The total concentration of carbon dioxide (CO2) in the atmosphere is above 400 parts per million (ppm). It crossed the 400 mark a year or two ago with many expressions of concern from some and complete ignorance from most. I have come to see that part of the problem is people's poor grasp of mathematics, and the way different uses of words can result in different emotional responses. My genetic counselor friends are aware of this, and have commented that people may react quite differently if they are told that the risk of some genetic event affecting their kids is for example 5% (seems small) versus '1 in 20' which seems larger because 20 is a bigger number than 5 even though it's in the denominator. Of course 5% and 1 in 20 mean exactly the same thing mathematically.

With that in mind, 400 sounds like a big number, but a million is so much bigger that people, if they think about it at all, are likely to say it doesn't seem very dangerous. But, 410 (the number last June, a bit lower in Hawaii atop Mauna Loa today) ppm is the same as 0.041%. Even that seems small, until you search the internet and find out that it's been reported that exposure to 2% CO2 can cause headaches, nausea, and cognitive problems (quoted from http://www.aragonvalley.com/en/effects-of-co2-in-humans/ , which says original source is Scripps Oceanographic Institute, I haven't verified yet). So how bad is 0.04% versus 2%? It's 50 times lower, which means if we keep burning fossil fuels at the same rate as today or higher, in a few decades unless CO2 is removed more rapidly than currently occurs, OUR AIR WILL BE UNBREATHABLE.

Seems pretty trivial to talk about sea levels rising a few feet, or heat waves, or climate change in general, compared to WE WILL ASPHYXIATE.

So my mission is to get everyone to stop talking about CO2 in parts per million, and start talking about percent. Maybe that will scare more people, which it should because it scares me plenty.