A new record low 2008 sea ice extent??
Much noise has been made over the internets about “sea ice recovery” this year, along with a list of other noisy distractions, like “Global Warming stopped in January 2008″ (after it stopped in 1998). But does that mean it has recovered? Most definitely not. The ice covering the Arctic Ocean is much younger and thinner than normal, and 2008 might in fact be a new record low. The previous record low was 2007 which beat out 2005 (lucky #2) by the size of California and Texas combined.
The colors are ice age, with green and purple being older ice, 5 and 6 years old. The older ice is rapidly being lost.
Meanwhile, Colorado researchers say there is a 3 in 5 chance that 2008 will have a new record low. Mr. Atmoz also has a post on this.
It is my non-quantified opinion that we’ve hit one of the first “tipping points” as far as global warming is concerned, or at least we will over the next few years– a commitment to seasonal loss of arctic sea ice regardless of what we do to CO2 emissions. We’ll be able to see by autumn if summer ice hit a new low, so stay tuned.
Felipe Vernaza said,
May 1, 2008 @ 9:26 pm
The high rate of melting in the Arctic Ocean ice cover can be explained through radiative feedback processes in the climatic system. These will probably be responsible for the complete disappearance of sea ice during the summer, in unfortunately not too long.
As shown above, greater regions of younger and thinner ice are being recorded in the Arctic Ocean. This obviously implies that during the summer, there was a greater area of sea water being exposed to the atmosphere, and hence to the surrounding climate. The energy that went once into melting the ice will now go on actually warming the water temperature, which in turn will accelerate the decline of sea ice. It is important to note that ice is more reflective than water, and hence the albedo will be reduced, further increasing the Arctic Ocean’s temperatures.
Another important feedback is related with the evaporation that occurs in that greater portion of water being exposed to the atmosphere, in conjunction with warming temperatures. There will be more evaporation (because there is more water being exposed to the atmosphere, and a warmer atmosphere can hold more water), and consequently there will be a stronger greenhouse effect from water vapour, which will lead to further warming. This warming will further accelerate the retreat of sea ice, which again will increase the warming and so on.
The above is the reason of most (if not all) AOGCM’s (Atmosphere-Ocean General Circulation Models) showing greater warming at high latitudes for a 2x CO2 doubling equilibrium response.
Alexander Ač said,
May 10, 2008 @ 7:12 am
well, are you going to offer a bet to William Connolley?
He thinks the chance of breaking the new record this year is lower than 50 % …
Bob Tisdale said,
May 31, 2008 @ 7:26 pm
But is the recent bout of elevated Arctic temperatures a result of AGW or an aftereffect of the 97/98 El Nino?
http://tinypic.com/fullsize.php?pic=zswazc&s=3&capwidth=false
Response- I doubt the ‘98 El Nino has much to do with the record declines in 2005 and 2007, but AGW is not the only thing going on either.
No one has succeeded in explaining the observed warming and sea-ice loss in the Arctic solely using natural variability; the changes are large and fast, and largely consistent with warming. Natural variability is large in the Arctic, however (e.g. the Arctic Oscillation is important for sea ice extent). The linked paper below suggests that the 2007 minimum was largely due to the preconditioning of low ice because of a long time spent in a warming climate, anomalous winds, and ice-albedo effects.
http://psc.apl.washington.edu/zhang/Pubs/Zhang_etal2008GL034005.pdf Chris
Bob Tisdale said,
June 2, 2008 @ 6:21 am
Chris: Many thanks for the link to the paper, but let’s drop back to the cause of the recent Arctic warming, which is one of the many reasons for the record decline in Arctic sea ice last year. I qualify it as recent so not to confuse it with past periods of elevated Arctic temperatures.
http://i27.tinypic.com/scxf7s.jpg
I do realize I’m taking this out of context, but, while the following RealClimate discussion is primarily about tropical troposheric trends, there are three things that cause enhanced tropical tropospheric warming AND A SIMILAR AMPLIFICATION IN THE ARCTIC: a doubling of CO2, a 2% increase in solar forcing, and El Nino’s. CO2 hasn’t doubled, not even close. TSI has risen since the mid-70s, but Solar Cycle 23 peaked in 2002. What does that leave us? El Ninos.
http://www.realclimate.org/index.php/archives/2007/12/tropical-troposphere-trends
To quote the group RealClimate authors: “If the pictures are very similar despite the different forcings that implies that the pattern really has nothing to do with greenhouse gas changes, but is a more fundamental response to warming (however caused).”
If the polar amplification is a response to the general warming, and if the warming is cyclic, then the difference between Arctic and global temperatures should eventually decline. I’ll put a note in my tickler file to get back to you in 20 years.
Regards
Response– A couple of things. Arctic amplification is already occurring now, and this area has already warmed around 2x the global average (find my post on Global Warming maps/graphs). You don’t need to wait around for a doubling of CO2 or an increase in solar to see the arctic warming considerably, just that the warming will be still more dramatic when/if that happens. Next, temperature is not the only thing that effects ice extent. We can bring wind and precipitation and other factors into the mix, it’s just that temperature seems quite important now.
Ice extent depends a lot on inital conditions (for example on the Greenland ice sheet, if you have the ice almost too warm, and warming causes a bit of thinning that lowers the surface and warms more, there is a threshold beyond which the ice sheet cannot survive, so in general the effect of a 1C warming is expected to be larger if the temperature before the warming is higher, and the same logic applies to sea ice). As another example, slight warming trends precondition the ice to be a little thinner. Then during a high AO period the ice is exported rapidly out of the Arctic. Because of the positive ice-albedo feedback, it may take a long period of negative AO and cold temperatures to regain even average thickness, so when decadal variability is superimposed on a rising trend, particularly in the nonlinear world of sea ice, the sea ice system can be pushed across a threshold and be unable to return to a cyclic state it previously held. This seems to be significant today.
The sea-ice was already in a period of decline after the satellite era and before the ‘98 El Nino. The last several years were very low. Temperatures are continuing to rise as well, and the AO shifted toward a more neutral phase by the late ’90s (which suggests that there is more going on than that). I don’t understand the logic of saying that the ‘98 El Nino is largely responsible for these anomalous years, or the long-term trend. - chris
Bob Tisdale said,
June 4, 2008 @ 5:03 am
Chris: Your post is about sea ice decline. There’s no debate from me about the multiple causes. There’s also no debate from me that it began to decrease much earlier than 1997/98. In fact, here’s a seldom-posted graph to illustrate that the current decline in sea ice began in 1965, almost ten years before the turning point in NH SST. So, agreed, there are many things taking place in the Arctic.
http://i31.tinypic.com/2ue4qzd.jpg
My two prior comments are about Arctic temperature, one of the many causes of the drop in sea ice. Those comments are not about sea ice, just the cause that the press extolls, temperature. The first graph I linked to was of UAH MSU data that illustrated that the excessive polar amplification appears to be an aftereffect of the 97/98 El Nino and not greenhouse gases. My second comment reinforces that, since an El Nino elevates Arctic temperature the same way that a doubling of CO2 does. Nothing more. Nothing less.
To again help illustrate the cyclic nature of Polar Amplification, here’s another graph, this time using GISStemp data. Note again that the changeover point to the current skyrocketing trend occurs around 1998. Also note, the Arctic combined land and sea temperature in the GISS data appears to change trend around 1965, agreeing with the change in sea ice extent.
http://i27.tinypic.com/29xgbh1.jpg
Imagine that. I’ve reinforced both of our positions.
Regards