Scientists at Mainz University study ice cores as a climate archive

JGU research team will focus on paleovegetation and wildfires

20 December 2019

Humans have a major impact on the climate. But what exactly was the climate like, say 10,000 years ago? What sort of vegetation was around at the time? These are two of the aspects scientists are investigating by looking at specific inclusions in ice cores. Until recently, the research focus was on inorganic compounds such as carbon dioxide, trace elements, or oxygen isotopes. However, the conclusions that could be drawn from this research were limited, since the results related first and foremost only to the temperatures at the time.

Beech, oak, or alder?

Researchers at Johannes Gutenberg University Mainz (JGU) now chose an approach that yields significantly more information. "Instead of only analyzing inorganic substances, we are currently focusing on the organic compounds trapped in ice cores," explained Professor Thorsten Hoffmann of the JGU Institute of Inorganic Chemistry and Analytical Chemistry. "This might answer some of our questions about the vegetation – not only whether coniferous forest, deciduous forest, or grassland predominated, but also about the distribution of different deciduous tree species."

Forests release huge amounts of organic compounds such as isoprene and terpenes into the air. These are the very substances responsible for the characteristic smell of coniferous forests. However, these compounds are rapidly oxidized in the atmosphere where they subsequently form aerosol particles. These particles can remain in the atmosphere for about ten days, which is long enough for them to be distributed around the globe. They also serve as condensation nuclei for cloud formation. Incorporated into raindrops or even snowflakes, they return to the ground and can remain preserved in glacier ice for thousands of years.

The JGU research team hopes that this approach will also help them generate data about wildfires in the past, so that they can determine how frequent and intense they were and the kind of vegetation that was burned. The presence of soot in ice cores also provides some insights into such fires, but the information is not always conclusive. "Organic markers can add to our findings and significantly expand the spectrum of available information," Hoffman pointed out.

160 meters of climate history

Scientists from the Paul Scherrer Institute in Switzerland extracted the 160-meter-long ice cores from a continental glacier in the Altai Mountains in Russia, camping there for several weeks. Before scanning the valuable ice samples with their spectrometers, the experts from Mainz are currently busy identifying suitable marker substances while also refining and optimizing the analytical techniques and measuring systems used for each substance to ensure that the results they obtain are reproducible. Investigation of the actual ice cores will start in 2020.