A remarkable run of observations began 60 years ago at a weather station high on a volcano in Hawaii. Charles Keeling began monitoring carbon dioxide in the clean air at 3,400 metres (11,150ft) on Mauna Loa, far away from vegetation and urban pollution. His first measurements in 1958 showed 315 parts per million (ppm) of CO 2 in the atmosphere, and what caught him by surprise was that every year after that the levels of CO 2 rose relentlessly in an upward curve, thanks to the carbon pollution pumped into the Earth’s atmosphere.



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Now the CO 2 has reached more than 400ppm, probably the highest for 800,000 years. It sounds a tiny amount of extra CO 2 , but it is having a huge impact on the climate by trapping more heat on Earth, driving world temperatures upwards. CO 2 in the air is now so plentiful that plants are growing fewer leaf pores to absorb the gas than they did centuries ago, and more CO 2 is being absorbed into the world’s seas, making them more acidic.



Keeling’s curve of rising CO 2 levels is a shocking picture of how much the world’s atmosphere has changed in 60 years, with no end in sight.



