400 or bust — next stop: 450?

"Current [atmospheric] CO2 values are more than 100 ppm higher than at any time in the last one million years (and maybe higher than any time in the last 25 million years)." — Climate scientist Dr. Charles Miller

CO2 Levels Reach Record-Breaking Milestone in Northern Hemisphere

By Jenna Iacurci

For the first time, carbon dioxide (CO2) levels have reached a record-breaking milestone, its monthly concentrations topping 400 parts per million (ppm) in April throughout the Northern Hemisphere, the World Meteorological Organization (WMO) reports.

This threshold reinforces the fact that human-caused greenhouse gas emissions are warming our planet to dangerous levels.

"Time is running out," warned WMO Secretary-General Michel Jarraud, according to a news release. "This should serve as yet another wakeup call about the constantly rising levels of greenhouse gases which are driving climate change. If we are to preserve our planet for future generations, we need urgent action to curb new emissions of these heat trapping gases."

The global annual average is set to exceed the 400 ppm level in 2015 or 2016, the agency added.

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