Washington, June 17 : In a new research, a team of scientists has investigated the climate of planet Earth as it was 440 million years ago, and have found that an ancient Ice Age, once regarded as a brief ‘blip’, in fact lasted for 30 million years.

The research, by geologists at the University of Leicester, UK, suggests that during this ancient Ice Age, global warming was curbed through the burial of organic carbon that eventually lead to the formation of oil, including the ‘hot shales’ of north Africa and Arabia which constitute the world’s most productive oil source rock.

The Ice Age occurred in the Ordovician and Silurian Periods of geological time (part of the Early Palaeozoic Era), an interval that witnessed a major diversification of early marine animals including trilobites and primitive fish as well as the emergence of the first land plants.

The Early Palaeozoic climate had long been considered characterized by essentially greenhouse conditions with elevated atmospheric CO2 and warm temperatures extending to high latitudes, and only brief snaps of frigid climate.

However, during his doctoral studies in the internationally renowned Palaeobiology Research Group of the University of Leicester, Department of Geology, Dr Alex Page and his colleagues Jan Zalasiewicz and Mark Williams, demonstrated how the ice age was probably of much longer duration.

The team demonstrated that the Late Ordovician and Early Silurian Epochs were characterized by widespread ice formation, with changes in the extent of continental glaciation resulting in rapid sea level changes around the globe.

They compared evidence of sea level change from the rock record of ancient coastlines, with evidence of sediments being deposited by glacial meltwaters or ice rafting at high latitudes, and with chemical indicators of temperature in the strata.

The team showed that although the Early Palaeozoic Icehouse was of similar extent and duration to the modern ice age, the workings of the carbon cycle appeared markedly different to that of the present day.

Unlike the modern oceans, the oceans of the Early Palaeozoic were often oxygen-starved ‘dead zones’ leading to the burial of plankton-derived carbon in the sea floor sediments.

The strata produced in this way include the ‘hot shales’ of north Africa and Arabia which constitute the world’s most productive oil source rock.

In fact, the burial of organic carbon derived from fossil plankton may have served to draw down CO2 from the atmosphere to promote cooling during the Early Palaeozoic Icehouse. (ANI)