Belem, Brazil

“One million dollars?”

The question was asked with eyes wide and a voice of incredulity. The person asking was Antonio Waldez Góes da Silva, the governor of the Amazonian state of Amapá, which has the biggest national park in the world. I had just shared with Gov. Waldez Góes a recent news article in The Hill, the Congressional newspaper, which said the total cost of stationing one U.S. soldier in Afghanistan for one year is $1 million.

What if we kept just one soldier back from Afghanistan and gave you the money, I asked the governor? What would it buy you? Gov. Waldez Góes mulled that over: “If you kept three soldiers back, that would be enough for me to keep the State University of Amapá running for one year, so 1,400 students could take different courses on sustainable development for the Amazon.”

O.K., I know. It is a bit misleading to take a war budget and assume that if it weren’t spent on combat, it would all go to schools or parks. And we do have real enemies. Some wars have to be fought, no matter the cost. But such comparisons are still a useful reminder that our debate about Afghanistan is not taking place in a vacuum. We will have to make trade-offs, and there are other hugely important projects today crying out for funding, as my colleague Nick Kristof has pointed out regarding health care.

Well, if America is going to assume the primary burden of fixing Central Asia, maybe, say, China, could help pick up the tab for saving what is left of the Amazon and the world’s other great tropical forests. Could President Obama raise that idea in Beijing?