"The MLO" is the Mauna Loa Observatory in Hawaii, USA. This is the famous but remote station where scientists have been measuring CO2 in the air for the longest time. Data at Mauna Loa produced the iconic Keeling Curve. The pioneering work of Charles David Keeling provided key, new insights about how the earth system works.
Halcyon's 52:52:52 campaign on Twitter, starting in early 2020, will help you address 52 issues with 52 responses over 52 weeks.