2016 was the hottest year on record, setting a new high for the third year in a row, with scientists firmly putting the blame on human activities that drive climate change.
Direct temperature measurements stretch back to 1880, but scientific research indicates the world was last this warm about 115,000 years ago and that the planet has not experienced such high levels of carbon dioxide in the atmosphere for 4 million years.
In 2016, global warming delivered scorching temperatures around the world. The resulting extreme weather means the impacts of climate change on people are coming sooner and with more ferocity than expected, according to scientists.
The natural El Niño climate phenomenon, which helped ramp up temperatures to “shocking” levels in early 2016, has now waned, but carbon emissions were the major factor and will continue to drive rising heat.
Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, said: “El Niño was a factor this year, but both 2015 and 2016 would have been records even without it.” He said about 90 percent of the warming signal in 2016 was due to rising greenhouse gas emissions. He expects 2017 to be another extremely hot year.
The new data shows the Earth has now risen about 1.1 degrees C above the levels seen before the Industrial Revolution, when large-scale fossil fuel burning began. This brings it perilously close to the 1.5 degrees C target included as an aim of the global climate agreement signed in Paris in December 2015.
The declaration of 2016 as a year of record-breaking heat comes just ahead of the inauguration of Donald Trump as U.S. president. Trump has called global warming a hoax and is filling his administration with climate change deniers and former ExxonMobil boss Rex Tillerson. Tillerson said recently that climate change does exist but that the ability to predict the effects of greenhouse gas emissions is “very limited,” a statement most climate scientists would reject.
Trump’s team has said it will strip away funding for “politically correct environmental monitoring.” Presenting the 2016 temperature data, Derek Arndt, at NOAA, said only: “We present this assessment for the benefit of the American people.”
The three temperature records are independent but reached very similar conclusions. “The datasets are all singing the same song,” said Arndt. The data from NOAA showed a run of 16 successive months from May 2015 to August 2016 when the global average temperature broke or equalled previous records, while no land area experienced an annual average temperature in 2016 that was cooler than 20th-century average.
NOAA also found Arctic sea ice fell to its lowest annual average extent on record and Antarctic sea ice to the second smallest extent on record. The warming in the Arctic in 2016 was “astounding,” Schmidt said.
Michael Mann, a professor and climate scientist at Pennsylvania State University, said: “The spate of record-warm years that we have seen in the 21st century can only be explained by human-caused climate change. 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.”
“While there may be some cost in mitigating climate change, there are already major costs in damages,” said Kevin Trenberth, a professor and scientist at the U.S. National Center for Atmospheric Research, who estimates the costs as already tens of billions of dollars a year. “Yet if sensible approaches are implemented in the right way for [cutting emissions] and building resilience, the increases in energy efficiency can actually make it a net gain, not only for the planet for for everyone.”
Bob Ward, policy director at the Grantham Research Institute on Climate Change at the London School of Economics, said: “Any politician who denies this evidence from world-class climate scientists will be wilfully turning a blind eye to rising risks that threaten the lives and livelihoods of their citizens.
“I hope that President-elect Trump and his team in particular will acknowledge and act on this important scientific information.”
The head of the World Meteorological Organization (WMO), Petteri Taalas, said in November: “The extra heat from the powerful El Niño event has disappeared. The heat from global warming will continue. Because of climate change, the occurrence and impact of extreme events has risen. ‘Once in a generation’ heatwaves and flooding are becoming more regular.”
A WMO report said human-induced global warming had contributed to at least half the extreme weather events studied in recent years, with the risk of extreme heat increasing by 10 times in some cases.
The record-smashing temperatures in 2016 led to searing heatwaves across the year: a new high of 42.7 degrees C (108.9 degrees F) was recorded in Pretoria, South Africa, in January; Mae Hong Son in Thailand saw 44.6 degrees C (112.3 degrees F) on April 28; Phalodi in India reached 51.0 degrees C (123.8 degrees F) in May, and Mitribah in Kuwait recorded 54.0 degrees C (129.2 degrees F) in July. Warm oceans saw coral mortality of up to 50 percent in parts of Australia’s Great Barrier Reef and bleaching of 75 percent of Japan’s biggest reef.
The level of CO2 in the atmosphere also broke records in 2016, with May seeing the highest monthly value yet — 407.7 ppm — at Mauna Loa, in Hawaii, the site of the longest-running measurements dating back to 1958.
Global carbon emissions have barely grown in the last three years, after decades of strong growth, according to an analysis published in November. The main reason is China burning less coal, but CO2 is still being emitted into the atmosphere at record levels. “CO2 will continue to rise and cause the planet to warm until emissions are cut down to near zero,” said Corinne Le Quéré, professor at the University of East Anglia.