It was a photograph that attracted international attention: In September 1988, a man in a wetsuit jumped from a police boat into the Rhine River close to the city of Mainz in western Germany and crawled to the shore for a few minutes.

The man in the photograph was prominent Christian Democrat (CDU) politician Klaus Töpfer. He was 50 years old at the time and had been Federal Environment Minister for about 18 months. By his own admission, he wanted to show that Germany's most important river was clean enough to swim in again after it was contaminated with chemicals which killed off massive numbers of fish.

Decades later, he said the stunt wasn't just proof that the water quality had been restored — it was a wager, too. During the 1987 state election campaign, the Social Democrat (SPD) opposing candidate had predicted that Töpfer, then environment minister in the state of Rhineland-Palatinate, would soon join the German federal government and that he should no longer be elected.

Töpfer responded with his daring wager. In 1987, his election campaign was spectacular and made the television news. Today, in the age of social media, it would just be one of many audacious publicity stunts. But after these pictures, everyone knew who Töpfer was and what he stood for: water quality and environmental protection.

Politics after Chernobyl

Töpfer's office confirmed on June 11 that the former environment minister had died on June 8 after a fall at an event in Munich. He was 85 years old. Töpfer was not Germany's first federal environment minister, but he was, as it was later said, the first "real" environment minister in the federal government.

The ministerial office was established in 1986 in the wake of the Chernobyl nuclear disaster. After 11 months with Walter Wallmann in the post, then Chancellor Helmut Kohl appointed Töpfer as Federal Minister for the Environment, Nature Conservation and Nuclear Safety in 1987.

The Chernobyl disaster had horrified and unsettled the world after radioactive substances from the exploded reactor in northern Ukraine spread across large parts of Europe. The Greens, which were founded as a political party in Germany in 1980 and had already been represented in several state parliaments and in the Bundestag since 1983, were gaining momentum in the polls. And environmental policy was not really a big issue for the conservative CDU.

Klaus Töpfer, born on July 29, 1938, in Waldenburg in Lower Silesia, southwest of Breslau in what is now Poland, was politically active and highly regarded in Mainz. And he always went further than his party in terms of environmental policy. Soon after taking office, he called for "a future without nuclear energy, but also with fewer and fewer fossil fuels."

The CDU, which pushed through the nuclear phaseout under Chancellor Angela Merkel in 2011, would be back in opposition to such words in 2024.

From Rio to Nairobi

Töpfer is regarded as one of the fathers of the Rio Declaration, the climate change convention adopted at a United Nations conference, the so-called "Earth Summit," in Rio de Janeiro in 1992, which became a milestone in the global commitment to climate change and climate protection. Töpfer headed the Environment Ministry in Bonn for seven years, and was succeeded by Merkel from the former East Germany.

Töpfer moved on to head the Federal Ministry for Regional Planning, Building and Urban Development. But this was by no means a step down for him. An economics graduate, he had worked extensively on location policy and spatial planning since the late 1960s and became professor and director of the Institute for Spatial Research and Planning at the University of Hanover in 1978.

Such issues were particularly important with regard to the logistics of the reunification of West and East Germany. Töpfer was also officially responsible for the relocation of large parts of the government from Bonn to Berlin.

Töpfer's second career, for which he gave up his post as federal minister in early 1998, took on a whole new significance. Then 59, he was unanimously elected by the UN General Assembly to become executive director of the UN Environment Program in Nairobi, Kenya. As the world's top environmentalist, Töpfer was the highest-ranking German at the UN and held this post for two terms until 2006. Anyone who visited him there at the time, in an elegant building complex in a green area of the city, met a committed player with a world view.

"I was head of the UN Environment Program in Nairobi for eight years and saw with my own eyes that we have to overcome poverty if we want to have stability in this world," he told DW in 2017. "And that is very much our own concern because the people who cannot free themselves from the poverty trap will move to places where they believe milk and honey flow, and that is Europe."

Climate protection as a 'global challenge'

Töpfer summarized that in the years that he had been able to help shape climate protection, it had been possible to make it a "global challenge."

"When I started as environment minister in 1987, the term 'environmental policy' didn't even exist. 'Climate policy' was completely unheard of. Renewable energies were ridiculed, if paid any attention at all. But to see that as my personal record would be a little presumptuous," he said.

Töpfer was held in high regard in Germany, regardless of his party affiliation. Always approachable, without arrogance and competent in many areas. After his time in Nairobi, he was even considered as a candidate for the office of German president.

Instead, he sat on specialist advisory committees and remained an expert advocate for the expansion of renewable energies and the abandonment of nuclear power. That was his message back in 1988, and it has remained relevant to this day.

This article was originally written in German.