Arctic Sea Ice July 2018

We're now well along in the Arctic sea ice melt season. It's time to review the status and make a too-early forecast. I've been watching it very closely and I don't see anything particularly special about this melt season - beyond the fact that the ice cover continues to disappear. The good news is I don't see any new records being set this year.

First, here's the sea ice extent for 2015 - 2018. The dark grey line is the long-term average. The inner and outer shaded regions show interquartile and interdecile ranges, respectively. The record low year of 2012 (dashed line) is included as a baseline and the low year of 2011 is also shown.

 

 

Source: NSIDC

The maximum extent occurred in March and was the second lowest maximum extent in the satellite record. However, it should be noted the last few years have all been right in the same range. Here's a detail showing the maximum ice extent for 2012 and the data for 2015 - 2018.

Source: NSIDC

An interesting feature is how the extent for each year closes to a narrow range in July of recent years. Here's a detail for that period and you can see that 2018 (the yellow line) is trending in the same range.

Source: NSIDC

The extents separate after August and there is a small range of minimum extents in September. Here is the minimum extent for 2015 - 2017 with 2012 also shown.

Source: NSIDC

There is no trend that immediately jumps out at me. The order going into this narrow range is not the same as the order coming out or the order at minimum extent. You cannot predict, based on the ranking of maximum extents or July extents, where a particular year will end up at the minimum. All we can see for sure is the extent is certainly decreasing and is dramatically below the long term average.

This graphic shows the ice extent with the average extent shown with a magenta line. We can see the current extent is quite a bit lower than the average.

Source: NSIDC

There is nothing radically different from the last few years in these graphs. The sea ice extent continues to decrease, but no significant, single event jumps out from this data.

Here is a plot of the ice surface temperature:

Source: Polar Portal

This is the ice thickness:

Source: Polar Portal

And, here's the ice percent cover. The most important thing to note here is that there appears to be some break-up of the ice throughout the Arctic Ocean. That could end up being significant and bears watching because broken ice melts much more quickly than solid ice.

Source: Polar Portal

Again, there's nothing here that strikes me as being out of the (recent) normal trend. Based on the data I've been following, I think the minimum ice extent in September will be 4.4 million square kilometers, plus or minus .2 million square kilometers. This would place it right in the middle of the pack of recent years. The trend line is definitely in the downward direction, but it has not made a big jump - one way or the other - in recent years.

This makes me wonder - Has the ice extent reached a plateau that is waiting for something to tip it? I don't know the answer. We'll have to watch it the next few years before we'll have a better sense of what's happening.

Trump is simply too stupid to understand the science

Trump likes to boast that he's "like, really smart." He goes even further, stating, "I think that would qualify as not smart, but genius." I've been reading his statements for many years, going back to the time I first saw him on 60 Minutes in 1985, and my conclusion, based on his own words, is that he's not very smart at all. Based on what I've seen, I would peg his IQ at about average - right around 100.

But worse than that, he's not well educated. I think this goes to his ego. When he comes across a topic he can't understand, he simply ignores it and makes up something to satisfy his need to feel superior. In short, he's not smart enough to understand science, so he rejects it. And, this is why he isn't just a climate change denier, he's a climate change hater and is bent on a war on science. Science makes him feel inferior, so he's going to do all he can to destroy it.

His most recent statements, in a British ITV interview, is a perfect example of his complete lack of understanding of science. In this interview, he stated, "There is a cooling, and there’s a heating." Really, Mr. President? Which one is it? Cooling? Or, heating? You can't have both. The planet is either heating up, or it isn't.

Doubling down on that lack of understanding, he simultaneously appeared to refer to the the false claim about global warming and climate change phraseology when he stated, "I mean, look, it used to not be climate change, it used to be global warming. Right? That wasn’t working too well because it was getting too cold all over the place.”

Actually, it still is global warming. Back in the W. Bush administration, there was concern about how the public was getting concerned about 'global warming,' and it was decided to start referring to it by another name that sounded less dire. So, the Republicans began referring to it as 'climate change.' This is known as the Luntz memo. Anti-science people like to claim scientists changed the name because there was no warming. In fact, it was the deniers who changed the name because there was too much warming. Scientists have adopted this extra term because it covers more than global warming - ocean acidification, for example.

