About 1400 kilometers east of the Philippines lies the archipelago of Palau in the West Pacific. Here, the air is particularly pure and low in pollutants - perfect conditions for studying the distribution of particles in the atmosphere and their influence on the climate worldwide. The Alfred Wegener Institute has been operating the Palau Atmospheric Observatory here since 2015, together with the University of Bremen, the Palau Community College and the Coral Reef Research Foundation. Now a delegation led by German Foreign Minister Annalena Baerbock has visited the observatory and learned about the latest findings.
On the campus of Palau Community College in Koror, stands the Palau Atmospheric Observatory (PAO). It was established in 2015, as part of the European StratoClim research project that investigated the role of the stratosphere in the climate system. From here, the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and its partners study the composition of the atmosphere in the region. Processes that take place here influence weather and climate worldwide, across Europe to the Arctic. Scientist Dr. Katrin Müller has now given an overview of the latest research results of the Atmospheric Physics Section at AWI to Foreign Minister Annalena Baerbock and a German delegation on site. In addition to the observatory, the group visited an island in the Rock Islands that has been devastated by climate change, as well as a taro plantation that has been flooded by salt water and is no longer usable.
How the air over Palau affects the polar regions
Palau is a strategically important location for atmospheric research. Here, one of two global "elevators" to the stratosphere operates: air rises from the ground in massive thunderstorm towers to an altitude of 18 kilometers, from where it slowly, almost unopposedly moves to the stratosphere, the second level of our atmosphere where the ozone layer is located. From there, the air is transported further towards the poles. Pollutants that enter the atmosphere over Palau can thus affect the chemical composition of the entire stratosphere and, for example, deplete ozone at the poles as well.
"What enters the stratosphere over the Palau region affects climate worldwide. Here, sulfur and halogen compounds are transported to higher layers of air, where they influence a large number of climate processes and also contribute to polar ozone loss. We understand this loss quite well, but there are still inconsistencies between measurements and models," says Prof. Markus Rex of the AWI. To resolve these discrepancies, the atmospheric scientist and his team led by Dr. Katrin Müller have started a series of measurements at PAO to continuously observe ozone and aerosols in the lower part of the atmosphere, the troposphere. Ozone acts as a greenhouse gas in the troposphere and is an indicator of air pollution from forest fires or industry, for example.
"We have observed the complex interplay of transport and chemical processes in the atmosphere over an extended period of time. This allows us to understand for the first time how tropospheric ozone develops over Palau during the seasons and how ozone-rich air from distant regions is transported into the otherwise clean air column over Palau," says Katrin Müller.