Dear Friends
There were a couple of inaccurate statements made in the past few days about the recording (since the 1950's) of CO2, its level now and its level over the period of time during which measurements have been made. CO2 has been measured for 185 years first using a chemical process (some 10's of thousands of measurements made at many locations). The precision ranges from extremely good (better than 1 part in 1000) to 1 part in 30. http://www.anenglishmanscastle.com/180_years_accurate_Co2_Chemical_Methods.p df This work has been ignored by the IPCC which for some reason claims the level was constant and less than 300 ppm, ignoring actual measurements. CO2 has been measured in Hawaii since the late 1950's using a different method. After a while it was upgraded. It shows a clear annual variation that coincides with northern hemisphere Spring and the melting of a huge amount of continental and Arctic ice and snow creating fresh water which absorbs a great deal of CO2 - about 1125 ppm, drawing down the concentration by about 6 ppm until the re-freezing starts again. The CO2 concentration in the atmosphere rises and falls when the climate changes (see Figs 1 and 2 at the link immediately above) Correction to the other post: The current CO2 concentration has not risen above 400 ppm - a correction was issued by NOAA (you heard about the correction in the media, right?) http://wattsupwiththat.com/2013/05/13/premature-400-ppm-fail-a-bration/#more -86162 http://www.latimes.com/news/science/sciencenow/la-sci-sn-carbon-dioxide-400- 20130513,0,7196126.story >From the LA Times article: "For the previous 800,000 years, CO2 levels never exceeded 300 ppm, and." This comment is erroneous and is contradicted by multiple sources. As ice cores show, the CO2 level lags temperature rises by about 800 years. As it was significantly (about 2 Deg C) warmer during the Minoan Climate optimum than it is now, it is highly likely that the CO2 level responded as normal during those millennia which means it rose. As there exist thousands of CO2 measurements made during a period long enough to experience significant climate cycles the idea that the temperature and the CO2 level were constant cannot be supported. Temperature, most importantly ocean temperature, has a significant though delayed effect on the CO2 concentration. How much has been contributed by burning fossil fuels is not clear as studies (based on isotopes) are not in agreement. Ocean heat content, the main determinant of atmospheric temperatures, is a relatively new field of study and has been brilliantly captured by Bob Tisdale in his book on the subject. See http://wattsupwiththat.com/2013/05/14/multidecadal-variations-and-sea-surfac e-temperature-reconstructions/#more-86210 for his most recent study (aimed at non-experts so it is quite appropriate). Regards Crispin
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