How best to reduce greenhouse gases in the air

A big round of talks are on in Bali right now on climate change. Kyoto is set to expire by 2012 and a new treaty is in the making - or is it? I think the discussion about the link between GHG emissions and global warming is over, at least in direction. (More GHG = warmer earth.)

No consensus exists on:

• How much global warming is expected
• What are the costs of global warming
• What kinds of carbon reduction efforts should be implemented and
• How much to invest in these efforts.

Env-econ has an interesting post on the role of forests in carbon reduction. Basically forests act as a carbon store (for protected areas) or a carbon sink (for managed areas being routinely harvested). The latter is a bit complicated: timber needs to be harvested, but if the tree is valued also for its ability to take carbon out of the air, then (if there are carbon reduction payments) forest managers would have to take this into account in timing their harvest and replanting. One interesting point: it would take about $200/ton carbon price for managers to cease harvesting - way beyond realistic estimates of maybe $20-30/ton.