Challenges to the Sustainability of Urban Cultural Heritage in the Anthropocene: The Case of Suzhou, Yangtze River Delta, China

Abstract

Among the diverse challenges to the sustainability of China’s rich tangible cultural heritage, climate change, associated with increased temperatures, altered precipitation regimes, and the augmented frequency and magnitude of extreme events, is regarded as one of the most prominent. However, there is a diverse range of rapidly emerging environmental and socio-economic hazards that threaten cultural heritage in the country but have thus far received scant attention in this context. Without adequate attention and intervention, the sustainability of the country’s historic urban heritage is highly vulnerable. Anthropocene threats to this important legacy include climate change, sea level rise, land subsidence, water and air pollution, rampant urbanization, and tourism. Suzhou, situated in the low-elevation Yangtze River delta within one or two meters of current sea level, lies in the heart of one of the fastest socio-economically developing and urbanizing regions in the world and is especially vulnerable to the range of threats. As one of the jewels in the crown of China’s architectural heritage, Suzhou represents a model case in which to consider the conflicting interests of socio-economic development and environmental and cultural conservation in the context of rapidly changing environmental conditions. In this review, we consider the diverse risks to the sustainability of Suzhou’s cultural heritage posed by these circumstances, highlight key problems, and prioritize the most urgent issues requiring attention. In recognizing the spatial and temporal nature of these multiple challenges, we highlight the need for integrated approaches to safeguard the sustainability of such valuable resources. Moreover, considering the imperative of accelerating progress towards the UN Sustainable Development Goals and reflecting on current theories of sustainable management of urban cultural heritage, we outline the potential policy and practice implications for the conservation of Suzhou’s historic buildings, canals, and gardens.

1. Introduction

It is widely accepted that urban cultural heritage is impacted by anthropogenic climate change, and there is increasing awareness that mitigating these impacts and appropriate planning is essential to ensure the future conservation of valuable historic resources in cities. Nowhere is this more important than in China, where the richness of the nation’s tangible cultural heritage faces particularly intense climate-related challenges since, along with much of the rest of Asia, its cities are experiencing exceptional levels of human-induced warming that is expected to intensify in the future [1].

As ominous as it is, climate change is only one of the challenges facing the urban architectural heritage of the country, for ongoing anthropogenic factors impose a wide range of pressures on valuable buildings, monuments, and other urban structures, including landscape architecture. Especially when such structures are historic and therefore of special cultural significance, they are vulnerable to an assortment of human impacts, many of which have been amplified or accelerated in the recent past due to, for example, population pressure and economic development. Such impacts pose a risk to cultural heritage globally, and, indeed, there is an expanding literature on the topic, especially in relation to climate change [2,3,4]. However, there is much more to the increasing magnitude of human impact in the Anthropocene than simply considering the effects of global warming, and the sustainability of our valuable urban cultural landscapes demands a more holistic approach. Moreover, China has an impressive array of cultural heritage places, including more than 50 World Heritage Sites (second in number only to Italy: https://whc.unesco.org/en/list/, accessed on 23 March 2025), and a very substantial proportion of these are urban structures.

Despite its obvious significance, there is virtually no literature on the potential impacts of climate change and related factors on the sustainability of China’s tangible cultural heritage. Accordingly, the aim of this paper is to identify the range of threats to the sustainability of urban cultural heritage and to evaluate these in relation to the city of Suzhou, Jiangsu Province, a city whose very ‘brand’ is based on heritage. This is achieved through a comprehensive and rigorous scoping review of the most recent literature relating, firstly, to the environmental challenges currently facing the sustainability of urban cultural heritage that have been identified in studies globally, and then by focusing specifically on how key Anthropocene threats have the potential to impact the urban heritage of Suzhou in particular (Figure 1). The literature from multiple databases was obtained by employing several online search tools, with an emphasis on the most recent publications, i.e., the last five years. The review therefore spans a wide range of themes relating to climate change, sea level rise, land subsidence, air and water pollution, urbanization, and tourism, all of which may negatively impact tangible heritage resources.

Suzhou has several key attributes that make it an ideal case to observe the current and potential future effects of ongoing human impact viz. (i) its geographical location in the heart of the Yangtze River Delta (YRD) megalopolis, one of the world’s most densely populated and economically productive regions; (ii) although not situated at the coast itself, the city lies in the floodplain within just a few meters of sea level and is therefore vulnerable to both terrestrial and marine flooding; (iii) it has world-renowned cultural heritage sites and a rich architectural legacy.

