Members of the Voluntary Human Extinction Movement, or VHEMTers, certainly don’t think the death of 7.8 billion people over the next hundred years is a natural disaster. For them, it’s a cause for celebration! But only so long as no humans are born to replace the diminishing population. VHEMTers encourage others not to reproduce. On their view, our gradual extinction will “allow the Earth’s biosphere to return to good health.” The voluntary extinction of our species would surely be the most successful collective action challenge ever undertaken. But who would know?