In addition to meteorological models of climate change, the IPCC uses economic models to measure the potential damage to society (the ‘damage function’) arising from climate change, usually expressed in terms of reduced rates of growth of GDP (Gross Domestic Product). But more recent socio-economic models have focused on the impact on nature. Yet economic models do not predict nor calibrate climate change; they are reliant upon the science and evidence of climatologists who get their data from tracking organisations such as the World Meteorological OrganizationWorld Meteorological Organization (WMO) (WMO) ( WMO (2024) Latest news https://wmo.int/ ) and the National Oceanic and Atmospheric AdministrationNational Oceanic and Atmospheric Administration (NOAA) (NOAA) ( NOAA (2025) About our agency https://www.noaa.gov/ ), that is, until the Trump administration started closing down many of its databases. Crucially, however, they are based upon the assumptions they make, and among the most crucial are those about how much importance society attaches to the future relative to the present. This is known as the rate of discount. Further, economic models need to treat climate change as an endogenous variable, reflecting the Anthropocene, as opposed to being an exogenous variable uninfluenced by human behaviour.