claim: While it's true that any single country's CO2 emissions reductions will make little difference, only if every nation agrees to limit CO2 emissions can we achieve significant cuts on a global scale.
evidence: At very high concentrations (100 times atmospheric concentration, or greater), carbon dioxide can be toxic to animal life, so raising the concentration to 10,000 ppm (1%) or higher for several hours will eliminate pests such as whiteflies and spider mites in a greenhouse.