Meanwhile, NOAA researchers' assessment placed 2017 as the third warmest year, reporting global average temperatures as 1.51 degrees F (0.84 degrees C) above average. It is the 41st consecutive year with global land and ocean temperatures above average. The agencies said the discrepancy in the rankings was the result of different methods that they use to analyze global temperature data, but that overall, their assessments on the state of the global climate are in agreement.
While 1.51°F may not sound like much of a departure from average, scientists say it can have noticeable impacts.
But one thing that has been common in both the reports is that 2017 has made the last four years the hottest period in their recorded history of 138 years.
Under the effect of a powerful Nino - a phenomenon known to push up the average global temperature that comes every three to seven years - 2016 is at the top of the list with 1.2 ° C more than in pre-industrial times (the United Nations uses the 1880-1900 period as a reference for conditions prevailing in the pre-industrial era), while 2017 wins the record for the hottest year without Nino.
NASA's Goddard Institute for Space Studies (GISS) said 2017 was the second-hottest year in their database, which extends back to 1880. "The long-term trend - and that's very important for the attribution of these - is very clear... no matter who is doing the analysis", Gavin Schmidt, director of NASA's Goddard Institute for Space Studies in NY, told reporters at a joint press conference with NOAA.
Another year, another dubious climate achievement.
This color-coded map displays a progression of changing global surface temperature anomalies up to 2017.
Government scientists published on Thursday that 2017 was one of the hottest years recorded. The last El Niño occurred from 2015 to 2016.
"Seventeen of the 18 warmest years on record have all been during this century, and the degree of warming during the past three years has been exceptional".
Last year was among the three warmest years since modern record-keeping began in 1880, according to reports published Thursday by two USA government agencies.
In March, WMO will issue its 2017 full Statement on the State of the Climate, which will provide a comprehensive overview of temperature variability and trends, high-impact events, and long-term indicators of climate change such as increasing carbon dioxide concentrations, Arctic and Antarctic sea ice, sea level rise and ocean acidification.
"We need increased levels of ambition to reduce greenhouse gas emissions combined with concrete actions to reduce disaster risk especially in least developed countries which contribute little to climate change", he underscored.