Monday, July 25, 2011

Current State of the Arctic Sea Ice - A Layman's Perspective **Update**

Updated NEP 7/25, NWP 7/24

Note: RealClimate has a very informative open thread on Arctic Sea Ice that is very much worth your time. There are some excellent comments and great links.  

Northeast Passage
UPDATE: Replaced the image with an annotated version; added link to a depth chart for the East Siberian Sea.

Finally, a nearly clear view of the last ice blocking the NEP. (Click for larger image.)
Based on the depth chart found here, it seems hugging the coastline is not a viable option for any large vessels with greater than between 1 - 3 fathoms' draft. This means we can consider the open water open only to vessels with very shallow drafts. All others must go through the ice, but given the 20 mile resolution of this image, that seems realistic, particularly with icebreakers on standby, as would be the case. I wish I had access to someone who navigates the Arctic to see if my thinking is realistic or B.S.

Northwest Passage
UPDATE 7/24 (Scroll down for earlier NWP post.)
It was looking more and more like the southern route of the NWP would open before the northern route, but today it's looking more like a horse race. If you click on the image for a higher resolution you can see significant cracking and deterioration of the ice is occurring in both the main channel and the southern route. The quality of the ice in the southern route appears to be lower than in the northern route. The East-West portion of the southern route is about 350 miles further south than the northern route, so this is not surprising. Passages through the Northwest Passage long ago sometimes had to use the southern route to complete the trip, in fact. If memory serves, the first documented passage of the NWP was through the southern route.

Here I have marked the advance of the ice breaking up for clarity.

And here I've marked the changes since 7/4.
The Northeast Passage
UPDATE 7/23:
This is the clearest image yet of the remaining ice blocking the Northeast passage. The scale at that resolution would indicate the thin slice of open water between the ice and the shore at the top of the image is at least 1 mile wide, though I have no idea of the depth. There's still some cloudiness, but I don't see any great impediment to shipping here. Our Arctic experts may disagree, of course.

UPDATE 7/22:
This image from CryosphereToday does not show ice concentrations under 15% which gives a more realistic view of how open the water is. Here we can see a very clearly open Northeast Passage. I've added outlines of the shore line and ice edge for clarity.

Here's an image showing the full NEP route.

The NE and NW Passages are important because they reduce shipping lanes compared to the Panama Canal by thousands of miles, reducing costs significantly in terms of fuel and shipping costs. Also, the melting of the Arctic Sea Ice opens the possibility of mining the Arctic ocean for natural resources, primarily fossil fuels. This would be a Very Bad Idea. Imagine the effects of a Deepwater Horizon oil spill on the Arctic ecosystem. imagine the effects on the ice. Some risks are beyond any monetary value they might bring


On July 5th, in a post titled "Current State of the Arctic Sea Ice - A Layman's Perspective", I stated there was a 50/50 chance the Northwest Passage and Northeast Passage would be open within two weeks. Two weeks later, July 19th, the NEP was not open (though it was cloudy and difficult to tell), but the remaining ice was finally breaking up; there was no solid pack ice blocking the NEP that i could see. As of today, July 21st, I consider the Northeast Passage open.

What does "open" mean? First, I write as a layman who has followed the state of the Arctic Sea Ice closely since 2006. Secondly, I write for other laypeople. I don't use a lot of figures, math or calculations, I just present a simple analysis based on systemic analysis. If you can handle the science behind the data, this post isn't aimed at you. I'd like to think my analysis has some unique characteristics and might be useful to very knowledgeable people, but I'm not kidding myself on that score.

Open, in my parlance, means, minimally, you can get through without an icebreaker, either by being careful or because you have a ship designed for Arctic/Antarctic waters. It doesn't necessarily mean Princess Cruises is taking reservations for a passage - though that will be likely possible soon enough.

The Northeast Passage appears to be navigable as of July 21, 2011. This is the earliest opening of the NEP I am aware of, and appears to be the earliest by several weeks.
I have marked the coastline in the image so you can see the open water between the ice and the coast more easily. The last contiguous ice was in the area of the bend, but has broken up. It probably broke up several days ago, but cloudiness made it difficult to make the call. Remember the caveat: The NEP may be open now, but winds and/or currents can close it up again. That said, this is a bit of a Big Deal.

