Japan's average carbon dioxide concentration set record highs at all observation points in 2016, the Meteorological Agency said Wednesday, underscoring the upward trend in global levels of the greenhouse gas.
Atmospheric data collected show that carbon dioxide concentrations have set new records each year since 1997, when the government raised the number of observation points to three. But last year's increase was larger than the average growth logged over the past decade.
The record high readings are believed to be partly caused by a fall in carbon dioxide absorbed by forests due to factors related to an El Nino climate cycle spanning from the summer 2014 to spring 2016.
The agency said concentration levels rose 3.8 parts per million from a year earlier to 407.2 ppm in Ofunato, Iwate Prefecture, gained 3.4 ppm to settle at 404.9 ppm on Minamitori Island in the Ogasawara island chain, and gained 3.2 ppm to 407.1 ppm in Yonaguni Island, Okinawa.
The Intergovernmental Panel on Climate Change has said that to limit the global temperature increase to 2 degrees above preindustrial levels, it is necessary to keep the global carbon dioxide concentration below 450 ppm by 2100.
Global carbon dioxide emissions have largely remained the same but the concentrations of the greenhouse gas has been on the rise. Even if emissions are cut and abatement efforts are improved, it is estimated that it will take around 10 years for the concentration reduction measures to take effect.
The international climate accord agreed in Paris in 2015 aims to effectively reduce net greenhouse gas emissions to zero in the second half of this century. Japan, the world's fifth-largest emitter of greenhouse gases, ratified the agreement last November.