Climate change to stop rain of records in Rio Olympics

Athletes at the Olympic Games may struggle to break world records as they compete with Brazil's rising temperatures caused by climate change.

Marathon runners, swimmers, volleyball players and even soccer referees will succumb to extreme heat and lose concentration during the games, in some cases risking their lives to heatstroke, according to a report released Monday by Observatorio do Clima, a Brazilian civil society group.

"Because of warming, sport will never be the same again," the report said.

Brazil heated up faster than the global average, warming 1 degrees Celsius (1.8 degrees Fahrenheit) in the last 54 years, and four cities smashed new heat records in 2015, according to the report. If countries don't deliver on goals to limit global temperature rises to "well below" 2 degrees Celsius, 12 Brazilian cities may have to limit play in similar games by the end of the decade, it said.

Even though the games are taking place during Brazil's winter, the heat may still impede performance, particularly in the marathon where Olympic records have only been broken in temperatures below 12 degrees Celsius. Runners perform best between 8 degrees and 11 degrees, well below the level expected this month in Brazil, it said.

Over the coming years, athletes are likely to "give into fatigue earlier on, even if they remain in the competition until the end," according to the report.

The heat is likely to be particularly painful for athletes from colder climates, says Brazilian tennis player Fernando Meligeni. He reckons European players won't be used to the humidity, which will make them sweat more than usual.

"I believe that the English and the Swedish, for example, will fade out," Meligeni said, according to the report.

Warm temperatures have already caught out athletes. Two soccer matches in the 2014 World Cup in Brazil required technical time when so-called "wet bulb" temperatures - a measurement used in occupational health - reached 32 degrees Celsius, which is the "stop play" threshold for FIFA. Several athletes in the test events for the Rio Olympics had heat-related injuries. Eleven of the 18 race walkers succumbed to the heat and one fainted, according to the report.

Textile companies are creating new materials that can help athletes cope with the heat while one physiologist has even tested an "ice helmet" that could form part of the kit for athletes. Yet these new technologies may prove too expensive for poorer athletes, making it harder for them to reach the top of their game, warned the report.