The outstanding preservation of Paleolithic decorated caves is related to the buffering properties of their karstic environment. However, long-term monitoring of air/wall temperatures and gas compositions has recently revealed disruption signs in cave microclimates that had been maintained stable for hundreds of centuries.

High precision and continuous temperature data records are currently monitored in various prehistoric caves in the South of France. Such operations have been promoted since the late 1990s by the French government for risk assessment and conservation.

The most striking feature is the positive drift of underground temperatures (air and wall) which is now obvious in most sites except for Niaux Cave (> 300 m undersurface) and in the deepest parts of Mas-d’Azil and Chauvet Caves (> 50 m undersurface). In tourist caves (Pech-Merle, Mas-d’Azil, Gargas, Villars), the positive thermal trends could not be related to the energy increase brought by visitors which number is now stable, nor to the lighting systems whose energy demand was strongly reduced. In addition, the underground thermal drift nearly starts at the same time in many caves with uncertainties of +/- 1 year: 2012 for Chauvet with +0.4 °C/decade, 2011 for Pech Merle with +0.32 °C/decade, 2011 for Marsoulas Cave with +1.09 to +0.36 °C/decade from the entrance to the deep gallery, 2011 for Gargas with +0.69 °C, +0.54 °C and +0.36 °C for the deeper station. It is worth noting that a 0.3-0.4 °C thermal drift is consistent with that predicted from global warming in these regions.  The thermal drifts were already in progress when monitoring began in Villars Cave in 1996 (+0.17 °C to +0.39 °C/decade), in Mas-d’Azil in 2012 and in Bruniquel in 2015. Marsoulas (+1.09 °C/decade) and Mas-d’Azil (more than +1 °C/decade in 6 of the 16 stations) present a much higher drift rate compared with that of surface, which suggests a thermal amplification process.

As measurements are performed in heterothermal zones, the long-term thermal drifts are modulated by persisting smoothed and out-of-phase yearly variations. A notable exception is the case of Bruniquel main gallery where the temperature records show a quasi-linear increase. In that case, the decadal evolutions of temperature +0.31 °C, +0.175 °C, and +0.24 °C, are not related to the depth of monitoring stations (32 m, 55 m, and 38 m, respectively) nor to their distances from the entrance. In 2018, those drift rates induced a permanent inversion of thermal gradient in the main gallery. In Gargas, the drift rate is more pronounced in the outer parts of the karst body, thus inducing a continuous evolution of the thermal gradients within the galleries.

Such underground microclimate disruption of patrimonial caves is a warning signal of direct threat on the preservation of remains. Karst physical organization and its related underground environment are themselves legacies of past climates; the current functioning of transfer zones of karst aquifers which includes the caves, are directly dependent on the outside climate. A more comprehensive approach and modelling of possible tipping points are urgently needed for conservation issues.

How to cite: Bourges, F., Lartiges, B., Perrier, F., Genty, D., Losno, R., Bonnet, S., Regard, V., Touron, S., Bousta, F., Girault, F., and Foucher, P.: Global warming evidence in long-term temperature monitoring of heritage karstic caves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13666, https://doi.org/10.5194/egusphere-egu23-13666, 2023.

Change in climate extremes and the increased risk associated with human-induced global warming is apparent. Less apparent is the impact such changes may have on vulnerable systems in our society. Climate change impact assessments using state-of-the-art climate models coupled with damage information can offer actionable insight for stakeholders to better protect vulnerable systems.

Cultural heritage is an example of a system that is vulnerable to climate change, especially built cultural heritage which is directly exposed to changing climate extremes. In the UK, significant development has been achieved to better understand the potential change in climate extremes following the release of UK Climate Projections 18 (UKCP18), however, understanding of risk posed by these climate extremes to built cultural heritage is poorly constrained. How to assess and quantify this risk is in its infancy.

We have developed a new methodology building on previous work by cultural heritage experts - the Cultural Heritage Climate Risk Assessment (CHCRA) framework. The CHCRA framework focuses on combining stakeholder engagement and high-resolution climate models to develop site-specific projections of potential damage to cultural heritage assets. This integrated framework when applied with adequate information allows estimation of expected damages to cultural heritage assets through the 21st century.

We applied the CHCRCA framework to cultural heritage buildings in the Edinburgh World Heritage Site, Scotland, considering one-day extreme rainfall events. This pilot study used UKCP18 2.2 km resolution climate projections alongside qualitative and quantitative damage data obtained from multiple sources.

