A two-day environmental summit of the Group of Seven (G7) nations plus the European Union and four invited countries kicked off in the Italian city of Bologna on Sunday.

The agenda set by host and G7 president Italy includes the fight against global warming and climate change, in spite of US President Donald Trump's withdrawal from the Paris Agreement, Xinhua news agency reported.

"In the environment, we all win together or we lose together," Italian Environment Minister Gian Luca Galletti told reporters on the sidelines of the summit. Continuing the dialogue is key, Galletti said.

"The positions expressed at the beginning will undoubtedly remain as they are, but … we definitely made a step forward towards dialogue — aside from climate, there is complete agreement on all the other issues," Galletti added.

Galletti and Scott Pruitt, Administrator of the US Environment Protection Agency, held a pre-summit meeting on Friday in which they agreed on the need to reduce food waste, which also has environmental implications.

One third of food destined for human consumption, worth $750 billion, is lost or wasted, according to United Nations data cited by Italy's environment ministry.

Host Italy's agenda also includes sustainable growth, green financing, Africa and the role of development banks, marine pollution, circular economy, removing environmentally harmful subsidies, and environmentally-minded tax reform, according to the environment ministry.

The summit hosted by Galletti sees the participation of his counterparts from Canada, Germany, France and Japan, plus British Under Secretary of State at the Department for Environment Therese Coffey, and US Environmental Protection Agency chief, as well as two members of the European Commission.

Chile, Ethiopia, the Maldives and Ruanda are the four invited countries. The environmental summit will end on Monday.