2.3 Marco de referencia
2.3.9 Otras investigaciones realizadas
Fisheries-dependent economies, coastal communities and fisherfolk are expected to experience the effects of climate change in a variety of ways. These include: displacement and migration of human populations; effects on coastal communities and infrastructure due to sea-level rise and changes in the frequency, distribution or intensity of tropical storms; and less stable livelihoods and changes in the availability and quantity of fish for food.
The vulnerability of fisheries and fishing communities depends on their exposure and sensitivity to change, but also on the ability of individuals or systems to
anticipate and adapt. This adaptive capacity relies on various community assets and can be constrained by culture, current institutional and governance frameworks or marginalized access to adaptive resources. Vulnerability varies between countries and communities and between demographic groups within society. Generally, poorer and less empowered countries and individuals are more vulnerable to the effects of climate change, and the vulnerability of fisheries is likely to be higher where the resources already suffer from overexploitation, the ecosystems are degraded and the communities face poverty and lack sufficient social services and essential infrastructure.
Fisheries are dynamic social-ecological systems and are already experiencing rapid change in markets, exploitation and governance. The combined effects of these changes and the biophysical and human impacts of climate change make it difficult to predict the future effects of climate change on fisheries social-ecological systems.
Human adaptation to climate change includes reactive or anticipatory actions by individuals or public institutions. These range from abandoning fisheries altogether for alternative occupations to developing insurance and warning systems and changing fishing operations. Governance of fisheries will need the flexibility to account for changes in stock distribution and abundance. Governance aimed towards equitable and sustainable fisheries, accepting inherent uncertainty and based on an ecosystem approach is generally thought to be the best approach to improve the adaptive capacity of fisheries.
Greenhouse gas contributions of fisheries and related supply chain features are small when compared with other sectors but, nevertheless, can be reduced with identifiable measures already available. In many instances, climate change mitigation could be complementary to and reinforce existing efforts to improve fisheries
sustainability (e.g. reducing fishing effort and fleet capacity in order to reduce energy consumption and carbon emissions). Technological innovations could include energy reduction in fishing practices and more efficient post-harvest and distribution systems. There may also be important interactions for the sector with respect to environmental services (e.g. maintaining the quality and function of coral reefs, coastal margins, inland watersheds), and potential carbon sequestration (Box 12) and other nutrient management options, but these will need further research and development. AQUACULTURE
Aquaculture now accounts for almost 50 percent of fish consumed by humans, and this share is expected to increase further to meet future demand. Of considerable concern is the long-term ability of capture fisheries production to produce the fishmeal and fish-oil supplies used as feed components in aquaculture. Alternatives, such as soybean, corn meal, rice bran and others, have not been perfected according to fish requirements, and the increased demand for these agricultural products created by expanding aquaculture could also have consequences.
Box 12
Blue carbon: the role of healthy oceans in binding carbon The facts
Black and brown carbon emissions from fossil fuels, biofuels and wood burning are major contributors to global warming. Green carbon, the carbon stored in plants and soils, is a vital part of the global carbon cycle. Blue carbon is the carbon captured by the world’s oceans and represents more than 55 percent of the green carbon. The carbon captured in living organisms in oceans is stored in the form of sediments from mangroves, salt marshes and seagrasses.
In addition to absorbing heat and regulating the earth’s climate, oceans are the largest long-term sink for carbon (see figure). Oceans store some 93 percent of the earth’s carbon dioxide (CO2) and capture more than 30 percent of the CO2 released annually. Most of the carbon captured is stored not for decades or centuries but rather for millennia. Importantly, restoration of green and blue carbon habitats alone could mitigate emissions by up to 25 percent.
Blue carbon sinks are also central to the productivity of coastal zones, which provide a wide range of benefits to humans (e.g. as buffers against pollution and extreme weather events, as sources of food and livelihood security and social well- being) and services estimated at more than US$25 trillion per year. Approximately 50 percent of the world’s fisheries stem from these coastal waters.
The threats
The annual rate of loss of coastal marine vegetal ecosystems (2–7 percent) is up to four times that of rainforests and is caused inter alia by unsustainable natural resource use, poor coastal development practices, and poor watershed and waste management.
Surface water temperatures are increasing, decreasing the amount of CO2 that can be dissolved in water. Combined with changes in acidification, water circulation and mixing and loss of blue carbon habitats, this means that the oceans’ ability to absorb and store CO2 is decreasing.
Coastal populations are in the front line of climate change and often the most vulnerable to its effects. Climate change will have impacts across all dimensions of food security as well as increasing risks at sea and the threat of damage to or loss of infrastructure and housing.
While coastal populations are growing, inflexible institutional frameworks persist in limiting adaptation strategies. In addition, monitoring and early-warning systems are deficient, and emergency and risk planning are not integrated into sectoral development.
The options
1. Establish a global blue carbon fund for the protection and management of coastal and marine ecosystems and ocean carbon sequestration.
2. Immediately and urgently protect seagrass meadows, salt marshes and mangrove forests through effective management.
3. Initiate management practices that reduce and remove threats, and that support the robust recovery potential inherent in blue carbon sink communities.
4. Maintain food and livelihood security from the oceans by implementing comprehensive and integrated ecosystem approaches to increase the resilience of human and natural systems to change.
5. Implement win–win mitigation strategies in the ocean-based sectors, including efforts to:
t improve energy efficiency in marine transport, fishing and aquaculture sectors as well as marine-based tourism;
Highlights of special studies
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t encourage sustainable, environmentally sound ocean-based production, including
algae and seaweed;
t curtail activities that negatively affect the oceans’ ability to absorb carbon;
t ensure that investment for restoring and protecting the capacity of the oceans’
blue carbon sinks to bind carbon and provide food and incomes is prioritized in a manner that also promotes business, jobs and coastal development opportunities;
t catalyse the natural capacity of blue carbon sinks to regenerate by managing
coastal ecosystems for conditions conducive to rapid growth and expansion of seagrass, mangroves and salt marshes.
Source: C. Nellemann, E. Corcoran, C.M. Duarte, L. Valdés, C. De Young, L. Fonseca and G. Grimsditch, eds. 2009.
Blue carbon: the role of healthy oceans in binding carbon. A Rapid Response Assessment. Nairobi, United Nations Environment Programme, and Arendal, Norway, GRID-Arendal (also available at www.grida.no/publications/rr/ blue-carbon/).
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92 750 121 610 1 580 300 3 000 50 3 4 100 38 100 150 6 650 50 6 0.2 96.1 0.8 0.5 1.5 60 8 60 40 1 020 90 1 020 8 Ocean surface Labile dissolved organic C Marine biota AtmosphereOil and gas fields Coal fields Soil Land-use change CARBON CYCLE Deep ocean Sediments
Carbon fluxes and stocks Storage: gigatonnes of C Fluxes: gigatonnes of C per year
Source: Intergovernmental Panel on Climate Change.
Biosphere Rivers