Galapagos marine iguanas are uniquely vulnerable to El Nino events that reduce algae availability, causing mass starvation. Climate change is increasing event frequency and severity.
Mass starvation during El Nino events causes prolonged suffering as marine iguanas gradually lose body condition over weeks before death from starvation and dehydration. Individual welfare during these events is extreme — entire populations of thousands of animals simultaneously experience starvation. While this is natural climate variability, anthropogenic climate change is increasing the frequency of events that cause this suffering at population scale. The welfare of individual marine iguanas during El Nino is a direct consequence of global climate decisions. The skeletal shrinkage adaptation, while remarkable, is itself an extreme physiological stress response indicating the severity of nutritional compromise during food shortages.