A new worldwide database charting the levels of 43 greenhouse gases over 2,000 years provides the clearest evidence yet that global warming is being caused by human activity.
Scientists from the Australian-German Climate and Energy College at the University of Melbourne, have created the database by collating historical and contemporary information on greenhouse gas levels, including from samples of air trapped in bubbles in ice cores at the North and South Poles.
The samples show a marked rise in the levels of carbon dioxide, methane, nitrous oxide and other greenhouse gases since the Industrial Revolution, and particularly since 1950.
The lead author of the study, Malte Meinhausen, says that the numbers tell us the story we already know, ‘only in more details and more colour’.
“If we look at the whole 800,000 years of this Earth’s history, we never had such big greenhouse gas concentrations ~ of CO2, of methane, and of a lot of other gases… so we are doing an immense experiment with the planet and we are seeing the effects right now.”
The study also showed humanity’s power to reverse these changes, as the authors note that levels of CFCs have dropped steadily since they were phased out due to the Montreal Protocol in the late 1980s. However, these gases are still making a large contribution to global warming.
The data will be used by scientists to create more detailed and accurate models of how climate change affects the planet we call home by looking at temperatures, weather patterns, sea level rise, and ice melting in relation to greenhouse gas levels. It will also be used to inform the Intergovernmental Panel on Climate Change’s next assessment report in 2021.
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