The hottest year 2014 debate

There has been a keen conversation whether the year 2014 was the hottest year since 2010 or not. Many objectors have pointed out that the difference between these years is only in maximum 0.04 degrees. This is less than the measurement accuracy of temperature measurement. In the climate change science it has become a habit that the final results are reported with higher accuracy than the measurements themselves. During my university studies, if a student reported in his physical laboratory exercises final results having higher accuracies than the measurements, the report has to be corrected before final acceptance. For example, IPCC reports that the temperature increase in 2011 has been 0.85 degrees even though the real accuracy of temperature measurements since 1750 is hardly better than 0.1 degrees, and probably much worse.

There are five global temperature measurements series commonly used. The differences between 2014 and 2010 (usually the hottest year in all series) are as follows: NOAA +0.04 °C, NASA/GISS +0.02 °C, HardCRUT4 -0.01 °C, UAH MSU -0.13 °C, UAH RSS -0.21 °C. The average value of these five series is -0.05 °C. Regarding that in three series the year 2010 was the hottest year and the average value also show that 2010 was the hottest year, we should admit that 2010 still the hottest year in this kind of analysis.

Actually, this debate has almost no meaning in analysing the climate change according to the temperature trends. The minimum time period in climate change science should be the length of the solar cycle which is about 11.2 years in average. The graph below gives an overall picture of the temperature changes since 1930.