Year-To-Date Average Sea Ice Extent

With 2018 just ending at a 2nd lowest average for the year for Arctic sea ice extent, now we have the first week of 2019 in the database, and the new year–to–date average is at 12.55 million km², which is only the 8th lowest on record. But remember these are still early days, literally, and a 7–day average, while more reliable than a daily figure, is a lot less indicative of where the year is going than, say, a 30–day or 100–day average. This could go either way!

Q: Where’s the data source for this plot?
A: Here: https://ads.nipr.ac.jp/vishop/#/extent
Q: How can anyone make a year-to-date average graph?
A: Easy. Use a computer. Add all the ice for every day so far this year, divide by the number of days.
Q: Why would I even do that?
A: Let’s say you want to know how much ice we have in 2019 compared to other years.