United States. In 2000, the carbon intensity (CO2 emissions) of U.S. coal thermal combustion was 2249 lbs/MWh (1,029 kg/MWh) while the carbon intensity of U.S. oil thermal generation was 1672 lb/MWh (758 kg/MWh or 211 kg/GJ) and the carbon intensity of U.S. natural gas thermal production was 1135 lb/MWh (515 kg/MWh or 143 kg/GJ). The Intergovernmental Panel on Climate Change (IPCC) reports that increased quantities of the greenhouse gas carbon dioxide within the atmosphere will "very likely" lead to higher average temperatures on a global scale (global warming). Concerns regarding the potential for such warming to change the global climate prompted IPCC recommendations calling for large cuts to CO2 emissions worldwide. Emissions can be reduced with higher combustion temperatures, yielding more efficient production of electricity within the cycle. the price of emitting CO2 to the atmosphere is much lower than the cost of adding carbon capture and storage (CCS) to fossil fuel power stations, so owners have not done so. Estimation of carbon dioxide emissions The CO2 emissions from a fossil fuel power station can be estimated with the following formula: CO2 emissions = capacity x capacity factor x heat rate x emission intensity x time where "capacity" is the "nameplate capacity" or the maximum allowed output of the plant, "capacity factor" or "load factor" is a measure of the amount of power that a plant produces compared with the amount it would produce if operated at its rated capacity nonstop, heat rate is thermal energy in/electrical energy out, emission intensity (also called emission factor) is the CO2 emitted per unit of heat generated for a particular fuel. As an example, a new 1500 MW supercritical lignite-fueled power station running on average at half its capacity might have annual CO2 emissions estimated as: = 1500MW x 0.5 x 100/40 x 101000 kg/TJ x 1year = 1500MJ/s x 0.5 x 2.5 x 0.101 kg/MJ x 365x24x60x60s = 1.5x103 x 5x10−1 x 2.5 x 1.01−1 x 3.1536x107 kg = 59.7 x103-1-1+7 kg = 5.97 Mt Thus the example power station is estimated to emit about 6 megatonnes of carbon dioxide each year. The results of similar estimations are mapped by organisations such as Global Energy Monitor, Carbon Tracker and ElectricityMap. Alternatively it may be possible to measure emissions (perhaps indirectly via another gas) from satellite observations. Particulate matter Another problem related to coal combustion is the emission of particulates that have a