2. Anthropocene Threats to Urban Cultural Heritage

Despite the decision by the International Union of Geological Sciences not to afford the Anthropocene formal status as an epoch [5], the term is widely used in numerous different contexts to symbolize the rapid socio-ecological transitions that characterize and problematize the relationship between people and nature. These transitions are emerging as expressed at all scales in the form of rapid changes and imbalances across the entire range of environmental and social processes and patterns [6]. Paramount among these, and certainly the most widely acknowledged, is climate change, which has received increasing attention globally in the context of cultural heritage, although other aspects of human impact have not been subject to the same degree of scrutiny, including sea level rise (itself a consequence of climate change), land subsidence due to excessive groundwater extraction, air and water pollution, rampant urbanization, and tourism. Here, with reference to the most recent literature, we consider each in turn, specifically in relation to urban cultural heritage.

2.1. Climate Change

Without doubt the most widely acknowledged global environmental issue, and one that is perhaps the most serious threat to the world’s cultural heritage [7], the impacts of anthropogenically induced climate change have rarely been studied in the context of China’s cultural heritage. In the two most recently published reviews of climate change effects on heritage resources, there is scant reference to China. A compilation of more than 170 studies addressing climate impacts on various elements of cultural heritage [8] identifies only 8 from Asia and only 1 from China [9], a study related to the effects of biodeterioration on artworks and not therefore relevant to urban heritage per se. Meanwhile, in a comprehensive assessment of hundreds of studies globally [3], only one addresses climate impacts in relation to Chinese conditions, highlighting the threat of sand encroachment on the Crescent Moon Spring [10]. In a review of 51 State of Conservation reports for UNESCO World Heritage Sites [11], only 2 of which relate to China. Clearly, research on China’s valuable cultural heritage has not thus far been directed towards the challenges posed by the increasingly pervasive problem of climate change.

The major underlying cause is the increase in atmospheric concentrations of greenhouse gases due, principally, to fossil fuel combustion, but other factors such as cement manufacture and land use change, in particular, deforestation, are major contributors. Indeed, increased atmospheric concentrations of carbon dioxide may induce accelerated weathering, especially of building materials, such as limestone and marble, through the so-called karst effect [12]. Frequently oversimplified as ‘global warming’, climate change is itself a composite concept comprising a wide array of interrelated phenomena, such that associated changes in parameters, including rainfall, wind, evaporation, and humidity, are spatially highly variable and difficult to model and predict. The Intergovernmental Panel on Climate Change (IPCC) assessment reports provide the ‘state of the art’ with regard to both the recent past, present, and future modeled climate trends at global and regional scales and are freely accessible (see: https://www.ipcc.ch/report/sixth-assessment-report-cycle/, accessed on 23 March 2025). Gradual anthropogenic changes in climate attributes, such as mean annual temperature or rainfall, cause problems, but the increased frequency and magnitude of extreme events, including storms, floods, droughts, and wildfires, must also be accounted for in terms of mitigation and adaptation. The Anthropocene is not only the ‘human age’ [13], it is also the age of increased risk [14], which augments the exposure of cultural heritage to potential disasters [15].

In this context, the major features of climate and climate change that pose a threat to the urban cultural heritage of the country are outlined. Climate impacts physical, chemical processes that degrade construction materials and structures. Moisture is arguably the most important decay factor in buildings generally and is therefore a key factor in relation to the deterioration of historical building construction materials and their susceptibility to climate change [16]. Changes in the precipitation regime may trigger increased flooding hazard, as reported in the historical city of Odense in Denmark [17]. Fluctuating groundwater levels are influenced by altered rainfall patterns and may augment damage to building foundations, as demonstrated in respect of the Shahe ancient bridge site in Xi’an, China [18]. Meanwhile, warmer temperatures, especially the extreme temperatures increasingly evident due to climate change, may intensify the process of thermoclastism by which materials expand and contract [19]. This in turn may accelerate the weathering of building stone [20] or promote the desiccation and cracking of wooden structures, especially when exposed to strong sunlight [21]. Other processes that are amplified under climate change include enhanced biological degradation caused by microorganisms, such as algae [22] and fungal growth [23].

2.2. Sea Level Rise

Recent rates of global sea level rise, which are themselves a product of anthropogenic climate change, are increasing in scale [24]. This has major implications for cultural heritage structures situated at or near the coast and, through associated impacts on groundwater levels, may create problems in low-lying floodplains situated a considerable distance from the actual coastline [25]. It has been estimated that almost 20% of World Heritage Sites globally may be swamped if global warming exceeds 3 °C, including 47 of the 49 in the Mediterranean by the year 2100 [26]. Coastal cities are frequently exposed to the effects of extreme storms and typhoons, the effects of which are exacerbated by sea level rise, with clear implications for building structures in low-lying coastal regions [27]. The impact of future sea levels on the archaeological heritage of coastal China has been evaluated [28], indicating that the country’s low-lying coastal platform is extremely vulnerable to inundation. The impact of sea level rise on cultural heritage adjacent to, or within a few meters of, modern sea level extends beyond the direct effects of inundation to include socio-economic factors, and traditional villages along the southeastern coast of the country are particularly at risk [29].