Climate science is primarily about long-term trends. Scientists are reluctant, with good reason, to extrapolate short-term changes to long-term trends. Thankfully, I am not a scientist. This is important because it is a very large downward signal of the long-term trend, in my opinion. Non-linear and/or chaotic systems tend to jump to new states suddenly, sometimes disastrously. For the NEP to open weeks earlier than before, and keep in mind it's only been opening at all on a regular basis over the last handful of years (the NWP and NEP have been navigated in the distant past, but it took, for example, two years to do it as ships waited for leads in the ice to open), and now we see a jump of three weeks?

This indicates to me that all the indicators, and others, discussed previously are definitely helping to increase the rate of ice loss in the Arctic Basin.

There seem to have been three primary effects on the melt process. The Arctic Oscillation peaked in it's negative phase (warmer Arctic) around the 8th of July and started reversing. It has been in a mild positive phase (cooler arctic) for the last week. This may have played a role slowing ice loss in the NWP. At the same time, there appear to have been a number of storms over the area of the NEP which might have accelerated break up of the ice in that area.  The basic geography of both obviously plays a part. The NWP is a closed channel with the remaining pack ice in an area between a near-90 degree bend at the western end and a set of islands and a narrowing passage at the eastern end. The NEP is relatively open water and is in the area of the ocean closer to current flowing through from the Pacific. There are large areas of open ocean along the coast on either side of the area we've been waiting to melt out; surely some of this extra energy is affecting the area we have been observing.

Whether some or all of these are actively affecting ice loss is supposition, of course, but each probably plays some part.

The Northwest Passage
The NWP finally started to break up a few days ago. It appeared winds  had been pushing ice back into the western end of the channel, packing it together. Faint cracks developed slowly, primarily on the northern or left side of the western end and remained static for over a week. Larger cracks began propagating and now have grown pronounced and cover the entire western half of the remaining ice, as clearly seen in this image from the 20th.

The eastern end of this main channel has been very static, but there is melt along the northern edge.
For perspective, here is the full channel on the 19th:

When I made the original post on the 5th, the southern route seemed static and inactive compared to the main channel. However, since then, there's been a lot of ice broken up and it's beginning to look like the southern route will open first.

With the Arctic Oscillation positive, the circumpolar winds help to keep the ocean somewhat isolated. I have no strong prediction at the moment except that we should expect the process to continue in non-linear fashion with alternating periods of abrupt changes and stable conditions. Judging by conditions during the negative AO, a return to a strongly negative AO might signal speedier disintegration.

Ice-Free Arctic Ocean
Will the Arctic be ice-free this summer? That seems doubtful. However, ice extent is at record lows for this time of year.
A simple continuation of this trend will result in a new record low ice extent. (Ice extent is the area that the ice is spread out over.) A new low ice area should also happen if extent is a record low. (ice area is the actual surface area of the ice itself, not how much of the ocean it covers.) If either of those happen, a new low ice volume (the actual total of ice, as if you were picking it up and measuring it) is virtually certain. We already assume the ice is very thin because of late onset freeze last fall, early onset melt this spring and general conditions since 2007. In fact, even if the lows are not new records for extent or area, but are close to the 2007 minimum, I'd still expect a new record low volume. Remember, the reports that the first year ice this season was measured to be 40 centimeters thinner than last year. For two meter thick ice, that's about 20% thinner.

Here is what I posted to RealClimate regarding sea ice predictions this season:

At this time, I think the weather is too great a variable to be certain we will see a new minimum extent or area, but offer these scenarios. Given the current state of the ice, let me state the obvious:

A. If weather is strongly supportive of ice loss, a 100% chance of new minimum in volume, and 95% chance of new minimum area and 90% chance of new minimum extent.

B. If weather is relatively neutral in impact, drop each by ten percent.

C. If weather is supportive of ice retention, perhaps a 60% chance of new minimum in volume, and 50% chance of new minimum area and 40% chance of new minimum extent.

D. If weather is strongly supportive of ice retention, perhaps a 45% chance of new minimum in volume, and 35% chance of new minimum area and 25% chance of new minimum extent.

I think the ice, overall, is less healthy than most think it is. I think our instruments are not recognizing differences at a high enough resolution causing us to still overestimate the health of the ice. In other words, as stated earlier, there may be lots of thin ice gluing together older ice. Cottage cheese.
I will do another update around the end of this month to check my prediction for both the NWP and NEP likely being open by then.


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