The actor warns that the cost of exclusion from a global biodiversity plan will be felt financially and in wellbeing

The actor Harrison Ford has called on the United States to ratify the international treaty governing conservation and urged consumers everywhere to shop more responsibly in order to limit the impact on the natural world.

Ford was speaking in Nagoya on the fringes of a crucial United Nations conference to establish a global action plan to protect the natural world. But the US – the world's biggest economy and consumer – is not taking a full part in the discussions because Congress has refused to ratify the UN Convention on Biological Diversity that the former president Bill Clinton signed in 1993.

"It's a matter of political will," Ford told the Guardian. "I'm not sure what objections the US has to taking the necessary steps. I know it's difficult to get things through Congress these days, but what needs to be done is have the president prioritise this process of congressional advice and consent on this treaty so we can be signatories."

With the Senate in blocking mode and US public opinion swinging against big international negotiations to protect the environment, this will be difficult. But Ford – a director of the US-based NGO Conservation International – says the cost of not signing will be ultimately felt in people's wallets and wellbeing because nature provides clean air, fresh water, carbon sequestration and food security.

"The economic benefits of biodiversity are recognised," he said. "If we can get the message across to the voting public that their interests are not being served by being outside the convention, they might make their dissatisfaction known."

Ford has made a substantial fortune from starring roles in blockbusters such as Star Wars, Indiana Jones and Patriot Games, but he did accept that he was part of a "Hollywood lifestyle" that has accelerated over-consumption. "I don't do celebrity endorsements," he said. "My work with Conservation International is a good use of whatever celebrity I might have to draw attention to important problems. I have the same responsibility as everyone to reduce consumption and to teach children to respect the environment."

In previous interviews, he has said his interest in the environment arose from a sense of stewardship over the land that he felt after buying a ranch in Wyoming. He has donated nearly 400 acres of the ranch to the Jackson Hole Land Trust.

In Nagoya, he is advocating Conservation International's goals to expand protected areas to 25% of the world's land surface and 15% of the oceans. "I care because I'm a father and I'm seeing the world around me degraded and misused and wasted for short-term profits," he said. "I think this is among the most important of the things I'm involved in. Time is short and nature is at a tipping point."