Saturday, August 27, 2016

Arctic Sea Ice 2016

We have about three weeks left to the Arctic sea ice melt season. Time to take a look at how it's going. Of course, this is the 21st century, so the immediate answer is it's not good. In fact, the current sea ice extent is already less than the minimum extent for every year before 2007. This figure, from the National Snow and Ice Data Center (NSIDC), shows the 2016 sea ice extent (the unfinished line in red) and every year from 1979 to 2006.

Source: NSIDC

In fact, the 2016 extent is already one of the lowest ever. Here is the 2016 extent compare to the years since 2006. Again, 2016 is the unfinished line in red. And, with about three weeks to go, 2016 is already the seventh lowest extent ever recorded.

Source: NSIDC

Like I said, the 21st century has not been good to Arctic sea ice. The big question at this point is, how low will it go?

Take a look at this plot of sea ice extent from the Polar Portal:

Source: Polar Portal

The darker the shading, the less ice is present. This figures shows the extent is not only very low, but large areas have little ice cover. Compare this extent to this figure of the extent from the Climate Change Institute:

Source: Climate Reanalyzer
The less colored in the ice, the lower the density. Plus, the blue line indicates the normal extent for this date. We can see the extent is drastically lower than normal and what little ice is there is very thin. This agrees with the Polar Portal image above which used different satellite data.

The reason the low extent is important to this conversation is that the open water absorbs sunlight and heats up. Normally, the water would be covered with ice, which reflects sunlight, and would stay cool. Here is one more plot showing the sea surface temperature anomaly for the Arctic region, also from the Climate Reanalyzer at the Climate Change Institute.

Source: Climate Reanalyzer

The redder the water is, the bigger the temperature anomaly. We can clearly see the exposed portions of the Arctic Ocean are very much warmer than normal. This does not bode well for sea ice.

Currently (August 27, 2016), the sea ice extent is 4.913 million square kilometers. Taking all of this data into account, I estimate the sea ice extent will decrease to between 4.2 and 4.3 million square kilometers, making it the second or third lowest extent ever recovered. Worse still, it is very close to being on track for the long-term trend of decreasing Arctic sea ice.

Source: NSIDC

At the current rate, we will see ice free Septembers some time in the 2060s. However, an anomalous year could produce an ice-free Arctic well before that time frame.

No comments:

Post a Comment