And, no, it isn't getting too cold 'all over the place,' as Trump stated. In fact, according to NASA and NOAA, 2017 was the second or third hottest year on record. According to NOAA, the five hottest years ever recorded have occurred since 2006. What is alarming about that figure is that there was no El Nino in 2017 to boost the atmospheric temperature. This is the new normal, as they say. 

Not having been satisfied displaying his ignorance, he went even further and stated “polar ice caps were supposed to be gone by now,” but instead they’re “breaking records.”

No, and no.

While some individuals made claims ice caps were supposed to be gone by now, the vast majority have been stating we should expect an ice-free Arctic Ocean during the summer sometime around the 2040 - 2050 time frame. I happen to think it will first occur in the 2030s. Which illustrates the point I'm making - even the pessimistic scientists haven't been predicting an ice free Arctic Ocean by now.

And, as for the 'breaking records,' he's not only wrong, he's very wrong. The minimum extent for 2017 was the eight-lowest minimum in the satellite record and was 1.58 million square kilometers below the long-term average. Even Antarctica is below average and experienced it's fifth lowest maximum extent this past September (summer time in Antarctica). Arctic sea ice extent is declining at a rate of 13.2% per decade.

It's bad enough when your neighbor, or coworker, or someone in the bar isn't smart enough to understand the science. But, when the President of the United States isn't, it's a serious problem. 

History of Sea Ice

The National Snow and Ice Data Center (NSIDC) had a very interesting posting concerning the history of sea ice extent since 1850. This is a rather nice piece of work involving historical records going back 130 years before the start of satellite monitoring. Researchers used "a compilation of maps, ship reports, and other records" to build the record. Then they plotted it and the story it tells is pretty graphic. Take a look:

Source: NSIDC

The extent is color-coded where extent greater than the 1850-2013 baseline is colored in shades of red and extent less than that baseline is colored in shades of blue. The calibration of the colors is displayed on the right-hand axis. The bottom axis is in years beginning in 1850 and going to 2013. The vertical axis is months of the year with January at the top and December at the bottom.

Before the 1970s, we can see the ice extent is displayed almost continuously in shades of red with an occasional block of blue here and there until an extensive blotch of blue extending from 1937 to 1943. The notable thing about that blue blotch is that it does not go into the winter months.

However, beginning in the 1970s we can see the extent becomes increasingly blue. At first, the deficit is limited to the summer months, but by the 1990s it's consistently blue even in the winter. By the 2000s, the graph shows a deficit in extent for all months. There has not been a red-shaded block since the mid-1980s. Recent years show a trend of increasingly darker shades of blue.

This is another graphic in the same article:

Source: NSIDC

In this graphic, they took 50-year periods and plotted the extent of the smallest minimum extent for each period. The periods are marked above each graphic while the specific year is displayed on the upper-left portion of each plot. You can see, even by the 1940s we were already beginning to see evidence of smaller extent. This is certainly clear by the third plot and the devastating 2012 extent is displayed in the last one.

There are a few more graphics, but I wanted to share one last one with you.

Source: NSIDC

These two graphs show the date the Beaufort Sea (top) and Chukchi Sea (bottom) ice-over for the period of 1979 - 2017.  In both cases, we can see these two seas are becoming ice-covered at a later and later date. Notice the data for the Chukchi Sea stops in 2016. That's because this sea did not ice-over before the end of 2017.

By the way, the Arctic sea ice extent is currently trending very close to the record low extent for this time of year.  The conclusion is very clear - Arctic sea ice is going away and will not be coming back.

Update on the 2017 Arctic Melt Season

I made a posting on March 22 where I made a way-too-early forecast on the Arctic sea ice melt season. In that forecast I calculated the sea ice minimum extent for this year would approach 3 million square kilometers, which would easily be the minimum extent ever measured. The season is well advanced, so I thought this would be a good time to update that forecast and see how things are panning out.

