From political pledges to quantitative mapping of climate mitigation plans: Comparison of two European cities

Abstract

Background: Urban agglomerates play a crucial role in reaching global climate objectives. Many cities have committed to reducing their greenhouse gas emissions, but current emission trends remain unverifiable. Atmospheric monitoring of greenhouse gases offers an independent and transparent strategy to measure urban emissions. However, careful design of the monitoring network is crucial to be able to monitor the most important sectors as well as adjust to rapidly changing urban landscapes.

Results: Our study of Paris and Munich demonstrates how climate action plans, carbon emission inventories, and urban development plans can help design optimal atmospheric monitoring networks. We show that these two European cities display widely different trajectories in space and time, reflecting different emission reduction strategies and constraints due to administrative boundaries. The projected carbon emissions rely on future actions, hence uncertain, and we demonstrate how emission reductions vary significantly at the sub-city level.

Conclusions: We conclude that quantified individual cities' climate actions are essential to construct more robust emissions trajectories at the city scale. Also, harmonization and compatibility of plans from various cities are necessary to make inter-comparisons of city climate targets possible. Furthermore, dense atmospheric networks extending beyond the city limits are needed to track emission trends over the coming decades.

Keywords: Climate action plan; Climate neutrality; Emission inventory; Fossil fuel emissions; Greenhouse gases; Urban planning.

Fig. 1

Population density of Paris (left) a) and Munich (right) b) and the corresponding surrounding area [41, 42]

Fig. 2

Flowchart of the applied methodology

Fig. 3

Emission trajectory of the two cities and emission targets

Fig. 4

Spatial distribution of the total annual emissions over the city of Munich based on the TNO 1x1km inventory according to the realization of the climate actions (Panel a, b, c). Panel d shows Munich in 2035 if the goal of 0.3 tons ${\text{CO}}_2$e per capita is achieved. CHP Combined heating and power plant, HP Heating plant

Fig. 5

Spatial distribution of the total annual emissions in t${\text{CO}}_2$ over Paris based on the 2019 TNO 1 km x 1 km inventory a) and the climate plan objectives for 2030 b), and 2050 c)