Nine of the 10 warmest years have occurred since 2005, with the last five years comprising the five hottest.
The report is the latest installment of a yearly analysis that compares the two agencies' independent global temperature measurements with historical data. Their separate analyses add to decades of evidence that the burning of fossil fuels, the clearing of forests and other human activities are releasing heat-trapping greenhouse gases into the atmosphere and causing the planet to warm.
The UN's World Meteorological Organization said in November that 2018 was set to be the fourth warmest year in recorded history, stressing the urgent need for action to rein in runaway planetary warming. "What happens at the poles does not stay at the poles but influences weather and climate conditions in lower latitudes where hundreds of millions of people live", he said.
"2018 is yet again an extremely warm year on top of a long-term global warming trend", GISS Director Gavin Schmidt said in a statement on Wednesday. This means 2018's average global temperatures were the fourth warmest since 1880, placing it behind 2016, 2017 and 2015.
An analysis of five worldwide datasets by the WMO showed that the global average surface temperature in 2018 was approximately 1° above the pre-industrial starting point.
It isn't unusual to see annual changes that seem to buck the overall warming pattern, like the apparent cooling on display between 2016 and 2018.
The year 2019 has kicked in where 2018 left off. "Those who live in denial of this fact are in denial of physics", Potsdam Institute climate scientist Stefan Rahmstorf said in an email. Increasing temperatures can also contribute to longer fire seasons and some extreme weather events, according to Schmidt. Instead, his administration is working to unravel Obama-era environmental rules in favor of policies that would allow more greenhouse gas emissions from cars, trucks and coal-fired power plants. The US temperature in 2018 was the 14th warmest on average, said NOAA climate monitoring chief Deke Arndt.
"There was no Greenland and sea level was about 25 meters higher".
The text written by the USA institutions also highlighted that much of Europe, New Zealand and Middle East regions, as well as Russian Federation, recorded higher temperatures on land, while areas of the South Pacific Ocean and the North and South Atlantic also suffered maximum temperatures in the sea surface.
The data released by WMO confirm the urgency of addressing climate action - as emphasized by the recent Intergovernmental Panel on Climate Change (IPCC) special report on the impacts of global warming of 1.5°C above pre-industrial levels.