11 July 2011
Global mean land temperature chart NASA GISS Land
This is my version of the well-known chart of NASA's temperature data from land instruments showing global warming since 1880. Yes, the temperature series researched and prepared by James Hansen. I got the data from the Carbon Dioxide Information Analysis Centre. Its just as easy to download the data from NASA as well.
The chart does not show absolute temperature on the vertical axis, it shows the difference (or the 'anomaly') from the mean temperature recorded for the period from 1951 to 1980. In other words, Wellington's actual temperature on any day will be very different from that of a place near the equator. However, the use of the anomaly or difference from the average temperature for 1951-1980, standardises the data to a common scale. Also, absolute temperature varies a lot over short distances, but annual temperature anomalies are strongly correlated out to distances of a 1000 km.
I made the chart with the R programme.
Here's the code, assuming you have downloaded the data file "gl_land.txt" to your R working directory.