The Paris Olympics have bold climate plans, but few specifics

PARIS: Organisers of next year's Paris Olympics say they want its carbon footprint to be half that of previous summer Games, but with a year to go observers say they still do not have enough detail to verify the plans.

Citing climate change as "the greatest challenge humanity has ever known", organisers have said they can reduce greenhouse gases from the Games with a variety of measures, including renewable energy and using existing venues rather than building new ones.

That would, they say, allow them to halve CO2 emissions from the estimated 3.5 million tonnes generated during the 2012 London and 2016 Rio Games.

"It's a fine promise," said Martin Muller, Professor of Geography and Sustainability at the University of Lausanne, adding the target itself is a first.

But "I don't have the figures to believe it," he told AFP.

Muller would like open access to precise data. Otherwise, he said, "I can't understand on what basis this has been calculated".

For the time being, the organisers have sketched out forecasts.

Expected emissions break down into three areas - travel, buildings and other activities like accommodation, security and catering - which each account for roughly a third of emissions.

With the venues themselves, the organisers say they have limited the construction footprint with a 95 per cent reliance on existing or temporary arenas, unlike the much-criticised football World Cup in Qatar.

This decision to use as much existing infrastructure as possible was praised by Gilles Dufrasne, of Carbon Market Watch, as a "thoughtful approach".

Other ideas include using renewable energy or serving "low carbon" meals with less meat.

"The other big item is emissions from spectators arriving by plane," said Muller.

Even if venues have to