A complete record of greenhouse gases

Australian scientists, led by CSIRO’s Climate Science Centre and the University of Melbourne, have published the most comprehensive and high-quality records of greenhouse gases ever. The records track the past and current changes in all 43 greenhouse gases that contribute to human-induced climate change.

CSIRO Principal Research Scientist and report co-author Dr David Etheridge said the paper is one of the largest Australian contributions to global climate change assessments ever, claiming its record of the past 2000 years “has been meticulously constructed by combining greenhouse gas measurements from dozens of laboratories around the world”.

“We took data from contemporary and archived air samples and from air trapped in ice bubbles in polar ice cores and compacted snow, also called firn,” Dr Etheridge said.

Australia is a major contributor to the global greenhouse gas record, using observations from the Bureau of Meteorology’s Cape Grim station in northwest Tasmania and from the Cape Grim Air Archive. CSIRO, the Australian Antarctic Division, the Australian Nuclear Science and Technology Organisation and other collaborators are also the primary source of greenhouse gas data in the pre-instrumental era, using measurements from air extracted from Antarctic ice and firn.

The record includes a set of 43 distinctive greenhouse gases that are released into the atmosphere as a result of human activities and industrial processes. According to Dr Etheridge, “These observations clearly show the relentless and near-continuous rise of some of the most important greenhouse gases like carbon dioxide, methane and nitrous oxide since 1750.”

Dr Etheridge added that a comprehensive database of measurements was combined with information on aerosol, solar, volcanic and land-use impacts on climate to accurately simulate observed climate over past centuries in climate models.

Lead author Dr Malte Meinshausen, from the University of Melbourne’s Australian-German Climate & Energy College, said the newly published database of continuous and high-quality data will drive global climate model simulations currently being conducted by international modelling groups ahead of the next Intergovernmental Panel on Climate Change (IPCC) assessment report, due in 2021–2022.

“Following the marathon of decades of efforts in Australia and around the world to collect and process all those data, our study was taking the last step of putting it all together into one coherent picture,” Dr Meinshausen said.

The paper has been published in the journal Geoscientific Model Development.

Image caption: Data from the Cape Grim Air Pollution Baseline Station has been used to create the most comprehensive collection of greenhouse gas data.