Lower Tropospheric Temperature for 2019 is the second warmest in recent history.

Date Added: 
Thursday, Jan 9, 2020


Data from satellites shows that for the lower troposphere, 2019 was the second warmest recorded since satellite observations began in 1979. 2016 was the warmest ever recorded, with 2017 in third place. The five warmest years since 1979 all occurred in the 2010’s, with 8 of the 10 years in the decade being in the warmest ten years since 1979.

Fig. 1. Annual mean, global (80S to 80N) temperature anomalies (difference from the long-term 1980-2009 average) for the lower troposphere (TLT).

The plot below shows the occurrence of record cold or record warm months since the beginning of the dataset. Five months in 2019 (June, July, September, November, and December) were record warm months in the satellite data. The last time a record cold month occurred in TLT was 1993, more than 25 years ago, and only 15 years after the beginning of the satellite record. Note that it is easier to set records at the beginning of the dataset because there are fewer previous measurements to compare against. The extreme case for this is 1980, where every month was a record because a given month in 1980 very, very, very likely to be either warmer or colder that the same month in 1979, the first year of the record.

Fig. 2. Temperature records in the lower troposphere (TLT). Each month with a blue dot is the coldest month observed to that date, and each month with a red dot is the warmest month observed to that date.

For this work, we used the “Temperature Lower Troposphere” (TLT) dataset from Remote Sensing Systems. TLT measures the temperature of a layer closer to the surface, extending from the surface to about 5 miles (about 8 km). For more details on the construction of this dataset, see Mears, C. A., and F. J. Wentz (2017), A Satellite-Derived Lower-Tropospheric Atmospheric Temperature Dataset Using an Optimized Adjustment for Diurnal Effects, Journal of Climate, 30(19), 7695-7718. This paper is available online (open access)

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