I spent a day a few weeks ago in São Paulo at the headquarters of a major Brazilian beef company — or, to put it another way, at the cutting edge of tropical conservation.

The image people have of conservationists in the tropics is often drawn from Indiana Jones films: intrepid biologists in the jungle swatting away mosquitoes while they discover a new species. What I'm finding is that it's not in the forest that I get that (rare) feeling of really having achieved something for conservation, but while wearing a suit in a place like São Paulo.

Yet I, too, began my conservation life swatting away mosquitoes (and much other insect life) in the Amazon, true to stereotype. The story of that journey from the Amazon to São Paulo reflects something of the direction in which tropical conservation as a whole is moving — and not the least of the many interesting issues it raises is how conservation organizations like The Nature Conservancy work together with campaign organizations like Greenpeace and Friends of the Earth.

My first conservation love is and will always be the Amazon, where I lived for over a decade. Overwhelmingly the most important driver of deforestation in the Amazon is ranching, with pasture having replaced more than 80 percent of the Brazilian Amazon cleared since reliable satellite records began, in the early 1980s.

When I returned in 1990 to the place I had done my doctoral fieldwork three years before, I had to be told when I'd arrived. The ranches had stripped away all the forest. All the landmarks I'd used to know where I was — the clump of trees behind the huts, the trail through the forest — had either been destroyed or lost their reference points.

So I've known for most of my adult life how important the beef market is to tropical conservation. Soy, biofuels, all the other commodities you may have heard linked to Amazon deforestation — they are as nothing compared to beef. There are good reasons why ranching thrives in the Amazon: land is free or cheap in most of it, cattle need minimal care, and they can walk to market.

I worked on greening supply chains in the soy industry in the Amazon for years, and made progress. But it was always with one eye on the beef sector. What I learned with soy would one day, I hoped, be applied to the beef industry. I tried to open up channels with the beef industry in Brazil for years, from 2003 on. I talked about the importance of not being linked to deforestation in a warming world, of monitoring supply chains and making sure your suppliers were doing the right thing. They listened politely, but I never got anywhere. The companies never felt any pressure to do anything, and in the absence of pressure, being environmentally responsible meant little more than costs and hassle. I didn't like it, but I could understand it.

Meanwhile, ranching was becoming more and more important in the Amazon. From 1996 to 2006, while the area of pasture actually fell in the rest of Brazil, in the Amazon it increased by 20 percent, to a total of over 61 million hectares (for comparison, about 200,000 hectares of soy is grown in the Brazilian Amazon). This is what lies behind the stubbornness of deforestation in the Amazon, year in and year out, even as Brazil and the world worry more and more about climate change and biodiversity loss.

Then, in June, something extraordinary happened. Friends of the Earth in Brazil and Greenpeace in Europe came out with separate reports detailing the role of the beef industry in driving Amazon deforestation. There was a media firestorm. Within days, all the major Brazilian supermarket chains (Carrefour and Walmart among them) announced new policies banning the purchase of meat linked to deforestation in the Amazon. Greenpeace and Friends of the Earth achieved in a couple of weeks what I'd tried to do for years with no success.

But there are big risks. Right now, none of the meat processing companies have any way of documenting land-use change in the ranches that supply their Amazon slaughterhouses, and thus no way of guaranteeing to the retailers that their meat is deforestation-free. Getting such a monitoring system up and running was the reason I was in that meeting in São Paulo. In those circumstances, the easiest option for the Walmarts of this world is "redlining" the Amazon – simply suspend meat purchases from the Amazon, and buy meat from somewhere else less risky.

There are two problems with that:

* One is that replacement beef will come from Brazil's Cerrado savannas and southern Brazil's Atlantic Forest, neither of which are as famous as the Amazon but are actually more threatened and also globally important, in conservation terms. Simply channeling demand away from the Amazon to elsewhere in Brazil is emphatically not a conservation win.

* But even more worrying is what happens when, as you must to see how this plays out, you put yourselves in the shoes of an environmentally irresponsible beef producer, who wants to keep on working as he (it's almost always a he) always has, without having to worry about all this deforestation nonsense.

The unfortunate fact is that you have alternatives. In 2008, the main export markets for Amazon beef were, in order — drum roll please – Russia, Venezuela and Iran! So, if Walmart gets all starry-eyed about the rainforest, you can always sell to the Russians or the Iranians.

The problem with trying to inject conservation into commodity markets is that they're global. The danger with the Greenpeace/Friends of the Earth approach is that it cuts off access to markets that could change the behavior of producers and influence them to stop deforesting, and throws them into the arms of the Russians. The supermarkets and consumers who shop in them would get that warm, self-satisfied feeling of having done something to stop deforestation, when in reality you could argue they're actually accelerating it.

The trick, then, is to mix honey with vinegar. After putting the fear of God into the market players — and nobody does that better than Greenpeace and Friends of the Earth — the campaigns, which thrive on simplicity, have to give way to something much more complicated: getting beef markets to work in a way that brings deforestation down, instead of simply switching the markets and consumers that drive it.

The trick here is to make sure there is responsibly produced Amazon beef to supply the market that Greenpeace and Friends of the Earth have played such an important role in creating, in volume sufficient to meet the demand. I'll be suiting up and heading to São Paulo for a long time to come, it seems.