London, Feb 29 (IANS) The mystery surrounding the formation of the Antarctic ice sheet - particularly its effect on ocean temperature - has been solved. Or so contends a new study. Cardiff University researchers say they solved the mystery by travelling to Tanzania and studying the temperature records of microfossils in ancient sea-floor mud, Sciencedaily.com reported.

The Antarctic ice sheet formation is one of the most important climatic shifts in earth’s history.

Scientists have, however, been puzzled by previous temperature records which suggest the oceans warmed, rather than cooled, during this period.

The Cardiff researchers, led by Carrie Lear, used the shell chemistry of pinhead-sized animals called foraminifera or forams to conclude that ocean temperatures did in fact cool by about 2.5 degrees Celsius.

“Forams are great tools for studying climates of the past. These new records help resolve a long-standing puzzle regarding the extent of ice-sheet growth versus global cooling, and bring climate proxy records into line with climate model simulations,” Lear said.

The team will now look for evidence of the ultimate cause of the global cooling using these Tanzanian microfossils.

They believe the prime suspect is a gradual reduction of carbon dioxide in the atmosphere, combined with a ‘trigger’ time when earth’s orbit around the sun made Antarctic summers cold enough for ice to be frozen all year round.