Remember those puddles at the North Pole that at first everyone said were not important, then when someone realized that they were only puddles so a new meme formed and everyone said they are not important? They’re important. From the abstract of a new study, just out:
The surface albedo of the Arctic sea-ice zone is a crucial component in the energy budget of the Arctic region. The treatment of sea-ice albedo has been identified as an important source of variability in the future sea-ice mass loss forecasts in coupled climate models. … Here we present an analysis of observed changes in the mean albedo of the Arctic sea-ice zone using a data set consisting of 28 years of homogenized satellite data. Along with the albedo reduction resulting from the well-known loss of late-summer sea-ice cover, we show that the mean albedo of the remaining Arctic sea-ice zone is decreasing.
New Scientist reports that the darkening is a result of the ice getting thinner and “… the formation of open water fissures, and partly because in the warmer air, ponds of liquid water form on the surface of the ice. The shallow ponds on the ice can dramatically reduce reflectivity and increase the amount of solar radiation that the ice absorbs.”
So now let’s get a new meme going. Maybe something with a polar bear and a puddle and …. a shark, because this is shark month after all!
Since 2001 the amount of Arctic Sea ice that has melted during the summer has generally increased. There may have been a long term trend in melting of ice in the northern hemisphere generally, including mountain glaciers, the Greenland glaciers, and seasonally, Arctic Sea Ice. But the seasonal melting of Arctic Sea ice seems to represent a metastable shift unprecedented in available data. There is probably a tipping point followed by positive feedback. From 2001 onwards, the amount of sea ice melted each summer has gone up, and this has resulted in two related effects: 1) The total amount of sunlight sent back into outer space by reflection from ice and snow has gone down and 2) the amount of warming of the Arctic Sea itself by that non-reflected sunlight has gone up. The result is a graph like this one (hat tip Arctic Sea Ice Blog):
Another view shows the numbers somewhat differently. The grey areas show the confidence limits for the 1979-2012 means, so it includes the reduced years, in volume, with the last four years plotted and the present year shown not as an estimate but as the actual measurement. This shows that we are on track to have a lot of melting:
These data include both good news and bad news, depending on how you want to spin it. The good news is that the seasonal reduction in sea ice volume is not lower then, or not a lot lower than, last years, so maybe we are seeing a leveling off in this phenomenon. The bad news comes in two parts. First, the volume of sea ice includes old ice, which tends to be thicker, and much of that has already melted away, so it can’t melt again because it is already gone. Second, being at the extreme low end of a disturbing trend does not mean that the trend is not disturbing. (See more discussion here.)
Let’s look at extent. This graph from the National Snow and Ice Data Center shows extent (not volume):
This shows that the current year is on track to look like last year. Notice the big dip last year’s ice took in just a few days from now. It will be interesting to see what the current year’s ice extend does over this same time frame. One of the differences between last year and this year is winds. There was a lot of wind facilitating the breakup of ice last year, but this years the winds are described as “slack.” Related to this, last year June had warmer temperatures over the ice. The last month this year has been relatively cold.
Time to start watching the Arctic Sea Ice breakup. This happens every year, but as you know, the total amount of ice left each summer has been reducing, and the “old ice” which forms a basis for the arctic ice refreeze is disappearing. The result of this change in arctic ice patterns has been a shift from one form of “arctic oscillation” to another which has resulted in changes in Norther Hemisphere weather.
The National Snow and Ice Data Center keeps track of the Arctic ice and regularly updates a graphic that shows us how it is tracking. This year’s Arctic sea ice has recently peaked. This year’s track has been following close to or below last year’s track, and both years are art or below 2 standard deviations below the 1979-2000 average. Here’s the graph:
It is important to get this right. There is something interesting happening in the Arctic right now, and some people are pointing to it and jumping up and down and yelling about how it is a major climate change event. But it may very well not be. Or it could be. The thing that is happening is something that normally happens, but there are features of the event that are odd. We won’t know its significance until the Northern Summer, and even then we won’t be sure if this is just an unusual thing for this year or a new trend because, by definition, trends run over periods of time.
Every year as you know a certain amount of Arctic Sea ice melts away, and part of that melting process involves the ice breaking into separate chunks and floating around in a big gyre. If you live on or visit a lake in the frozen regions of North America, during the spring, you’ve probably observed the phenomenon. Well, this happens Big Time in the Arctic.
Ice is still forming in some regions of the Arctic, and may continue to form and thicken for some time to come, though the average effect at the moment is melting (see below). But for some reason a large region of ice has started to break up and float around loose, earlier than expected.
One possible outcome of this would be the more rapid melting of ice in that region once extensive melting starts, because broken up ice melts faster than continuous solid ice. Another possible outcome is that it all refreezes in place and has very little effect on what happens in the coming Northern Summer.
It is normal for the ice to crack and for leads to occur. However, this is very extensive cracking and there are some very big leads, and all of it seems to come earlier than expected. Given last year’s melting mayhem and the low amount of multi-year ice, it makes one wonder whether this early cracking will have any effect in the melting season to come…. Maybe this will have zero influence. We don’t know. That’s why we watch.
So, how is the march of melt going in the Arctic, independently of this breaking up event? Here is a graph from the National Snow and Ice Data Center, which is quickly becoming a very important source of critical information, showing the current state of Arctic Ice in relation to expectations:
Robert Scribbler, in a recent blog post, is predicting rapid and extensive melting. He cites as important factors “…cracking, rapid ice movement, thin ice, warmer than average air temps, and negative Arctic Oscillation…” and describes each of these factors.
Sitting here in late March in a Minnesota covered with a thick blanket of snow and above-freezing daily temperatures happing over the coming week for the first time in months (still no overnight thaws) it is hard to imagine the Arctic as being warm, but if you think about it a bit it makes sense. The Arctic, the Subarctic and the northern Temperate region are simply sharing their air masses in a different way than they usually do. It is a bit like someone drilled a big hole in the bottom of the freezer, connecting it to the refrigerator below. Down here in the fridge (Minnesota) the milk is freezing, but up there in the freezer, the ice is wet and sloppy.
I wonder how long it will be before cruise ships start to regularly ply the Arctic Sea for recreational purposes?