WASHINGTON (AP) — Scientists report the amount of heat-trapping carbon dioxide in the air peaked again this year at record levels.
The National Ocean and Atmospheric Administration said Thursday that carbon dioxide levels averaged 411.25 parts per million in May at a federal observatory in Hawaii, up from a peak of 409.65 a year ago.
Carbon dioxide is a major greenhouse gas and comes from the burning of coal, gas and oil.
May is traditionally the highest month for carbon dioxide levels. In late spring and summer, plants suck the heat-trapping gas out of the air.
NOAA’s Pieter Tans says the increase from last year is a little less than past years but much more than in the 1990s.