On Tuesday, United Nations weather agency World Meteorological Organization released a report revealing that carbon dioxide levels in the atmosphere reached a record high in 2013.

The report said that last year, carbon dioxide in the atmosphere reached global concentrations of 396 parts per million, which is an increase of 2.9 parts per million from 2012 -- the largest change from one year to the next since 1984.

The global concentration of carbon dioxide is also 42 percent higher than it was before the Industrial Age (280 parts per million).

"We know without any doubt that our climate is changing and our weather is becoming more extreme due to human activities such as the burning of fossil fuels," WMO Secretary-General Michel Jarraud said, according to NBC News. "Time is not on our side, for sure."

According to BBC News, the report, which comes out annually and is known as the Greenhouse Gas Bulletin, measures the amount of gases that increase global temperature staying in the atmosphere after "complex interactions" between air, land and oceans.

"The Greenhouse Gas Bulletin shows that, far from falling, the concentration of carbon dioxide in the atmosphere actually increased last year at the fastest rate for nearly 30 years," Jarraud said. "We must reverse this trend by cutting emissions of CO2 and other greenhouse gases across the board."

The report is also unnerving scientists as the increase in carbon dioxide was created by the Earth biosphere's "reduced carbon uptake," according to BBC.

"We don't understand if this is temporary or if it is a permanent state," said Oksana Tarasova, a WMO scientist. "And we are a bit worried about that. It could be that the biosphere is at its limit, but we cannot tell that at the moment."

The report also addressed ocean acidification for the first time. Ocean acidification happens when oceans absorb carbon, according to NBC. The report found that carbon absorption "appears unprecedented at least over the last 300 million years."

On Sept. 23, global leaders will meet for a summit in New York as requested by Ban Ki-Moon, U.N. secretary general.

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