Hong Kong is an autonomous territory on the eastern side of the Pearl River estuary in South China. With over 7.4 million people in a territory of 1,104 square kilometres, Hong Kong is the fourth-most densely populated region in the world. Hong Kong is the world's seventh-largest trading entity in both exports and imports and is also the world's largest transshipment centre. The territory's economy is dominated by the services sector, as services alone constitute 92.7% of the economic output.
Hong Kong has the most skyscrapers in the world and the city centre forms a very dense urban region. The city is tackling seasonal air pollution that originates from neighbouring industrial areas of mainland China, which has resulted in a high level of atmospheric particulates in winter. The air pollution is further compounded by Hong Kong's geography and tall buildings. Hong Kong is tackling numerous other climate challenges than air pollution and densification, such as water scarcity, flooding, biodiversity loss and climate driven health issues.
Despite Hong Kong's intense urbanisation, it has tried to promote a green environment. The city has ambitions to implement nature-based solutions like stormwater retention ponds, green spaces, permeable pavements and green facades. Hong Kong’s recent focus has been on the integration of permeable pavement systems to improve urban drainage and stormwater harvesting to mitigate seasonal water shortages.