The concentration of carbon dioxide in the atmosphere surged in 2016, reaching the highest level in 800,000 years, says a report released Monday by the World Meteorological Organization (WMO).

WMO's annual Greenhouse Gas Bulletin says the surge occurred with "record-breaking speed in 2016."  The WMO is an agency of the United Nations.

"The abrupt changes in the atmosphere witnessed in the past 70 years are without precedent," a summary of the report states.

Scientists within the organization say human activity and a strong El Niño were to blame for global average concentration's rising from 400 parts per million in 2015 to 403.3 parts per million in 2016.  In an El Niño year, the Pacific Ocean warms, which also causes a temperature rise on land and alters precipitation, setting off a complex climate cycle that can lead to more carbon in the atmosphere.

The new data mean that current carbon concentrations are 145 percent higher than in pre-industrial levels.  Pre-industrial is dated to about the year 1750.

"Rapidly increasing atmospheric levels of CO2 and other greenhouse gases have the potential to initiate unprecedented changes in climate systems, leading to severe ecological and economic disruptions," said the summary.

The report also says that, although recent years saw rises in carbon concentrations, year-to-year increases appear to be leveling off and may have reached a plateau, based on data from the Global Carbon Project.

Still, the latest data are not good news. Earth has experienced big concentrations of greenhouse gases before, but the last time was three million to five million years ago when temperatures were 2 to 3 degrees Celsius higher than current temperatures and sea level was 10 to 20 meters higher.

"Without rapid cuts in CO2 and other greenhouse gas emissions, we will be heading for dangerous temperature increases by the end of this century, well above the target set by the Paris climate change agreement," said Petteri Taalas, WMO's secretary-general.

Carbon dioxide goes into the atmosphere after fossil fuels are burned.  It is removed from the atmosphere when plants can absorb it.

Also concerning scientists: Levels of methane, an even more potent greenhouse gas, are at 257 percent of pre-industrial levels.  Nitrous oxide is at 122 percent of pre-industrial levels.

The Trump administration, which shuns the term "climate change," is rolling back Obama-era rules designed to slow global warming by restricting greenhouse gas emissions from coal-fired power plants, as well as regulations aimed at methane.