The leaders of the world’s biggest economies are gathering in Germany for the G-20 Summit.

They’ll discuss global challenges — from climate change to trade.

But ahead of the meetings, mass protests and violent clashes with police on the streets of Hamburg.

CGTN’s Natalie Carney has more.

President Xi started his second day in Germany meeting with South Korea’s President Moon Jae-in, reaffirming China’s support for a return to dialogue between South Korea and their northern neighbor.

President Xi also focused talks on the healthy development of bilateral ties.

Before leaving Berlin, President Xi also met with Martin Schulz, the leader of Germany’s Social Democrat Party and candidate for German chancellor in upcoming September elections.

Then it was off to Hamburg for the G-20 summit, where climate change is expected to play high on the agenda.

Despite the United States withdrawal from the Paris climate accord, China said it doesn’t plan on signing a G-20 climate protection statement if it excludes the U.S.

German Chancellor Angela Merkel, at the helm of this year’s G-20, said her country is committed to finding a solution to resolve differences.

“We know the United States have withdrawn from the Paris agreement,” Merkel said. “All others – or at least as far as I know, many many others – are still committed to the Paris agreement and how that turns out is something we will tell you at the end when we have finished the communique.”

Meanwhile, demonstrations ahead of the summit escalated on Thursday with police firing water cannons at protesters.

“I pay taxes every day and I’m angry that my taxes are spent for a party for about two days,” protester Mathis Haultz said. “And if I calculate I think OK with the same money we can pay nurses in the hospitals in Hamburg for maybe 50 years…so that’s the main point for me.”

“We are not living in an ordinary time because the world is in crisis and the world is demanding revolution,” Rosa Abbas, another protester said. “Overthrowing this capitalists system and replacing it with a system which functions for the majority of human beings and also the planet.”

Protesters said they will continue to protest the summit with a mass demonstration planned for Saturday.

Meantime, delegations are getting ready for what will likely be a challenging summit. Simmering tensions with the DPRK are likely to play a role in Hamburg, and when President Trump and President Xi meet for the second time this year on the side lines of this year’s G20.