2.3. Land Subsidence

Land subsidence is a global challenge, none more so than on coastal plains and deltas, where it also exacerbates relative sea level rise [30]. The phenomenon results from a variety of factors, but groundwater extraction and the associated decline in water table levels are the principal correlates. Perhaps the most widely known example of this problem in relation to cultural heritage is the city of Venice, where the ongoing sinking of the island threatens the foundations of many famous structures, not only through inundation but also due to the deleterious effects of increased groundwater salinity [16]. In China, a recent national-scale remote sensing study [31] has identified land subsidence in all of the country’s major cities, many of them on the coast, with almost half of them subject to annual rates exceeding 3 mm. The potential for this to impact urban cultural heritage is clear, although no explicit studies on possible effects in China have thus far been published.

2.4. Water and Air Pollution

One of the most pervasive impacts of human activity in the Anthropocene is atmospheric and water pollution. Acidic and oxidizing gases, as well as particulate matter in the atmosphere, are corrosive agents that represent a major threat to the conservation of cultural heritage [32]. The impact of air pollution has recently been evaluated in China [33], revealing that, depending on location, gaseous pollutants such as SO₂, NO₂, and ozone generally exert the most severe negative effects, although particulates, including black carbon, also cause chemical degradation and disfigure building materials [34]. While much attention has been focused on atmospheric pollution, the deterioration of water quality is also a potential problem, especially in cases where water is a prominent element of cultural heritage. Many cultural heritage sites in China feature lakes and ponds as important features of their landscape architecture, e.g., the Summer Palace in Beijing or the Classical Gardens of Suzhou [35]. Eutrophication, associated with algal or cyanobacterial blooms, is a major problem in many lakes and wetlands in China, not least in the Yangtze River floodplain [36] and, along with other forms of organic or chemical pollution, could seriously impact the aesthetics of an important cultural resource or, worse, result in health problems.

2.5. Urbanization

Urbanization in China has been rampant, and having passed a rate of 50% in 2012, the urban population in the country has continued to grow and, despite the recent trend of slight overall population decline, has now reached 63% (https://data.worldbank.org/indicator/, accessed on 23 March 2025), and will likely exceed one billion within the next few years. In China, realizing the ‘urban dream’ has witnessed arguably the ‘greatest human resettlement experiment’ in history [37]. For cultural heritage resources within cities, or even on their margins, such rapid change has major implications, many of them negative. There are many examples globally of where seemingly unconstrained urbanization, and its hunger for land, has led to the loss of heritage resources, including in some of China’s cultural heritage protected cities [18]. It has even been suggested [38] that rapid urbanization has led to the gradual neglect of traditional culture in general, let alone its tangible assets. Meanwhile, gentrification, which is a common process accompanying urban redevelopment, further threatens the authenticity of urban cultural heritage since original occupants are excluded by landowners in response to spiking property values. In some cases, for example, Taipingqiao in Shanghai, redevelopment is actually heritage-led [39]. Increased urbanization also has an impact on climate through the urban heat island effect, therefore potentially exacerbating any regional climate change arising from greenhouse gas emissions [40].

2.6. Tourism

There is a vast literature on the relationship between tourism and cultural heritage. At the heart of the issue lies the conundrum, if not conflict, that, on one hand, tourism revenue is often essential to ensure the economic viability of a heritage resource, while on the other, tourists exert a significant environmental, social, and even ethical impact, and, without appropriate management, the problems can easily outweigh any financial benefits. While there has long been a focus on the environmental footprint of cultural tourism [41], socio-cultural effects are now also being explored [42]. Mass tourism is especially challenging, and, indeed, China has many cultural heritage sites that are visited by swarms of tourists annually, more so during ‘Golden Week’, which is characterized by serious overcrowding at sites such as the Forbidden City [43]. Increasingly sophisticated visitor attraction management methodologies have emerged as an essential intervention in the quest to maintain the integrity and authenticity of popular sites against the tidal wave of tourism numbers [43], notably in the case of the Forbidden City [44].

