by Janet Sawin, Worldwatch Institute - While some of the world’s largest emitters of greenhouse gases (GHGs) hem and haw about how to—or even if to—limit their contributions to climate change, at least two small countries are blazing trails for the world to follow. Both Costa Rica and New Zealand have declared over the past several months their intentions to become carbon neutral. Together, they accounted for about 0.15 percent of the world’s carbon dioxide emissions in 2005, according to the World Bank.