It's entirely appropriate that President Obama and the Indian Prime Minister Manmohan Singh will discuss climate change in their meetings today. After all, there's substantial disagreement between the two nations about the issue going into the Copenhagen conference next month. But you do get the feeling that climate change has become the safe topic of conversation, at least publicly, when Obama is with world leaders. I'm no China hand like my colleague, James Fallows, but you couldn't help but notice when Obama did his town meeting in Shanghai, he kept returning to climate change. He deftly touched on questions of openness and transparency and freedom but climate change was the topic he kept steering back to and it makes sense. The same was true at this morning's press conference where it's harder to deal with thornier issues like nuclear double standards--the U.S.-Indian nuclear deal forged by Singh and Goerge W. Bush ended America's ban on sharing nuclear technology with India, which had been in place since it joined the nuclear club. Kashmir is thornier. Afghanistan is thornier. They'll all come up, but climate change has kind of become the safe topic of conversation at least publicly: like an awkward dinner conversation that's veered dangerously into sex or politics or child rearing, climate change is the topic everyone can agree to discuss--even when it's hard to resolve anything.