Importantly, UKCP18 2.2 km model is a Convection Permitting Climate Model with the ability to better represent extreme rainfall events. Furthermore, expert elicitation through interviews with practitioners from cultural heritage organisations within Edinburgh were carried out to obtain damage information specific to cultural heritage buildings in the Old and New Town Edinburgh (ONTE), part of the Edinburgh World Heritage Site. A damage function was derived based on expert elicitation and other sources.

Key findings include annual expected damage per year increases from 0.6% in the baseline period (1981-2000) to 1.5% in 2021-40 and 2.3% in 2061-80. A three-to-four-fold increase in annual expected damage to cultural heritage buildings in the ONTE is expected towards the end of the 21^st century.

This is the first application of the CHCRA framework. This pilot study considered only one climate stressor, extreme one-day rainfall events. Damage at built cultural heritage is likely exacerbated and accelerated by other climate stressors, as well as non-climate related factors such as poor maintenance. Furthermore, damage caused by pluvial and/or fluvial flooding mechanisms were not taken into consideration, as well as no consideration given to reduction in risk due to adaptive measures.

This study provided insight into the changing risk posed by an impactful climate stressor to cultural heritage buildings in the ONTE. The study highlights the importance of stakeholder engagement from the outset when carrying out a climate change impact assessment. Further work may benefit from considering a more wide-ranging array of climate stressors to capture synergistic damage processes.

How to cite: O'Neill, S., Tett, S., and Donovan, K.: Extreme rainfall risk and climate change impact assessment for Edinburgh World Heritage sites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2440, https://doi.org/10.5194/egusphere-egu23-2440, 2023.

A large number of stained glass windows were installed from the 13^th century. During the Middle-Ages, most of glass pieces have a Si-K-Ca composition with a relatively low SiO₂ content, but high content of K₂O and CaO.  This chemical composition means that medieval stained glass deteriorates during environmental exposure, from climate and environmental pollution. These alterations are manifested in the form of an alteration layer and secondary phases (mainly gypsum or syngenite). The alteration layer is generally depleted in K and Ca, but rich in Si, Al and Fe. Its thickness varies up to 300 µm after 6 or 7 centuries of alteration. In order to reconstruct the alteration history and predict the deterioration of stained glass windows in the future, it is necessary to determine alteration rates as a function of the climate and environmental parameters.

Several methodologies can be used to achieve this. First, short-term exposures or laboratory experiments can assess the first stages of the alteration and short-term kinetics. From these results, dose-response functions (DRF) were established for sheltered and unsheltered rain conditions. They correlate relevant environmental factors (temperature, rain quantity, rain pH, relative humidity, SO₂ concentration) with the response of the materials in terms of alteration layer thickness. The second methodology consists in laboratory experiments that aim at parametrizing kinetic laws as a function of specific parameters (temperature, pH of rain, and relative humidity). These kinetic parameters do not directly consider pollution, but they can be extrapolated over long periods and can be inputs to geochemical models. In this study, we have compared both methodologies to simulate the alteration of a model stained glass at different European sites (using data from the ICP-Materials program). Both models give good results, but the geochemical model tends to underestimate the alteration at polluted sites. This indicates that the pollution via the concentration in SO₂ for example should be included to improve the model.

How to cite: Verney-Carron, A., Sessegolo, L., Lefèvre, R.-A., and Brimblecombe, P.: Comparison of different kinds of models to simulate the alteration of medieval stained glass as a function of climate and pollution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8060, https://doi.org/10.5194/egusphere-egu23-8060, 2023.

The conservation and protection of cultural heritage, seen in its broadest definition, face ongoing and new challenges as a result of the impacts of slow and extreme climate changes. Therefore, there is the need of further studies and the development of improved methods in order to support decision makers and public authorities in preparing plans to manage and mitigate the correlated risks.

The present contribution aims at analysing and assessing the impacts of pollution and climate change induced extremes on the built heritage located in the historic centre of Rieti (Italy). This research has been conducted in the framework of the Interreg Central Europe Project STRENCH (STRENgthening resilience of Cultural Heritage at risk in a changing environment through proactive transnational cooperation, 2020–2022) and the National Italian Project "Piano Straordinario di Monitoraggio e Conservazione dei Beni Culturali Immobili'', coordinated by the Ministry of Culture. First, the pollutants data (NO₂, SO₂, O₃, PM_2,5 and PM₁₀) extracted from air quality monitoring station at Rieti (IT0867A) were analysed and interpreted in accordance with the limiting values mandated by Italian law (legislative Decree 155 of 2010) for the characterization of air quality. Further, surface recession of carbonate stones for the period of 2011-2021 was calculated using Lipfert (1989) and Kucera et al. (2007) damage functions. Then, the “Risk Mapping tool for Cultural Heritage Protection” (https://www.protecht2save-wgt.eu/) was exploited: time series based on earth observation data (e.g. Copernicus C3S reanalysis and NASA GPM IMERG products), historical changes based on EOBS dataset and future hazard maps at territorial level based on outputs from regional and global climate models (EURO-CORDEX initiative) were investigated.

