China and the European Union redoubled their commitment to a strong climate pact on Monday in a Brussels summit, as the Asian giant readied its widely-anticipated pledge for submission. Heads of the world’s number one and three emitters of greenhouse gas emissions signed a joint agreement on climate change and heralded a “new starting point” after 40 years of relations.

It sees a deepening of Sino-European ties as new chiefs seek to overcome former diplomatic hostilities, with Chinese investment earmarked for a European infrastructure fund and greater collaboration on issues from migration to the Greece crisis.

“This year is critical in terms of global climate change governance,” said Chinese premier Li Keqiang, who travelled to the Belgian capital for the first time. “We are willing to work together with the EU side to jointly tackle the challenge posed by climate change that observes principles of common but differentiated responsibility, equity and respective capabilities to implement climate change solutions,” he told reporters in a press conference.

China would submit its “intended nationally determined contribution” before the end of June confirming months of speculation, Keqiang said. Accounting for over a quarter of emissions, it is a significant player in crafting a global warming agreement.