Ancient climate records back global warming predictions: report

Scientists studied relationship between CO2 levels and climate change of a warm phase in history to estimate how climate will respond to increasing CO2 levels

By Geetika Singh
Published: Monday 09 February 2015


Current predictions on climate change can be backed by the past records of carbon dioxide in the atmosphere millions of years ago, says a recent study published in the science journal Nature.
The findings from this research are in tandem with the future projections made by the Intergovernmental Panel on Climate Change (IPCC). Evidence from the last warm phase in Earth’s history indicates that the climate will respond the rising level of CO2 as has been predicted. 

Ancient plankton fossils drilled from the ocean floor were key to solving this mystery. Shells of these creatures gave clue about the global climate pattern cycling between Pleistocene epoch (the period that lasted from about 2.5 million years to 11,700 years ago) and Pliocene epoch (the period that extends from 5.3 million to 2.6million years before present).The climate during the epochs moved from cool to warm.

UK and Australian scientists used these ancient records to recreate the CO2 content of the Earth’s atmosphere, and compared it to the CO2 record acquired from the bubbles of ancient atmosphere which had remained trapped in the ice drilled from the Polar Regions.

Scientists also studied the relationship between CO2 levels and climate change of a warm phase in Earth’s history and came to estimate how climate will respond to increasing levels of CO2, a parameter known as climate sensitivity.

Professor Richard Pancost of the UK’s University of Bristol Cabot Institute said, "when we account for the influence of the ice sheets, we confirm that the Earth's climate changed with a similar sensitivity to overall (radiative) forcing during both warmer and colder climates."

In the Pliocene epoch, the temperature was quiet often much higher than in the pre-industrial era. The atmospheric level of CO2 were similar to the levels reached over the past few years (400 ppm) at around 350-450 parts per million (ppm).

Co-researcher Gavin Foster of Southampton University stated, “We have shown that the change in Earth's temperature for a given change in CO2, once the effect of the growth and retreat of the highly reflective continental ice sheets was taken into account, was not only identical during both the cold Pleistocene and warm Pliocene periods, but was also similar to the understanding recently summarised by the IPCC."

Commenting on the future predictions of climate, he said, “This implies that as we approach a Pliocene-like future, the IPCC range of climate sensitivity is likely to be suitable for describing the degree of warming we should expect.”

So, it turns out that greenhouse gases like carbon dioxide played a significant role in governing the global climate way back in Earth’s history. The lesson which we as a civilisation should be mindful of is that the climate system is delicately poised, even a little stimulus might dive a great change.

Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records

Subscribe to Daily Newsletter :
Related Stories

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.