The level of carbon dioxide in the atmosphere has broken above 400 parts per million for the first time in human history, US monitors announced Friday, indicating that climate change has reached a new high.
Levels of carbon dioxide rose hand-in-hand with warming at the end of the last Ice Age, according to a study Thursday that deals a blow to climate skeptics.
A scientific conundrum that has puzzled climate experts for years may have been solved with the publication of research showing how an increase in carbon dioxide levels in the atmosphere contributed to rising temperatures millions of years ago.
The question of whether carbon dioxide should be considered a pollutant under the Clean Air Act and regulated by the Environmental Protection Agency has been a political football for the past decade.
