REGREEN aims to address urban challenges in China by i) assessing and mapping drivers and pressures; ii) modelling ecosystem services provided by Nature-Based Solutions in a holistic and systemic way and iii) valuing the contribution of NBS to health and well-being. Main environmental pressures and challenges in each of the REGREEN Chinese ULLs are described below. More information is available in the recent REGREEN deliverable 2.1 ‘Report on assessment of drivers and pressures leading to urban challenges, across the ULLs, including spatial and temporal components’ here.
Smog has been the number one air pollution problem in Beijing in the last decade. In recent years, through rigorous enforcement of regulations to cut emissions, the smog problem has been alleviated significantly. Nevertheless, ozone pollution has emerged as a new problem. The rising number of cars is an important source of nitrous oxides, which are the precursor of ozone. Other than air pollution, the urban heat island (UHI) intensity in Beijing has been increasing over recent decades. The UHI magnifies the warm and humid summer climate in Beijing and poses a health risk, especially to vulnerable groups such as the elderly. The problem will get more significant because it is predicted that Beijing will become warmer due to climate change.
Image 1: Afforestation in Beijing to counter air pollution. Photo: Jun YANG, Tsinghua University
Climate change will also intensify another problem: urban flooding. The rapid urbanization in Beijing has increased impervious surface coverage in the urban part of Beijing. One consequence is that urban flooding events occur more frequently. In some events, significant damage to property and loss of lives have occurred. The urban runoff also carries pollutants into the rivers and lakes. Beijing has taken a “sponge city” approach that integrates many engineering and non‐engineering measures to control urban flooding.
As a city that has more than five million privately owned cars and various other vehicles that serve the daily needs of twenty million people, road noise is a severe issue in many parts of Beijing. The annual average noise level in the built area was 53.7 dB, higher than the 50 dB limit recommend by the World Health Organization.
Other than challenges from environmental problems, Beijing is also facing the challenge of maintaining biodiversity. For example, Beijing is located on the East Asian‐ Australasian Flyway for migrating birds. Each Spring and Fall, large flocks of migrating birds choose Beijing as an important stop‐over site. Studies have shown that many bird species have disappeared from Beijing as the city has continued to grow. Therefore, an important task faced by Beijing residents is to share the space with wildlife.
Meishan Island (Urban Living Lab) is located in the east of Ningbo, China, which is the part of Ningbo‐Zhoushan Port. It aims to become a distinctive bonded port, a recreational and liveable ecological island and a vibrant harbour city. With the advent of the era of economic globalization, ports have become a window and platform for information and goods exchange between countries around the world. Heavy urbanization across the east coast of China (following the conventional engineering‐driven approach of constructing ports, dams, bridges, roads and buildings) has brought about major water issues for Ningbo, relating to both quality and quantity, various port activities are the likely cause for poor water quality inside the port area.
Image 2: Wetland ecosystem to improve water quality and quantity, enhance biodiversity and provide recreation opportunities. Photo: Cai CHEN, Institute of Urban Environment
In order to develop the tourism economy of port cities, artificial beaches and lakes have been built in the Meishan Island. However, the occurrence of harmful algal blooms in the artificial lagoon has been seen as an increasingly critical challenge, as it poses the greatest threat to water quality and ecosystem services, with negative effects on public sport and recreation on the waterbody. The concrete dams have limited water flow and nutrient transportation beyond the artificial lagoon, creating highly favourable conditions in which harmful algal blooms can occur, most often during the summer season.
Excessive artificial intervention on the near coast will reduce the biodiversity of the near coast, increase engineering noise, and reduce the green space in the island. In addition, the Meishan Island still suffers from excessive air pollution, which is mainly caused by dust pollution, including material loading and unloading dust, road dust, and wind erosion dust from stockpile, bare soil. Meishan Island needs to pay attention to the solutions that contribute to the release of carbon and increasing its sequestration, without compromising currently ordered vernacular ecosystems, are required, especially for small territories.
Increasing the resilience of small islands to these losses, including spatial management to prevent and adapt to climate change while preserving biodiversity. More importantly, future predictions show that nutrient concentrations could increase, as urban runoff during the monsoon storm season can contribute substantially to non‐point sources of pollutants and the area of impervious surface across Ningbo is increasing rapidly, through heavy urbanization, with the development of conventional grey infrastructure.
The urban heat island effects in Ningbo are not obvious in the city centre, but in the industrial land, with high energy consumption. The old urban area has obvious heat island effect compared with the new urban area. As it is a coastal city, extreme heat is not obvious. At present, a certain amount of noise pollution exists in Ningbo, mainly from industrial noise, such as heavy vehicle transportation. However, there is a certain distance between the areas producing the noise and residential areas, and roadside trees or other measures have been taken to block noise. There are many urban green spaces in the main urban areas, but only some low trees or shrubs in the industrial areas, which lack green spaces. With the heat emitted by industry and less green space, especially in summer, the temperature of Ningbo industrial zone will be significantly higher than other functional areas.
Compared with the northern cities of China, Shanghai, located at the mouth of the Yangtze River, should naturally be relatively water‐rich. However, due to the large population and the pollution of industrial cities along the middle and lower reaches of the Yangtze River, Shanghai has water shortage issues, as well as water quality issues. For these reasons, water‐related challenges are the most critical environmental issues for the people and government of Shanghai. The attention of China’s big cities to air quality has long been very important, which is reflected in the adoption of PM2.5 as one of the key indices of weather forecasts and reports.
Image 3: Mangrove cultivation, Shanghai, to create a shelter belt against violent coastal storms while providing valuable habitats for biodiversity, purifying water resources, reduce siltation and sedimentation and create expanded beach regions for the benefit of residents. Photo: Bin ZHAO, Fudan University
As typhoons and rainstorms often occur during the summer months in Shanghai, flooding is a substantial threat in Shanghai. It is a seasonal environmental problem, so it ranks below the water and air‐related challenges.
In such a large city, where space is at a premium, an increasing population means that per capita allocations of space are often insufficient. In addition, the demand for ecological space (non‐built‐up areas) and the increase of the number of private cars make the incongruity more and more obvious. In the traditional consciousness, the function of a metropolis is different from that of countryside and wild space, therefore, few people might pay attention to urban biodiversity. However, the public awareness of environmental protection has increased in recent years. In particular, due to the impact of the covid‐19 epidemic, people pay more attention to urban biodiversity than ever before. For instance, scientists informed the public that COVID‐19 is a zoonosis (a human disease of animal origin), which is likely to have its ancestral origins in a bat species, but it probably reached humans through an intermediary species, for example pangolins. This involves numerous wild animals, making people feel that direct contact with wild animals will lead to an outbreak of unknown epidemic, especially in urban areas. This not only enhances people’s understanding of biodiversity, but also promotes the improvement of wildlife protection laws.
Carbon sequestration is not considered by most people to be a function of the urban areas. However, because Shanghai is located in an estuary, an area representing a huge carbon sink, the concept of carbon sequestration in Shanghai is paid more attention by all parties.
Due to the legislation and management of urban noise in Shanghai, the public does not currently view it as a priority issue. According to the national standard of China, the noise in residential areas should not exceed 50 dB during the day, and should be lower than 45 dB at night. The standard attainment rate is 97.2% during the day and 65.7% at night.
The heat is regarded as a typical climatic characteristic of Shanghai, so people hope to get a more pleasant environment through other improvements.