PRINN, Ron. Professor of Atmospheric Science at 83-Nobel-Laureate MIT: "We are actually at 478 ppm of CO2 equivalents right now."

Dr Ron Prinn (Professor of Atmospheric Science in 83-Nobel-Laureate MIT’s Department of Earth, Atmospheric and Planetary Sciences, Director of MIT’s Center for Global Change Science (CGCS), Co-Director of MIT’s Joint Program on the Science and Policy of Global Change (JPSPGC), and who studies the chemical evolution of atmospheres): “What’s not appreciated is that there are a whole lot of other greenhouse gases (GHGs) that have fundamentally changed the composition of our atmosphere since pre-industrial times: methane, nitrous oxide, chlorofluorocarbons (CFCs), and hydrofluorocarbons. The screen of your laptop is probably manufactured in Taiwan, Japan, and Eastern China by a process that releases nitrogen trifluoride—release of 1 ton of nitrogen trifluoride is equivalent to 16,800 tons of CO₂. But there is a fix to that—the contaminated air in the factory could be incinerated to destroy the nitrogen trifluoride before it’s released into the environment. Many of these other gases are increasing percentage-wise faster than CO₂ . In the Advanced Global Atmospheric Gases Experiment (AGAGE), we continuously measure over 40 of these other GHGs in real time over the globe. If you convert these other GHGs into their equivalent amounts of CO₂ that will have the same effect on climate, and add them to the NOAA measurements of CO₂, you find that we are actually at 478 ppm of CO₂ equivalents right now. In fact, we passed the 400 ppm back in about 1985. So, 478 not 400 is the real number to watch. That’s the number people should be talking about when it comes to climate change” (Ron Prinn, “400 ppm CO2? Add other GHGs and its equivalent to 478 ppm”, Oceans at MIT, 6 June 2013: http://oceans.mit.edu/featured-stories/5-questions-mits-ron-prinn-400-ppm-threshold ).

[Editor’s note: the IPCC argues for a limitation of temperature rise to 2^oC through limiting greenhouse gas (GHG) pollution of the atmosphere to 450 ppm CO2 -equivalent (see The IPCC, “Climate Change 2014 Synthesis Report, Approved Summary for Policy Makers”, 1 November 2014: http://www.ipcc.ch/pdf/assessment-report/ar5/syr/SYR_AR5_SPM.pdf) but Professor Prinn says that we have already reached 478 ppm CO2-equivalent].