Greenhouse gas levels in the atmosphere reached a record not seen since sea levels were 10 meters to 20 meters (33 feet to 66 feet) higher than they are now, the World Meteorological Organization said in a report.
Concentrations of carbon dioxide and other Earth-warming gases rose last year and are 41 percent higher than in 1990, driving a long-term increase in the global temperature, the United Nations organization said in its annual assessment of the trend.