3. Suzhou’s Tangible Cultural Urban Heritage

Suzhou, a prefecture-level city of more than 8 million people, lies west of Shanghai in the heart of the YRD in SE China (Figure 2). With a history stretching back 2500 years, it is internationally renowned as one of the most prominent heritage cities in China, having been declared a National Historic City in 1982, while significant cultural places within Suzhou were entered into the list of World Heritage Sites as early as 1997 [35]. In fact, Suzhou was a pioneer in terms of history and culture, as it was the first city in China to prepare a management plan relating to heritage and, furthermore, was designated by UNESCO as a pilot city for the implementation of the historic urban landscape approach to conservation [45]. Sometimes referred to as the ‘Venice of the East’ [46], Suzhou’s reputation as a place of exceptional beauty is epitomized in the proverb ‘heaven above, Suzhou and Hangzhou below’ [47]. However, as a modern commercial and industrial center, regarded as one of the vanguards of globalization in China [46], the juxtaposition of ancient and modern poses significant planning challenges, not least to the protection of its highly regarded tangible cultural heritage that lies within and, to a lesser but nevertheless significant extent, beyond the old city walls. Historically of strategic military significance, Suzhou was founded in 514 BC and developed quickly following the completion of the Jiangnan section of the Grand Canal that linked Beijing with Hangzhou [48]. Today, it is regarded as one of the nation’s most important trade centers and has diversified from a traditional focus on textiles and the famous Suzhou-style silk embroidery to become export-oriented with a focus on technology [49]. Nevertheless, Suzhou’s tangible cultural heritage is unarguably the foremost brand of the city [46], as the urban planning master strategy positions Suzhou primarily as a national historical and cultural tourist city and secondly as a high-tech industry center. Key tangible heritage features of the city include its famous classical gardens, the Grand Canal, the courtyard and folk houses, streets, canals, and bridges of the ancient city, the city gates in what remains of the city wall, and a number of pagodas and temples.

Suzhou’s iconic classical gardens [50] are perhaps the most prominent and certainly the most sought-after features of the city’s heritage by tourists. Collectively, they have been afforded World Heritage status, and nine of them, namely the Humble Administrator’s Garden, Lingering Garden, Net Master’s Garden, the Mountain Villa with Embracing Beauty, the Canglang Pavilion, the Lion Grove Garden, the Garden of Cultivation, the Couple’s Garden Retreat, and the Retreat and Reflection Garden, are regarded as the most preeminent examples of their type in China (https://whc.unesco.org/en/list/813/, accessed on 23 March 2025). Indeed, Suzhou’s classical gardens represent the essence of Chinese gardening art [47].

The construction of private gardens began as early as the Tang Dynasty (618 to 907 AD) but peaked in the Qing and Ming dynastic eras that spanned 1368 to 1840 AD [46]. Typically constructed by scholars and merchants, the classical garden is essentially a means of bringing downscaled nature into the urban form, with aesthetically pleasing ensembles of rocks (mountains), ponds (lakes), and streams (rivers) alongside ornamental flower beds and groves of trees with strategically positioned pavilions and pagodas. Perhaps the most famous and frequently visited [49] is the Humble Administrator’s Garden (拙政园) which, with an area exceeding 5 ha, is the largest in the ancient quarter, and is regarded as an icon of holistic unity between architecture and landscape [51].

Given its low elevation and topography, along with its proximity to Taihu Lake, among many others, it is hardly surprising that water has played a principal role in the history and development of Suzhou [52], not least in terms of facilitating trade. The Jiangnan section of the Beijing-Hangzhou Grand Canal, linking the Yangtze River northwards with the Huaihe River, was constructed in 486 BC. Taken as a whole, the Grand Canal stretches some 1794 km, connecting all five major rivers of Eastern China, and is arguably the world’s greatest pre-Industrial Revolution example of hydraulic engineering [53]. Of course, the most important function of the canal was–and still is–navigation for the purposes of transporting goods. However, it is also now a major heritage feature and was afforded World Heritage listing in 2014 considering its cultural significance, especially the role it played in unifying the Chinese nation [54], as well as for its extraordinary engineering advancements. While the 96 km section of the structure that is known as the Suzhou Canal is culturally significant for the canal per se, it must be emphasized that associated features, including water conservancy projects and administrative facilities such as customs houses, settlements along the banks, and other associated buildings, have all contributed to its importance as a heritage resource [48].

Most of the other important sites of cultural heritage in Suzhou lie within the boundary of the old walled city and moat, the oldest existing depiction of which, the so-called Pingjiang Map (Figure 3), dates to 1229 and was carved on a stone tablet at the time of the Song Dynasty [35]. The complex, crisscross network of roads and canals is the ancient quarter of the city and today represents its cultural core, occupying an area of some 14.2 km² and home to more than 150,000 residents, which distinguishes this from other old city precincts in China where residents have been typically evicted to accommodate tourist developments [46]. The ‘double-chessboard’ pattern of streets and narrow waterways of this area is fronted by houses that back on to the network of canals, crossed by numerous bridges, many of which have now been restored. The buildings are characterized by grand courtyard houses and smaller ‘folk houses’, all of which back on to the canals and are typical of the traditional architecture of the region [55].

