A recent report from NASA shows 2019 was the second warmest year globally on record. Modern record keeping began in 1880, so that's what we are using as a data set. The only year warmer than 2019 was 2016.
Remember this is evaluating global temperature; there was actually part of the United States that was cooler than normal this year, which you can see in the map above of global temperature anomalies for the year.
The past five years have been the hottest years on record (2015-2019), and we also were able to say the same thing last year (2014-2018). The NASA study used annual mean temperature data from NOAA (National Oceanic and Atmospheric Administration) and found 2019 was the 34th warmest year on record for the Lower 48.
In the study published by NASA, Director Gavin Schmidt at the Goddard Institute for Space Studies said, “every decade since the 1960s clearly has been warmer than the one before.” You can see that growth trend he is talking about in the image below from Climate Central.
2019 was tied as the fifth warmest year on record in Louisville, according to the local National Weather Service office, with an annual mean temperature of 60.1º
The study also addressed warming in the Arctic region where sea ice is decreasing. The image above shows in September there was more than two million square kilometers less sea ice than average in this region. NASA added, "the Arctic region has warmed slightly more than three times faster than the rest of the world since 1970."
The warm ocean water is not just concentrated in the Arctic. The image above from the NASA study states "upper ocean heat content was the largest on record." All of this data was collected "from more than 20,000 weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations," according to this report.
Bottom line: 2019 was the second hottest year on record, and the last decade was the hottest decade on record.
