Not So Hot
Introduction
Around 50 million years ago, Earth was the hottest in the planet's history. But new evidence indicates the temperature may not have been quite as high as previously thought. Scientists analysed chemical signatures trapped in the fossilised shells of molluscs that lived in what is now Alabama.
The study suggests that during the Eocene era, water temperatures in the subtropics hovered around 27°C, slightly cooler than earlier studies predicted. Also, previous studies suggested that at that time, Earth's polar regions were very hot— 30°C. Modern temperatures in the study area average 24°C. Geology,
Source
Down To Earth, August, 2011