Among these streets, the most well-known is Pingjiang Street (Figure 4), located in the northeastern part of the ancient quarter [56], although there are many others of a similar style and structure. Many of the more substantial courtyard houses were built by wealthy landowners and were doubtless from the outset aimed at establishing a significant architectural status [35]. Such houses are, of course, given due respect, and many are now restored and protected. However, there are numerous other more humble buildings in the old part of the city that were constructed for more commonplace purposes and which now, due to their antiquity or rarity, or because they typify a particular historic style of building, have achieved, or hold, the potential for cultural heritage status. In the more popular areas, including the Pingjiang Historical Cultural Quarter, these buildings have been repurposed, mainly as shops selling food and drink, silk clothing, and local craftwork to cater to the tourist market. The ancient quarter is also notable for a number of other historical structures, including the city gates, although only three of the original eight remain [46], and there are also several pagodas and temples that are of obvious cultural heritage significance. In the Suzhou context, issues of ‘significance’ and ‘valorization’ may be exemplified by the difference between ‘Heritage’ and ‘heritage’ whereby the former comprises assets that have been deliberately selected and packaged for presentation (typically to tourists), while the latter have similar attributes but have not been so selected, and thus still lie ‘beyond the tourist gaze’ [35]. The opportunity exists, of course, for the ‘ordinary’ to be transformed into the ‘extraordinary’ as, no doubt, has transpired for buildings in the old city under the influence of gentrification [57]. It is beyond the scope of this paper to expound on the varied impacts of this economic development process on the local citizens; suffice it to say that the effects of urban renewal on residents are not always positive.

Water is front and center for Suzhou, and the gridded pattern of small canals is itself of considerable heritage significance [58], although the history of these waterways suggests that they have not always been valorized. Indeed, the earliest Pingjiang map records only the names of streets and stone bridges, ignoring the canals. Indeed, the network was historically crucial to commercial and social activities, but many were subsequently filled in and replaced by roads for surface transport, residential homes, and commercial properties [59]. Nevertheless, as their heritage and aesthetic value become more integrated with what is effectively the city’s tourism trademark, the canals are now receiving more attention from the local government, and some have been restored, along with numerous stone bridges [35]. Indeed, many of the streets and buildings in the old city have benefited from recent conservation and revitalization projects, which were greatly needed, since many of these structures, along with most of the city walls, were repurposed or destroyed during the ‘Great Leap Forward’ between 1958 and 1961 and endured further desecration during the Cultural Revolution between 1966 and 1976 [56].

4. Threats to the Sustainability of Suzhou’s Tangible Cultural Heritage in the Anthropocene

Having earlier outlined the key Anthropocene threats to urban cultural heritage in general, in this section, we explore these issues in the particular context of Suzhou. The discussion is based on the main challenges to the city’s heritage resources in relation to the interrelated problems of climate change, sea level rise, and land subsidence, as well as those posed by atmospheric and water pollution, urbanization, and burgeoning tourism.

4.1. Climate Change, Sea Level Rise, and Land Subsidence in Suzhou

The critical combination of processes associated with global climate change and accelerated sea level rise that are, in turn, exacerbated by land subsidence represents a substantial challenge for cities like Suzhou located in the low-lying YRD. Anthropogenic climate change in the urban context is comprised of two elements, viz. (i) the effects of increased temperature accompanied by changes in other climate parameters resulting primarily from increased concentrations of greenhouse gases in the global atmosphere, and (ii) augmented temperature increases associated with the urban climate per se. The overall outcome is that the jointly aggravating effects of climate changes, arising from both regional and local scale factors, are very challenging for Suzhou. In this paper, we only focus on tangible elements of urban cultural heritage, but climate change has the potential to disrupt other activities that may ultimately affect the city’s economy. Take, for example, the effect of global warming on silk farming [60]. Silk is synonymous with Suzhou, and the vulnerability of silk production to climate change has the potential to impact the city’s heritage trademark.

