This week, I was asked an interesting question as part of the Q&A session following a talk I gave at the Fortune Brainstorm Green conference in California.
To paraphrase journalist Marc Gunther, who moderated the evening: "You are a vegan. You also lead the world's largest conservation organization. Why doesn't The Nature Conservancy make changing people's diets one of its strategies? Wouldn't changes in diet lead to better environmental outcomes? And what about GMOs?"
Indeed, I have been a vegetarian for a long time, and I recently became a vegan. There are many reasons for my choice. Among those reasons: as an environmentalist, I think our global consumption of meat is far too high.
Cattle, for example, need large areas of land -- not just for pasture, but for growing their feed. That footprint is primarily tropical, in the most bio-diverse areas of the globe. Globally, if current meat production were distributed per capita, everyone would have enough protein and we could freeze the footprint of production at current levels.
Given those facts, you might expect my answer to Marc's question to be straightforward: that environmentalists should say no to meat, and that we should focus on changing what people eat in the interest of saving the planet.
But it's not quite so simple. Here's why.
A campaign to change global diets quickly runs into two enormous obstacles. First, and most fundamentally, no one wants to be told what they can and cannot eat. Few things are as powerfully evocative as food, with deep ties to family, culture and tradition.
Second, as global incomes rise, we will see -- among many other positive outcomes -- a trend toward improved nutrition. Tradition and culture suggest that this will mean an increase in protein-rich diets.
Instead of trying to change this trend, I think we should focus on producing more meat from existing pasture and farmland. That means paying more attention to soil health, water conservation and agricultural extension, giving farmers the support they need to produce more and do it smartly.
But in a time of shrinking budgets for many governments, in too many places public funding for agricultural research and extension is declining. This trend is disturbing. We should invest in solutions, even when public funding is tight.
There is also a role for the private sector. Major agribusinesses (and companies in other economic sectors as well) are increasingly concerned about sustainability. No sustainability translates to no long-term supply. Companies that thrive in the long run will be those that analyze their supply chains, examine how current farming practices impact soil and water and work with farmers to improve those practices.
Getting more from land already under cultivation is key. Nevertheless, some expansion of farming and grazing is inevitable. So another vital challenge is to channel that expansion to areas where it will do less harm. This process inevitably involves some trade-offs, but we have the science to identify where controlled expansion could take place with relatively fewer environmental impacts and costs.
We also should pay attention to regulatory frameworks. Without them, increased production leads to increased returns for farmers, and that draws more people into farming. The result is more expansion of farmland, not less. Both regulatory and voluntary frameworks should ensure this doesn't happen. Initiatives like Cargill's voluntary moratorium on the purchase of soy from newly deforested areas in the Amazon are of enormous importance.
Technology is also important. Precision agriculture, for example, could be a game-changer. By targeting inputs like water and fertilizer more accurately, farmers can improve environmental outcomes and produce more while using less.
Yet it's still unclear how we can bring those technological changes to the people who could most benefit from them: smallholder farmers without access to the capital and knowhow available to richer farmers in richer countries. Making technology more accessible so that its benefits can be more widely shared is a major challenge.
Another agricultural technology we should consider carefully is genetic modification. The National Academy of Sciences has found no adverse health effects from GMOs, and also concluded that they can be environmentally beneficial in some ways. Yet having a thoughtful debate on the merits and risks of GM foods has become nearly impossible. The arguments are often based not in science but in ideology.
Like all new technologies, biotech products should be carefully assessed on a crop-by-crop basis and appropriately regulated. We would also be smart to put more focus on making GMO technology available to lower-income farmers, given the potential benefits that climate-resilient GMO crops could bring to the developing world. As the technology advances, I think we should be vigilant in assessing environmental and health risks, and also respecting the views of people who as a matter of personal choice seek to avoid GMOs. But we cannot have such careful analysis if each side in the debate paints the other as evil or ignorant. We need passion on our side, but not at the expense of sound science and open minds.
My answer to Marc Gunther's question is far from simple. What's clear, however, is the urgency of meeting our growing demands for food and water without destroying our planet. Can changing your diet make a positive impact on the planet? Of course. But in my view, our biggest hope for widespread change lies in "greening" our meat, for those who choose to eat it.