The amount of heat-trapping carbon dioxide in the atmosphere averaged more than 400 parts per million globally for the first time ever in March, according to U.S. government measurements.
The recording was based on air samples taken from 40 sites around the world, the National Oceanic and Atmospheric Administration said in a statement Wednesday. It’s the highest level of the gas in at least a million years.
Increasing CO2 emissions are blamed for global climate change that causes stronger storms, melting Arctic ice and rising sea levels, according to scientists. This is the first time the emissions have reached that level on a global basis -- sites in the Arctic and Hawaii recorded CO2 concentrations over 400 ppm in 2012 and 2013, respectively.
“This marks the fact that humans burning fossil fuels have caused global carbon dioxide concentrations to rise more than 120 parts per million since pre-industrial times,” Pieter Tans, lead scientist for the agency’s Global Greenhouse Gas Reference Network, said in the statement. Half of that rise has occurred since 1980, he said.
Concentrations of CO2 are rising at about 2 to 3 ppm a year. The United Nations has said that greenhouse gases should peak at no more than 450 ppm this century to maximize the chance of limiting the global temperature rise to 2 degrees Celsius (3.6 degrees Fahrenheit).