The researchers analysed the development of human heat adaptation and measures of future heat exposure, frequency and magnitude until 2100 in major world cities and considering 15 possible climate and socio-economic scenarios.
They used the well-established metric 'minimum mortality temperatures' (MMT), a metric indicating the lowest risk of heat-related mortality, as a function of climate change and socio-economic progress across 3820 cities. While the adaptation model suggests that negative effects on health from global warming can broadly be kept in check, the trade-offs are highly contingent to the scenario path and location-specific.
For example, in 'business as usual' climate scenarios (e.g. RCP8.5) the maintenance of uninterrupted high and economic growth by 2100 is a hard requirement to level-off the negative health effects from additional scenario-driven heat exposure. Furthermore, the projections for this scenario paired with a fast and unsustainable growth (SSP5) point at a high risk for human health among urban populations in cities in the Sahel, Northern Africa, across the Middle East into Pakistan and India, as well as in the southwestern US and northern Mexico.
However, the study also shows that choosing a 2 °C-compatible climate trajectory alleviates the dependence on fast growth for adaptation while leading to a reduction in mortality risk in 80-84% of the major world cities. These would profit from both exposure reductions and a moderate increase in heat adaptation.
The paper has been picked up by the UN Office for Disaster Risk Reduction and is featured on their website 'Prevention Web'. The article is available here.
