World heritage under threat from global warming

In 2002, a so-called 100-year flood put large parts of Dresden under water — and threatened numerous cultural treasures. The baroque Zwinger palace was also flooded. The city founded a task force to be prepared for future extreme weather events. Today there are global efforts underway to use climate modelling to better plan for the protection of cultural monuments in the future.

The city, built on islands, struggles against the influences of water anyway, but climate change means that natural disasters such as the 2019 floods will become more frequent. The recital hall of the opera (above) was under water, as were palaces and churches. Researchers are not only examining such extreme weather events, but also the long-term effects of climate change.

In the past, high humidity was a particular problem for cultural assets. Now, it is the increasingly dry air. This is also the case in the baroque Moritzburg castle in Saxony, where there is a large collection of baroque leather wallpapers. Their paintings have already been extensively refurbished, as they showed damage such as shrinkage cracks. These can be traced to periods of extreme heat.

A historical city wall encircles the city of Gubbio in Italy's central Umbria region. Like the palazzo and its archaeological excavations, the wall is threatened by shifting foundations and moisture. Part of the city wall collapsed after rain loosened the mortar and stones fell out. A European research team is using electromagnetic scans to assess the structural health of the ancient monuments.

The fortress of Koules stands guard at the entrance to the Cretan capital's harbor, as it has since the early 16th century. Although it has withstood a lot over the centuries, changing wave patterns are now eroding the building. Climate change has caused a change in wind patterns, altering the wave direction. The salt water penetrates and erodes the walls, damaging the monument.

The UNESCO World Heritage Site has existed for more than 4,000 years. Now moles churn the ground in such a way that it threatens to collapse in the long term. Behind this is a climate-related cycle: Mild winters increase the mole population and earthworms, a preferred food for moles, multiply due to warmer and more humid soil conditions. Heavy rains also saturate the soil.

Wismar's old town, with its historic gabled buildings and waterworks (see photo) is as culturally important as the old towns of Lübeck and Stralsund. In the long term, all three cities are threatened by rising sea levels. If global warming continues unchecked, future archaeologists will have to search for our heritage underwater. The city centers of Naples, Bruges and Istanbul are also at risk.

Climate change affects more than just buildings and the treasures housed within. Historic parks and gardens, such as the one surrounding the Sanssouci Palace in Potsdam near Berlin, must also be prepared for new climatic conditions. Several projects are testing models to improve the resistance of plants, as well as adjusting the planted species to better withstand new climatic conditions.