A new study has offered stronger evidence to the current predictions on climate change from the United Nations’ (UN) Intergovernmental Panel on Climate Change (IPCC) as it has uncovered records of green house gas carbon dioxide in the atmosphere millions of years ago.
An international team of researchers at the University of Southampton has studied the new records that showed the carbon dioxide content present in the Earth’s atmosphere between 2.3 and 3.3 million years ago, over the Pliocene.
Our living planet was approximately 2 degree C warmer than it is in present day during the Pliocene, while atmospheric carbon dioxide levels were roughly 350-400 parts per million (ppm), which is similar to the levels in recent years.
By analyzing the link between climate change and carbon dioxide levels during a warmer period in the history of the Earth, the scientists successfully estimated how the climate will be responding to the rising levels of CO2. This is a parameter called climate sensitivity. The study of the relationship between the two will also help in showing how it can vary over the long term.
According to study co-author Gavin Foster, the Earth is still trying to adjust to the recent rapid CO2 increase caused due to human activities, while the longer-term Pliocene records document the complete response of warming related to CO2.
Miguel Martinez-Boti, study lead author, said that their new records revealed a crucial change at nearly 2.8 million years ago, when levels quickly declined to values of nearly 280 ppm, similar to those witnessed prior to the industrial revolution.
According to Martinez-Boti, this has further led to a dramatic global cooling which started the ice-age cycles that have largely dominated the climate of the Earth ever since.
Foster added that the climate sensitivity estimates lie within the range of 1.5 to 4.5 degree C surge per doubling of CO2, which was briefed in the latest IPCC report.
The findings of the study were published in the journal Nature.