The main concern with public policies and strategies for integrating nature-based solutions is to facilitate access to innovative interventions to reach cities and communities that are more sustainable and climate resilient. However, there is an impediment to linking information on the results of projects and the expected impact of the European Commission in the framework programmes for research funding. Here we show how projects targeting nature-based solutions help to implement and review public policies under the EU Strategy for Adaptation to Climate Change 2013 – 2020 and European Green Deal. These policies have a positive impact in various areas, especially in green transition, with the potential to analyse the link between the scientific results of nature-based projects and the strategic orientations of research and innovation. We focused on the evaluation of 150 projects funded at the Horizon 2020 and Horizon Europe level, within three main programmes that provide funding for projects based on nature, resilience and adaptation to climate change: (1) Climate action, Environment, Resource Efficiency  and Raw Materials, (2) Climate, Energy and Mobility and (3) Food, Bioeconomy, Natural Resources, Agriculture and Environment. The main analyzed elements are the number and type of partners, the level of funding, the main objectives of the projects, types of nature-based solutions and their distribution by geographical regions in Europe. This analysis leads to the filling in the existing knowledge of the results that produce science, so that it can be exploited throughout the community. Our results consist in (1) overview of climate challenges in EU R&I framework programmes Horizon 2020 and Horizon Europe, (2) Main NBS designed by European R&I organizations, (3) NBS for climate resilience implemented through EU R&I funding in Horizon 2020 and Horizon Europe, (4) NBS for climate resilience – key pathways of knowledge valorization for ecosystem restoration, preservation and management. Overall, they show that the aspects analyzed in the selected funded projects support the development of nature-based solutions and what are the main actions that lead to long-term impact.

How to cite: Barbu, G.-R. and Niță, M.-R.: Nature-based solutions for climate resilience in EU R&I framework programmes Horizon 2020 and Horizon Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19213, https://doi.org/10.5194/egusphere-egu24-19213, 2024.

Nature-based solutions are an important tool to adapt to climate change in cities. Green spaces including nature reserves, parks and green streetscapes are essential to mitigate urban heat and also provide important recreation opportunities that benefit peoples physical and mental health. Effectively planning climate resilient and liveable cites thus requires quantitative, spatially explicit information about these ecosystem services. Such data are especially important in dense cities where vacant land is limited and trade-offs must be made to prioritise certain services. Here we present a multi-ecosystem service assessment for Singapore using the urban InVest models to evaluate urban cooling and urban nature access. We generate future greening scenarios based on policy targets to plant one million trees and increase the land area of parks by 50% by 2030 and compare ecosystem service provision for each scenario when either cooling or nature access is maximised in the spatial configuration of scenarios. We compare the benefits and trade-offs achieved by each scenario and explore the potential to quantify these through health indicators. Finally, we discuss how multi-ecosystem service assessment cans be integrated into urban planning and the implications for cities in an uncertain climate future.

How to cite: Ramsay, E., Tan, L., Wang, Y., and Hamel, P.: A multi-ecosystem service assessment for urban climate adaptation in Singapore , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18701, https://doi.org/10.5194/egusphere-egu24-18701, 2024.

To mitigate climate change impacts in cities, nature-based solutions are broadly promoted due to their supposed benefits for biodiversity, rainwater management, evaporative cooling, and sequestration of carbon. Among existing solutions, green roofs show the advantage of tackling the lack of space available for greening in urban areas. But green roofs are still underdeveloped due to their cost and the lack of scientific knowledge around their potential, especially for carbon sequestration. Quantifying the various contributions of green roofs using reliable scientific approaches is a major challenge. Thus, it is essential to build a numerical model capable of simulating green roofs development and functioning at city scale in order to provide information to decision-makers with relevant indicators.

Here, the urban canopy model Town Energy Balance (TEB) with the module TEB-GREENROOF is used to model green roofs. The TEB-GREENROOF model, evaluated in previous study for heat and water transfers, is improved by activating the photosynthesis model ISBA-A-gs in order to represent the CO₂ exchanges of the vegetation implemented on the green roof. The modelling is informed by 6 years of continuous CO₂ flux data on a non-irrigated extensive green roof located in Berlin (Germany) in partnership with the Technische Universität Braunschweig. In order to evaluate and improve the thermal, hydrological and respiration characteristics of the ISBA-A-gs model on a green roof, an initial simulation is carried out by forcing the monthly evolution of the leaf area index (LAI) by LAI data estimated experimentally. The model is then applied with a dynamic calculation of LAI in order to enable it for simulations of roof greening scenarios on a city-wide scale under any climate with no information on the LAI.