Mean annual temperature has increased by approximately 1.5 degrees C over the last few decades (Figure 5). Although there is regional-scale climate change across the YRD as a whole, the role of urbanization appears to be the dominant cause of recorded warmer temperatures across the region, since the rate of increase has been faster in the more densely populated areas [61]. The urban heat island (UHI) effect has been intensely studied in Suzhou [62,63,64], and the evidence is clear that not only has the effect intensified over time, but it has also extended spatially as the urban footprint of the city has expanded. Increased temperatures per se may not have any direct impact on Suzhou’s cultural heritage, although the increased frequency of heatwaves [65] is doubtless a management challenge for the horticulturalists who tend to the famous classical gardens, and surely this negatively affects the tourist experience as well in the summer. Of greater significance, however, is the impact of climate change on rainfall patterns, as this has implications for runoff and flooding. Mean annual rainfall in Suzhou has increased significantly since 1960 (Figure 5), with obvious implications for runoff management in the city. The effect of climate variability on water resources in Suzhou points to an overall increase in rainfall in recent decades associated with increased runoff, further augmented by decreased evaporation [66]. Indeed, a significant increase in flood levels in Suzhou has been reported [67]. These observations are supported by simulations [68] demonstrating that urbanization itself in the Taihu Lake region has augmented rainfall. If sustained, the combination of higher rainfall and higher temperatures certainly poses problems for the conservation of heritage building materials, as this will likely increase the rate of building stone weathering and favor fungal and microbial growth on wooden structures. There are obvious implications also for the management of water levels throughout the city, and flood control systems are likely to become increasingly challenged. Urbanization in the YRD has substantially increased the risk of exceptional meteorological incidents associated with the summer monsoon season [69]. Given the potential impact of this on water levels in the low-lying historical city, the predicted increased frequency and magnitude of extreme rainfall events should therefore be of concern to heritage managers.

Coupled with ongoing climate change and the intensification of the UHI in the region, as outlined above, the increased frequency and magnitude of flooding seem inevitable in the low-lying topography of the YRD. The World Bank classifies the level of hazard for coastal and river flooding in Suzhou as ‘high’ (see: https://www.thinkhazard.org/en/, accessed on 23 March 2025) and this seems likely to be exacerbated given the precipitation trends highlighted above. The reported higher net inflow and increased levels of nearby Taihu Lake [70] are a manifestation of this trend, with catchment hardening associated with rapid urbanization an additional contributory element [71]. An increase in the frequency of extreme rainfall events has also been recorded in Suzhou [72], which is likely to exacerbate periodic flooding. Such observations underscore the need for continuous monitoring and adaptive management strategies to mitigate the impacts of changing precipitation patterns and flood hazards in Suzhou. This flooding is exacerbated by two important additional factors, i.e., sea level rise and land subsidence. While Suzhou is itself not on the coast, in general it lies within a meter or two of mean sea level, and, even 100 km from the coast, the effect of rising seas on groundwater levels renders the city highly vulnerable to flooding, especially during high tides and storms that may also result in saltwater intrusion [73]. Moreover, these effects are compounded by the fact that, since 1980, the sea level has been rising more than three times faster in East China than the global mean [74]. This precarious situation is further compounded by land subsidence, a product of a combination of groundwater extraction, the weight of buildings, and natural geological factors, which is prominent in almost half of the major cities in China [31], including Suzhou. Excessive groundwater exploitation has been a major cause of land deformation in the city, although the process has been subject to government restrictions that appear to have the process under control [75]. Notwithstanding this, rates of land subsidence in some industrial sectors of the city have reached 90 mm per year [76]. Clearly, whatever the scale of subsidence, coupled with groundwater effects arising from climate change and sea level rise, the potential impact of ground deformation on cultural heritage must be a serious consideration.

4.2. Air and Water Pollution in Suzhou

Cities are typically characterized by higher levels of atmospheric pollutants than their surrounding hinterlands, and Suzhou is no exception. Costabile et al. (2006) reported elevated sulfur concentrations from Suzhou’s industrial areas, while also highlighting the strong influence of motor vehicle emissions on air quality, although this latter observation may well need reevaluating in light of the recent exponential increase in the use of electric vehicles in China [77]. Air pollution is, nevertheless, a particular challenge during winter months when stable atmospheric conditions and temperature inversions lead to higher concentrations of PM_2.5, substantially exceeding recommended standards [78]. It is perhaps moot as to whether elevated levels of such pollutants pose a direct threat to Suzhou’s cultural heritage per se, although they must affect the health of residents and doubtless influence the visitor experience. Given the significance of trees, shrubs, and herbaceous borders in the classical garden landscapes, the differential impacts of air pollution on plant species are important, as some species are clearly more susceptible than others [79]. Nevertheless, in response to government policy interventions, atmospheric pollution has declined in most cities in China during the last few decades [80]. Indeed, environmental degradation and development are showing early signals of decoupling in the YRD [81]. Of greater concern in the context of Suzhou’s cultural heritage is the pollution of water. Measurements of water quality in the Grand Canal suggest that it is seriously polluted [82,83,84] both by nutrients and heavy metals, especially from October to March [82], and that this compromises the sustainability of an important heritage resource [85]. Meanwhile, the organic pollution of groundwater has been reported as widespread in Suzhou [86], and there are problems with heavy metal accumulation in both groundwater [87] and in the wetlands around the city [88]. Such observations highlight stark management challenges relating to Suzhou and its surrounding water towns.

