The quest for carbon neutrality seeks to balance the amount of carbon dioxide a country releases by burning fossil fuels with the amount that it captures or offsets by, for example, planting trees. At a United Nations climate conference last month, the U.N.'s Environment Program launched a new online network of countries engaged in the carbon-neutral endeavor. At the 154-nation talks, Monaco, the host country, became the fifth to commit to carbon neutrality, joining Norway, New Zealand, Iceland, and Costa Rica. The smart money may be on Costa Rica to get there first, experts say, even though the small Central American country faces a host of problems, from illegal logging to overdevelopment fueled by tourism....