Since 1958, initially under the direction of Charles Keeling, followed by his son Ralph and later Elmer Robinson, Mauna Loa Observatory (MLO) has been monitoring and collecting data relating to atmospheric change, and is known especially for the continuous monitoring of atmospheric carbon dioxide (CO2), which is sometimes referred to as the Keeling Curve. The observatory is under the Earth System Research Laboratory which is part of the National Oceanic and Atmospheric Administration (NOAA). According to the NOAA, Mauna Loa is the world's oldest continuous CO2 monitoring station, and the world's primary benchmark site for measurement of the gas.