Star-shaped cities alleviate trade-off between climate change mitigation and adaptation

Abstract

To deal with climate change, cities must reduce their greenhouse gas (GHG) emissions and at the same time mitigate climate impacts associated with the physical infrastructure of the built environment. One strand of literature demonstrates that compact cities of sufficient density result in lower GHG emissions in the transport and the buildings sectors compared to sprawled cities. Another strand of literature, however, reveals that compactness hinders climate adaptation by amplifying the urban heat island (UHI) effect. As a result, mitigation and adaptation objectives of cities appear to contradict each other. Here, we develop a geometrical optimization framework and model of a three-dimensional city that minimizes this conflict. It makes use of the observation that low-carbon efficient transport can be realized via linear public transport axes, and that GHG emissions and UHI effects scale differently with varying geometric properties, thus enabling design that reflects both the economics and the climate of cities. We find that star-shaped cities, in contrast to radially symmetric cities, are well suited to alleviate the problematic trade-off. We also demonstrate that urban design considerations depend on transport fuel prices. The results are of particular importance for city planners of rapidly urbanizing cities in Asia and Africa who still have the potential to shape urban layout.

COVID-19 lockdown induced air pollution reduction over India: A lesson for future air pollution mitigation strategies

“…However, there is lack of systematic approach to envisioning this joint institutionalisation of climate change mitigation and adaptation. Thus a model of three-dimensional cities has been proposed, according to which star-shaped cities could serve as a better approach to climate mitigation than radially symmetric cities (Pierer and Creutzig 2019). In India also, several air pollution mitigation policies and legislative laws are implemented to achieve ''National Clean Air Program (NCAP)'' goal.…”

Les villes et le climat : Bâtiments et urbanisme

“…En effet, au-delà des questions de transport, une ville dense présente de nombreux avantages (limitation de l'artificialisation des terres agricoles), mais aussi de nombreux défauts [Lohrey and Creutzig, 2015] : exposition accrue aux nuisances (bruit, et, potentiellement, pollution de l'air), faible présence d'espaces verts au sein de la ville, effet d'îlot de chaleur urbain accru, et donc vulnérabilité accrue aux canicules etc. La recherche reste active sur comment concilier tous ces enjeux (voir par exemple OECD, 2018 ;Pierer and Creutzig, 2019).…”

Mobility Disruptions in Accra: Recurrent Flooding, Fragile Infrastructure and Climate Change

“…Existing research on sustainable transport in cities in the Global South is primarily concerned with mitigating the contribution of urban transport sectors to climate change. A range of studies highlight measures to curb emissions, including compact development [11,12], star-shaped urban form [13], dispersion of housing and industries [14], investments in mass transit systems [15][16][17][18][19][20] and non-motorized transport modalities [21][22][23]. The reverse enquiry, how urban transport systems are affected by extreme weather events, likely to be exacerbated by climate change, has so far received limited attention in the context of the Global South [2].…”