Obtained results reveal that a constant slight decline trend of pollutants annual average is shown over the years from 2011 to 2019. During 2020, lower values for each pollutant component were observed, partially attributed to the lockdown caused by the Covid19 pandemic. It was also observed that each investigated gaseous pollutant and PM fractions were within the limits regulated by the Italian Law.

Regarding the surface recession analysis, it was observed that it has been decreasing over the past 10 years from 2010 with slight increases occasionally. Also here, a decline in 2020 attributed to the lockdown is clearly observable. Moreover, most of particles contributing to PM can be certainly attributed to vehicular traffic, among anthropogenic sources, and are therefore in the fine fraction.

Finally, climate future projections, with spatial resolution of 12x12km, show a general increase of the changes of the extreme indices taken into consideration (R20mm and Rx5day); the biggest variations are typically foreseen for the far future (2071-20100), under the pessimistic scenario (RCP 8.5), highlighting a high likelihood of heavy rain and flooding risk in the area of Rieti.

How to cite: Sardella, A., Canesi, L., Prashanth Setty, N., Gaddi, R., and Bonazza, A.: Impact Assessment of Pollution and Climate-Induced Damage on Historic Centre of Rieti (Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3237, https://doi.org/10.5194/egusphere-egu23-3237, 2023.

Since the Industrial revolution and due to increasing anthropogenic emissions, the composition of the atmosphere has been modified, leading to climate change and pollution. The impacts of pollution were depicted through paintings and writing from the beginning of the 19^th century, but pollution measurements are relatively recent. In order to obtain ancient air pollution data, proxies in urban area need to be found.

Black crusts formed on limestone and marble monuments in urban area seem to be a good candidate as local proxy. Mainly composed of gypsum (CaSO₄.2H₂O), they are a chemical alteration pattern resulting from the reaction of the dissolution of the calcite (CaCO₃) of the stone and of sulfation by sulphur dioxide (SO₂) from the atmosphere. Particulate matter accumulates in the newly formed gypsum layer in sheltered area from the rain, thus giving the black crust a passive sampler potential.

To use black crusts as past air pollution archives, samples were collected at Père Lachaise cemetery (Paris) on ancient, dated (1820-1887) and unrestored limestone or marble tombs. Different types of analyses were performed to study sample morphology (by Optical Microscope), particulate matter (by Scanning Electron Microscopy) and chemical composition (especially major elements and trace metals by ICP-AES, LA-ICP-MS). Results underline two important features to use black crusts as past air pollution archives. First, the low variability of chemical composition of black crusts from Père Lachaise cemetery highlights that the black crusts are representative of the site and register the background pollution. Then, the morphology (laminar vs. dendritic) of black crusts is a key parameter to sample black crusts as the stratigraphy is much better preserved in laminar black crusts.

How to cite: Ropiquet, M., Verney-Carron, A., and Chabas, A.: Selection of relevant black crusts samples as ancient air pollution archives, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11948, https://doi.org/10.5194/egusphere-egu23-11948, 2023.

Built heritage is rich in cultural and economic values and is an essential part of urban environments. These buildings are abundant in city centres that have been the site of development for several centuries. This has produced a dense environment, exhibiting strong urban heat island effects. Green initiatives are increasingly being implemented to mitigate current climate stressors and improve the health and well-being of residents. However, built heritage is often excluded from these approaches due to concerns about their impact on materials and structural integrity, which is poorly understood. 

This research scopes the technical compatibility of vertical greening with built heritage in an urban environment regarding the degradation of historic building materials. Vertical greening here is understood to include plants, rooted in the ground, growing along a vertical surface by either attaching themselves to the façade or trellising. Investigating the impact of vertical greening on the local microclimate by monitoring case studies, lab experiments and analysing current literature can help us understand how vertical greening affects common forms of degradation caused by salts, frost, bio-activity and air pollution. Each method has its own approach to understanding the relationship of vertical greening with built heritage and is complementary to the others. The lab experiments explore the three main factors impacted by vertical greening such as temperature and relative humidity, incoming solar irradiation and precipitation exposure. Temperature and relative humidity are inseparably connected with each other and therefore analysed together. The impact of vertical greening on the aforementioned environmental parameters is investigated separately to provide better insights into those microclimatic changes that determine the risk of weathering of historic building materials.