To start with, this is the Charctic graph from NSIDC for July 4:

Source: NSIDC

As you can see, the current extent is competing with the lowest extents ever recorded for this date.The actual extent NSIDC reports for July 15 this year is 7.857 million square kilometers, which is more than 1.7 million square kilometers below the 1981-2010 average extent of 9.564 million square kilometers for that date.

This is the sea extent as shown by the Climate Change Institute (click on the image to view a larger version):

Source: CCI

The light blue line shows the 1979-2000 average sea ice extent. The ice-covered area is designated with a white-to-gray coloration. The more gray it is, the more broken-up the ice is with solid ice shown as pure white. As we can see, none, or very little, of the sea ice is shown as pure white. It is almost all some shade of gray. It also easy to see that areas that were historically ice-bound this time of year are now ice free. Take a look at Hudson Bay. It is almost entirely ice free (and has been for several weeks now), but historically would still have extensive amounts of ice. The Northwest Passage across northern Canada and Alaska is almost open, which would be a historically early occurrence for this rare event.

Here is the map of the sea ice extent from the Danish Polar Portal:

Source: Polar Portal

Again, the shade of the ice indicates the amount of coverage with sold ice being pure white. We can see, once again, that there is very little area that is pure ice. Most of the Arctic sea ice is broken up to various degrees. This is important because breaking the ice up into smaller pieces increases the surface area and makes it easier for it to melt. Broken ice will melt faster than solid ice.

But, extent isn't the only factor we need to consider. We also need to look at the ice thickness. This is the sea ice thickness as provided by the Polar Institute with the scale shown on the bottom of the image:

Source: Polar Portal

The cooler the color, the thinner the ice. This shows the ice is not only breaking up, but is also very thin.

Comparing these graphs makes me believe we will see all of the dark blue, purple and violet areas in the above graph melt by the end of the melt season in September. The red and white areas will survive. At this time of year, I think the green areas will, too, but in a much thinner state. Which leaves the light blue areas and I think about half of those areas will melt. On the map above, I estimate the minimum extent will still cover about half of the circular area around the pole and fill approximately two of the 10-degree blocks south of that circle. Using the same math I used in my March 22 posting, this comes out to be about 2 million square kilometers for the northernmost circle and about 325,000 square kilometers for each of the squares. This comes out to a total of approximately 2.7 million square kilometers.

A major factor is the weather. The Arctic weather started the year much warmer than average, but it has been mild-to-cold this summer and not as conducive to melting sea ice as in previous years. Here is a graph from NSIDC showing the cumulative freezing days starting on July 1 of the previous year and continuing to July 1 of the current year. The shaded areas show the percentile ranges (as listed) over the period 1981 through 2010:

Source: NSIDC

We can see the 2017 season has been significantly warmer than any other year and has been far outside of the percentile ranges. But, we can also see the difference from the base-line has decreased in recent weeks.


The weather factor is discussed at length in this PIOMASS posting. In particular, take a look at the graph of the Daily Average Arctic Sea Ice Thickness From PIOMASS located at the bottom of the posting, right before the comments section. This graph shows the thickness is not only historically low, but it has been all year. But, one of the things documented in this post is that the difference between 2017 and 2012 (the year of record low extent) is closing, where 2017 was much lower than 2012 to begin with. Using this input, let's postulate that the ice melt will not occur quite as severely as I speculated above. Based on that input from PIOMAS and NSIDC, let's bump the minimum extent estimate up to an even 3.0 million square kilometers.

This estimate is consistent with my March estimate and would be dangerously lower than the previous lowest minimum extent of 3.4 million square kilometers that occurred in 2012.

2017 Arctic Sea Ice Melt Season Has Started

The National Snow and Ice Data Center (NSIDC) has not yet announced the Arctic sea ice maximum extent for this year, but I expect them to do so momentarily. (UPDATE: NSIDC made the announcement mere hours after I wrote this.) And, I expect them to announce the maximum extent for 2017 was 14.420 million square kilometers and occurred on March 7. When this is confirmed, it will be the lowest maximum extent ever recorded and 2017 will be the third year in a row to experience the record low maximum. (UPDATE: You can read a nice article about the changes in the sea ice here.) The graphic below shows the sea ice extent for 2017 (light blue), 2016 (red), 2015 (dark blue) and the 1981-2010 median extent (dark grey). The shaded areas are one and two standard deviations from the median.

