Radiation with frequencies of 5–30 Hz is ducted between Earth's surface and ionosphere with little attenuation; at the lowest frequencies, waves travel several times around the Earth before losing most of their energy. Much of this radiation is produced by lightning. Here we assume that all of this radiation is produced by lightning, and attempt to invert the observed electric and magnetic fields to infer the global lightning activity. We show 10 days of inversions. For these 10 days, the inferred average rate of vertical charge transfer squared is only 1.7 105 (C km)2/s. Other studies suggest that the root mean square moment change of a flash is about 166 Coulomb kilometers. If we naively assume that each of these flashes is composed of four equally sized strokes, then we conclude that our entire observed signal could be produced by only 22 flashes per second.