The findings, providing new signs of the impact of greenhouse gases, were issued two days before the inauguration of U.S. President-elect Donald Trump, who questions whether climate change has a human cause.
Average global surface temperatures in 2016 were 0.83 degree Celsius (1.5 Fahrenheit) above a long-term average of 14 degrees Celsius (57.2F) from 1961-1990, according to the U.N.-affiliated World Meteorological Organisation (WMO) in Geneva.
Temperatures, lifted mainly by man-made greenhouse gases and partly by a natural El Nino weather event that released heat from the Pacific Ocean, beat the previous record in 2015, when 200 nations agreed a plan to limit global warming.
That peak had in turn eclipsed 2014.
"We don't expect record years every year, but the ongoing long-term warming trend is clear," said Gavin Schmidt, director of NASA's Goddard Institute for Space Studies.
The WMO data were based on records compiled by NASA, the U.S. National Oceanic and Atmospheric Administration (NOAA) and Britain's Met Office.
Global temperature records date back to the 1880s. It was only the second run of three record-breaking years after 1939-41, said Deke Arndt of NOAA's National Centers for Environmental Information.
Temperatures this year are unlikely to set a new record after the fading of El Nino, scientists said. But heat-trapping gases from burning fossil fuels, especially from China and the United States, will keep building up in the atmosphere.
"Unless we have a major volcanic eruption, I expect the record to be broken again within a few years," said Piers Forster, climate expert at the University of Leeds. Ash from big eruptions can dim sunlight.
Among last year's extreme weather events, wildfires in Alberta were the costliest natural disaster in Canada's history, while Phalodi in western India recorded a temperature of 51 degrees Celsius (123.8 Fahrenheit) on May 19, a national record.
North America also had its warmest year on record, the Great Barrier Reef off Australia suffered severe damage from rising temperatures, and sea ice in both the Arctic Ocean and around Antarctica is at record lows for mid-January.
At a summit in Paris in late 2015, governments agreed a plan to phase out fossil fuels this century and shift to renewable energies such as wind and solar power.
They agreed to limit warming to "well below" 2 degrees Celsius (3.6F) above pre-industrial times, while pursuing efforts for a 1.5C (2.7F) limit. By that yardstick, the WMO said temperatures in 2016 were 1.1C (2.0F) above pre-industrial ties.
"Long-term indicators of human-caused climate change reached new heights in 2016," said Petteri Taalaas, head of the WMO, referring to rising levels of carbon dioxide and methane.
He also said that warming was having other knock-on effects, such as melting Greenland ice that is pushing up sea levels.
Trump, who has described climate change as a hoax, has threatened to cancel the Paris Agreement and shift to exploiting cheap domestic coal, oil and gas. At a meeting in Marrakesh days after Trump's victory, however, almost 200 nations said it was an "urgent duty" to combat climate change.
Trump's choice to lead the Environmental Protection Agency, Oklahoma Attorney General Scott Pruitt, was quizzed by Democratic senators at a confirmation hearing on Wednesday about his fossil fuel industry ties.
"The hottest year on record is such a clear warning siren that even President-elect Trump cannot ignore," said Mark Maslin, Professor of Climatology at University College London.
|© REUTERS/Pascal Rossignol. People cool off in fountains as hot summer temperatures hit Paris|
2016 was the hottest year on record -- again
Last year was officially the Earth's warmest since record-keeping began in the 1880s, the World Meteorological Organization announced Wednesday morning.
That means 2016 set a global heat record for the third year in a row according to NOAA and NASA, who held a joint press conference on Wednesday to discuss the record.
Not only was this the third consecutive year to rank hotter than all previous years, it also means 16 of the 17 hottest years on record have occurred since 2000, according to NOAA. To put this in perspective, the last time we had a record cold year was 1911.
Temperatures over the Earth's continents and oceans in 2016 were 1.1 degree Celsius (1.98 degrees Fahrenheit) above the pre-industrial average, according to the WMO. That means we are already a majority of the way to the 1.5-degree warming goal set at the Paris Climate Agreement in 2015.
Climate scientists say greenhouse gas pollution, which humans are creating primarily by burning fossil fuels and chopping down rainforests, likely contributed to the 2016 record.
And the pollution certainly is behind the long-term trend toward warming, scientists say.
"(T)he spate of record-warm years that we have seen in the 21st century can only be explained by human-caused climate change," said Michael Mann, director of the Earth Science Center at Pennsylvania State University.
"The effect of human activity on our climate is no longer subtle. It's plain as day, as are the impacts -- in the form of record floods, droughts, superstorms and wildfires -- that it is having on us and our planet."
Humans are contributing to warming
A record El Niño lasting from 2015 into 2016 played a role in further pushing the planet's temperature higher. El Niños are weather phenomena that warm the Pacific Ocean and pump lots of excess heat into the atmosphere, raising global temperatures.
But El Niño is only one factor in the warming of the planet.
And climate scientists say it is a relatively small one when compared to the role that humans are playing.
"The record is due to a combination of the (natural) strong 2015-2016 El Niño (warming of the tropical Pacific Ocean surface) and the strong global warming trend that has continued from 1970 to the present," James Hansen, former director of the NASA Goddard Institute for Space Studies, told CNN.
But "the human-caused, long-term warming trend is the bigger contributor," he added.
To come up with its figures the WMO combined different global temperature datasets from various sources, including NOAA, NASA, the UK Met Office and the European weather and climate center, ECMWF.
Despite using different methods to compile and analyze the temperatures, all those agencies reached the same conclusion -- that 2016 "continued the long-term trend of warming we have seen since the 1970s ... and have not paused in any way," said Gavin Schmidt, director of NASA's Goddard Institute for Space Studies.
