier post.......bipolar seesaw. It is the most logical explanation yet, as to why this incredible increase in sea ice is occurring in the Antarctic.

[Jonger]

GHG forcing fits that general trend well - slow increase - then more rapid in past 50 years. What natural factor fits that trend?

The OHC increase between 1910 - 1945 was about the same rate globally as 1970 - 2010.

So 10-20 ppm co2 caused the same warming as the earth with an extra 50 - 120 ppm co2.

My theory, co2 is enhancing a natural background warming. The background warming is probably much more than the co2.

[Isotherm]

The bipolar see-saw is something I've suspected for awhile given the apparent symmetry between the Arctic and Antarctic ice progression over the past 20-25 years. I think it's more than a coincidence that lower Antarctic ice corresponds to higher Arctic ice, and vice versa.

 

Note the shift from high Arctic / low southern hemisphere in the 80s - mid 90s, to low Arctic / high southern hemisphere over the past 20 years. If the trend continues, I'd expect the Arctic to continue to experience increasing ice relative to normal as the AMO gradually shifts negative, while the southern hemisphere slowly declines again.

 

 

 

 

 

[chubbs]

The OHC increase between 1910 - 1945 was about the same rate globally as 1970 - 2010.

So 10-20 ppm co2 caused the same warming as the earth with an extra 50 - 120 ppm co2.

My theory, co2 is enhancing a natural background warming. The background warming is probably much more than the co2.

You are invoking some mysterious background factor which doesn't exist. GHG forcing has been increasing for 250 years and can explain all of the long-term warming.  

[Jonger]

You are invoking some mysterious background factor which doesn't exist. GHG forcing has been increasing for 250 years and can explain all of the long-term warming.  

 

250 years? 

 

You got some splainin to do.

[Jonger]

This is probably the earliest notable GHG attributed to man in any significant amounts. Even today it's below a single w/m^2. 

 

^{250 years ago it was insignificant.}

 

[chubbs]

250 years? 

 

You got some splainin to do.

 

No wonder we've been warming since the little ice age ended.

 

[chubbs]

Here is how CO2 contribution compares to other man-made GHG

 

http://www.esrl.noaa.gov/gmd/aggi/aggi.html

 

[Jonger]

No wonder we've been warming since the little ice age ended.

 

GHG Index2.png

 

That means little to me... and does not explain why OHC rose at the same rate from 1910 till 1945, until it stopped for 30 year. 

 

The GHG index was around 0.25 to 0.35 during the 1910 to 1945 global OHC rise, the same duration and strength as the 1970 to 2010 rise, which was during a GHG index of 0.6 to 1.30.

 

We have a natural warming taking place, with co2 enhancing it. It would be a total guess as to how much each is responsible for.

[chubbs]

That means little to me... and does not explain why OHC rose at the same rate from 1910 till 1945, until it stopped for 30 year. 

 

The GHG index was around 0.25 to 0.35 during the 1910 to 1945 global OHC rise, the same duration and strength as the 1970 to 2010 rise, which was during a GHG index of 0.6 to 1.30.

 

We have a natural warming taking place, with co2 enhancing it. It would be a total guess as to how much each is responsible for.

No its not a guess. You can't identify a single natural factor that is causing the long-term warming. The natural factors that cause the OHC to vary over 30 year periods like ENSO, PDO, AMO etc are cyclical and tend to cancel out with time. Sure natural factors contributed to the 1910 - 1945 warming but those factors have all changed many times since then. Only GHG forcing is  significantly different now than in 1910. 

[StudentOfClimatology]

You are invoking some mysterious background factor which doesn't exist. GHG forcing has been increasing for 250 years and can explain all of the long-term warming.

The early 20th century warming was mostly natural, probably a recovery from the little ice age. There wasn't nearly enough radiative forcing (anthropogenic) to account for it.

All that proves is that the climate system is highly sensitive to perturbation, and that the paleoclimate studies suggesting a high climate sensitivity to radiative forcing are probably accurate.

[StudentOfClimatology]

You're talking 0.2-0.5W/m^2 from 1910-1945 in CO^2, assuming our interpolations are accurate. That'd be good for maybe 0.1C anthropogenically?

People look at these things wrong all the time. The the greater the variability in past climate, the higher climate sensitivity to CO^2 must be.

[Jonger]

No its not a guess. You can't identify a single natural factor that is causing the long-term warming. The natural factors that cause the OHC to vary over 30 year periods like ENSO, PDO, AMO etc are cyclical and tend to cancel out with time. Sure natural factors contributed to the 1910 - 1945 warming but those factors have all changed many times since then. Only GHG forcing is  significantly different now than in 1910.

