If you spent much time outside last summer and thought that it wasn’t that hot in past years, you were right. NASA and NOAA have announced that the global surface temperatures in 2018 were the fourth warmest since 1880. That means 2018 was the fourth hottest year recorded in over 100 years.
The top three hottest years on record were 2015, 2016, and 2017. Collectively the four years are the warmest recorded since 1880. NASA and NOAA analyzed the same data independently and came to the same conclusion.
Global surface temperatures have risen by about 2 degrees Fahrenheit since 1880. This is in part due, according to NASA, from increased emissions in the atmosphere of carbon dioxide and other greenhouse gases created by human activity.
NASA does point out that weather dynamics affect regional temperatures, so not every region on Earth saw similar amounts of warming. For instance, NOAA found that the 2018 annual mean temperature for the contiguous 48 United States was the 14th warmest on record.
The strongest warming trends are seen in the Arctic region with continued loss of sea ice in 2018. Mass loss from the Greenland and Antarctic ice sheets combined to add to sea level rise. NASA’s data takes temperatures from 6,300 weather stations along with ship and buoy-based observations of sea surface temperatures along with measurements from Antarctic research stations.
NASA notes that with weather station locations and measurement practices changing over time, the interpretation of the data has some uncertainty. NASA figures its data is accurate within 0.1 degrees Fahrenheit with a 95% certainty level.