Dead planet, living planet

result in the recovery of important services, such as their capac- ity to oxygenate coastal waters, serve as nurseries helping restore world fish stocks or the shelter the shoreline from storms and tsunamis (Hemminga and Duarte 2000; Danielsen et al ., 2005). For instance, the ongoing national wetland conservation action plan in China has been estimated to involve a potential for an increased carbon sequestration by 6.57 Gg C year -1 (Xiaonana et al ., 2008). Andrews et al . (2008) calculated that the net effect of returning of returning some 26 km 2 of reclaimed land in the UK to intertidal environments could result in the burial of about 800 ton C year -1 . A first involves the regulation of activities responsible for their global loss, including coastal reclamation, deforestation of mangrove forests, excess fertilizer application on land crops and inputs of urban effluents of organic matter, siltation de- rived from deforestation on land, unsustainable fishing and fixing of coastlines through coastal development (e.g. Borum et al ., 2004; Hamilton and Snedaker 1984; Melana et al ., 2000; Duarte, 2002; 2009). A second step should involve efforts for the large-scale restora- tion of the lost area, which is likely of the same order (if not larger) than the area currently still covered by these aquatic habitats (Duarte 2009; Waycott et al ., 2009). For instance, some countries in SE Asia have lost almost 90% of their man- groves over the last 60 years (Valiela et al ., 2001). Large-scale restoration projects have been successfully conducted for man- groves. The single largest effort probably being the afforesta- tion of the Mekong Delta forest in Vietnam, completely de- stroyed by the use of Agent Orange in the 1970’s and replanted by the Vietnamese people (Arnaud-Haond et al ., in press). Salt- marsh restoration is also possible and has been applied largely in Europe and the USA (e.g. Boorman and Hazelden 1995). Restoring lost seagrass meadows is more complex, as the labor required to insert transplants under the water increases cost (Duarte et al ., 2005b), so has to be supported in parallel with actions to remove the pressures that caused the loss in the first place. While green forest can only grow upwards, seagrasses can spread horizontally at exponential rates. Most efforts to restore blue forests have been driven by the need to restore coastal protection by vegetated habitats and their value as habitats for key species (Boorman and Hazelden, 1995; Fonseca et al ., 2000; Danielsen et al ., 2005).

term resilience (Harris, 2006; Erwin, 2009). It is also crucial to ensure that restoration objectives are consistent with local needs and aspirations, to ensure long-term success. In this way, ecosystem restoration can provide an effective climate change mitigation strategy. Restoration of seagrasses and mangroves There is sufficient evidence to support that reversing the global decline of vegetated coastal habitats and recovering the lost area of blue forests would provide a very large improvement in the ecological status of the global coastal environment. This could Past mitigation efforts concentrated on brown carbon, some- times leading to land conversion for biofuel production which inadvertently increased emissions from green carbon. The proposed REDD (Reducing Emissions from Deforestation and Forest Degradation) instrument is based on payment for carbon storage ecosystem services and could lead to an esti- mated halving of deforestation rates by 2030, cutting emis- sions by 1.5–2.7 Gt CO 2 per year. The estimated costs range from USD 17.2 billion to USD 33 billion/year whilst the esti- mated long-term net benefit of this action in terms of reduced climate change is estimated at USD 3.7 trillion in present value terms (Eliasch 2008). Delaying action on REDD would reduce its benefits dramatically: waiting 10 more years could reduce the net benefit of halving deforestation by USD 500 billion (Eli- asch, 2008; McKinsey 2008; TEEB, 2009). ‘Brown carbon’ : industrial emissions of greenhouse gases that affect the climate. ‘Green carbon’: carbon stored in terrestrial ecosystems e.g. plant biomass, soils, wetlands and pasture and increasingly recognised as a key item for negotiation in the UNFCCC (in relation to forest carbon and mechanisms such as REDD, REDD-Plus, or LULUCF). ‘Blue carbon’ : carbon bound in the world’s oceans. An esti- mated 55% of all carbon in living organisms is stored in man- groves, marshes, sea grasses, coral reefs and macro-algae. ‘Black carbon’ : formed through incomplete combustion of fuels and may be significantly reduced if clean burning tech- nologies are employed. How to mitigate climate change: The role of natural ecosystems

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