The data are updated monthly from analyses of air measurements at Cape Grim, which, under baseline conditions, experiences some of the cleanest air in the world and accurately reflects global changes in greenhouse gases.

The atmospheric level of carbon dioxide, which is the most important long-lived greenhouse gas influenced by human activities, is at its highest level in more than a million years. It is currently increasing at about 0.5 per cent each year.

—Dr. Paul Fraser from CSIRO Marine and Atmospheric Research

Dr. Fraser, who has been analysing atmospheric greenhouse gas concentrations for more than 35 years, says it is important to ensure that the community at large has access to data that clearly illustrate the impact of human activities on the atmosphere.

The measurements testify to a steady rise in carbon dioxide concentrations in the Earth’s atmosphere, mainly caused by the burning of fossil fuels and deforestation. The graphs we’ve made available online will enable people to examine the evidence about the major driver of recent climate change. This is fundamental information in determining the global actions needed to avoid greenhouse gases rising to dangerous levels.

—Paul Fraser

The website employs a dynamic interface to allow users to analyse the behaviour of the three important greenhouse gases influenced directly by human activities and natural variability: carbon dioxide, methane and nitrous oxide. Data for the synthetic greenhouse and ozone depleting gases, such as CFCs, also are available. Water vapor, although an important greenhouse gas, is not significantly influenced directly by human activities.

The website puts the increase in greenhouse gas concentrations over recent decades in the context of longer-term variations over the past 1,000 years—determined by analysing air extracted from tiny bubbles trapped in the Antarctic ice. Dr Fraser says carbon dioxide is currently rising at nearly 2 parts per million molar (ppm) per year.