Kaiho uses historic records of diversification, starting with the early evolution of metazoans from cnidarian ancestors 700-500 mya, to predict the future of metazoan life on Earth. In analyzing past records of diversification, environmental drivers beyond the typically considered meteorite impacts and volcanism, such as variations in solar irradiance and inherent climatic fluctuations, are included as major additional drivers. These analyses lead to the proposal that metazoan life will likely go extinct on Earth within the next 700 million years. This extinction will be driven by long-term increases in physiological stress resulting from warming due to increasing solar radiation, as well as decreasing O2 and increasing CO2 concentrations in Earth’s atmosphere. While gradual changes in the Earth system will likely cause a decline in metazoan prevalence, the final thrust to extinction will likely require a global-scale geological or astronomical event.