Emissions trading market in pollution-licenses is more widely applicable than the market in emission-licenses. The international community began the long process towards building effective international and domestic measures to tackle GHG emissions (carbon dioxide, methane, nitrous oxide, hydroflurocarbons, perfluorocarbons, sulphur hexafluoride) in response to the increasing assertions that global warming is happening due to man-made emissions and the uncertainty over its likely consequences. That process began in Rio in 1992, when 160 countries agreed the UN Framework Convention on Climate Change (UNFCCC). The UNFCCC is, as its title suggests, simply a framework; the necessary detail was left to be settled by the
Nitrous oxide dominant. In a vacuum thruster, this may provide a monopropellant specific impulse ("I") of as much as 180 s. While noticeably less than the "I" available from hydrazine thrusters (monopropellant or bipropellant with dinitrogen tetroxide), the decreased toxicity makes nitrous oxide an option worth investigating. Nitrous oxide is said to deflagrate at approximately at a pressure of 309 psi (21 atmospheres). At 600 for example, the required ignition energy is only 6 joules, whereas at 130 psi a 2500-joule ignition energy input is insufficient. In vehicle racing, nitrous oxide (often referred to as just "nitrous") allows the engine to burn