The global air temperature increase is an inadequate measure of global warming, which rather should be considered in terms of energy. The ongoing global warming means that heat has been accumulating since 1880, in air, ground, and water. Before explaining this warming by external heat sources the net heat emissions on Earth must be considered. Such emissions, from e.g. the global use of fossil fuel and nuclear power, must contribute to global warming.The aim of this study was to compare globally accumulated and emitted heat. The heat accumulated in air corresponds to 6.6% of the global warming, while the remaining heat is stored in the ground (31.5%), melting of ice (33.4%), and sea water (28.5%). It was found that the net heat emissions 1880-2000 correspond to 74% of accumulated heat, i.e. the global warming, during the same period. The missing heat (26%) must have other causes; e.g. the greenhouse effect, natural variation of the climate, and/or underestimation of net heat emissions. Most measures already taken to combat global warming are beneficial also for current explanation, though nuclear power is not a solution but part of the problem.