The CO,concentration has increased markedly in the 21st century,at a rate of 2.0 ppm/yr 400 Atmospheric Carbon Dioxide Measured at Mauna Loa,Hawaii 380 夏威夷空气的CO2浓度逐年增加 360 M 全年C02浓度变化 Annual Cycle 340 320 Jan Apr Jul Oct Jan 1960 1970 1980 1990 2000 2010 The Keeling Curve of atmospheric CO2 concentrations measured at the Mauna Loa Observatory.The Keeling Curve of atmospheric CO2 concentrations measured at the Mauna Loa Observatory. The CO2 concentration has increased markedly in the 21st century, at a rate of 2.0 ppm/yr 夏威夷空气的CO2浓度逐年增加 全年CO2浓度变化