Cameron is speaking at the U.S.-China Climate Leaders Summit in Los Angeles on Sept. 15. During the summit, leading cities from both countries will share city-level experiences with planning, policies, and use of technologies for sustainable, resilient, low-carbon growth.

Cameron’s talk with Sam Kass, former White House senior nutrition policy adviser, is titled “Food for Sustainable Nations”. Cameron, who went completely vegan four years ago along with his family, will focus on food systems (consumption and production) and the relationship between food and climate change. Cameron explains how cutting out meat and dairy products can help lower carbon emissions in this exclusive interview with Fortune.

How did you get involved in the food systems aspect of fighting climate change?

I’m a child of the ‘60s and ‘70s and I’ve always had an environmental awareness, but over the last decade and a half I’ve been very focused on climate change and renewable energy. I was really starting to lose hope that we were going to be able to meet our emission goals just because of the lack of international cooperation and government inactivity. And one of the things that gave me the most hope was when I realized what an enormous contributor the animal agriculture was to greenhouse gases. It’s 14.5%. It’s greater than the entire transportation sector combined, not by much, but all the tailpipe and smokestack emissions from ships and jet engines and everything on the planet combined is about 13.5%. So this is an area where we could make a big immediate change just by empowering people to make a change in their lifestyle and their behavior. It doesn’t require an enormous technical rollout. It doesn’t require new innovation and new engine designs, electrification of the transportation system, or a massive rollout of renewable energy.

What role do you hope this summit plays in getting that global conversation started?

We spent 18 months and a significant amount of money looking into the numbers and the research. And the thing that became abundantly clear to us when we met with the experts who are working in nutrition and energy sustainability and climate change is that we can’t actually meet our emission goals if we don’t address animal agriculture, and that’s the thing that’s been left out of the conversation. Everybody’s focusing on the energy sector, which of course is huge, and to a lesser extent the transportation section, but they’re missing the second biggest single contributor to greenhouse gas emissions. This is a thermostat that we can turn down just by our personal choices. We can do it instantly.

What are some of the business imperatives when it comes to sustainable food?

I’m not going to tell business and innovators what to do. The answer is we need to do this for the survival of our civilization, and it’s going to cost us a lot more to try to fix the effects of climate change than to fix climate change. People don’t really understand that because they haven’t really made the connection between the impact of animal agriculture and climate. We’re in this big feedback loop where climate will effect food security among many things because of drought, desertification, saltification, loss of acreage and deltas, which are some of our most fertile areas because of sea water rise and things like that. It’s going to negatively impact our food supply and our food security at exactly the same time that we need to increase our food production by 70%. By 2050 we’re supposed to have 9 billion people on this planet. These two things are moving in the wrong direction. And yet the second biggest way we can control climate change is by reducing our reliance on meat and dairy.

What role does technology and innovation play in this situation?

When you look at the situation and realize that this is a survival level crisis, ultimately things are going to need to change. So you can either be on the leading edge of that, you can lean forward into it and look for the opportunities and the innovations, or you can sit back and try to clutch onto business as usual until you become extinct as a business. A classic example of that is Kodak, which held onto their position that film was best when everything went digital in movies. They flew that plane right down into the ground. Businesses need to look at a landscape that must change, food choices that must change, agricultural systems that need to be more sustainable, land use choices that need to be more weighted toward plant production than meat and dairy production; and either be part of the solution or get left behind.

What role do you see city-level government playing in this issue?

I agree with the principle that cities and regional governments could ultimately be more effective than even national governments. These are the principles that my friend Arnold Schwarzenegger espoused and went all over the world and got governors working together. The idea of mayors working together is critical. If you can reduce emissions through specific urban initiatives, also reducing particulate pollution from coal plants and from tailpipe emissions and all that, then that’s all a step in the right direction.

What’s your message to people out there when it comes to meat and dairy?

I don’t think we have to ask people to go cold turkey. We just have to ask them to be aware of how the choices that they make of what they put on their plate is having a direct impact on climate. Seventy-five percent of deforestation in the Amazon is for either pasture land or crop land for soy, which is primarily used as a feed stock for concentrated animal feeding operations. It’s all a big related thing, but it’s all very complex. It’s hard for people to understand, but the simple resounding message is you can be healthier and your planet can be healthier based on a very simple thing that you can do today. And you’ll also save money because eating a plant-based diet is just frankly cheaper. It’s cheaper to produce plants. It’s less carbon footprint, less water footprint, less money footprint and better for you. I keep waiting for the bad news to this story.

Sign up for Data Sheet, Fortune’s daily newsletter about the business of technology.

For more Fortune coverage of climate change, watch this video: