The high levels of carbon dioxide -- a man-made greenhouse gas blamed for the raising temperatures on the planet over the years -- was recorded at a U.S. government agency lab situated on Hawaii's Mauna Loa volcano, the BBC reported.
Professor Sir Brian Hoskins, director of the Grantham Institute for Climate Change at Imperial College London, said governments should be looking into ways to tackle climate change.
"Before we started influencing the amount of carbon dioxide in the atmosphere, over the last million years it went between about 180 and 280 parts per million," Hoskins said. "Now, since the Industrial Revolution and more in the last 50 years, we've taken that level up by more than 40 percent to a level of 400 and that hasn't been seen on this planet for probably 4 million years."
While the European Union has been backing off the issue, the United States and China have agreed to co-operate on clean technology.
"But around the world, there are things happening, it's not all doom and gloom," he added. "China is doing a lot. Its latest five-year plan makes really great strides."
Sign language interpreter at Mandela service called out as fake on Twitter
Wisconsin business offering 'therapeutic cuddling' forced to close