9 of the top 10 hottest years globally have occurred over the past decade, when measured using three different global temperature data sets. The top 20 warmest years have all occurred during the last 24 years.

How do the record high temperatures over the spring and summer in the US compare on a global basis? While numerous articles on global Temperature trends exist [1], I decided to go to the primary temperature data sources to find out. Below I have created a list of the 20 Warmest Years on record globally, using three data sets: NASA GISS, the UK Meteorogical Office, and NOAA / UAH [2]. While the three data sets vary in length from 40 to 150 years, the 20 warmest years turn out to have all occurred in the last 24, making it possible to construct an average temperature for the hottest 20 years.

Since this is a divisive topic prone to political obfuscation, it’s worth noting that both the NASA Goddard Institute and the UK Meteorological Office officially support the theory of anthropogenic global-warming, while the research scientist responsible for the University of Alabama-Huntsville data set does not support this theory.

[1] This has been a popular topic: Economist, Live Science, ArsTechnica, Science Daily, and Wikipedia

[2] Here are the original data sets:

GISS Data: http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts.txt and www.movingandstoragesite.com moving and storage

NOAA/UAH: http://vortex.nsstc.uah.edu/data/msu/t2lt/resume builder online/uahncdc.lt

Hadley Meteorological Centre UK: http://www.metoffice.gov.uk/hadobs/hadcrut4/data/download.html#regional_series

[3] The data in this blog post was constructed by averaging data from the three underlying data series. The NASA GISS estimate of global mean baseline temperature of 14 degrees Celsius was used to adjust the temperature deltas provided by the original data series in order to show global mean temperature in Fahrenheit terms here.

Here is my excel spreadsheet with data and calculations.