The UN's World Meterological Organisation 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.
Americans escaped the worst of it last year though; while the rest of the planet cooked, the US experienced only its 14th-warmest year.
Gavin Schmidt, a climate scientist at NASA, says the message is clear: "The planet is warming". The Earth's average temperature in 2018 was one degree celsius higher than the average temperature in the late 19th century, at the end of the Industrial Revolution, and the beginning of a serious uptick in manmade production of greenhouse gasses and carbon dioxide. 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. Greenland ice sheets continue to suffer mass loss, which together with similar ice sheet loss in Antarctica, contributed to sea level rise. Increasing temperatures can also contribute to longer fire seasons and some extreme weather events, according to Schmidt.
NASA's global temperature analyses use surface temperature recordings from 6,300 weather stations around the world, incorporating ship- and buoy-based measurements of ocean surface temperatures as well as measurements of surface temperatures from Antarctic research outposts.
Though there are minor variations from year to year, all five temperature records show peaks and valleys in sync with each other.More news: Drinking beer or wine first has no effect on severity of hangover
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A still image pauses the onslaught of warmer temperatures in NASA and NOAA data summarizing global climate changes. Deathly record lows are real in the United States of America, but don't be fooled by the cooling that we have been witnessing, global warming is real also. It was the fourth highest since 1880, the earliest year for which records are available.
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. Taking this into account, NASA estimates that 2018's global mean change is accurate to within 0.1 degree Fahrenheit, with a 95 percent certainty level.
The 2018 global temperature reports were originally scheduled for release in mid-January, but they were delayed because the 35-day partial government shutdown prevented government scientists from finalizing their calculations.