Researchers Reconstruct 900 Years of Climatic History Using Tree Rings

Researchers have achieved the first long temperature reconstruction for the eastern Mediterranean using the stable carbon isotopes found in tree rings found in the region.

The study examines the months from January to May in order to target the period in which the trees shift from winter dormancy to springtime reactivation. In doing so, the researchers were able to reveal new insight into the climatic history of the region -- a subject largely shrouded in mystery.

In all, the researchers were able to piece together nearly 900 years of history, including the medieval warm period and "little ice age" that took place between the 16th and 19th century.

According to Ingo Heinrich from the GFZ German Research Center for Geosciences, the current warming trend was not uncovered in the new chronology.

"A comparison with seasonal meteorological data also demonstrates that at several places in the Mediterranean the winter and spring temperatures indicate long-term trends which are decreasing or at least not increasing," Heinrich said.

The researchers found that temperature reconstructions taken from sites in extreme topographical regions, such as high mountains, did not always reflect the climate of the geographical region, the study showed.

Furthermore, the carbon isotope ratios in the trees from Turkey indicated that the region's trees are especially sensitive to temperature during late winter and into early spring, with the cellular plant tissue known as cambium undergoing more damage than usual in cold winters. When this happens, the researchers found, the trees have to work extra hard to recover during the following spring.

The rate of photosynthesis, the data revealed, is also slowed during cold weather.

Heinrich concluded: "Our results stress the need for further research of the regional climate variations."