In the past 40 years, the destruction of Cayman’s mangroves forests for commercial, residential and tourist developments have increased the amount of CO2 released into the atmosphere – thereby adding to the problem of climate change.
Unless that destruction is drastically reduced or eliminated altogether, those emissions will continue at an ever-increasing rate. Every time the mangroves of Grand Cayman are destroyed – by development or illegal clearing – it is estimated that more than 900 tons of CO2e per acre are released into the atmosphere. At least 70% of mangroves have already been lost on the western side of Grand Cayman, representing about 3,844 acres since 1976 (DoE). Including additional deforestation that has occurred in South Sound and east of Red Bay, as much as 10 million tons of CO2e may have already been released into the atmosphere.
Coastal ecosystems such as mangroves store more carbon per unit area than terrestrial forests and this “blue carbon” is now being recognised for its importance in slowing climate change. These ecosystems also provide essential benefits for climate change adaptation, including coastal protection and food security for coastal communities. However, if mangroves are destroyed or damaged their carbon sink capacity is lost and the carbon stored is released resulting in the emission of carbon dioxide (CO2) contributing to climate change.
A study to determine the amount of carbon stored in the Central Mangrove Wetland (CMW) of Grand Cayman was compiled by Catherine Childs, Education Programmes Manager from the National Trust of the Cayman Islands. This study will be highlighted in Ms. Child’s presentation for the first training session of the new Cayman Mangrove Rangers to be held this Saturday (22 August) at the Clever Fish on Walkers Road. The morning will be followed by a mangrove field trip conducted by Sea Elements. The National Trust for the Cayman Islands is pleased to be able to support this innovative Rangers programme by providing educational support.
In addition to learning in depth about mangrove ecology, the Rangers will be learning about the impacts on climate change by their destruction.
Climate change is the defining issue of our time. From stronger storms to rising sea levels the impacts of climate change are global in scope and unprecedented in scale. Stronger hurricanes are just one of impacts we face in Cayman.
According to NOAA, we are already experiencing global average temperatures that are 2o F higher since record-keeping began in 1880, with each year is hotter than one before. Carbon dioxide levels are exceeding 414 parts per million, the highest recorded in the last 650,000 years; Arctic ice levels are decreasing 13% per decade; polar ice mass is being lost at the rate of 427 gigatonnes per year; and sea levels are rising 3.3 mm/year, causing a global average sea level rise of nearly 7 inches over the past 100 years. Without drastic action today, adapting to these impacts in the future will be difficult and costly.
Ms. Child’s field studies were conducted in a largely undisturbed area of the Central Mangrove Wetlands (CMW) to investigate the carbon content of the vegetation and the soil. While all green plants remove carbon dioxide (CO2) from the air through photosynthesis, mangroves store that carbon away in the trees as well as in the deep soil beneath. Measurements were therefore conducted analyzing the vegetation while soil samples were taken using a deep coring auger which were then tested at a specialized laboratory.
Grand Cayman’s mangrove ecosystems were found to be a significant sink for CO2. Oceanic mangroves such as those found in Grand Cayman are some of the highest carbon pools of any forest type in the world while being among the most vulnerable to the effects of land-use change and global climate change including sea level rise.
Because mangrove ecosystems are so rich in carbon, deforestation or disturbance of these regions results in large emissions of CO2 to the atmosphere, exacerbating climate change. Using a conservative assumption that the first three feet of soil is disturbed when mangrove habitats are converted or damaged, if just 5% of the CMW was damaged, approximately 388,800 tons of CO2e would be emitted to the atmosphere. For reference, this figure correlates to taking approximately 84,521 vehicles off the roads for a year (US EPA).
Despite the significance of these coastal areas, Grand Cayman has lost much of its original mangrove cover. More than 50% of the island was originally covered in mangrove forests but most of the wetlands on the western end of the island have been converted to residential and commercial developments. Fortunately, in the centre of the island the Central Mangrove Wetland, the largest contiguous mangrove ecosystem in the Caribbean, remains largely undisturbed – it is, however, being encroached upon from all sides by rapidly increasing development pressures.
The results of this study indicate that mangroves with deep sediments such as those in the CMW must be considered high priority for preservation. Because of their large ecosystem carbon stocks, as well as the numerous other critical ecosystem services they provide, Cayman’s mangroves must be protected.