Pope Francis said on Sunday that recent heat waves across many parts of the world and flooding in countries such as South Korea showed that more urgent action was needed to tackle climate change.

"Please, I renew my appeal to world leaders to do something more concrete to limit polluting emissions," the Pope said at the end of his Angelus message to crowds in St. Peter's Square.

"It is an urgent challenge, it cannot be postponed, it concerns everyone. Let us protect our common home," the pope added.

Francis has called on the world to rapidly ditch fossil fuels and made the protection of the environment a cornerstone of his pontificate. He noted in his landmark 2015 "Laudato Si" (Praised Be) encyclical that the planet was "beginning to look more and more like an immense pile of filth".

On Sunday, the pope expressed solidarity with those who were suffering from the climate crisis and those helping them.

Parts of the southern United States have baked in a record-breaking heat wave, while extreme temperatures have also been recorded in China and southern Europe, including Italy and Greece.

A wildfire raging on the Greek island of Rhodes forced thousands of tourists and island residents to shelter in schools and indoor stadiums on Sunday after they were evacuated from coastal villages and resorts.