'When you have that gas in the atmosphere it is like having a blanket around the Earth and so it just kind of warms the Earth up,' said Stephen Hill of Trent University.

A climatologist believes Earth may have reached something that humans have never seen: carbon dioxide levels that not only have reached 400 parts per million, but levels that are unlikely to ever dip below that.

The National Oceanic and Atmospheric Administration has released a new finding: that global greenhouse gas concentrations have reached their highest levels since record keeping began in 1958.