4.3. Urban Expansion in Suzhou

Over and above the impact of urbanization on the climate and air quality in Suzhou, as discussed above, the process invokes major spatial planning problems for urban heritage in the city. Following the opening-up of China from 1978 onwards, Suzhou, as did all cities in China, grew rapidly in response to escalating industrialization and globalization (Figure 6). Urban growth here has been characterized by infilling, expansion, and even ‘leap-frogging’ [89], the latter two of which have clearly impacted the urban fringe, leading to the rapid transition of the peri-urban and rural landscape that is typical of urban sprawl [46], and which has no doubt markedly impacted some of Suzhou’s ‘water towns’. However, it is likely the process of infilling most obviously threatens Suzhou’s urban heritage, as the ancient city harbors its most sensitive and valuable resources. Indeed, there is ongoing redevelopment in several areas of the central city, including within and adjacent to the ancient quarter, with substantial impacts on the historical area skyline in places [90]. Notwithstanding the planning efforts on the part of the authorities, the ancient quarter has long been subject to a variety of threats associated with urban expansion. The opening up of the first ring expressway in 2005 meant that the historic part of the city, which lies at the confluence of major traffic routes, imposed further pressures amplified by the influx of increasing numbers of tourists [46]. Meanwhile, an impact assessment based on the degree of exposure, vulnerability, and probability in relation to a range of urbanization criteria [91] revealed negative impacts on the classical gardens of the Gusu district; somewhat alarmingly, several of the gardens have been classified as being exposed at the highest level of risk. In short, an array of problems facing Suzhou’s current heritage conservation strategy have arisen due to rapid urbanization, leading to calls for the ancient quarter, with its gardens and other key attributes, to be more fully incorporated into the city’s urban planning and, indeed, that the entire urban landscape should be considered as an integrated ensemble, failing which the continuity of the urban context and the very identity of Suzhou as a place may be lost [90].

4.4. Tourism and Suzhou

Tourism is central to the economy of Suzhou and is a key element of its ‘brand’ as a modern commercial and industrial city that has roots firmly planted in cultural heritage. The benefits of tourism to Suzhou are founded on the numerous attractions of the ancient quarter that have been the object of revitalization efforts by the local government, perhaps best illustrated by the regeneration project in Pingjiang and Shantong streets initiated more than 20 years ago, the main motivation for which appears to have been both economic and political [56]. It could be argued, on this basis, that restoration of the ancient quarter had more to do with generating tourist revenue than a concern for the conservation of the urban cultural heritage resource itself. Despite the setback caused by the COVID-19 pandemic and associated lockdowns, domestic tourism remains a potent economic engine for the city of Suzhou, and tourist volumes and associated income have once again breached record levels (Figure 7). Indeed, during the week of the 2025 Spring Festival Holiday, official figures suggested that Suzhou tourist visits over the eight-day period were up by more than 7% compared to 2024 1.

Pingjiang and Shantang streets highlight the way postmodern consumption has altered the historic center of Suzhou and how this has brought about the commodification and associated reorganization of material space [87] (Figure 8). In essence, tourism and leisure consumerism have emerged as key spatial drivers in the ancient quarter of Suzhou, with obvious implications for its cultural authenticity [56] in this regard. Moreover, despite the obvious economic benefits of attracting large numbers of tourists that yield many financial advantages, there are substantial environmental and social challenges, such as controlling traffic flow and parking, managing visitor numbers (especially to hotspots such as the Humble Administrators Garden), and increased noise, litter, and pollution.

5. The Future of Suzhou’s Cultural Urban Heritage

If Suzhou’s magnificent cultural heritage is to remain a significant cultural resource for future generations, then transformations, arguably even radical changes, are needed to ensure ‘good Anthropocene’ outcomes [93]. Indeed, perhaps we need to rethink and reprioritize heritage in these precarious times [94]. The ‘great acceleration’ that has precipitated the multiple aggravations of climate change, sea level rise, land subsidence, pollution, urbanization, and tourism inflicts substantial pressures on the sustainability of our historical past, and investment in additional conservation measures to mitigate the multiple challenges that these processes demand is surely needed. Some idea of the range of challenges facing the authorities is illustrated in Figure 9. Piecemeal efforts will likely not produce effective results, and integrated planning solutions are imperative. An integrated planning approach that incorporates bottom-up perspectives from residents and business owners to promote the preservation of Suzhou’s cultural heritage, while at the same time stimulating livability, has been advocated [90]. The Historic Urban Landscape (HUL) concept, initiated by UNESCO [95], has considerable potential in China towards achieving sustainable urban development [96]. Despite the implementation of the ‘Fourteenth Five-Year Plan for Suzhou’s National Economic and Social Development’2 in 2021, it has been suggested [87] that there remain striking imbalances in the current planning approach and argued that the authorities need to consider the broader urban context of the city going forward.

