Can Paris 2024 deliver a 'climate positive' Olympics?

"We want to show that we can do these Games with half the emissions," Georgina Grenon, Paris 2024's director of environmental excellence, said with 500 days to go before the world's biggest sporting extravaganza gets underway in the French capital.

"Within the limit of what is technically feasible in 2024, we will have made every effort to cut, cut, cut."

But for Lindsay Otis Nilles of Carbon Market Watch, "to say that an event has a positive impact on the climate is misleading.

"The event itself generates greenhouse gases which are bad for the climate. The financial support of the organisers for external projects does not change this."

Paris organisers say their calculations are based on reducing greenhouse gases and offsetting residual emissions linked to the event, in addition to financing projects to offset the effects of pollution.

Organisers insist they can halve CO2 emissions from the estimated 3.5 million tonnes generated during the 2012 London and 2016 Rio Games.

The construction footprint is limited thanks to 95 per cent reliance on existing venues.

Most of the polluting will be linked to travel, with 25 per cent of total emissions from spectator transit alone, and operations, including accommodation, security and catering.

Organisers have also favoured the use of electricity from renewable energy sources, with most venues near public transport, and serving spectators "low-carbon" dishes with less meat at venues.

"By offsetting even more CO2 emissions than those we are going to emit, we will become the first major sporting event with a positive contribution to the climate," organisers said.

Environmental compensation includes financing the planting of trees to absorb carbon dioxide, and projects to conserve and restore