Carbon dioxide is a greenhouse gas that remains in the atmosphere for hundreds of years. The amount of carbon dioxide in Earth's atmosphere reached 419 parts per million in May, its highest level in more than four million years. We should take it as warning and take real action.
"We are adding roughly 40 billion metric tons of CO2 pollution to the atmosphere per year," said Pieter Tans, a senior scientist with NOAA's Global Monitoring Laboratory, in a statement. "If we want to avoid catastrophic climate change, the highest priority must be to reduce CO2 pollution to zero at the earliest possible date."