Arctic is warming faster
While the warming for the planet was just over 1 degree Celsius, the Arctic continued to warm much faster, with temperatures more than 3 degrees Celsius -- 5.4 degrees F -- above what they were in previous decades.
"The Arctic is warming twice as fast as the global average" according to the WMO Secretary-General Petteri Taalas, and "we have also broken sea ice minimum records in the Arctic and Antarctic."
The polar warmth is not just a problem for the polar bears, it lead an entire village in Alaska to vote to relocate.
And the impacts extent much further.
"The persistent loss of sea ice is driving weather, climate and ocean circulation patterns in other parts of the world. We also have to pay attention to the potential release of methane from melting permafrost," said Taalas.
What about 2017...and beyond?
Many scientists believe 2017 is unlikely to break the record for a fourth consecutive year.
That's because El Nino, a natural phenomenon that creates more warming, may not be present this year.
That doesn't mean climate change has stopped, though.
Humans continue to pump greenhouse gases into the atmosphere, warming the planet in the long term.
And Schmidt said on Wednesday that 2017 is still likely to be "a top-5 year" for global temperatures.
"Though some years will be warmer than others, the overall trend over multiple decades will inevitably be upward as long of concentrations of CO2 in the atmosphere keep increasing," said Gerald Meehl, a senior scientist at the National Center for Atmospheric Research.
Climate models consistently show that if CO2 continues to be released into the atmosphere at the current rate, temperatures will continue to climb well above 2 degrees Celsius, according to the latest from Intergovernmental Panel on Climate Change.
That creates real consequences, from rising sea levels -- threatening low-lying islands and cities like Miami Beach, Florida -- to searing droughts and mass-extinction in the natural world.
Politics of record heat
Meanwhile, it seems unlikely the world's second-biggest climate polluter, the Untied States, will shift away from fossil fuels soon. As news of the hottest year on record circulated the Internet, President-elect Donald Trump's pick to head the US Environmental Protection Agency, Scott Pruitt, testified on Capitol Hill.
Pruitt expressed doubt about the certainty and seriousness of human-caused climate change, despite overwhelming evidence. Research shows 97% of climate scientists -- almost all of them -- conclude people are warming the planet.
Trump has called for the United States to scrap the Paris Agreement on climate change, which aims to "green" the world's economy; and the Clean Power Plan, which aims to clean up power plants in the United States.
The American public, meanwhile, favors more action on this issue.
According to a poll released Wednesday by the Yale Program on Climate Change Communication and the the George Mason University Center for Climate Change Communication, nearly 7 in 10 Americans support US involvement in the Paris Agreement; and almost 80% want to tax or regulate global warming pollution.
Critically, the poll found 60% of Americans realize climate change already is affecting the weather.
So the Trump Administration may find itself out of step both with the science -- and the public.
The last time the Earth was this warm was 125,000 years ago
The planet sizzled to its third straight record warm year in 2016, and human activity is to blame, federal scientists announced Wednesday.
The last time the world was definitely warmer than today? Some 125,000 years ago based on paleoclimatic data from tree rings, ice cores, sediments and other ways of examining Earth's history, said NASA climate scientist Gavin Schmidt said.
The average temperature across the Earth's land and ocean surfaces in 2016 was 58.69 degrees, a whopping 1.69 degrees above average, according to the National Oceanic and Atmospheric Administration (NOAA). It was largest margin by which an annual global temperature record has ever been broken, NOAA said.
Although less than 2 degrees above average may sound small, it's quite a large number in climate science, where records are often broken by tenths or even hundredths of degrees.
A separate analysis of data from NASA concurred with NOAA's findings. Most of the warming has happened in the past 35 years, and 16 of the 17 warmest years have occurred since 2001, NASA said.
Record high temperatures were set in 2016 on nearly every continent. No land areas were cooler than average for the year. Eight straight months (January through August) were also each the warmest since records began 15 years after the Civil War ended.
The warmth last year contributed to fierce and deadly heat waves in Asia and the Middle East, a "mega"-wildfire in Canada, record low sea ice in the Arctic, and devastating coral bleaching in the Great Barrier Reef near Australia.
The record warmth was 80-90% the result of the long-term climate trend and 10% the result of the natural El Niño climate pattern, Schmidt said.
The warming trend over the past few decades can be linked to the burning of oil, gas and coal that releases "greenhouse" gases, such as carbon dioxide and methane, into the atmosphere. These gases have caused the Earth's temperature to rise over the past century to levels that cannot be explained by natural variability.
“No world leader can afford to ignore these results, which show that people all over the globe are being exposed to increasing impacts of climate change," said Bob Ward of the London School of Economics and Political Science. "Any politician who denies this evidence from world-class climate scientists in the United States will be willfully turning a blind eye to rising risks that threaten the lives and livelihoods of their citizens."
Since the start of the 21st century, the annual global temperature record has been broken five times — 2005, 2010, 2014, 2015, and 2016 — NOAA said.
"Though some years will be warmer than others, the overall trend over multiple decades will inevitably be upward as long of concentrations of carbon dioxide in the atmosphere keep increasing,” said Gerald Meehl, a scientist with the National Center for Atmospheric Research.
Other data sets in the United Kingdom and Japan this week also concurred with the findings from the U.S. agencies.
“The science is clear and headed in one direction," said Lou Leonard with the World Wildlife Fund. "Human-caused changes in climate are putting the lives of both people and wildlife at risk. From disappearing Arctic ice in Alaska to greater storm surges along our nation’s coastlines to heatwaves in America’s heartland, nature is sending a distress call."
Last year was the USA's second-warmest on record, NOAA said last week.
Looking ahead, Schmidt said that 2017 will likely be a "top 5" warm year for the planet.