The World Meteorological Organization's (WMO's) annual Greenhouse Gas Bulletin shows the levels of greenhouse gases in the atmosphere rise to record-high levels in 2013. These increases were driven by a rise in atmospheric concentrations of carbon dioxide, according to the report. Nitrous oxide and methane were also tracked in the study, and found in historically-high concentrations.
Between 1990 and 2013, greenhouse gases were responsible for a 34 percent increase in the amount of warming occurring to the climate, known as radiative forcing. During those years, concentration of carbon dioxide rose to a level 142 percent greater than the middle of the 18th Century, before mass industrialization. The amount of nitrous oxide climbed 121 percent over 1750, and methane concentrations were up 253 percent during that time.
Levels of carbon dioxide in the atmosphere rose between 2012 and 2013 by the greatest amount seen in a single year since 1984. This could be due to an increase in the amount of carbon dioxide being utilized by living things, as well as increased production of the greenhouse gas, by human activities.
Carbon dioxide in the atmosphere does not stay in the air all the time. Roughly a quarter of the gas produced is taken up by the oceans, and the same amount is absorbed by living beings. The WMO report studies the amount of greenhouse gas that remains after the reductions. Absorption of carbon dioxide by oceans lowers the pH of the water, leading to acidification. Investigators believe the global ocean is more acidic now than it has been in 300 million years.
"Carbon dioxide remains in the atmosphere for many hundreds of years and in the ocean for even longer. Past, present and future CO2 emissions will have a cumulative impact on both global warming and ocean acidification. The laws of physics are non-negotiable," Michel Jarraud, secretary-general of the WMO, said.
Radiative warming was mostly driven by carbon dioxide, which was responsible for 80 percent of the warming, according to the study. Concentrations of this gas were 396 parts per million (ppm), up 2.9 ppm from the previous year. Climatologists believe these levels could pass 400 ppm sometime in 2015 or 2016.
Methane is produced from natural sources, such as wetlands and termites. Roughly 60 percent of the gas in the air is produced from man-made sources, such as waste gases from cattle, burning of biomass, and landfills.
Nitrous oxide has an impact on climate nearly 300 times greater than an equal mass of carbon dioxide.
Political and scientific leaders will meet in New York on 23 Sept. to discuss possible solutions for global climate change.
