An expert witness said a tidal wave emanating from a melting glacial lake is unlikely, as an oral hearing began on Monday in a civil case brought by a Peruvian farmer against Germany energy giant RWE.

In the lawsuit, which began in 2015, 44-year-old mountain guide and farmer Saúl Luciano Lliuya from the town of Huaraz wants RWE to contribute to the costs of protective measures for his house, which is threatened by a potential flood wave from the Palcacocha glacial lake in the Andes.

RWE does not operate in Peru but the farmer is being supported by German environmental organizations Zukunftsfähigkeit and Germanwatch in the civil case in the western German city of Hamm.

He says RWE shares responsibility for the risk to his house because the company produces large quantities of greenhouse gases through its power plants in Germany, Europe and the United States.

This contributes to global warming, which may lead to the glacial lake melting, he argues.

Geoscientist Rolf Katzenbach told the Hamm Higher Regional Court that the probability of a flood feared by the farmer is a “ridiculously small” 1%.

If a flood wave does occur, the plaintiff’s property will be flooded to a maximum height of 20 centimetres and the structure of the building would not be affected, Katzenbach added.

The first oral hearing is expected to conclude on Wednesday.