How to cite: De Groeve, M., Kale, E., Orr, S. A., and De Kock, T.: The technical relationship between vertical greening and built heritage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12449, https://doi.org/10.5194/egusphere-egu23-12449, 2023.

Moisture and salts cause considerable damage to built and rock-hewn heritage. Rock moisture is a key factor for numerous decay processes, but there is limited knowledge of salt and moisture distribution because measurements of spatial and temporal moisture distribution still remain challenging. The medieval cave town of Uplistsikhe (Georgia) is hewn out of very soft Lower Miocene sandstone and is a typical example of a heritage site suffering from progressive decay. We present data on moisture and salt distribution derived from a multi-method approach, including microwave sensor monitoring (MW-mon; continuously over 2 yrs), microwave handheld sensors (MW), 2D-resistivity profiles (ERT), rock sampling by drilling, and salt extraction by paper pulp poultices (PPP).

Microwave monitoring was applied for the first time (to our knowledge) in a long-term monitoring of heritage sites. We used equipment from hf-sensor (Germany) with two types of microwave reflectivity sensors penetrating approx. 7 cm and 13 cm deep, respectively. The sensors were installed inside and outside of two prominent caves (Grand Hall and Long Hall). MW, ERT, PPP and drilling were carried out in four caves (the two mentioned plus Blackberry Hall and Teatron). Careful laboratory calibration using samples from the site was necessary to produce quantitative results for MW-mon, MW and ERT.  

MW-mon showed pronounced annual fluctuation with highest moisture saturation occurring in summer. The moisture maximum in the caves lags 2 months behind the spring precipitation maximum and might be partly caused by air humidity condensation amplified by salts. Heavy rainfall events cause additional moisture pulses by seeping through the rock or by capillary rise. Spatial moisture distribution derived from MW shows relatively dry rock outside the caves and different patterns of moisture ingress into the caves: Capillary rise from the base, ingress through fractured or otherwise water-permeable areas of the roofs or back walls. The spatial patterns are confirmed by ERT; however, calculated moisture saturation differs between MW and ERT due to electrical conductivity effects of salty pore water.

All drill samples from the caves are significantly saltier on the respective surfaces, which points to the rate of evaporation being smaller than the outward migration of salts. Outside the caves, flaking of thicker layers (several cm) point to deeper layers of salt concentration caused by higher evaporation from the surface; flaking at the "lips" above the caves is probably also amplified by stronger temperature and moisture fluctuations. The main ions everywhere are  Ca²⁺ and SO₄^2- (subordinate K⁺) while at the strongly flaking surfaces of Grand Hall, Na⁺, Cl^- and NO₃^2- are also present. Summing up, the results show very diverse and complex patterns of moisture and salt distribution at an apparently homogeneous site.

How to cite: Sass, O. and Fruhmann, S.: Spatiotemporal rock moisture distribution at the medieval cave town of Uplistsikhe, Georgia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8442, https://doi.org/10.5194/egusphere-egu23-8442, 2023.

The prospect for the sustainability of the Gallo-Roman archeological site located in Genainville (France), where relics and artifacts dated to the 2rd century CE have been excavated is threaten by groundwater ingression. The in-situ building heritage materials and structures comprising a two cellea temple and an amphitheater made of limestones, are submitted all days to rising and changing groundwater levels; water being the main agent or vector of damage processes (salt weathering or freeze-thaw cycles). As part of a multi-disciplinary effort to support archeological expeditions and conserve the site structures. We report the results of groundwater monitoring and hydrogeological studies as well as tidal subsurface analysis executed to quantitatively evaluate hydraulic and geo-mechanical characteristics of the subsurface sequences toward a nondestructive approach. Continuous groundwater level data recorded in three wells in the archeological site were decomposed into constituent events that impact the observed fluctuations. The groundwater levels and barometric pressure data were acquired at 60 seconds intervals to study the response of the aquifer to strain and stress prevalence at the site. Using the method of regression deconvolution, the response to barometric pressure was disentangled from the measured water levels. Theoretical Earth tides parameters were computed using the PyGtide code, based on the ETERNA PREDICT program, at intervals of 1 minute. Harmonic analysis of the raw and filtered data using the classical Fast Fourier transform (FFT), and Singular Spectral Analysis (SSA) identify M₂, S₂, K₁ and O₁ tidal constituents as the dominant amplitudes. The SSA technique has the advantage of resolving the events into individual strands compare to the spectra of the composite data produced by the FFT. Hence, an event decomposed in the data is isolated in terms of it frequency and amplitude, and visualized. The K₁ and S₂ harmonic constituents were present in the filtered and raw data sets with different amplitudes. The amplitude response method was used to compute the poroelastic properties of the aquifer and characterize the subsurface heterogeneity. The model identified a semi-confined aquifer as the main groundwater storage system in the site.