 

So why did the earth go into one big hiatus from 1940's till the late 1970's? There was quite a bit of co2 and methane.

 

Do you really think there was enough forcing in the 1910 till 1945 period, to drive OHC to rise at the same rate as the 1970's till today?

[Isotherm]

The the greater the variability in past climate, the higher climate sensitivity to CO^2 must be.

 

 

Not sure how your first statement logically dovetails into the second. Significant climate variability over previous centuries and millennia was due to other factors such as eccentricity of Earth's orbit, Milankovitch cycles, solar forcing variability, among other mechanisms. Thus I'm not sure how the climate's sensitivity to Co2 has much relevance in reference to the vast majority of Earth's history.

 

Unless of course you're arguing that natural Co2 was a primary driver of temperature spikes / declines long ago, in which case I'd strongly disagree there.

[tacoman25]

Global sea ice anomalies have actually been running above normal for most of the past 18 months.

 

[CAD_Wedge_NC]

No its not a guess. You can't identify a single natural factor that is causing the long-term warming. The natural factors that cause the OHC to vary over 30 year periods like ENSO, PDO, AMO etc are cyclical and tend to cancel out with time. Sure natural factors contributed to the 1910 - 1945 warming but those factors have all changed many times since then. Only GHG forcing is  significantly different now than in 1910. 

 

Sorry to burst your bubble, but it is a guess. No one has accurately identified the power of the natural feed-backs that are present, and until that is known, we can't possibly know how much GHGs play a role in our climate.

[The_Global_Warmer]

If this is epic and unprecedented.  The Southern Ocean sea ice area being 1.5 million km2 above normal with 95%+ of it being a half meter thick on average(adding less than 5% extra volume) over waters that would be around 0C otherwise.

 

What do you call the arctic sea ice being 2-3 million km2 below normal losing 75% of it's volume and water warming anywhere from 1-15C+ above normal?

[chubbs]

So why did the earth go into one big hiatus from 1940's till the late 1970's? There was quite a bit of co2 and methane.

 

Do you really think there was enough forcing in the 1910 till 1945 period, to drive OHC to rise at the same rate as the 1970's till today?

 

You're talking 0.2-0.5W/m^2 from 1910-1945 in CO^2, assuming our interpolations are accurate. That'd be good for maybe 0.1C anthropogenically?

People look at these things wrong all the time. The the greater the variability in past climate, the higher climate sensitivity to CO^2 must be.

 

To clarify, below is a table showing estimated contribution of AGW vs natural factors to temperature change for various periods since 1880. Early on, GHG forcing increased at a slow rate so AGW was very much a background factor and natural variability was the main factor in temperature change. Over long periods of time however, 60+ years, natural factors like ENSO, PDO, sun etc have all tended to cancel out leaving AGW as the main factor driving change. Agree with SOC on small AGW contribution to warming between 1910 and 1945. Main point here AGW has contributed to warming during both warm and cool periods.

 

[Isotherm]

The IPCC admits that the sea ice anomaly increase in the southern Hemisphere is generally contrary to most model projections and expectations for the past 10-15 years.

 

"The observed upward trend in Antarctic sea ice extent is found to be inconsistent with internal variability based on the residuals from a linear trend fitted to the observations, though this approach could underestimate multi-decadal variability. The CMIP5 simulations on average simulate a decrease in Antarctic sea ice extent , though Turner et al. (2013) find that approximately 10% of CMIP5 simulations exhibit an increasing trend in Antarctic sea ice extent larger than observed over the 1979-2005 period. However, Antarctic sea ice extent variability appears on average to be too large in the CMIP5 models."

[stadiumwave]

Sorry to burst your bubble, but it is a guess. No one has accurately identified the power of the natural feed-backs that are present, and until that is known, we can't possibly know how much GHGs play a role in our climate.

BINGO!!!!

[The_Global_Warmer]

If this is epic and unprecedented.  The Southern Ocean sea ice area being 1.5 million km2 above normal with 95%+ of it being a half meter thick on average(adding less than 5% extra volume) over waters that would be around 0C otherwise.

 

What do you call the arctic sea ice being 2-3 million km2 below normal losing 75% of it's volume and water warming anywhere from 1-15C+ above normal?

 

Cheque please.

[AvantHiatus]

Sorry but sea ice expansion in Antarctica makes perfect sense. The damned thing is pretty much isolated from all landmasses and contains trillions of tons of melting land ice. The surrounding oceans are being flooded with frigid melt-water, this stuff kills the ocean salinity like nothing else. It also snows like crazy just outside of Antarctica, another water vapor feedback from AGW.

