NSIDC Arctic sea ice news June 2012

The NSIDC has released its latest analysis for the month of June.
Here are what I find the most interesting excerpts:

The last three Junes (2010-2012) are the three lowest in the satellite record. June 2012 ice extent was 140,000 square kilometers (54,000 square miles) above the 2010 record low.

(...)

The ice extent recorded for 30 June 2012 of 9.59 million square kilometers (3.70 million square miles) would not normally be expected until July 21, based on 1979-2000 averages. This puts extent decline three weeks ahead of schedule.

 

(...)

In June, the Arctic lost a total of 2.86 million square kilometers (1.10 million square miles) of ice. This is the largest June ice loss in the satellite record. Similar to May, the month was characterized by a period of especially rapid ice loss (discussed in the mid-month entry, June 19th) followed by a period of slower loss.

(...)

Prior to the onset of melt, the ice was thicker than observed in recent years – around 1.8 meters (5.9 feet) as compared to typical conditions of around 1.4 meters (4.6 feet) [At Barrow, N.]. Despite this thick ice at the beginning of the season, melt proceeded relatively rapidly. Melt ponds began forming on June 4—a typical timing for recent years, but high temperatures, sunny afternoons, and foggy nights combined to speed the melt of ice thereafter.
Low June snow extent
Snow cover over Northern Hemisphere lands retreated rapidly in May and June, leaving the Arctic Ocean coastline nearly snow free. June 2012 set a record low for snow extent (for a 45-year period of record spanning 1967-2012) by a significant margin. Snow extent for June 2012 was more than 1 million square kilometers (386,000 square miles) below the previous record set in 2010. Snow extent for 2011 was a close third lowest. May 2012 had third lowest snow extent for the period of record. This rapid and early retreat of snow cover exposes large, darker underlying surfaces to the sun early in the season, fostering higher air temperatures and warmer soils.

Interesting bits about the ice off Barrow (which has broken op on June 29th, by the way, the earliest since 2004, when the ice wasn't well-grounded) and the NH snow cover anomaly. Read the whole analysis here. Diablobanquisa has some more info (in Spanish).

Comments

[Rob Dekker]

Neven, you beat me to it !
So my two comments on the NSIDC June report :
http://neven1.typepad.com/blog/2012/07/asi-2012-update-6-piggy-bank.html?cid=6a0133f03a1e37970b016768331e04970b#comment-6a0133f03a1e37970b016768331e04970b

should be posted here.

Allow me to repeat the part I posted about the albedo change due to the snow anomaly, since I really think it explains a lot about summer melt and why even a harsh winter does not seem to affect the melting rate much at all :
--

The June record anomaly clocks 6 million km^2 less snow-covered land than the long-term average.

These last graphs made me wonder how much more heat was accumulated over June just because of that snow anomaly. Here goes :

From our discussion a few weeks ago, we know that around the Arctic perimiter, insolation during June is on average something like 280 W/m^2 (remember the 'close to Sahara' discussion).

If you count that albedo changes from something like 0.8 to 0.1 when snow melts, that means that on average, the now snow-free land absorbed 200 W/m^2 heat MORE than what it would do on average.

Over 6 million km^2, that means the Arctic absorbed a whopping 1180 TW (yes, that is Tera Watt) extra solar power.
Know that global energy use (all fossil fuels and the rest) combined is some 17 TW.
And to keep the Barents sea open ocean during winter requires 70 TW (see Neven's reference blog on ocean heat flux).
Ouch.

1180 TW over the entire month of June is 3 * 10^21 Joule. This is enough heat to melt some 9300 Gton ice (1/3 of total winter Arctic sea ice volume), and the equivalent of 6 M km^2 of FYI (1.5meter).

Since the wind blows both on and off the ice, roughly half that increased heat may go to melting the ice (and the other half warms (cools less) the NH), then just this June snow anomaly would explain a drop of some 3 million km^2 ice area w.r.t. the long-term average. Which kind of sounds about what we are observing.

I realized that half the heat to snow melt is probably an overestimate (not all of the snow anomaly is in the Arctic, and increased heat also makes radiation to space go up), but it should be in the ball-park.

