It seems that clouds may hold the key to what scientists call our planet’s supergreenhouse episodes.
Climate experts know it was much warmer during the Cretaceous and Eocene periods, roughly between 146 and 35 million years ago. Average temperatures in the tropics were above 100 degrees Fahrenheit and polar temperatures were in the 50-degree Fahrenheit range.
Previously, they worked on the theory that increases in gases like carbon dioxide caused the warming. Now they believe it was reduced cloud cover, which in turn changed the Earth’s albedo (the amount of sunlight reflected into space).
According to researchers, there may have been changes in the production of cloud condensation nuclei, the tiny particles around which water condenses to form rain drops and cloud droplets. This would have led to fewer and less bright clouds and increased the sun’s warming effect.