Results show that the model is able to estimate the annual net ecosystem exchange of the Berlin green roof and to correctly reproduce the CO₂ fluxes for both diurnal cycles and annual variation under climate variability, with drier years showing less carbon sequestration.

How to cite: Mirebeau, A., de Munck, C., Weber, S., Lemonsu, A., and Masson, V.: Modelling CO2 flows from extensive green roofs within the TEB (town energy balance) urban canopy model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6169, https://doi.org/10.5194/egusphere-egu24-6169, 2024.

The proliferation of climate-induced stressors has deterred countries' green spaces (GS), which in turn degrade and deplete natural green barriers. Hence, Urban Green Infrastructure (UGI) modelling is grabbing global attention perceiving it as a nature-based mitigation/adaptation strategy to enhance the resilience of urban areas to fight climatic risks. UGI protects and improves the socio-ecological wellness of urban and rural regions. This research intends to investigate thirteen sustainable UGI indicators and their functional linkage with the five vital taxonomies of nature-based green solutions (at the neighborhood level) under a community participatory (CP) approach; out of ten GS elements and twenty-two sustainable UGI indicators developed by the author in his earlier research study [2-5]. It is to develop a sustainable UGI indicator-based framework (tailored to the native-built context) for climate-resilient urbanisation.

The results of the in-depth household survey (192 questionnaires), executed in three KP districts, Charsadda, Peshawar, and Mardan, and results were generated through Relative Importance Index (RII) and Interquartile Range Technique (IQR) show a very good level of coefficient alpha (α) value, (α = 0.7) — an acceptable threshold level [6, 7]. Furthermore, this study acknowledges key GS taxonomies that have achieved RII value ≥ 0.72. This performs a pivotal role in quality improvement and strengthening the resilience (health) of the respective UGI indicators. This scientific research study provides a foundation for an eco-regional paradigm in KP territory that paves the way for an effective implementation of green urbanism to naturally ameliorate the vulnerability to potential climatic stresses (like flooding, drought, the UHI effect) and disastrous impacts on the socio-ecological wellness.

Keywords: sustainable green infrastructure (GI) indicators; participatory planning (PP); nature-based green initiatives; climate change (CC); socio-ecological wellness; KP, Pakistan

References

1. Mell, I. C., Henneberry, J., Hehl-Lange, S., & Keskin, B. (2013). Promoting urban greening: Valuing the development of green infrastructure investments in the urban core of Manchester, UK. Urban Forestry & Urban Greening, 12(3), 296–306. http://dx.doi.org/10.1016/j.ufug.2013.04.006

2. Rayan, M., Gruehn, D., Khayyam, U., (2021b). Green infrastructure planning. A strategy to safeguard urban settlements in Pakistan. In: Jafari, M., Gruehn, D., Sinemillioglu, H., Kaiser, M. (Eds.), Planning in Germany and Iran. Responding Challenges of Climate Change through Intercultural Dialogue. Mensch und Buch Verlag. Berlin, pp. 197–220.

3. Rayan, M., Gruehn, D., & Khayyam, U. (2021a). Green infrastructure indicators to plan resilient urban settlements in Pakistan: Local stakeholder’s perspective. Urban Climate, 38, 100899. https://doi.org/https://doi.org/10.1016/j.uclim.2021.100899

4. Rayan, M.; Gruehn, D.; Khayyam, U (2022a). Frameworks for Urban Green Infrastructure (UGI) Indicators: Expert and Community Outlook toward Green Climate-Resilient Cities in Pakistan. Sustainability 2022,14, 7966. https://doi.org/10.3390/su14137966.

5. Rayan, M.; Gruehn, D.; Khayyam, U (2022b). Planning for Sustainable Green Urbanism: An Empirical Bottom-Up (Community-Led) Perspective on Green Infrastructure (GI) Indicators in Khyber Pakhtunkhwa (KP), Pakistan. Int. J. Environ. Res. Public Health 2022, 19, 11844. https://doi.org/10.3390/ijerph191911844

6. Cortina, J. M. What is coefficient alpha? An examination of theory and applications. J. Appl. Psychol (1993).

7. Peterson, R. A. A Meta-analysis of Cronbach’s Coefficient Alpha. J. Consum. Res (1994).

8. Wu, J., & Wu, T. (2012). Sustainability indicators and indices: an overview. Handbook of Sustainability Management, 65–86. http://dx.doi.org/10.1142/9789814354820_0004

How to cite: Rayan, M., Gruehn, D., and Khayyam, U.: Community-driven sustainable green infrastructure (GI) indicators to plan an eco-friendlier and climate-resilient city-state in Khyber Pakhtunkhwa (KP), Pakistan., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8806, https://doi.org/10.5194/egusphere-egu24-8806, 2024.

