The inability to quantify which threats matter most across species and ecosystems is a problem for policymaking and resource allocation (see S. L. Maxwell et al. Nature 536, 143–145; 2016). Biodiversity conservation could learn from public-health metrics and go beyond simply counting the number of recorded threats to quantify the contribution of each one to species loss.
Public-health priorities are set using disability-adjusted life years (DALYs), a measure of healthy years of life lost to a disease as a result of death or sickness. DALYs can be compared among diseases, regions or populations; summed to assess total disease impact; and used to evaluate the effectiveness of interventions (C. J. L. Murray et al. Lancet 386, 2145–2191; 2015). The absence of these key functions from existing biodiversity risk assessments limits their usefulness (see, for example, the IUCN Red List).
Although they are not without flaws, DALYs have led to fundamental changes in public health, for example by refocusing efforts on diseases that cause the most harm, such as malaria. They have also prompted reassessment of underlying threats that exacerbate illness, such as malnutrition. And they have highlighted areas in which funding exceeds the share of all DALYs, notably in breast cancer. The availability of an accessible metric, comparable across threats, has also contributed to new funding streams such as the Global Fund to Fight AIDS, Tuberculosis and Malaria.
A comparable metric is urgently needed for more precise analysis of biodiversity threats.
Read the article in Nature: Correspondence.