Targeted Climate Modification on land – A matter of scale

Geoengineering strategies can be classified into two primary categories: i) Solar Radiation Management (SRM), which aims to mitigate the absorption of sunlight by the Earth, and ii) Carbon Dioxide Removal (CDR), involving the active extraction of carbon from the atmosphere for storage in terrestrial or marine environments. The ongoing discourse on geoengineering, particularly SRM on a global scale, is marked by polarization, primarily due to the challenging nature of predicting remote consequences. This presentation endeavors to demonstrate two key points. Firstly, it will present a range of evidence indicating that local mitigation and adaptation, employing ecohydrological processes in regional models, yield more pronounced effects on regional temperatures and moisture compared to studies that use global climate models. Secondly, it will highlight that various bottom-up interventions in the energy-carbon-water nexus significantly impact maximum temperatures and moisture availability. For instance, a recent review (van Woesik et al., 2024) identifies over 50 of such interventions for East Africa. While advocating for the efficacy of local solutions, this presentation acknowledges that such interventions, including reforestation and afforestation (e.g. Staal et al. 2024), can lead to remote consequences due to the interconnected energy-carbon-water dynamics, affecting for instance shifts in local precipitation patterns (e.g. van Theeuwen et al. 2024). Consequently, local-scale CDR solutions influence both local and remote energy balances, blurring the distinction from SRM. This challenges the applicability of conventional IPCC terminologies for climate mitigation and adaptation at the local scale. The prevalent global focus of IPCC research, derived from global models, has impeded the analysis of local ecohydrological interventions. The central proposition of our research is that Targeted Climate Modification should be approached and analyzed from a bottom-up perspective rather than a top-down one. Therefore, we propose terminology shifts from mitigation and adaptation to Targeted Climate Modification. We hypothesize that such locally targeted interventions can benefit humanity and biodiversity by inducing cooling, enhancing agricultural productivity, and mitigating extremes in droughts and floods. However, our research also calls for ethical and governance discussions. Acknowledging that local Targeted Climate Modification may yield negative remote consequences and substantial impacts on biodiversity loss, it advocates for the development of a new framework to analyze ethical, social, and environmental issues associated with Targeted Climate Modification.   References: Staal A, Theeuwen JJE, Wang-Erlandsson L, Wunderling N, Dekker  SC (in press) Targeted rainfall enhancement as an objective of forestation. 2024. Global Change Biology. Theeuwen JJE, Dekker SC, Hamelers BVM, Staal A,  Ecohydrological variables dominate local moisture recycling in Mediterranean-type climates, 2024, submitted to JGR-Biogeosciences van Woesik FM, Dekker SC, van Steenbergen F, de Boer HJ. A review of Local Climate measures to increase Resilience of East African Agroecological Systems. To be submitted to Journal of Environmental Management