If you really want to understand a country, a society, or even a civilization, don't turn to its national museums or government archives. Head to the tip.

According to Annie Leonard – former Greenpeace activist, unwavering optimist and waste obsessive – the tip is akin to society's secret journal. "Stuff" became a fascination for Leonard in her teens, choosing field trips to landfills while at university when she began to question how we came to build an economy based purely on resources.

That was 20 years ago, and a lot has changed. Waste and recycling are now burning policy issues. Forty countries, hundreds of factories and still more landfills later , Leonard worries we have not grasped the fundamental problem with our materials economy. "It is a linear system and we live on a finite planet. You cannot run a linear system on a finite planet indefinitely. Too often the environment is seen as one small piece of the economy. But it's not just one little thing, it's what every single thing in our life depends upon."

In 2007, Leonard tried a novel medium – a YouTube video – to convey the message. The Story of Stuff was a frank and cleverly animated short film telling the story of the American love affair with stuff and how it is quite literally trashing the planet. Three years on and it's a viral online phenomenon; seen by 10 million people in homes and classrooms all over the world. Now she has followed up the video with a book of the same name.

Leonard has surprised many, though, by not actually being against stuff. She isn't even anti-consumption. In fact, she feels lots of people should be consuming more. Just not most of us in the western world who often over-consume.

Consumption can be good, she says. "I don't want to be callous to the people who really do need more stuff".

But consumerism is always bad, adding little to our wellbeing as well as being disastrous for the planet. "[It's] a particular strand of overconsumption, where we purchase things, not to fulfil our basic needs, but to fill some voids about our lives and make social statements about ourselves," she explains.

"It turns out our stuff isn't making us any happier," she argues. Our obsessive relationship with material things is actually jeopardising our relationships, "Which are proven over and over to be the biggest determining factor in our happiness [once our basic needs are met]."

Leonard calls upon wider research to argue the sociological and psychological consequences of our all-consuming epidemic, including that of Tim Kasser and Robert Putman. Kasser identified a connection between an excessively materialistic outlook and increased levels of anxiety and depression, while Putman argues we're paying the ultimate price for our consumeristic tendencies with the loss of friendships, neighbourly support and robust communities. Together they suggest we are witnessing nothing short of the collapse of social fabric across society.

Part of the problem, according to Leonard, is our confused sense of self. We've allowed our citizen self to be dwarfed by a relatively new reflex action – consume, consume, consume. "Our consumer self is so overdeveloped that we spend most of our time there. You see it walking around – we usually interact with others from our consumer self and are most spoken to as our consumer self. The problem is that we are so comfortable there that when we're faced with really big problems [like climate change], we think about what to do as individuals and consumers: 'I should buy this instead of this.'

"If you're going to vote with your dollar that's fine," Leonard says. "But you need to remember that Exxon has a lot more dollars than you. We need to vote with our votes; re-engage with the political process and change the balance of power so that those who are looking out for the wellbeing of the planet dominate, instead of those who are just looking our for the bottom line."

Like George Monbiot, Leonard doesn't think so-called ethical consumption, or greensumption is going to get us out of the problem either. "The real solution is not perfecting your ability to choose the best option, it's getting that product off the shelf," she says. "It's increasingly looking like buying green delays people engaging with the political process."

Leonard's film has its critics. Fox News branded it "full of misleading numbers". And the free market and climate sceptic think tank The Competitive Enterprise Institute, called the project "community college Marxism in a ponytail." But many have found it hard to argue Leonard doesn't live up to her values. At her home in California she and another five families have chosen community over stuff, tearing down the fences between their homes. "Its not a big deal", she says. "We don't have matching clothes and its not like a commune of anything. We are all just regular families in these six houses [who] share things. And we just have so much fun."

The Story of Stuff is about America, but how is the UK faring? Leonard does note some positive differences: the NHS, our liberal political discourse – allowing us to utter the words capitalism and unsustainable in the same large breath, and she likes the fact that washing lines are not a threatened species. One thing that does bug Leonard about this country, though, is our pyromania. Specifically, she's worried about our leaders' love affair with waste incinerators. "It's just so depressing. Incinerators are such a regressive way of dealing with waste materials. We need to promote zero waste as an alternative."

Zero waste is a term that gets thrown around a lot, most recently this week by environment secretary Caroline Spelman. For Leonard, a complete overhaul in our approach involves a real cradle-to-cradle revolution; marrying intelligent design upstream and consumer incentivised recycling and composting downstream.

This may well be one of the answers, and the book provides a few more. But Leonard doesn't pretend to have them all, and she's reluctant to commit to a new economic paradigm, either, because "we haven't invented it yet."

She is sure of one thing though: "Change is inevitable. You can't keep using one and a half planet's worth of resources indefinitely."

Many have argued against the minor details of the book, but few have questioned the fundamental premise that our current use of resources is unsustainable. Even fewer have doubted her optimism. "Environmentalists need to figure out a way of talking about this stuff in a more engaging and inviting way, and that is what I hope I'm doing with this book."