CSIRO High-precision Measurement of Atmospheric CO2 Concentration in Australia. Part 2: Cape Grim, Surface CO2 Measurements and Carbon Cycle Modelling

Abstract

A companion paper discusses the history of, and rationale for, the development of a CSIRO programme of atmospheric carbondioxide (CO2) concentration measurements in Australia based on aircraft air sampling, field and laboratory measurements.1 Here, we describe parallel efforts to establish a permanent, ground-based atmospheric Baseline Station at Cape Grim, north-west Tasmania, the political activity required for its establishment, and the work undertaken to select a site commensurate with its long-term objectives. Additional CO2 measurements undertaken to complement the aircraft and Cape Grim measurements are discussed. The development of the Australian Baseline Station was part of an emerging international effort to obtain high-precision measurements of trace gas and aerosol composition of the atmosphere, and to quantify any changes in composition that might be occurring and their possible impact on global climate.We discuss the early development of global carbon cycle models, including the representations of atmospheric transport, and the interpretation of modern atmospheric CO2 data and historic air samples encapsulated in Antarctic ice and firn. The accumulated knowledge from these research activities, together with that collected by international colleagues, forms the basis of our understanding of changes occurring in CO2 concentration. It has contributed to an understanding of the mechanisms of the past and present biogeochemical cycling of CO2, providing predictions of future changes in CO2 concentration.