Coal-fired power plants influence climate via both the emissions of long-lived carbon dioxide (CO<sub>2</sub>) and short-lived ozone and aerosol precursors. For steadily increasing emissions without substantial pollution controls, we find that the net global mean climate forcing ranges from near zero to a substantial negative value, depending on the magnitude of aerosol indirect effects, due to aerosol masking of the effects of CO<sub>2</sub>. Imposition of pollution controls on sulfur dioxide and nitrogen oxides leads to a rapid realization of the full positive forcing from CO<sub>2</sub>, however. The long-term forcing from stable (constant) emissions is positive regardless of pollution controls, with larger values in the case of pollutant controls. The results imply that historical emissions from coal-fired power plants until ~1970, including roughly 1/3 of total anthropogenic carbon dioxide emissions, likely contributed little net global mean climate forcing during that period. Those emissions likely led to weak cooling at Northern Hemisphere mid-latitudes and warming in the Southern Hemisphere, however. Subsequent imposition of pollution controls and the switch to low-sulfur coal in some areas kept global SO<sub>2</sub> emissions roughly level from 1970 to 2000. Hence during that period, RF due to emissions during those decades and CO<sub>2</sub> emitted previously was strongly positive and likely contributed to rapid global and regional warming. Most recently, construction of coal-fired power plants in China and India has been increasing rapidly with minimal application of pollution controls. Continuation of high-growth rates for another 30 years would lead to near zero to negative global mean climate forcing in the absence of expanded pollution controls, but severely degraded air quality. However, following the Western pattern of high coal usage followed by imposition of pollution controls could lead to accelerated global warming in the future.