Note: This includes the corrections just announced by GISS and replaces the previous article - see comments here. (h/t David Sanger)
Every month since March, I've posted a chart of the progressive year-to-date global average surface temperature, from GISS. This is the update with June included. I'll repeat the explanation with each update and add what seem to be things to watch.
I've added a chart of annual temps for GISTemp, comparing the version put out in June with the (corrected) version put out in July. That's so that you can see what difference the shift to ERSST v4 makes.
Worth noting - now with corrections from GISS
- June was an average of 0.80°C above the 1951-1980 mean and is hottest June on record.
- No other month this year was hottest on record.
- The highest anomaly this year is now March at 0.90°C, which makes it the third hottest March after March 2010, at 0.92°C and March 2002 at 0.91°C.
- 2015 is still hottest on record so far. With the adoption of ERSST v4, some of the temperatures are higher. So are those of some other years, particularly in 2010, temperatures have been upped quite a bit. But all have changed.
- April and May are still relatively cool, unlike in some other data sets. By cool I don't mean cold. May was 0.76C above the 1951-1980 mean. It's just that most people thought it would be among the hottest of Mays, particularly since ERSSTv4 was very high in May this year.
- The lowest anomaly was in April this year, at 0.74°C above the 1951-1980 mean.
- The progressive year to date average up to and including June is 0.82°C above the 1951-1980 mean. In June 2010 it was 0.78°C above. (In June 2014, the hottest full year to date, it was 0.72°C above.)
Explaining the chart
The chart is a progressive year to date average for all years from 1995 to the present. What that means is for January each year, it just shows the anomaly for January. For February it shows the average of January and February for each year. For March, its the average of the monthly anomaly from January to March.
If you look at December, each year shows the annual average temperature for the full year. For November, each year has the average for the year up to November, not including December. (As before, I've made it extra large because of all the fine detail.)
|Data Source: NASA GISS|
2015 is still tracking as the hottest on record. The years to watch are 2014, 2010 and 2005. I've plotted them with slightly thicker lines so they stand out more easily.
The coldest year of the lot was 1996, which still ended up more than 0.3°C above the 1950 to 1981 average. The next time someone tries to tell you that "it hasn't warmed since 1996" then show them this chart :)
GISTemp changes with ERSST v4
Now that GISTemp is using ERSST v4, the temperature data has changed some over all years. Below is a chart showing the annual average for the June version and this latest July version, which uses ERSST v4. I've also plotted the difference between the two versions. It's really piddly in the whole scheme of things as you can see. (There's some discussion of ERSST v4 in this HotWhopper article about NOAA revisions).
|Data Source: NASA GISS|
Points to note:
- The 2015 temperature for both series is year to date average to May (not including June), so they can be compared.
- The "difference" is the July version minus the June version. Positive means the July version is higher than the June version.
- As you can see, the biggest difference is 1944 and 1945, which are 0.13 and 0.12 respectively. Most years it's +/- 0.01C to 0.05C.
- The July version is higher than the June version at both ends. There's barely any difference in the middle of last century.
- The biggest changes are in the more recent years but it's not the same every year. (Eg increases from 2009 onwards are larger than in the late 1990s).
- There's that questionable peak in the 1940s that someone will undoubtedly be able to sort out one of these days. (Probably because something different happened on war vessels to how the temps were usually taken.)
- Click here to see a spreadsheet showing the differences with this version with ERSSTv4 over previous version with ERSST v3b.
Here is the link to the table for the top Year to Date chart.