Large animal restoration and carbon storage across climate-relevant timescales.

By virtue of their size and mobility, large animals can play important roles in Earth's carbon cycle. This has led to suggestions that restoring their populations can contribute to mitigating the climate crisis through removal and storage of atmospheric carbon. However, as animals can affect both release and sequestration of carbon, understanding when, where and how much they impact climate-relevant carbon is critical for evaluating their potential to become a trustworthy climate nature-based solution. Here, we review scientific evidence for the carbon impacts of elephants and great whales - two well-studied animal groups commonly cited for climate mitigation and suggested for carbon monetization. We identify six lessons to guide future research, policy and practice: first, large animal carbon impacts vary considerably by individual, species, ecosystem and biospheric conditions, making predictions of future impacts hard and wildlife-based carbon investments high-risk; second, meaningful carbon impacts will likely take longer to manifest than the Paris Agreement's mid-century net-zero target, but wildlife restoration should nonetheless begin now to realize immediate co-benefits and potentially support longer-term climate recovery; third, current conservation remains highest priority, as loss of animals may exacerbate climate breakdown; fourth, caution is needed when incorporating wildlife into climate policy to prevent false confidence in mitigation potential or perverse outcomes; fifth, potential wildlife carbon benefits should be communicated transparently and cautiously to manage expectations; sixth, robust monitoring and validation are essential to ensure carbon sequestration is real and durable. With these lessons in mind, conservation and restoration of large animals may realize their potential to aid long-term climate recovery as well as ecological resilience and adaptation under ongoing global change.