I think the question of how we value and account for nature—or how we make nature count—will be the most important question of our century.

But how did a bookish girl like me end up in the badlands of global accounting?

A strange twist of fate—a job in an art gallery in Venice and an economics degree in quick succession—left me obsessed with accounting. When I discovered that modern accounting was born in Venice in 1494 with the publication of the first treatise on bookkeeping and that its author was a celebrity Renaissance monk called Luca Pacioli who taught Leonardo da Vinci mathematics, I was hooked. I started piecing together the long forgotten life of this extraordinary monk and ended up writing a history of accounting. While researching it, I stumbled across a speech made by Senator Robert Kennedy in 1968 a few months before he was assassinated.

Speaking about the Gross National Product of the United States, Kennedy railed against the many “bads” which are counted as national wealth—highway carnage, pollution, the destruction of forests and “the loss of our natural wonder in chaotic sprawl”. I realised there was something very wrong with our accounting systems and sought to investigate how the way we measure and account for nature shapes the way we treat it.

The problem is that our measures of wealth—GDP and profits—only count nature when it’s destroyed, transformed into things like jeans, houses, smartphones. Living nature—trees, honeybees, oceans, the atmosphere—counts for nothing. We have inadvertently programmed our economies to ruin the earth. I knew this intuitively, but now I’d isolated the mechanism which actively works to destroy the planet: our accounting system.

We still use the medieval accounting system that Luca Pacioli codified in 1494. It worked well to measure the capital of merchants, the output of factories, the economic growth of nations after the Second World War, but it’s useless in the 21st century. Our planet is now bursting with people and we’ve been polluting, burning, extracting and cutting down vast swathes of nature for centuries with little regard for the environmental consequences.

It’s now time to consider those environmental consequences. I found that some accountants are doing just that: taking account of nature by redefining it as “natural capital”—or “the world’s stocks of natural assets which include geology, soil, air, water and all living things”. In 2012, the United Nations gave natural capital equal status to GDP in national accounts and 40 financial institutions signed the Natural Capital Declaration to add it to business accounts.

At first I liked the idea of valuing nature as natural capital. It seemed to me to solve the challenge of making nature count, because it puts a monetary value on nature and so makes us pay for destroying it, which should discourage us from doing so. But I soon realised that this approach brings its own dangers. By putting a price on nature, it extends the market further into nature’s realm and risks its becoming financialised and privatisatised.

The idea of pricing nature to save it made me realise the full bankruptcy of western civilisation. Our only apparent common measure of value, of right or wrong action, is the rule of money.

And so I began to look for other ways of systematically protecting nature. Which led me to Christopher D Stone, whose searching and influential essay Should Trees Have Standing? shifts the question from one about counting nature to one about making nature count. With Stone, nature becomes a subject in its own right. He argues that trees and other natural entities should be given legal rights—and thus overturns long-held perceptions enshrined in western legal codes that nature is property to be possessed, governed and used by man for man.

But the real force of Stone’s essay lies in his understanding that by giving nature rights, we’d also be creating what he calls “a new ‘us’ that includes the environment”. His new “us” embraces a continuum of humans and nature. This is the mindshift or change of values we all must make on a global scale: that nature is not some object out there. It is continuous with us. We are of it.

I think the future depends on a profound shift in the way we see our place in the rest of nature. We are not above it, with nature as a capacious store of resources freely and infinitely available for us to turn into stuff, while also acting as a huge garbage tip in the great beyond. There is no free infinite store. There is no great beyond. Both are the finite planet beneath our feet. As Stone puts it, we need to give up “some of our sense of separateness and specialness in the universe”.