 

It will take a long long time to respond and melt out completely, initial discharge has started this whole feedback so you cannot sit there and believe that AGW and Antarctica sea ice expansion are un-related. I don't see any signs of significant effects, this is especially apparent in the Southern Hemisphere ocean heat content, which shows a stronger rise than the Northern Hemisphere.

 

The Antarctica phenomenon has no chance of prolonging our binge party. There is no mechanism to transport the Antarctica cooling to the rest of the Earth. Besides that, as explained by TGW, the albedo factor is very minimal as the fringe ice melts out very fast in the Spring while being counter-acted by decreasing albedo in the Arctic

 

If it was actually exchanging heat properly we would of never departed from the Pliocene temperature range. The opening of the drake passage sealed the deal.

 

[StudentOfClimatology]

That Steig et al paper is crap. We've got much better alternatives to the erroneous interpolations in that paper.

For one, warm(er) waters are fed right into the circumpolar current via the Atlantic, Pacific, and Indian Ocean gyres. Diffusion is also a very effective thermal-transport mechanism within a fluid.

Second, there has been no warming observed over the Antarctic region since the start of the satellite era:

The real reason behind the cooling Antarctic is related to the +SAM tendency as a result of O^3 depletion via both anthropogenic CFCs and a weakening magnetic field.

See the trend in the AAO:

The SAM index (SAMI) or AAO index (AAOI) is defined as the difference in the normalized monthly zonal-mean sea level pressure (SLP) between 40¡ãS and 70¡ãS (Nan and Li, 2003). This SAMI is a modification of the AAO index defined by Gong and Wang (1999), which is the difference in the normalized zonal-mean SLP between 40¡ãS and 65¡ãS. The modified SAMI is used here because the negative correlation in the zonal-mean SLP anomalies between 40¡ãS and 70¡ãS is stronger than that between 40¡ãS and 65¡ãS.

[AvantHiatus]

CFCs are downtrending. Whatever the cause of SIE expansion, it seems to be temporary and operating on a cycle alongside AGW. Considering the connections, a rapidly increasing antarctic sea extent is probably a warning signal for abrupt events in the future.

 

[StudentOfClimatology]

Possibly true, yes.

Thing is CFC's are still quite abundant, and there may be a lag effect given the intertia of the system.

[ORH_wxman]

That Steig et al paper is crap. We've got much better alternatives to the erroneous interpolations in that paper.

For one, warm(er) waters are fed right into the circumpolar current via the Atlantic, Pacific, and Indian Ocean gyres. Diffusion is also a very effective thermal-transport mechanism within a fluid.

Second, there has been no warming observed over the Antarctic region since the start of the satellite era:

The real reason behind the cooling Antarctic is related to the +SAM tendency as a result of O^3 depletion via both anthropogenic CFCs and a weakening magnetic field.

See the trend in the AAO:

 

 

 

The paper itself was rebutted less than a year after it was published by O'Donnell et al.

[chubbs]

This recent paper finds rising and freshening seas around Antarctica due to increasing losses from the Antarctic ice sheet. 

 

Rapid sea-level rise along the Antarctic margins in response to increased glacial discharge

·        Craig D. Rye, Alberto C. Naveira Garabato, Paul R. Holland, Michael P. Meredith,

·        A. J. George Nurser, Chris W. Hughes, Andrew C. Coward & David J. Webb

• Nature Geoscience (2014) doi:10.1038/ngeo2230

Published online

31 August 2014

 

The Antarctic shelf seas are a climatically and ecologically important region, and are at present receiving increasing amounts of freshwater from the melting of the Antarctic Ice Sheet and its fringing ice shelves^1, 2, primarily around the Antarctic Peninsula and the Amudsen Sea. In response, the surface ocean salinity in this region has declined in past decades^{3, 4, 5, 6, 7, 8, 9}. Here, we assess the effects of the freshwater input on regional sea level using satellite measurements of sea surface height (for months with no sea-ice cover) and a global ocean circulation model. We find that from 1992 to 2011, sea-level rise along the Antarctic coast is at least 2  ±  0.8 mm yr⁻¹ greater than the regional mean for the Southern Ocean south of 50° S. On the basis of the model simulations, we conclude that this sea-level rise is almost entirely related to steric adjustment, rather than changes in local ocean mass, with a halosteric rise in the upper ocean and thermosteric contributions at depth. We estimate that an excess freshwater input of 430 ± 230 Gt yr⁻¹ is required to explain the observed sea-level rise. We conclude that accelerating discharge from the Antarctic Ice Sheet has had a pronounced and widespread impact on the adjacent subpolar seas over the past two decades.