Extreme climate chamber experiments on nature-based solutions: insights from GreenStorm project

The European GreenStorm project (Gromaire, Sage 2024; Seidl 2025) investigates the performance and resilience of nature-based solutions for urban stormwater management (NBS_SW) under current and future climate extremes. To explore the potential and limitations of real-scale climate-chamber experiments, two experiments were conducted at the Sense-City facility to analyze the hydrological, thermal, and vegetation responses to heatwaves in 2024 (Seidl et al. 2025) and 2025.

The experiments focus on a 10-m-long and 6-m-high canyon street equipped with two types of NBS_SW: stormwater trees and a rain garden. The Sense-City (IFSTTAR 2018) climate chamber allows controlling of air temperature, humidity, and radiation, enabling the reproduction of extreme conditions derived from observed heatwaves and future climate projections. The simulated climate scenario included a 5-day reference period representing typical summer conditions in Paris, followed by a 5-day heatwave based on the 95th percentile of RCP8.5 2023-2050 (Soubeyroux et al. 2024) projections and 2003 heatwave (Meteo France 2003).

A comprehensive monitoring system was deployed, including continuous measurements of meteorological variables, soil moisture and surface temperatures, complemented by repeated physiological observations of vegetation. Leaf pigments and stomatal conductance were measured twice each day with continuous monitoring of tree sapflow and stem diameter. These observations were used to assess both the physiological responses of different vegetation types to extreme climatic forcing in relation to NBSSW hydrological conditions.

Preliminary results highlight: (1) the ability of the climate chamber to reproduce global diurnal climate cycle and its limits to reproduce realistic climate gradients, (2) significant uncertainties associated with key climatic parameters, (3) fast adaptation of the studied vegetation to climate extremes in the presence of sufficient soil moisture reserve, and (4) contrasted responses between stormwater trees and the rain garden vegetation in terms of transpiration and physiological stress. These findings contribute to a better understanding of how experimental climate simulations can support the assessment of NBS_SW resilience under future extreme climate conditions.

 

REFERENCES

GROMAIRE, Marie-Christine ,and SAGE, Jérémie, 2024. GREENSTORM. 2024. https://arceau-idf.fr/en/projects/greenstorm

IFSTTAR, 2018. Sense-City, Tester la ville de demain. Trajectoire. 2018. Vol.15, n juin, pp.7‑10.

METEO FRANCE, 2003. Bulletin climatique Aout 2003 Meteo France. https://donneespubliques.meteofrance.fr/donnees_libres/bulletins/BCM/202308.pdf

SEIDL, Martin, 2025. Le projet GreenStorm, c’est quoi ? Ingenius 15 septembre 2025. https://ingenius.ecoledesponts.fr/articles/le-projet-greenstorm-cest-quoi/

SEIDL, Martin, SANDOVAL, Santiago, SAGE, Jérémie, GROMAIRE, Marie-Christine, LAPORTE, Stephane ,and ULANOWSKI, Yann, 2025. EGU25-18974: Towards an understanding of the limits of extreme event  studies on Nature Based Solutions Copernicus Meetings. https://meetingorganizer.copernicus.org/EGU25/EGU25-18974.html

SOUBEYROUX, Jean-Michel, DUBUISSON, Brigitte, BERNUS, Sebastien, SAMACOÏTS, Raphaëlle, ROUSSET, Fabienne, SCHNEIDER, Michel, DROUIN, Agathe, MADEC, Thumette, TARDY, Marc ,and CORRE, Lola, 2024. A quel climat s’adapter en France selon la TRACC?  Meteo France. https://hal.science/hal-04797481v1