The Mauna Loa readings of atmospheric carbon dioxide for July 2014 (monthly mid month mean) were 399 parts per million, which was a rise of 1.8 parts per million compared with July 2013. The measuring site is 3400 metres above sea level, and concentrations are marginally higher there than at sea level. the monthly mean for marine sea level sites for July 2014 was 397.82.
Mauna Loa has the longest continuous record of carbon dioxide concentration, stretching back 130 years. It shows that each year carbon dioxide concentration has risen, but rises in a stepped way, so that measured concentrations in summer fall, compared with the previous few months, but nevertheless rise when compared with the previous summer.
The year on year rise in atmospheric concentration is such that by next summer I expect measurements to show a consistent reading for each month in excess of 400 part per million.
Quite where this takes our climate, no one knows. Some take succor in the argument that there has been a global warming pause in the past ten years, but they take false succor from that, because it is not true. There has been nearly a pause (in fact a very slight rise) in land surface global warming in the past ten years, but only one third of the surface of the planet is covered by land; there has been a significant rise is sea temperature over the past ten years, but ten years, within the context of a global warming trend, is not significant. The UK’s Met Office thinks that trends should be taken from at least thirty year periods, and on this basis the odd pause in global warming appears to happen about twice every century.
Filed under: carbon emissions, climate change, energy, global warming | Tagged: atmospheric carbon dioxide, carbon dioxide concentration, carbon dioxide Mauna Loa, climate change, global warming, mauna loa, sea level |