NASA That's a question a host of speakers from across the globe aim to explore over the next two days at Columbia University. The Earth Institute's biennial conference gets underway today and we can expect updates from: Kofi Annan on the progress of a "green revolution" (read modern agricultural technologies like fertilizer) in Africa, a technique that has seen some success in Malawi, as well as John McArthur who co-heads the Earth Institute's own Millennium Villages Project. U.N. humanitarian affairs chief Jan Egeland on the prospects for peace in our time (never good) as well as talk from David Victor, director of Stanford University's Program on Energy and Sustainable Development, on how institutions such as a competent judiciary or an uncorrupt power authority play a role in that. Tonight will see a debate on whether or not this country"the U.S."still the largest emitter of greenhouse gases by citizen, will solve the climate change problem or not. And then there's tomorrow: Sustainable energy to replace the dung, wood and other power sources of the world's poorest and a report on the rapid changes underway in the Arctic, including the record sea-ice melt this past September (which is imperiling that scourge of nations: the polar bear). Here's the full agenda. If there's anything on this list that strikes your fancy, they're doing a live Webcast here (you need to register). Ultimately, this is the Jeff Sachs show. As head of the Earth Institute, columnist for our magazine and all-around development expert (which means not without controversy), Sachs has spent his career arguing that seemingly intractable problems such as poverty can be solved at low cost. He calls it "a two-day brainstorming on the state of the planet and specifically the challenge of sustainable development" in his opening remarks. "Real people, real places, real solutions": that's the conference's tagline. And we better get them since many predict we may be approaching"or have already passed"the point of significant change. Certainly a lot of the things covered in the last iteration, covered here by Scientific American's editor in chief, John Rennie, last time around, have not been solved. For example, the conference is "carbon neutral""but it's a little unclear what that means. (Did they plant some trees for all the people who flew here?) I promise to look into it.