Scientists have announced that Carbon dioxide levels in the Earth's atmosphere have hit the highest point in human history. The Co2 levels are measured at the top of the Mauna Loa observatory, which shows that the levels have broken the 400 parts-per-million (ppm) boundary for the first time. That means for every million molecules in the atmosphere, 400 of them are carbon dioxide. They say it's highly unlikely that levels will go back at this point in our lifetime. The impact is a reminder of the growing threat from climate change.
The UN's Intergovernmental Panel on Climate Change (IPCC) has predicted that once we go over the 450 ppm threshold, the results could be catastrophic. It would contribute to warming the planet by two degrees and cause unpredicted shifts in weather patterns on Earth. Current predictions are that if humans don't cut emissions by 40-70 percent, we'll break the 450 ppm mark in about twenty years.