Make no mistake about it, today is a day that we never thought we’d see happen. Despite the decades spent fighting climate change, today’s news shows us how far we still have to go and how much harder we all have to work.

The National Oceanic and Atmospheric Administration (NOAA) recently announced that the amount of carbon dioxide in the Earth’s atmosphere reached 419 parts per million in May. This alarming new milestone has alerted us to a reality of living in a world with an atmosphere not seen in four million years.

Now more than ever, the efforts for nations to cut carbon emissions and other greenhouse gases must be intensified.