Key Idea This Key Idea has an illustration and text explaining that cumulative impacts result from multiple threats that occur to resources. Cumulative impacts from non-climate change threats degrade and weaken the natural systems and make them more sensitive to climate change impacts. Click "View Source" on the right to see the illustration and read the detailed description.

A degraded highly threatened ecosystem is typically more vulnerable to long-term impacts from climate change. In contrast, a healthier system has a greater probability of withstanding or recovering from climate change impacts. This section focuses on watersheds, coastlines and coral reefs to explain how existing threats can combine with climate change impacts to have greater overall negative impacts on important habitats and resources.

Degraded Watershed: Climate Change (CC) threats of changes in weather patterns and rising air temperatures combine with existing threats of destruction of forests/vegetation, pollution (e.g., piggeries, trash), runoff from cleared land and mono-cropping. The combination results in cumulative impact and increased potential for damage or loss of crops and native plants, contamination or loss of drinking water, flooding of homes, soil erosion and landslides, sediment near shore and on reefs, invasive species, and stress on people. Together these will also have increased negative impact on food, income, and health of the community (e.g., vector- and water-borne diseases).

Degraded Coastline: CC threats of sea level rise, coastal erosion and increased sea surface temperature combine with existing threats. These include clearing of coastal vegetation, dredging of sand, unsound development of coastal areas and infrastructure, unsustainable clearing of mangroves for firewood and construction material, and over-harvesting. The combination results in cumulative impacts and increased potential for flooding and damage from storm surges, coastal erosion, sedimentation of the reef, and damage to habitat important for food fish and shellfish. Together these will have negative impacts on food, income, coastal land, property, and the health of the community.

Degraded Coral Reefs: CC threats of increased sea surface temperature and increased acidity of the ocean combine with existing threats. These include overfishing, destructive fishing practices, anchor damage, oil spills, invasive/nuisance species, dredging, runoff and sedimentation. The combination results in cumulative impacts and increased potential for coral bleaching and death, damage to habitat important for food fish and shellfish, flooding and damage from storm surges, coastal erosion , and decrease in fisheries. These cause increased negative impact on food, income, coastal property.

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