The U.S. National Oceanic and Atmospheric Administration says 2016 surpassed 2015 as the warmest year on record, citing the combined influence of long-term global warming and an unusually strong El Niño weather pattern.
The agency's annual report, released Thursday, was based on contributions from nearly 500 scientists from more than 60 nations. NOAA said the report took into account tens of thousands of measurements from independent data sets, reflecting global climate indicators, notable weather events, and measurements of greenhouse gas emissions, sea level, ocean salinity, snow cover and sea ice.
The State of the Climate report said 2016 was the third consecutive year of record global warmth. Global warmth records have been kept for the past 136 years.
Watch: Scientists Confirm Warming Planet as Trump Reviews Climate Report
Greenhouse gases were found to be the highest on record, and the current level, 402.9 parts per million, surpassed 400 parts per million for the first time in the modern atmospheric measurement record as well as in ice core records dating back as far as 800,000 years. It was also the largest annual increase observed in the 58 years since such measurements have been kept.
The report also said the global surface temperature observed was the highest on record last year, aided by the strong El Niño early in the year. The temperature of the region of the atmosphere just above the Earth's surface, known as the troposphere, was also the highest on record, as was the global average for the surface of the sea.
Global sea level was also the highest on record, at 82 millimeters higher than the average in 1993, when records began to be recorded with the current method. The report said 2016 was the sixth consecutive year in which the global sea level increased compared with the previous year.
The report also said a warming trend was continuing in the Arctic, and the Antarctic saw a new record low in the extent of sea ice coverage.
Story on draft report
The report came out just days after The New York Times published a draft U.S. government report on climate, which said that the average temperature in the United States had risen rapidly and drastically since 1980, and that recent decades had been the warmest in the past 1,500 years.
The draft report was compiled by scientists at 13 federal agencies and concluded that Americans were already starting to feel the result of climate change, despite expectations that the change would not be felt for several more decades.
The draft report directly contradicted claims by the Trump administration that the contribution of human activity to climate change is uncertain and unpredictable.
The report was leaked online in January but received little notice until the Times published the findings this week. Scientists have expressed fear that the Trump administration might try to suppress the findings since they contradict the stated positions of top U.S. officials, including Scott Pruitt, administrator of the U.S. Environmental Protection Agency. Pruitt has said repeatedly that he does not believe human activity plays a large role in climate change.
The authors of the leaked study disagree with that stance, writing in the report: "Many lines of evidence demonstrate that human activities, especially emissions of greenhouse gases, are primarily responsible for recent observed climate change."
That report is a special section of the National Climate Assessment and is published every four years. The National Academy of Sciences has approved the study, and authors are now waiting on the Trump administration to give the approval for its release.