Cities and urbanizing spaces combine heat stress from both heat island effect due to the built environment as well as global warming.  India with its high rate of urbanization is no exception. However, many Indian cities have blue and green spaces with various levels of protection from land-use and land-cover change. 

Blue and green spaces (BGS) are potentially nature-based solutions for mitigating heat stress through evaporation and transpiration besides sequestering carbon and as a habitat for urban biodiversity.  The effectiveness of BGS in mitigating heat stress depends on size, shape, weather, and climate variables, especially humidity.  

We use satellite derived land surface temperature (LST) to quantify and map negative temperature anomalies (cooling) with respect to spatial average across the city in years with different levels of summer temperature, especially due to El Nino.   We analyse the diverse types of blue and green spaces in three metropolitan cities in India and classify them in terms of biodiversity value (using e-bird data and other published sources). 

Cooling more than few degrees Celsius with respect to city wide averages from blue and green infrastructure has been observed and is much higher if compared to nearby built areas.  The geometry and landscape ecology of existing urban blue and green infrastructure can help inform future planning for blue and green spaces as adaptation in a warming urban environment. 

How to cite: Krishnaswamy, J., Chandrasekharan, K., Mayavel, D., and Jambhekar, R.: Role of blue and green spaces in mitigating heat stress and providing biodiversity co-benefits in India’s cities , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20974, https://doi.org/10.5194/egusphere-egu24-20974, 2024.

Nature-based solutions are now a key part in climate change adaptation, particularly for urban environments. The integration of natural systems within the urban fabric has the potential to increase cities’ resilience to the predicted changes in climate. Urban forests are one of the most used methods for adding ecosystem services to an urban environment and at the same time address urban-specific climate change challenges such as heat-island effect, intense rainfall and water management. However, the effects of climate change in the long-term on urban forests are not often taken into account when planning interventions such as afforestation. Species selection for urban forests should, among other factors, be based on an assessment of local future climatic conditions, so to ensure the long-term viability of the project. Here we propose a methodology easily applicable to any place in Europe. We use data from interpolated publicly available climate datasets and species distribution data from the European Tree Atlas in order to analyse climatic niches for tree species in Italy. These climatic ranges are then compared to local climatic data, obtained from homogenised time-series measured by a weather station in the city of L’Aquila. The results are summarised in a suitability matrix providing vulnerability scores for each species based on predicted climate changes for the local area. The analysis ranks the species which are less vulnerable to projected future climate conditions. The application to the pilot area of L’Aquila suggests that some species already present will still be suitable also in future climate (e.g. Quercus pubescens) while others will not (e.g. Quercus petraea), and species not traditionally present may become suitable (e.g. Quercus ilex). The importance of obtaining accurate local climate data from observations is a key aspect for municipalities to consider as results of this analysis are greatly dependent on this.

How to cite: Gala, C., Curci, G., Pace, L., Marucci, A., and Del Tosto, D.: Assessing the vulnerability to climate change of tree species for urban afforestation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11439, https://doi.org/10.5194/egusphere-egu24-11439, 2024.

Nature-Based Solutions as a tool to reduce coastal risks have gained in popularity in the last 10 years. However, in France, their development still faces some limits and oppositions from local populations and stakeholders. The main reasons for this are the lack of knowledge and feedback, and the fear of being less protected with against floods with Nature-Based Solutions than with sea walls. This work will present the example of Criel-sur-Mer, in the North of France, where a project of restoration of intertidal habitats to reduce coastal risks is currently discussed and capitalize on feedbacks from three finalized projects from the Netherlands and England.

