A coalition of local environmental groups gather in Washington, DC, to introduce the number 350 - as in 350 parts per million of CO2 in the Earth's atmosphere - as part of an International Day of Climate Action. Many climate scientists point to that number as the tipping point where global warming starts to impact the planet. The current amount of CO2 in the atmosphere is around 390 parts per million.
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Produced by <a href="mailto:email@example.com">Andrew Satter / CQ-Roll Call Group</a>