Agence France-Presse: Nigeria and South Africa are the main emitters of greenhouse gases in Africa, accounting for almost 90 percent of the emissions in the continent, environmental experts said Saturday. "Nigeria produces almost 45 percent of the greenhouse gas emissions in Africa from its gas flaring by oil firms in the Niger Delta while South Africa produces as much from industrial pollution," Stefan Cramer told AFP. Cramer, the director of the Nigeria office of Heinrich Boell Stiftung, a German …