This study is part of a PhD work on the mobilization of Nature-Based Solutions in coastal protection projects. This presentation is based: on field trips conducted between March and April in the Netherlands and England, on the sites of Hedwige & Prosperpolder (Netherlands, Belgian border), Freiston Shore and Abbotts Hall (England), and in September 2022 and March 2024 in Criel-Sur-Mer (France); on semi-structured interviews conducted with stakeholders on those sites; on semi-structured interviews conducted with 39 coastal engineers and environmentalists between June and August 2023 in Artelia, the engineering firm in charge of the project of intertidal habitats restoration in Criel-sur-Mer; and on observative participation to a public consultation workshop with local actors and stakeholders for the project of Criel-sur-Mer.

The cross-study of the three Dutch and English projects gives us useful examples of the effectiveness of Nature-Based Solutions used as a tool to reduce coastal risks, that can be reused to enrich the project of Criel-sur-Mer. As the two English projects have been finalized in 2002, they are a source of extensive feedback on the evolution of intertidal ecosystems with managed realignment and their efficiency facing storms. The Dutch example started in 2005, but was finalized only in 2023, as it faced numerous social and political oppositions. These projects can thus be used as feedback on governance, project structuration and finding the right balance between different interests for the Criel-sur-Mer example.

How to cite: d'Avdeew, M.: Nature-Based Solutions for coastal risks protection: lessons learned from Dutch and English examples, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20731, https://doi.org/10.5194/egusphere-egu24-20731, 2024.

Coastal zone ecosystems’ global importance is the primary driver of the wide scientific efforts for their restoration and protection. Over the past three decades, there has been a growing global momentum in the pursuit of initiatives aimed at conserving nature. Regardless of the wide scientific interest, and despite the notable exposure of these ecosystems to degradation and deterioration, numerous habitats, and species, in Europe, have 'vulnerable', or 'near threatened' conservation status. Even in the most favourable circumstances, factors including strong human pressure, urbanization and agriculture, and climate change, exhilarate the current, already, negative trends indicators, related to biodiversity and their associated ecosystem functions and services provision. This project proposes a set of existing and emerging methodologies and solutions for the restoration, conservation, and management practices, which are crucial to improving these profoundly delicate ecosystems in the Mediterranean and similar environmental contexts.

Traditional and innovative ecological restoration solutions have been designed and applied in two such areas along the Greek and Italian coasts, ‘Nestos Delta’ and ‘Bosco di Palo Laziale’, respectively, to improve the conservation status of 'Pannonian-Balkanic turkey oak-sessile oak forests' (habitat 91M0), ‘Alluvial forests with Alnus glutinosa and Fraxinus excelsior’ (habitat 91E0), and 'Mediterranean temporary ponds' (*3170) that have been increasingly exposed to climate change and inappropriate forest and water management.

Analogous, ecological restoration practices include selective trimming of encroaching shrub vegetation (and alien invasive shrubs in the Nestos area), remote-controlled irrigation system, origin-controlled and pathogen-free forestry nursery, ex-situ micro-propagation and in-situ reinforcement of keystone plant populations. An in-depth assessment and quantification of abiotic and biotic factors of the sites' ecosystems were preliminarily conducted to tailor these interventions to the habitats' geo-morphological, climatic, pedological, and physiological conditions.

The EU project LIFE PRIMED (LIFE17 NAT/GR/000511), operates at the Delta of River Nestos in Greece, and the Forest of Palo Laziale in Italy. The results in both areas, thus far, have demonstrated that the collaborative development of innovative water harvesting systems, coupled with adaptation measures, has the potential to enhance water resilience in already degraded forest ecosystems. To date, the project has successfully tackled the effects of escalating irregular rainfall patterns on Mediterranean coastal habitats by implementing a hydraulic system and a wellpoint-based water distribution network in Palo Laziale and Nestos Delta, respectively.

Monospecific approaches for climate and human-related phenomena, such as extreme weather events and agriculture pressure, are disfavoured. Therefore, the LIFE PRIMED project, comprised of an interdisciplinary team of Botanists, Zoologists, Foresters, and Environmental Engineers, has developed and delivered Nature-based transnational, ecosystem-oriented holistic solutions that will have the potential to be replicable and transferable with the greatest aim to recover dysfunctional, poorly managed coastal forest areas, across the Mediterranean region.

How to cite: Makaronidou, M., Emanuele Cambria, V., Korakaki, E., Georgiadis, C., and Petrou, N.: Opportunities to Restore and Protect Coastal Ecosystems with Enhanced Interdisciplinary Management - The Mediterranean Model., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9173, https://doi.org/10.5194/egusphere-egu24-9173, 2024.

