This March, global levels of CO2 passed 400 parts per million.
Although short-term local measurements of 400 ppm have been recorded previously, this marks the first time since record keeping began that CO2 levels were above 400 ppm globally for a month.
Already we're seeing the deadly effects of climate change in the form of rising seas, monster storms, wildfires, and extreme weather of all kinds. Passing 400 ppm is an ominous sign of what might come next -- and it sends a clear signal that the world must act ahead of the UN climate talks in Paris this December.
The safe level of carbon dioxide in the atmosphere is 350 parts per million. The only way to get there is to immediately transition the global economy away from fossil fuels and into into renewable energy, energy efficiency, and sustainable farming practices.
The last time CO2 levels were this high, humans did not exist. Our dependence on fossil fuels is fundamentally changing the nature of the planet -- and it's time to act.