Veteran climate negotiation observers say the oil industry is starting to sweat as United Nations climate talks heat up and threaten to plug fossil fuel-belching wells for good. A reported letter from OPEC’s leader pleading with the oil cartel’s member countries to block any U.N. language that would phase out or phase down fossil fuels hit negotiations like a thunderclap. Host and fellow petro-state United Arab Emirates is trying to tamp down its reverberations in a process where one or two key nations can block everything. Environmental activists are smirking at signs that the mighty cartel was circling the wagons.