The most famous graph in all of Earth science is the Keeling curve. This graph is the result of the persistence, vision, and skill of Charles David Keeling (1928–2005). It shows the results of measuring atmospheric carbon dioxide concentrations or amounts since 1958. There was no instrument to measure CO2 concentrations accurately until Keeling invented one. Keeling showed the rest of humanity that the amount of CO2 in the atmosphere can be measured accurately, that it is increasing, and that the increase is due to human causes, mainly burning fossil fuels: coal, oil, and natural gas. His attention to detail and his passion for accuracy were legendary. His measurements of atmospheric CO2 are universally acknowledged to be rock-solid. The measurements are now being carried on by other scientists, including his son, Ralph Keeling. CO2 is only part of the human-caused strengthening of the greenhouse effect. Additional strengthening is due to methane, nitrous oxide, ozone, chlorofluorocarbons, and a few other greenhouse gases, plus some small particles, called aerosols.