An independent analysis by NASA and the National Oceanic and Atmospheric Administration (NOAA) has revealed that 2018 was the fourth hottest year since 1880.
Global surface temperatures last year were 0.82 degrees Celsius (1.5 degrees Fahrenheit) warmer than the 1951 to 1980 mean temperature. However, it still ranks behind 2015, 2016 and 2017. Regardless, the past four years are the hottest on record.
“2018 is yet again an extremely warm year on top of a long-term global warming trend,” said Gavin Schmidt, Director of NASA’s Godard Institute for Space Studies (GISS).
However, because weather dynamics in different parts of the globe affect regional temperatures, not every region on Earth experienced similar amounts of warming. The NOAA found that 2018 mean average temperature for the mainland United States was the fourteenth warmest on record.
Warming trends were strongest in the Arctic region, which continued to experience continued loss of sea ice in 2018. Loss of ice from Greenland and the Antarctic also continued to contribute to rising sea levels.
Schmidt warned that global warming is already resulting in increased extreme weather events, saying “The impacts of long-term global warming are already being felt — in coastal flooding, heat waves, intense precipitation, and ecosystem change.”
Temperature analysis methods used by NASA for this study incorporated surface temperature measurements from 6,300 weather stations, ship, and buoy-based recordings of ocean surface temperatures and measurements from Antarctic research stations. These were analyzed using an algorithm that considers the varied spacing of stations around the globe as well as ‘heat island’ effects in urban centers which could impact the accuracy of the study’s conclusions. These same calculation techniques produced the global average temperature deviations from the baseline period from 1951 to 1980.
NASA estimates that their estimate of global mean temperature change for 2018 is accurate to within 0.1 degrees Fahrenheit, with a 95 percent certainty level.
NOAA scientists used much of the same raw temperature data, but with a different baseline period and different interpolation into the Earth’s polar and other data-poor regions. NOAA’s analysis found 2018 global temperatures were 0.79 degrees Celsius (1.42 degrees Fahrenheit) above the 20th-century average.
Scientists have warned that if global warming is to be restricted to 1.5 degrees Celsius above pre-industrial levels, the world will have to completely eliminate greenhouse gas emissions by the year 2050. This will not completely undo the damage done by climate change, however, it could prevent the most catastrophic outcomes of global warming.