By David Suzuki with Faisal Moola

How do you feed nine billion people? It's a daunting question, but one we really need to be asking ourselves if we hope to feed humanity without severely degrading the earth's natural systems.

It may be hard to believe, but when I was born in 1936, there were just over two billion people in the world. In my lifetime, that has more than doubled. Today, United Nations' population estimates show that between now and 2050, another 2.9 billion souls will be added to our little planet. That's a lot of mouths to feed. But feeding them is just part of the challenge. Current intensive agricultural practices have a number of unwanted side effects — from pesticide use and fertilizer run-off, for example — that can harm wildlife, pollute water and otherwise damage the natural systems that we ultimately rely on for our health and well-being too.

So the question really is, how do we sustainably feed nine billion people? A new report recently published in the journal Science provides us with some indication. As part of a comprehensive study, researchers with the University of Reading in the UK looked at bird population trends to develop a threat-based risk assessment model that will predict the impact of agricultural practices on biodiversity and ecosystem services.

Birds are especially relevant for such a study because they can be very sensitive to agricultural practices. Populations of wild birds in the UK have plummeted nearly in half since 1970 and the government has committed to reversing the decline by 2020. Unfortunately, according to the assessment in Science, government policies designed to help the birds don't go far enough and, unless they are changed, bird populations will continue to decline.

Researchers developed their "crystal ball" assessment model by examining three basic needs for all birds: they all need a place to nest, they need a place to forage for food, and they need to be able to find food in their forage areas. The model also takes into account how vulnerable specific bird species are to changes in any of these areas. Some birds, for example, will only nest in a few specific types of bushes. If those bushes disappear, so do the birds.

To test their model, the researchers examined the major factors in which agriculture in the UK has changed and intensified over the past 40 years. These include: switching from spring to fall sowing, increasing chemical fertilizer use, the loss of wild natural areas, increasing drainage of the land, and increasing intensity of grassland management.

When they plugged these changes into their assessment model and looked at what it predicted would occur to 57 bird species, the results strongly correlated with actual historical data. In both their matrix and in reality, bird populations fell as these agricultural changes became more increasingly common across the country.

Next, researchers used their model to look at the future of 62 bird species. Much attention in the UK has been paid to the importance of conserving hedgerows to protect birds. Indeed, hedgerows are important nesting habitat. However, when researchers used their model to predict the future of these species, it came out as rather bleak. Most of them continued to decline, even if hedgerow conservation measures were successful. It turns out that the birds' future depends much on what happens in the fields, not just the hedgerows — so changing farming practices will be essential to their survival.

Predicting the future of species using this kind of analysis is never going to be perfect, but it's an important and useful tool. As the researchers point out: "Unless the foot-print of agriculture is carefully managed through sustainable development, both agricultural systems and remaining natural ecosystems will suffer further degradation, increasing the proportion of the world's species threatened with extinction and further limiting the ecosystem services they are capable of providing."

In other words, status quo isn't really a healthy option for humanity or the rest of nature — so we'd better use every tool at our disposal.

January 26, 2007