Rising sea levels also increase the exposure of coastal cities to storm events. As well as destroying coastal infrastructure, severe storms can have long-term impacts on coastal morphology, eroding beaches and reshaping river mouths, especially when stabilizing vegetation has been removed. Storm surges (caused by strong winds that push seawater onshore) are the main driver of coastal flooding (Resio and Westerink 2008). In 2019, the storm surge from Hurricane Dorian resulted in $4.6 billion of damage in the Bahamas, the United States and Canada. On the island of Grand Bahama, the storm surge reached over seven metres (Le Page 2019). Similar levels of destruction are common across the tropics and modelling suggests that the number of extreme weather events could double in coastal cities by 2050 (Vitousek et al. 2017).


In some cases, the impacts of higher tides from rising sea levels and increasing storms are exacerbated by significant land subsidence caused by groundwater extraction and building on compactable coastal sediments. Residents of many coastal cities, such as Jakarta, Venice and Bangkok, as well as urban atoll islands, are already directly or indirectly experiencing these negative impacts (IPCC 2014). Moreover, continued population growth in these high-risk coastal areas is likely to mean more people will suffer adverse physical, social and economic consequences.


Finally, wild-catch fisheries and mariculture are financially and culturally important to many coastal communities. Rising ocean temperatures, nutrient run-off, pollution and acidification are already impacting mariculture and wild fish catches, threatening the livelihoods and food security of communities (Bindoff et al. 2019). Major wild-catch fish- producing countries in South-East Asia and South America


are likely to be disproportionally affected by the impacts of climate change on fish stocks (Nong 2019). Moreover, in many communities women dominate near-shore fishing and gleaning, meaning they are likely to be most affected by the degradation of coastal marine resources (FAO 2016).


3.2.5 Land and soil


As hubs of human activity, cities require land-based resources such as food, fodder, fibre and forest products that mainly depend on land areas beyond their limits. Land also provides other services such as shelter, property and cultural identity (UNCCD 2017). Land in urban areas and beyond can also be significantly impacted by urban planning decisions, which can have both positive and negative effects on residents. Many of these aspects are affected both directly and indirectly by environmental degradation and urban settlements are no exception. Indirect impacts due to telecouplings are more common than direct impacts and the biggest impacts are arguably on the most important resources of cities. Food and water, for example, mainly come from beyond the city, meaning changes in those areas can significantly affect urban life (chapter 4).


Changing land cover in rural and wild areas indirectly impacts cities. For example, there are causal links between deforestation in the Brazilian Amazon and droughts in southern Brazil, including in cities like São Paulo (Nobre 2014). If deforestation of the Amazon basin continues, it may jeopardize the rainforest’s role as the source of rainfall for areas beyond it and could reduce the availability of water in cities and rural areas (Lovejoy and Nobre 2018). The degradation of land resources is associated with changing land cover, fragmentation, desertification and erosion, all of


The State of the Environment in Cities


49


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