The level of carbon dioxide in the atmosphere has never been higher, scientists at a prominent Hawaii observatory announced last week. This was the most recent environmental milestone in a year that has been marked by the Trump administration dismantling many Obama-era environmental policy initiatives. CO2 is especially significant because it traps heat in the atmosphere and is seen as being one of the primary contributors to global warming. Measurements conducted at the Mauna Loa observatory recorded global CO2 levels that exceeded 411 parts per million in May.