Climate driven changes in hydrologic regimes are increasing riverine flood risks in many parts of the world. Societies that have historically relied on structural flood management infrastructure, e.g., levees and dams, may face significant challenges as these types of infrastructure can be expensive and politically difficult to retrofit for non-stationary and uncertain future flood hazards. Hybridizing conventional infrastructure systems with nature-based solutions (NbS) can help communities adapt to non-stationarity and improve flood resilience. However, despite advances in the academic literature, NbS have failed to become mainstream in many societies. The United States (US) is no exception and has an extensive history of engineering rivers with structural systems to support immediate-term economic growth and with limited consideration for non-stationarity. For example, there are thousands of kilometers of continuously leveed river corridors in the US and many of these levees were built as close to river banks as possible to maximize the commercial prospects of flood protected land use. Such levees are relatively sensitive to non-stationarity and the communities they protect are becoming increasingly vulnerable to climate change-driven flooding. Our research focuses on how to bridge the gap between the scientific development of NbS and implementation in professional practice. We are doing so by example, with levee setbacks on America’s longest river -- the Missouri -- and in collaboration with the US’s primary action agency of flood risk management -- the US Army Corps of Engineers. Setbacks are implicitly an adaptation strategy that buffer a community against uncertainty and non-stationarity by providing additional room for floodwater conveyance. Unfortunately, they are fraught with social and political challenges because -- as a form of managed retreat -- they require some community members to relinquish private property rights so that the broader community can have greater flood protection. Critical to bridging the gap between levee setback research and implementation is understanding the performance of setbacks at scale and the development of simple and repeatable methods for designing setbacks to successfully deliver multiple ecosystem services. The most fundamental of which is how to “size” a setback – in other words – how big of a floodplain reconnection is required to achieve a desired improvement in flood protection services? In this talk, we will discuss sizing methodologies for achieving multiple services, as well as practical engineering, social, ecological, and administrative constraints that have arisen in the process of translating NbS research to practice. The example of levee setbacks on American rivers is particularly useful because it affords experimentation with repeatability (given the thousands of kilometers of continuously leveed river corridors) and the spatial scale of reconnection required to achieve multiple benefits (given the massive size of many levees and floodplains). The results of which may be relatable to many engineered river corridors around the world and will hopefully support mainstreaming NbS in other social and political contexts.

How to cite: Chambers, M., Crane, D., van Rees, C., Shudtz, M., Landry, C., Ferreira, S., Nelson, D., Suedel, B., Woodson, B., and Bledsoe, B.: Nature-based solutions for leveed river corridors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-467, https://doi.org/10.5194/egusphere-egu24-467, 2024.

The introduction of Natural Based Solution (NBS) into sustainable agricultural practices is a key issue on which the balancing of intensive agricultural activities with environmental protection depends. In lowland areas with intensive agricultural production, occurrences of extreme amounts of excess water, caused by climate change, increase the need for efficient drainage systems. Within the comprehensive framework of drainage system improvement, NBS are emerging as key and versatile interventions. The principal challenge lies in reconciling these solutions with the prevalent technical paradigms in both land reclamation and agriculture. The most important change is the strategic integration of the use of riparian buffers as supplementary melioration measures in delineated areas, especially aimed at reducing the inflow of excess water into the canal network. Deciding where to implement NBS for better drainage systems comes down to assessing the risks that may occur as a consequence to natural resources such as water and soil. When the implementation of NBS determines the crucial factors and evaluates them effectively, then it can categorize and map the optimal places where improvement of the drainage system is possible and efficient. In this study the aim was to delineate suitable zones for implementing nature-based solutions along watercourses through the application of Geographic Information System (GIS) methodology. By overlaying different layers, including pedological and geomorphological maps, digital terrain models indicating land slope, land use classifications, and drainage classes, it is intended to analyze and identify optimal locations. Some of the characteristic drainage systems in Vojvodina have been selected to provide a relevant case study illustrating how GIS can be applied to demonstrate the potential of nature-based solutions in improving drainage systems. This approach not only enhances the efficiency of the existing drainage systems. It also provides insights for strategic afforestation and the increase of biodiversity in agricultural areas.

How to cite: Vranešević, M., Knežević, M., Zemunac, R., and Meseldžija, M.: Suitability assessment of the location for the Natural Based Solution application on drainage systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18875, https://doi.org/10.5194/egusphere-egu24-18875, 2024.

