A lake in the north western region of Spain, known as the Principality of Asturias, is revealing data of climatic changes as far back as 12,000 years ago. Lake Enol was formed by a retreating glacier 40,000 years ago and, as the lake began to grow and deepen, then so did the organic sediment. Now a team of researchers comprising members from the Universities of Zaragoza, La Coruna, Valencia and Cadiz, together with members of the Pyrenean Institute of Ecology, have been examining the sediment. What they have found shows that, what had been thought of as a stable climatic period, was in fact quite turbulent.
     Their findings have centred around two types of studies. The first was a study of the physical composition of the sediment, including the quantity of organic carbon. The second centred around the study of the pollen which had been trapped in the sediment. These studies revealed 4 distinct climatic phases. Stage one (11,500 to 9,600 BCE) was cold and dry. Stage two (9,600 to 6,700 BCE) was warmer and more humid. Stage three (6,700 to 2,650 BCE) swung back to drier and this, in turn, was followed by another humid period. Also revealing was the study of the sediment for the last 200 years. This mapped the changes farming and grazing had precipitated in plant types and growth.

Edited from EurekAlert! (3 February 2012)