The former president of Ireland Mary Robinson has called on developed nations to cut their consumption levels.
Mrs Robinson, 72, negotiated with world leaders ahead of the Paris Agreement on climate change, arguing strongly for "climate justice", and speaking at the One Young World Summit in Ottawa, Canada, she once again stressed the need for change.
"We don't need to consume as much as we have in the world," she said.
"We have a world where there's inequity and inequality. We can be simpler in the parts of the world that have benefited from fossil fuel."
Mrs Robinson used the number of toys her grandchildren have as an example of over-consumption, adding: "We have to change, we cannot go on with business as usual.
"We need each of us to think about our carbon footprint. Eat less meat, or no meat at all. Become vegetarian or vegan.
"Let's commit to the Paris agreement. Let's commit to leave no one behind."
The former United Nations High Commissioner for Human Rights was speaking at the summit, which brings 1,300 current and future young leaders from 196 nations together in order to discuss issues ranging from peace and security to business and education.