Broadcaster Sir David Attenborough has been speaking at a public inquiry to support plans for a 70m-high (230ft) wind turbine in the Sussex Downs.
Sir David Attenborough listens to the opening of the inquiry
Glyndebourne Opera House wants to build the 850kw turbine, which it says would generate the equivalent of its entire annual electricity consumption.
But the plan has split local opinion and protesters with placards gathered outside as the hearing got under way.
The six-day public inquiry is being held at the White Hart Hotel in Lewes.
About 100 people packed the first day of the inquiry to hear evidence from Sir David, who has been a long-term supporter of the plan.
Sir David, 81, told the inquiry he had a great affinity for the area and had been visiting Glyndebourne since the 1950s.
"I have seen first-hand how human beings have destroyed much of the wildernesses of the world and species that live within them," he said.
"There is not only no doubt of humanity's involvement in climate change, but if we continue in the way that we have been going, in particular if we continue to generate power by burning hydrocarbons, then we ourselves and the natural world in general will be facing catastrophe.
"Action is imperative.
"I therefore greatly applauded the plan by Glyndebourne Opera to erect a wind turbine to help power its operations."
The opera house wants to site the turbine at Mill Plain, New Road, in Ringmer, where a windmill once stood.
Chairman Gus Christie told BBC South East Today: "At Glyndebourne we all feel that we want to reduce our carbon emissions and combat climate change and we are in a unique position to do so.
"We own land around the site and we have a good wind resource on some of this land."
During cross-examination at the inquiry he was accused of hypocrisy because of the number of visitors to the opera house who travel to it by car and even helicopter.
But he said the wind turbine was just one of many initiatives that Glyndebourne was planning to reduce its carbon emissions and become more environmentally sustainable.
Glyndebourne says the turbine would cut emissions by 71%
Conservationists including the Campaign to Protect Rural England are against the turbine.
Ringmer Parish Council, the South Downs Society and Natural England have also objected to the plan because of its impact on the area, designated as a National Park.
"We are in favour of renewable energy but it needs to be in keeping with the landscape," said South Downs Society director Jacquetta Fewster.
"We don't have that many areas of unspoilt countryside left in this country and the areas that we have like the South Downs are national treasures.
"We go there for quiet recreation and we don't want monster machines there."
The proposal was originally passed by Lewes District Council but the government decided an inquiry should be held.
The inquiry inspector will then report to the government for a decision later in the year.