Keyword: Heritage site, groundwater ingress, harmonic constituents, hydraulic properties

How to cite: Nkitnam, E. E., Maineult, A., and Wassermann, J.: Investigations of shallow aquifer groundwater systems of a Gallo-roman anthropized site using earth tide analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6252, https://doi.org/10.5194/egusphere-egu23-6252, 2023.

Built heritage, which gives identity to the urban fabric and fosters the collective memory of the community, is at risk of deterioration due to climate stressors. These stressors result from rapid urbanisation, covering surfaces with hard materials, and a disconnection from nature.

Today, nature-based solutions have become a growing trend as a way to reconnect with nature and mitigate the impact of climate change. Green infrastructures (GI), in particular, offer numerous environmental and social benefits, especially in dense urban areas, including improved air quality, reduced heat island effect, increased biodiversity and improved stormwater management, and stress-reducing and restorative effects on individuals.

Although built heritage sites form an important part of the urban fabric, they are often excluded from this green transition due to the risk of invasive species damaging historic buildings' structural and aesthetic integrity. Therefore, there is a lack of research analysing rigorously designed examples of GI in a historical context.

This study aims to narrow the focus to the sociocultural perception and acceptance of GI in a historical context. We will analyse spatial-perceptual patterns and socio-cultural motivations behind the deliberate use of GI in this context, using biophilic design principles and architectural perception theories as frameworks. Using GIS monitoring as a methodology, we will map and collect inventory data on real-life examples of GI applied to historical buildings in Belgium-Antwerp. The goal is to understand the correlations between spatial-perceptual factors and the use of GI in built heritage contexts.

How to cite: Kale, E., De Groeve, M., and De Kock, T.: Exploring the Socio-Cultural Compatibility of Green Infrastructures in Built Heritage Contexts: A Case Study in Antwerp (Belgium), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5685, https://doi.org/10.5194/egusphere-egu23-5685, 2023.

Not only ecosystems are particularly sensitive to extreme weather as a result of climate change. Historical buildings, museum’s collections and historical gardens can also be affected by extreme weather conditions. Assessing the extent to which cultural assets are endangered by such weather and climate events is an interdisciplinary task that requires the collaboration of climate scientists together with cultural heritage managers, monument conservators, restorers and engineers. However, this discussion is currently hardly taking place in Germany, both on a scientific and on policy levels.

Therefore, the BMBF-funded project KERES addresses the following questions:

• What safety risks of our cultural heritage are caused by extreme weather events?
• Which practical solutions need to be addressed and managed the current and emerging impacts of climate change on cultural assets in Germany?

In close cooperation with the relevant stakeholders and potential users, such as the Prussian Palaces and Gardens Foundation (SPSG), Fraunhofer IOSB is building a web-based knowledge platform that combines the research results and best practices for adaptation and mitigation measures of the historical buildings and historical parks property. This aims to create the greatest possible degree of user orientation so that the knowledge platform can be used sustainably in the long term. This platform is able to collect and integrate multisource information in order to effectively provide complete and updated situational awareness and decision support for innovative measurements improving cultural heritage resilience, in particular new solutions for maintenance and conservation. It is based on the open source; easily configurable and extendable. It can be accessed by the wide range of users via the web interface.

Several levels of data integration, aggregation and linking are aggregated:

• integration of expert knowledge,
• connection of sensors for comprehensive monitoring

and reporting,

• data analysis of complex processes with an open interface

for easy integration of new algorithms,

• semantic and geographic linking of analysis data and
• multiple domain information.

The backbone of this information network is an ontology, which connects the data of the different domains, like cultural heritage, climate change, environmental data, crisis management, regulations, sensor data management, buildings, materials and many more. The platform is flanked by two other applications, such as a planning tool for the evacuation of art objects:

• This is a tool for creating route maps for the fire brigade to evacuate cultural objects.
• The decision-maker supports finding individual measures against damage caused by climate change.

The applications for preventive and reactive measures to deal with potential or acute damage situations are examined as well. The designed methods are tested for five case studies including historical buildings and historical gardens in Germany.

How to cite: Moßgraber, J., Hellmund, T., and Kotova, L.: IT support for climate resilient cultural heritage - examples from the KERES project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13243, https://doi.org/10.5194/egusphere-egu23-13243, 2023.