Scientists from Heidelberg University have conducted a study to understand how past climate and vegetation changes in the Mediterranean region can help predict the effects of human-made climate change. They analyzed fossil pollen from a sediment core in Greece to examine the impact of natural climate fluctuations on Mediterranean forests over the past 500,000 years. The study suggests that if current drought conditions continue, as predicted by climate models, the Mediterranean forests may face desertification in the near future.
The Mediterranean forests are important for their biodiversity and services such as soil erosion protection, climate and hydrological regulation, and food and timber supply. These forests are also sensitive to climate change, which is becoming a concern due to human-caused CO2 emissions and global warming. Dr Andreas Koutsodendris, a member of the research group of Prof. Dr Jörg Pross, is investigating the environmental and ecosystem dynamics of the Earth at Heidelberg University's Institute of Earth Sciences.
To understand how Mediterranean forests have reacted to climate changes in the past, a group of scientists from Heidelberg University and other countries collected drill cores from Tenaghi Philippon in Greece. These cores provide a record of the past 500,000 years, and contain fossil pollen grains that give information about vegetation development. The scientists correlated this information with data on precipitation fluctuations. They found that in the past, Mediterranean forests turned into steppes within a few decades when certain levels of precipitation were crossed.
The scientists used ecological models to investigate what caused the changes in precipitation patterns. They found that changes in atmospheric CO2 levels affected the amount of precipitation in the Mediterranean region. Dr. Koutsodendris explained that in the past, a decrease in rainfall of 40 to 45 percent was enough to cause a sudden change from forest to steppe biomes. Therefore, if no action is taken to protect them, the forests of the Mediterranean region may undergo a similar change in the near future.
Funding for the research was provided by the German Research Foundation, the State of Hessen in the context of its state initiative for the development of scientific and economic excellence, and the Wilhelm Schuler Foundation. The research results were published in the journal Nature Communications.