Beginning in January of this year, headlines screamed 2016 to be the hottest year since 1880, highlighting July as the hottest month ever (here, here, here, and here).  Stories referenced the Goddard Institute for Space Studies, that part of the National Aeronautics and Space Administration (NASA) dedicated to climate change instead of space exploration.  Indeed, NASA itself posted a news release January 18 highlighting 2016 as the hottest year, followed by news releases February 15 and March 15, respectively, highlighting January and February to be the third warmest and second warmest months on record.  But, scrolling down on the NASA News and Feature Articles page, one finds reference to the above three releases – but nothing for the temperatures of March, April, and May.  Why is that?

Perhaps the answer is that year-over-year temperatures have declined, now for eight consecutive months, beginning in October 2016, and ending with May 2017.  This information can be found on the NASA website, but it is not highlighted.  NASA publishes charts about the 15th of each month depicting the cumulation of temperature anomalies to include the previous month, such as the one below published June 15 for months through May.  The year-over-year declines for the five months of 2017 are evident in the chart.  What is less evident is what was happening the last several months of 2016.  NASA would provide a great service if it could depict months of the previous year with a differentiating symbol.

A little sleuthing on NASA's website uncovers files of the raw data, in 0.01 deviations Celsius from a 1951-1980 base, for Land-Ocean Temperatures, of which a select amount is replicated below.  Leaving aside questions of the reliability of these deviations derived from temperature measurements, one notices that the last three months of 2016 were lower than the corresponding months of 2015.  So that make eight months of year-over-year lower temperatures.  Could that be the start of a trend, or at least a reason to downplay the relationship?