In fire-adapted forests around the world, nature-based solutions (NbS) are increasingly used as a tool to promote resilience to catastrophic fire through actions like fuels reduction and prescribed burning. This work also has many potential co-benefits, including climate change mitigation through stable carbon storage and biodiversity through habitat protection. One key mechanism for realizing both of these co-benefits is the protection of large and ancient trees, keystone components that sequester a disproportionate amount of carbon and serve as unique habitat for old forest associated species, many of which are declining or at risk of extinction. However, climate change poses a substantial risk to both tree recruitment and survival, either directly (temperature and drought tolerance) or indirectly (wildfire and insect occurrence). These impacts are not fully understood in the scientific literature nor, as a result, fully accounted for in the design of NbS management projects.

Therefore, to help inform near-term NbS restoration priorities, we investigated how a changing climate will impact the retention of large trees on the landscape and the ecosystem functions they support. Focusing on the Sierra Nevada, California, USA, a biophysically diverse and at-risk mountain ecoregion, we evaluated the intersection of current and future climate with large tree occurrence and two critical functions: carbon storage and habitat for the California spotted owl (Strix occidentalis occidentalis; CSO), an old growth associated species whose core population is limited to the Sierra Nevada and that requires large trees for nesting habitat. We mapped large trees across the Sierra Nevada, evaluated the climatic drivers of large tree biogeography, and forecasted how conditions supportive of large tree populations might shift geographically in the future under two emission levels (RCP 4.5 and 8.5). Using a bivariate fuzzy logic approach, we mapped the joint probability of current CSO occupancy and carbon storage and then evaluated future climate vulnerabilities and associated management strategies. We found that carbon and CSO occupancy corresponded closely with the current distribution of large trees in the Sierra, primarily at mid-elevations in the central Sierra. Similarly, we found that these mid-elevation montane forests are likely to continue to support large trees and CSO habitat and carbon storage through mid-century (e.g., consistent with "monitor" and "protect" climate-informed management strategies). Conversely, climate conditions in the southern Sierra and the upper elevations of the central Sierra are likely to constrain the persistence and recruitment of large trees, affecting the potential to recruit CSO habitat and enhance the carbon storage of higher elevation forests. 

We hope these findings will encourage the design of and investment in climate-informed NbS projects, and we propose that this method could be used in other ecosystems to jointly assess the climate change mitigation and biodiversity impacts of NbS-based management.

How to cite: Maurer, T., Manley, P., Anderson, C., Povak, N., Saksa, P., Kramer, A., and Peery, Z.: Leveraging the co-benefits of large tree protection to inform nature-based management of a forest ecosystem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13018, https://doi.org/10.5194/egusphere-egu24-13018, 2024.

The Great Green Wall (GGW) is a multibillion-dollar African initiative to combat desertification in the Sahel by restoring 100 million hectares of degraded land. The idea of a physical green wall of trees has now been developed into the implementation of scattered green zones throughout arid areas, providing sustainable reforestation, revegetation, and land management. In West Africa, the most important climate feature is the West African Monsoon (WAM), which brings rainfall over the Sahel during the Northern Hemisphere summer. Climate dynamics associated with WAM changes could also play a role on the Atlantic Tropical Cyclones (ATCs) formation and variability. The potential climate impacts of the most recent GGW plan on northern Africa and tropical Atlantic have not yet been adequately evaluated, raising concerns about unforeseen climate ramifications that could affect stability in northern Africa and impact on the ATC variability. Here, we use a high-resolution (~13 km) regional climate model to evaluate the climate impacts of four GGW scenarios with varying vegetation densities under two extreme emission pathways (low and high). Higher vegetation density GGW scenarios under both emission pathways show enhanced rainfall, reduced drought lengths and decreased summer temperatures beyond the GGW region relative to the cases with no GGW. However, all GGW scenarios show more extreme hot days and heat indices in the pre-monsoonal season. Furthermore, in spite of a strong variation in the African Easterly Waves activity, no significant changes are found in terms of ATCs frequency, intensity, meridional motion and translation speed over the North Atlantic area. Small changes in the TC densities are found in front of the cost of West Africa,  in the eastern side of the Main Development Region. These findings highlight the GGW's contrasting climatic effects, emphasizing the need for comprehensive assessments in shaping future policies.

How to cite: Ingrosso, R. and Pausata, F. S.: On the climate impacts of four different Great Green Wall scenarios on the northern Africa and the Atlantic Tropical Cyclones variability., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2883, https://doi.org/10.5194/egusphere-egu24-2883, 2024.