Oxygen isotopic ratios in the dating of ice cores
Instead the sources appear to be in places like the Amazon Basin, southeast Asia, and tropical Africa — not so much the places with large human emissions of CO2!But CO2 is a well mixed gas so it’s not possible to definitively sort out the sources or sinks with CO2 measurements around the globe. Instead the way to unravel the puzzle is to look at the one long recording we have (at Mauna Loa, in Hawaii, going back to 1959) and graph the changes in CO2 and in C13 from year to year.The higher levels of CO2 in recent decades appear to be mostly due to natural sources.He presented this research at the IUGG conference in Melbourne recently, causing great discussion and shocking a few people.He’s been a visiting professorships at Paris, Stockholm, Jerusalem, and Kyoto, and he’s spent time at the Bureau of Meterology in Australia.
So if the C13 to C12 ratio is falling (as more C12 rich carbon is put into the air by burning fossil fuels) then we can’t know if it’s due to man-made CO2 or natural CO2 from plants.C12 makes up 99% of carbon in the atmosphere (nearly all atmospheric carbon is in the form of CO2). Plants don’t like the rarer C13 type as much; photosynthesis works best on the C12 -type -of-CO2 and not the C13-type when absorbing CO2 from the air.Prof Salby points out that while fossil fuels are richer in C12 than the atmosphere, so too is plant life on Earth, and there isn’t a lot of difference (just 2.6%) in the ratios of C13 to C12 in plants versus fossil fuels.Salby says he sat on the results for six months wondering if there was any other interpretation he could arrive at, and then, when he invited scientists he trusted and admired to comment on the paper, they also sat on it for half a year.
His speech created waves at the IUGG conference, and word is spreading.
A book will be released later this year: Physics of the Atmosphere and Climate. 5 we see that the yearly-average CO2 increase at Mauna Loa ends up being anywhere from 0% of the human source, to 130%.