Many Small Island Developing States are highly dependent on subsistence fishing and agriculture for the bulk of their food supply. Some islands states have successfully provided for the nutritional needs of their people in this manner for thousands of years. Climate change is threatening these two activities and leaving small islands increasingly reliant on imported food.
Climate change threatens subsistence fishing in a number of ways. Rising sea surface temperatures can lead to coral bleaching, and in extreme cases, the death of whole coral reefs. Coral reefs are the foundation of many coastal ecosystems, without which many fisheries would collapse. Ocean acidification is also an emerging threat for coral reefs, inhibiting the ability of coral to form its calcium carbonate skeleton.
Subsistence agriculture on small islands is also threatened. Flooding due to rising sea level can leave salt deposits in the soil, damaging many traditional crops and forcing farmers to switch to more salt-tolerant varieties. Rising sea level can also lead to saltwater intrusion into the groundwater supply, damaging an important source of water for agriculture. Climate change is also likely to lead to more frequent and more intense periods of drought in some regions, with obvious implications for subsistence agriculture. Higher air temperatures are altering the length and timing of the growing season, and in some cases making the climate inhospitable to traditional crops. Increased crop stress can also be an open invitation for new disease and invasive species. Lastly, soil erosion from intense rainfall can literally wash away productive land.