Scientists are warning the planet has now reached a grim climate milestone not seen for two or three million years. The National Oceanic and Atmospheric Administration says the amount of heat-trapping carbon dioxide in the atmosphere has topped 400 parts per million. The 400 ppm threshold has been an important marker in U.N. climate change negotiations, widely recognized as a dangerous level that could drastically worsen human-caused global warming. Democracy Now! speaks to leading climate scientist Michael Mann, author of the recent book, “The Hockey Stick and the Climate Wars: Dispatches from the Front Lines.” Mann warns, “If we continue to burn fossil fuels at accelerating rates, if we continue with business as usual, we will cross the 450 parts per million limit in a matter of maybe a couple of decades. With that amount of CO2 in the atmosphere, we commit to what could truly be described as dangerous and irreversible changes in our climate. … Mitigating climate change is in fact a planetary insurance policy.
When asked about the Keystone XL pipeline proposal, he adds: "We’re actually simply developing more and more of the available fossil fuel reserves at a time when we have to be ramping them down.”
