According to the National Oceanic and Atmospheric Administration (NOAA), the amount of carbon dioxide (CO2) in the Earth’s atmosphere reached 419 parts per million in May. These are the highest carbon dioxide levels in over four million years.
The last time that the atmosphere held comparable levels of CO2 was during the Pliocene period, when the Earth looked completely different from what it does today. Sea levels were 78 feet higher, temperatures were 7 degrees Fahrenheit warmer and large forests covered parts of the Arctic tundra.
What do these record CO2 emissions mean for climate change? The atmosphere acts as a heat-trapping blanket. Greenhouse gases, like CO2, keep temperatures on Earth comfortable for human survival.