Source: NSIDC

This means the 2017 Arctic sea ice melt season is now underway and, considering the terrible shape of the maximum extent, we already have to be concerned about the minimum extent coming in September. Given this situation, I decided to make an attempt at a very early prediction on the minimum. I predicted the maximum would be 14.2 million square kilometers and would occur in the first week of March, so I was pretty close.

One of the dire situations that doesn't show up in the above graph is the ice thickness, which is in even worse shape than the extent. This is a plot of the ice thickness from the Polar Portal.

Source: Polar Portal

I expect all ice 2 meters thick and thinner to completely melt by September. That is the ice colored light blue to purple and violet. Likewise, I expect all of the ice 3.5 meters thick and thicker to survive, albeit in a much thinner condition. That would be the yellow, red and white colored areas. The green areas are a toss-up. A great deal of the melting depends on the weather in the Arctic region during the summer. If the summer is cloudy and cold, more of the green area will survive. If the summer is clear and sunny, more will melt. I used a figure of 50% melt for the green areas in my estimate. That only leaves adding up the areas, which really wasn't all the difficult. The Polar Portal conveniently included some marked blocks. I merely had to find the area of the marked areas.

The surface area of a part of a globe is called a spherical cap and the math is straight forward. I have included a description of the math below. These calculations gave me 3.9 million square kilometers for the area inside the most poleward dotted circle. I used an even four million for my estimate. The circle indicates 80 degrees north. The next larger dotted circle indicates 70 degrees north. This area is also divided up into 10 degree-wide blocks. I calculated the area of each block to be 323,000 square kilometers and I rounded up to 325,000.

I estimate one half of the area of the 80 circle to still have ice in September (even including the land area as 'ice free'). This is 2 million square kilometers. Of the 10-degree squares, I expect there will be only three blocks worth of ice remaining at the minimum. That is another 975,000 square kilometers. Let's call it an even one million.

So, my very early forecast is for the 2017 minimum extent to be about 3 million square kilometers. This would be the lowest minimum extent ever recorded and would easily shatter the previous record low of 3.387 million square kilometers set in 2012. 

Of course, we'll have to wait until September to see how well I do with this forecast. Unfortunately, I feel that my estimate is conservative and fear the actual extent will be even lower. Let's hope I'm wrong.


MATH USED

A spherical cap is the surface area of a sphere cut off by a plane. If the plane cuts the sphere in half, the spherical cap is called a hemisphere.

The area of a cap is found by the equations

A = 2πrh  = π(r² + a²)

A = the area of the cap

r = the radius of the sphere

h = the height of the cap

a = the radius of the cap

r = 6400 kilometers (one Earth radii)

θ = 10^o (90^o - 80^o) for the 80^o circle and 20^o (90^o - 70^o) for the 70^o circle        

a = r sinθ = (6400 km)sin10^o = 1111 km (80^o circle)

and

a = r sinθ = (6400 km)sin20^o = 2189 km (70^o circle)

h = r - rcosθ = 6400 km - (6400 km)cos10^o = 97 km (80^o circle)

and
h = r - rcosθ = 6400 km - (6400 km)cos20^o = 386 km (70^o circle)

The area of the 80^o circle is simple and is merely 2π(6400 km)(97 km) = 3.9 million square km
The area of the 70^o circle is 2π(6400 km)(386 km) = 15.5 million square km

If you use the alternative equation as a check, you get the same results.

However, we don't want the surface area of the 70^o circle, we want the area outside of the 80^o circle, so we need to subtract the area of the smaller circle from the larger one and this is equal to 11.6 million square km. This is the area of the band between the 70^o circle and the 80^o circle. This area is divided up into 36 10-degree-wide blocks, giving us 323,000 square kilometers per 10^o x 10^o block on the Polar Portal graphic.