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PressuresLand- and marine- based human activities [Drivers]world’s cities with populations of over five million arelocated in at-risk areas. 179 With sea level projected to risefurther, large numbers of people might have to relocateand several small island developing States (SIDS) are at riskof being submerged. It is even possible that areas - andcountries - might become uninhabitable long before theyare submerged (e.g. due to intrusion of saltwater intocoastal aquifers). 180Important classes of threats identified by contributingexperts and their drivers and pressures are illustrated inTable 3-2, an adaptation of the Drivers-Pressures-State-Impacts-Responses (DPSIR) framework which intends toorganize information about the state of the environmentand reflects the complex chain of cause-and-effect in theinteractions between society and the environment. 181Table 3-2. Drivers and pressures of important classes of threats affecting the nexusClimate change Marine pollution Unsustainable extraction ofmarine resources• Any activities leading torelease of greenhousegas into atmosphere(e.g., combustion offossil fuels, animalrearing, land-use change)• Potential impacts ofemerging activities, suchas ocean geo-engineering(e.g. CO 2 injection, oceanfertilization)• Ocean warming• Ocean acidification• Sea level rise• Changes in circulationpatterns (ocean currents)• Increased frequency andintensity of weather andclimate extremes• Changes in hydrologicalcycles (e.g. freshwaterflow, water storage,evaporation)• Agriculture• Aquaculture• Industrial activities• Maritime transport• Fishing operations• Dumping at sea• Abandoned, lost and otherwisediscarded fishing gear (ALDFG)• Solid waste disposal• Industrial and municipal sewagedischarge• Damming of rivers and lakes,dredging• Offshore infrastructure; oil andgas production; seabed mining• Introduction of:• Heavy metals• Persistent organic pollutants(POPs)• Pesticides• Nutrients (nitrogen andphosphorus)• Oil• Plastics• Munitions• Hazardous substances• Radioactive material• Anthropogenic underwater noise• Other particulate matter• Alien invasive species• Overfishing• IUU fishing, includingharmful subsidies thatcontribute to IUU fishingand overcapacity; abusiveand unsafe labour practicesand exploitation of poormigrant workers• Destructive fishingpractices, including harmfulbottom trawling, use ofexplosives and poisons• Inappropriatedeployment/deployment inwrong areas of fishing gear• Ballast water (shipping)• Deep sea mining, offshoreoil and gas drilling• Seabed disturbances ordamage• Removal of aggregatesPhysical alterations anddestruction of marine andcoastal habitats and landscapes• Unsustainable coastaldevelopment• Submarine infrastructure (e.g.cables)• Unsustainable tourism andrecreational activities• Shipping/Fishing operations infragile or vulnerable marineareas• Harvesting by localcommunities for buildingmaterials and energy• Unsustainable aquaculture• Dredging / marine sedimentextraction (e.g. sand removal)• Potential impacts of emergingactivities, such as ocean geoengineering(e.g. CO 2 injection,ocean fertilization)• Land reclamation• Beach nourishment• Seabed disturbances ordamage• Changes in sediment fluxesTable 3-3 summarizes the impact of important classes ofthreats on the nexus, enumerates some illustrativescientific reports and contains areas for further researchsuggested by contributing experts.59