[Artful Dodger]

Total Solar Irradiance (TSI) for June 2012 was about 0.8 w/m^2 greater than in June 2007, as the Sun continues to gain intensity in it's 12 year cycle.

http://lasp.colorado.edu/sorce/total_solar_irradiance_plots/sorce_tsi_plot.html

Photons starting to come home to roost... if the coming el Nino coincides with the coming Solar Maximum, then well howdy!

[L. Hamilton]

While June NSIDC extent was the 3rd-lowest in their record, NSIDC area was the lowest by far -- 8.02, which is 300k below runner-up 2010 at 8.33.

[Kevin McKinney]

Clearly a remarkable season is underway. But is this the 'new 2007'--or the 'new 2006', which set the table for the record? (Or maybe a new 2010, if we get a late-season fizzle?) I for one am staying tuned...

[Aaron Lewis]

Rob
Add in the fact that without snow condensing water vapor out of the atmosphere, there is more water vapor in the NH atmosphere to act as a green house gas. More water vapor in the air keeps the nights warm and gives the warmth a chance to penetrate down to the permafrost earlier in the season. This means the permafrost will not be as much help cooling the ground next fall, and air will have to get colder before the snow sticks next fall. Freeze up will be late.

I say it again, "This year Arctic sea ice melt records will be obliterated!"

[Artful Dodger]

Kevin, in the immortal words of Dennis Hopper (circa 1989) "the 90's is gonna make the 60's look like the 50's"...
Flashback!

[Artful Dodger]

Joe Romm writes "It’s looking increasingly likely we’ll see an El Niño starting this summer. If so, next year will almost certainly be the hottest year on record."

http://thinkprogress.org/climate/2012/07/05/511372/noaa-chances-increase-for-el-nino-may-be-good-for-us-in-short-term-but-would-lead-to-rapid-warming/

[Rob Dekker]

Thanks Aaron,
Yes, increased water vapor will serve as a blanket to prevent that IR radiation to space would significantly increase in a a warming Arctic. I think there was a paper published about that, not to long ago.

With or without that water-vapor blanket, the NCEP/NCAR IR radiation numbers for June show there is only a 10-15 W/m^2 anomaly for OLR (space-bound IR radiation) from the Arctic perimeter here suggest that OLR does not do to reduce the 280 W/m^2 increase in insolation that the snow anomaly causes.

Also, I am actually kind of shocked by the numbers I found. 1180 TW is an awefull lot of solar power, and the ice-reduction that this may cause (2-3 million km^2 lower than the long-term average) seems to be remarkably close to the actually observed reduction in sea ice area, and alarmingly significant.

For example, 1180 TW spread out over the entire planet is something like 2.3 W/m^2. That is more effect than the entire GHG effect itself is causing. Of course, this is only the snow albedo effect in June, and other months will be much less, but still....

Also, with respect to 2011, 1 million km^2 snow is lost in June, which, following the same calculations, would eventually (September) lead to an ice loss of some 500 k km^2 sea ice area below beyond 2011. And that was just the influence of June snow anomaly, with May ignored and July still to come, as well as the additional albedo effects that these ice-free areas will endure before the melting season is over.

Can someone please find a mistake in my calculations, to easy my uneasyness ?

If not, then it seems like the little itty bit of extra ice in the Chukchi (ballpark estimate is 20cm thicker ice than normal, based on simple physics) incurred by coldest winter on record in the West Arctic does not even remotely stand a chance during this melting season...

Not to mention the effects on the Arctic sea ice extent/area minimum in September....

[Rob Dekker]

Oops. Can you remove that "<" character in this post, Neven ?

[Done, N.]

[Seke Rob]

Artful, 11 or 12 years, the magnetic activity cycle is around 22 years where about every 11 years the polarity of the sunspots flip [the sign of a new half cycle, now numbered 24]

http://en.wikipedia.org/wiki/Solar_cycle

At the earth's surface, the variance is about 0.21Watts/M^2, just a fraction of what we've added in forcing [say 20%] and the knock on feedback [say 80%]. Does the 0.21W/M^2 matter? It's equated to be good for +/- 0.1C. As expressed before, more worries about ozone layer depletion [polar hole regions particularly] and increased UV penetration [even if that component were 2% of total, it goes deeper].

