As I looked into global CO2 levels for the purposes of writing this blog I very quickly saw through both the module and outside scientific publications that we as a species are nearing a record level for carbon dioxide concentration. 400 Parts per million. The last time the planet had that level of concentration of CO2 modern humans weren’t around.

Some scientists argue about when exactly it was that it was this high, but the range can be estimated to be between 2.5 and 5.3 million years ago. At this point in time the earth was on average 11 degrees warmer (on a fahrenheit scale that’s about 12 degrees celsius.) oceans were about 100 feet higher, and gigantic sea sharks were in that ocean. Suffice it to say nothing about this time in the Earth’s history sounds like a great place to be.

Measuring CO2 levels is important because apparently it’s the longest living greenhouse gas. So if we really want to take a good measurement of the temperature of the earth in 2050, that’s what one would use.

Apparently to make a guess at what the temperature of the earth was hundreds of thousands of years ago scientists would have to use oxygen isotopes from ice cores. This clicked in my brain because it reminded me of the novella “At the Mountains of Madness” which is about finding spooky alien skeletons in ice cores. I guess I’v elearned a lot already in the first week of this class.

http://www.climatecentral.org/news/the-last-time-co2-was-this-high-humans-didnt-exist-15938

http://www.psmag.com/nature-and-technology/whens-the-last-time-our-co2-levels-were-this-high