Diesel generators. The sputtering, screeching devices were in the back of Emellie O'Brien's mind during last month's Golden Globe Awards, and they will be there again throughout tonight's Academy Awards. O'Brien consults with film studios on ways to cut their carbon footprint, so when stars like Joaquin Phoenix and Cate Blanchett take the stage and start talking about the scourge of climate change, she knows better than most what is happening.
As climate change has become more visible and pressing, Hollywood studios have made efforts to halt certain dirty practices.
Some are transitioning to solar power while others are focusing on energy-saving measures, such as cutting down on waste and using LED light bulbs on set. But there is a long way to go before the film industry aligns with the climate goals espoused by stars and scientists alike.
"I think that a lot of productions are paying attention to this and are making an effort," says O'Brien, whose company is called Earth Angel. "But people just aren't talking about it enough. And that makes it really challenging to gauge."
Many of the hallmarks of inefficiency have not changed since O'Brien first started consulting in 2013: mounds of wasted food, energy-hungry sound stages, reliance on single-use plastic and frequent travel by plane. In some respects, the industry has got worse. Film makers' increasing use of computer-generated graphics, for instance, add to a project's energy budget.
Douglas Rheinheimer, vice-president for studio services at Paramount Pictures and the person who procures energy for the studio's lot in Hollywood, considers managing emissions to be part of his job. One of the biggest opportunities he saw to reduce emissions came in 2011, when rates for conventional power were rising about 7pc per year.
According to filings with the City of Los Angeles, the Paramount lot was consuming more than 40 million kilowatt hours of electricity annually, about as much as a small city. The rising costs threatened to crush Rheinheimer's budget.
Solar was not an option, as many of the buildings on the studio's 62-acre lot date to before World War Two and could collapse under the weight of the panels. Many of the lot's iconic set pieces used in films like The Godfather and Sunset Boulevard are on historic registries, which limits changes. The studio eventually settled on an alternative energy project involving small, natural gas-powered turbines, which reduced emissions by 35pc per year but continued dependency on fossil fuel.
Several times a year, Rheinheimer would meet with representatives from Warner Bros, Disney, Sony Pictures and other studios to share what he was learning. They still sometimes meet to discuss carbon-cutting, he says, but "it's sort of faded away". While some changes can be affordably and permanently made on the lot, many productions are like a circus moving between towns to incorporate different settings.
The only reliable way to power the lights and trailers is by running generators powered by diesel, the most polluting refined oil product. Diesel emits almost 40pc more carbon dioxide than natural gas when burned.
Most studios attempt to track the impact of those generators, along with other emitting activities. The data is compiled in a carbon footprint report for each movie or TV show, using a form designed by the members of the Green Production Guide, an initiative sponsored by most of the major studios.
Those reports are kept private, however, making it difficult to know the environmental impact of any motion picture. The lack of transparency also makes it difficult to track whether productions are becoming more sustainable on average.
Only one parent company of a major studio, Sony, received an 'A' rating from the Carbon Disclosure Project, which assesses what companies reveal about their environmental impact.
O'Brien says studios will move more quickly once the actors pushing sustainability in award show speeches start insisting that measures be taken on set. Frances McDormand made a call for inclusion riders to ensure diversity at the Oscars in 2018.