Cape Grim Station Marks 50 Years of Monitoring Global Atmospheric Changes

The Kennaook/Cape Grim Air Quality Testing Station, located on Tasmania's north-western coast, began operations in 1976. Managed jointly by the Bureau of Meteorology and CSIRO, the station measures baseline atmospheric composition. It features an 80-meter tower and facilities for continuous air sampling.

The site was established following observations of rising carbon dioxide levels in the early 1970s.

Graeme Pearman, a former CSIRO scientist, participated in the station's setup. In the early 1970s, Pearman measured CO2 concentrations above a wheat crop in Australia, finding levels similar to those recorded by Charles David Keeling in Hawaii. This similarity occurred despite differences between the hemispheres, one primarily oceanic and the other land-based with varying population densities.

Subsequent aircraft observations confirmed that CO2 levels were increasing globally, linked to fossil fuel use.

Plans for a permanent station followed over the next three years. Initial equipment was housed in a NASA caravan previously used during Apollo missions. The station draws air from inlets, including one at 80 meters on the tower, for 24-hour analysis.

Strong westerly winds from the Southern Ocean, known as the roaring forties, deliver air that has traveled thousands of kilometers without land contact, providing samples of global background atmosphere.

Cape Grim is one of three premier global baseline stations. Measurements at the site reflect global atmospheric conditions without local pollution. Melita Keywood, CSIRO scientist leading the aerosols and reactive gases program, stated that changes in these clean air samples indicate global shifts.

“Once we see a change in the clean air that we're measuring at Cape Grim, we know that something's happened globally. So that's what's really important about Cape Grim.”