Our scoping review of the recent literature reveals that the various related challenges posed by climate change from the cultural heritage perspective have received remarkably little attention. Over and above the need to understand the nature and scale of the problem, increased monitoring efforts are required. A number of methodological approaches are available to mitigate the deleterious effects of accelerated weathering of building materials and protect structures against expansion, shrinkage, and extreme events such as flooding or high winds. For example, there is much to be learned from studies published in the special issue of the journal Geosciences devoted to this topic [97]. Adaptive measures and solutions to minimizing heritage risk and damage due to climate change are available [98,99]. In terms of flooding, the city already has a Large Encirclement Flood Control Project to divert overflow to the outskirts of the city [100], but any further increases in the frequency and magnitude of either heavy rainfall events or flooding due to exceptionally high tides on the back of higher sea levels will demand enhanced scrutiny and improvement in disaster relief planning. The land subsidence effects of groundwater harvesting may be largely controlled in Suzhou since groundwater is no longer directly extracted [75], but ongoing monitoring is necessary; indeed, there are newly available technologies to substantially improve its efficiency and accuracy [101]. Remote sensing applications in general have great potential in addressing a range of environmental challenges, including evaluation over time of progress towards the sustainability of urban heritage [102] and in the application of 3D LIDAR to refine the high-resolution monitoring of urban structures [103]. Other issues, such as atmospheric pollution, eutrophication, and heavy metal contamination of the city’s canals and groundwater resources, are typically handled by the local and regional government as part of their ongoing management responsibilities. Monitoring and control of visitor numbers clearly need to remain under the spotlight in a city that is justifiably a magnet for tourists. Diversifying cultural events to spread the excessive load during Golden Week and developing some of the lesser-known attractions are possible interventions, while ongoing efforts to enhance tourism infrastructure and services should continue to be intensified.

In the wider context, it is important for a modern city such as Suzhou to consider its cultural heritage as part of the overall achievement of the UN Sustainable Development Goals (SDGs). There are excellent resources available in this regard [104], and the city’s level of sustainable development has already been evaluated with a view to establishing a systematic evaluation framework [105]. Appropriate planning of urban cultural heritage can be a very effective tool in promoting sustainability, and there is a strong relationship between heritage-led urban regeneration and making progress towards achieving the SDGs [106]. In evaluating the role of urban cultural heritage in the context of the SDGs, the potential contribution that it can make in relation to all 17 has been evaluated [107] as ‘very high’ in relation to Goals 1 (Zero Poverty), 3 (Health and Well-being), 4 (Education), 8 (Decent Work and Economic Growth), and 11 (Sustainable Cities), with further positive impacts on all the others. Conserving Suzhou’s cultural heritage is therefore not only essential to its continued economic development but can also materially assist in it becoming more sustainable.

6. Concluding Remarks

In this paper, we argue that the future of Suzhou’s rich urban cultural heritage relies on continuing to develop appropriate planning responses to the diverse challenges that characterize a rapidly evolving Anthropocene. Risks associated with climate change and related issues, as well as urbanization and tourism, are likely to escalate. Fully integrating heritage into Suzhou’s urban planning strategy obviously enhances the image of the city and further improves its investment potential. However, focusing mainly on economic benefits may jeopardize heritage because commodification and packaging for the tourism market promote the fabrication of ‘fake’ architectural landmarks or even ‘disneyfying’ the historic city and thus seriously compromise its authenticity [35]. It should be noted that Suzhou already boasts a fine reputation for efforts to ensure conservation of its remaining historical infrastructure. Indeed, the city has adopted innovative approaches and strategies to restore and enhance both its tangible and intangible heritage. Nevertheless, a broader, sustainable development approach can go further in not only preserving heritage but also promoting progress towards a substantial number of the SDGs, since environmental, cultural, and educational factors are all advanced in the process. A more structured incorporation of SDG principles into Suzhou’s urban heritage planning—through policies that balance conservation with urbanization, pollution control, and community participation—can serve as a model for sustainable heritage management in rapidly urbanizing regions globally. Strengthening heritage conservation as a pillar of urban sustainability ensures that cultural identity remains an asset rather than a casualty of modern development. In other words, confronting and mitigating Anthropocene challenges is essential, not only because the tangible cultural heritage of the city is a key economic asset, but also because it is a core element of urban sustainability as a whole. Harnessing the multiple, self-reinforcing, benefits of integrated sustainable urban planning holds the greatest promise for Suzhou’s urban cultural heritage in the face of the many uncertainties that threaten the future of its past.