Biodiversity Engel Curves: Estimating how income and inequality shape consumption-driven biodiversity loss

We examine the relationship between household incomes and the biodiversity footprints of consumption in the United States from 1996 to 2022. Combining detailed household expenditure surveys with environmentally-extended multi-regional input-output accounting methods, we calculate consumption-based (i) land-use and (ii) species-loss footprints as proxies for overall biodiversity pressure. We find thatthe average biodiversity footprints of US households declined between 1996 and the early 2010s but began increasing again thereafter, as rising consumption pressure outpaced technological improvements. To characterize the relationship between household income and biodiversity footprints, we construct Environmental Engel Curves (EECs). Just like aggregate footprints, EECs shifted downwards until the early 2010s but have moved upwards in recent years, mainly due to a more biodiversity-intensive composition of expenditures, as we show. Moreover, EECs for land use are concave, implying a "biodiversity-equality trade-off" of moderate size. In 2022, full redistribution to achieve perfect income equality would have raised aggregate land use by 3.2% all else equal, calling for additional efforts to maintain a given biodiversity conservation goal.