Arctic Sea Ice Continues to Decline at Record Pace

The decline of Arctic sea ice extent continues to decline at a record pace. As noted here two weeks ago, January sea ice extent was the lowest in the modern satellite record. Well guess what - February 2016 sea ice extent was the lowest February on record.

Larger here.

As the graph above shows, sea ice extent in February has been declining for many years, with the linear rate of decline at 3% per decade. [The previous post explains how to read the graphs] NASA and NOAA also note that February continued the trend of ten straight months of record-breaking high global surface temperatures, with the Arctic being especially hot (more than 4 degrees Celsius above the baseline).

It could have been even worse. Most of the month had almost no ice growth, in a time of year where it should be growing substantially (sea ice extent grows in winter, falls in summer). Only a late month burst of growth got it to where it was - and it was still a record low for the month. That's how bad it is.

Let's take a closer look:

The chart above is kind of busy even though I've only selected the most recent years. You can go here and use the interactive chart to include whatever years you want.  I highly encourage looking at all the years going back. The previous post explains what the lines and shading mean.

As you can see, sea ice extent grows in winter and shrinks in summer. This happens every year, so what you want to look for is how much it grows and shrinks compared to previous years. Keep in mind that the baseline mean (the black line and gray shaded area) was lowered recently to reflect the continuing declines. [This means if we had kept the old baseline the current sea ice extent would be even worse]

The current year is the burnt red line in the upper left corner, right at the bottom of the other lines shown. Right now it's about the same as where last year was at this time (darkish blue), but only because of that late-February bump up. We're right about the maximum now, though we won't know officially until we get a little further along. That doesn't bode well as last year was only barely above the second worst minimum extent years (see where the lines reach their most downward loop around September).

Starting the melt season in such a bad maximum doesn't mean we'll set a new record minimum. You can see that at this time in 2012 the maximum in late March (dashed green line) was higher than it was in ensuing years, yet 2012 smashed the previous record minimum year of 2007 (light blue line). Because sea ice extent is highly sensitive to local weather conditions (especially wind), we simply won't know how bad the minimum will be this year until we reach it in September. But we do know that it will be a bad year because every recent year has been a bad year. All you have to do is look at where all the lines fall compared to the baseline mean - they are all below. That means the baseline mean will again have to be lowered at some point, once again tracking the race to the bottom. At some point we're likely to see an ice-free Arctic for part of the summer.

And that is not a good thing. Not a good thing at all.

What is Happening to the Arctic? How to Read the Graphs

As 2016 starts off even hotter than the record-breaking heat of 2015 because of man-made climate change, one of the fastest warming areas of the planet is the Arctic. This year one of the key measures of Arctic "health" - sea ice extent - is showing signs of even more severe impact than normal. This fact has scientists fearful of a major speed up in climate change effects. It also has fossil fuel lobbyists scrambling to find new ways to deny the science.

So how do normal people (that is, us) know what's going on in the Arctic and elsewhere? This post gives a basic primer on how to read the graphs put out by the National Snow & Ice Data Center (NSIDC). The NSIDC collects data from a variety of sources and provides a monthly update. For this post I'll focus on Arctic sea ice extent as reported in NSIDC's Arctic Sea Ice News and Analysis page. As I write this the last update was in early February covering the status through the end of January. The next update will be in early March covering up through February.

One of the first things visitors to the see will be the "Daily Image Update" in the top right corner. As of today it shows:

See it larger here.

The graphic is fairly simple but shows a lot of important information. The bottom scale shows the months from November to March, so this represents the winter period where Arctic sea ice extent is expected to grow, which it does every year. [In the summer months it shrinks every year] The left scale shows extent in millions of square kilometers, but for now you don't need to worry about that; focus on the graph lines themselves.

See that thick black line running through the gray area? That represents the baseline sea ice extent from 1981 to 2010. It's essentially an average. One important point - that average was recently recalculated because all of the years after the end of the old averaging period were much lower than average. Therefore, the baseline has been lowered. What that means is that we should roughly see as many years over the average line as below. That hasn't been happening, even after lowering the bar. That's a bad thin. But let's not forget the gray area. That represents a range around the average. It gives you some idea of where the current year levels stand compared to the baseline years.

Which gets us to the solid blue (2015-2016) and dashed green (2011-2012), which represent the current year and the year with the record low ice extent. As you can see, the current year (blue line) is tracking well below the record low year. That's not a good thing, but we need more information so NSIDC also gives us the following graph, a bigger version of which can be seen here:

As you can see, this graph is the same as the previous one but shows several more recent years to provide context (note they changed the color of the 2011-2012 record year to purple instead of green, but it's still the only dashed line). You can see that the ice extent lines wiggle along; that's because short-term weather systems can either increase or decrease sea ice extent for any given time period, while man-made climate change is the reason for the longer trends. More on that shortly.

Want even more data? You can pick the years you want to plot on the graph with this handy Chartic Interactive Sea Ice Graph, which is also on the NSIDC page in the right hand column.

The graphs for 2015-2016 (the current winter) show that sea ice extent is dramatically lower than any other year. January was a record low and it looks like February will be too. Scientists are worried that we may have already seen the yearly maximum, which would be very early and dramatically lower than normal. It's from this point that the sea ice extent decreases until it reaches its yearly minimum (usually in September).

That doesn't necessarily mean we'll see a record low sea ice extent minimum this year. If you look at the Charctic Interactive graph you'll see that even though last year started out much lower in winter, it managed to reach only the fourth lowest minimum on record. That's not good at all, but it could have been worse. We won't know how bad this year will be until we reach the minimum, but based on where we're starting and the historic trend, we're pretty much assured it will be bad.

That gets us to the last graph I'll talk about today (larger):

This graph is for January but you can pick any other month and it will reflect exactly the same trend.
What the graph shows is the trend for that month over the years, that is, what the sea ice extent is in January each year from 1978 to 2016. Because of those short-term factors that make the lines in the first graphs wiggle, you see some years where the January extent is higher and some years lower. But look at the trend. The blue line shows how the sea ice extent has been decreasing for decades. The end of the black (and blue) line to the right of the graph is this year, the lowest ever recorded. You can see that this isn't a one-off problem, it's the continuation of a long-term decline in sea ice extent. Again, this graph shows January but every other month shows the same downward trend.

Bottom line: We're losing ice. Big time.

There are more graphics and information on the Arctic Sea Ice and Analysis page, plus information on Antarctica, Greenland, glaciers, and other snow and ice-related topics on the National Snow & Ice Data Center website. These are accurate, scientific sources of information that readers should save for future reference.