[Rob Dekker]

Thanks Neven. The link is here

[Jim_pettit]

I've been on the road for ten days, so have been a little late updating things; just wanted you to know that the PIOMAS "death spiral" chart has been updated to include the June data: (Click for full-size):

It's the tightening up of the spiral that's most alarming, I think. Given the way the ice melt is speeding up, I can't imagine how small the orange ellipse denoting the current decade's average will be once the decade is complete. (Or maybe I can, and am afraid to...)

[Account Deleted]

DMI chart shows that 2010 is behind 2012. Now moving 2012 on same level in 2011 and 2007.

[Nightvid Cole]

R. Dekker,

The actual amount of added solar heat input in much less than 1180 TW. The albedo of *very old* snow in the visible is around 0.6 (less still if contaminated with soot), and in the near- and mid- infrared, around 0.1 . Since only around 40% of the solar radiation is in the visible (and over 50% is IR), the actual difference the loss of snow makes is less than 29% of the value you got, i.e. under 340 TW .

Here I assume diffuse radiation, since the Arctic in June tends to be largely cloudy. Corrections could be made to account for other conditions, and also to account for atmospheric absorption and scattering of any reflected radiation, but that's complicated...

[Rob Dekker]

Nightvid,
That (340 TW for 6 million km^2 snow loss in June) does not quite sound right.
Let me go through your argument here.

Albedo effect if snow : You are right that the albedo effect of "very old snow" is around 0.6.
I worked with an albedo of 0.8 which is typical for fresh snow.
Assuming that the snow in the area of the 6 million km^2 anomaly varies between these extremes, I think it is fair to see your estimate as a 'low' bound, and mine as a 'high' bound for the albedo.

Still, that difference does not explain the difference in absorption we obtain (1180 vs 340 TW).
It seems that you brought in the spectral dependency of snow albedo, but I'm fairly sure that this spectral dependency is already included in the albedo numbers. In fact, the paper that I often consult when estimating radiative effects of snow
http://www.atmos.washington.edu/~sgw/PAPERS/1982_RGSP.pdf
rather explicitly states

All-wave albedo has been routinely measured on polar expeditions for many years. Time series of albedo snow high all-wave albedos (75-90%) in late winter and early spring, dropping as snow melt begins to about 60%.

This matches your low bound (0.6) and my high bound (0.8) quite nicely, and thus I don't think you should do a spectral analysis (and cut off near-IR and IR) after you already applied the all-wave albedo factor.
Does this make sense ?

The second issue you brought up is cloud cover.
Here, I would like to note that in the "insolation" number I used (280 W/m^2) cloud cover was already included.
The number suggests insolation "on-the-ground" during the month of June.
I obtained my numbers from here which suggests 280 W/m^2 at the Arctic ocean perimeter. Insolation is only a bit lower (250 W/m^2) in the Boreal forest latitudes) where most of the snow anomaly occurred.

In summary, for the 6 million km^2 snow anomaly in June :
if we take the 'high' numbers for albedo and insolation that I presented, we obtain 280 * (0.8-0.1) * 6 * 10^12 = 1080 TW.
Using the 'low' numbers (old snow at lower latitudes), we obtain 250 * (0.6 - 0.1) * 6 * 10^12 = 750 TW.

Either way, it's an massive amount of extra solar power (much higher than the GHG forcing that presumably caused it) absorbed by the Northern Hemisphere and the Arctic specifically. Quantified like this, snow albedo seems a classic example of 'Arctic amplification', which undoubtedly has affected sea ice melt over the past decade that the anomaly became very significant.

[Kevin McKinney]

FWIW, this amateur's logic says you are right, Rob: from (not first, but much more primary) principles we know that while atmospheric gases respond to radiation in a quantized fashion, absorbing and emitting at relatively specific wavelengths, earth and sea are 'Very Dark Greybodies.' Hence they'll warm when (or if) they absorb 'all waves.'