Nature has unique resources to regulate the temperature on the planet. Known as carbon sinks, which are natural deposits such as oceans, forests, and soils that absorb and sequester carbon dioxide (CO2) from the atmosphere, reducing its presence in the air and increasing oxygen (O2) concentrations. The main carbon sinks were from the production of coal, oil, natural gas, methane hydrates, and limestone rocks. Today it is the oceans, and plant environments, such as forests.
Carbon sinks have functioned for thousands of years without alterations until the carbon cycle was altered and began to suffer consequences from the burning of fossil fuels, increasing and accelerating the concentration of CO2 in the atmosphere. According to the organization Global Carbon Project (2022), it is estimated that since the Industrial Revolution until today, the concentration of carbon dioxide in the air has gone from 278 ppm to more than 400 ppm. Unfortunately, due to the disproportionate increase in greenhouse gas emissions, the main carbon sinks are only capable of removing 31% from circulation.
It is estimated that at least 50% of CO2 emitted by anthropogenic activities is absorbed by forests and oceans. However, the impact of human activities has also wreaked havoc on the main carbon sinks. Deforestation has caused many forests to no longer act as sinks but as sources of emissions and the oceans are being seriously affected by acidification, so we must join forces to preserve and enhance them so that their retention capacity remains efficient in oxygenating our planet.
Retention in soils and forests
Greenhouse gas emissions generated by our human activities are concentrated in the atmosphere, causing global warming. The main sources come from emissions from fossil fuels and industries and from fires, deforestation, and changes in land use. 30% of these gasses are reabsorbed by soils and forest areas through photosynthesis. Plants absorb CO2 from the atmosphere or water and with the help of the sun they store the carbon and return oxygen (O2) to the atmosphere. In the case of terrestrial sinks, carbon is stored resiliently and long-term in two compartments: in forests through wood and in the soil thanks to vegetation.
Soils represent a short and long-term carbon storage medium and contain more carbon than all terrestrial vegetation. Plant waste and other biomass accumulate as organic matter in soils and are degraded by chemical erosion and biological degradation. However, this function has been rapidly deteriorated by cultivated agricultural soils. Increasing the amount of humus and organic matter is a key factor in improving soil quality and the amount of carbon stored. Other methods significantly enhance carbon sequestration in soil including no-till farming, residue mulching, cover cropping, and crop rotation, all of which are more widely used in organic farming than in conventional farming.
Forests are generally carbon sinks when they are high in diversity, density, and size. But, they can also become sources of carbon emissions if these factors decrease due to deforestation, climate change, forest fires or pests. The life expectancy of a forest varies around the world, depending primarily on tree species, site conditions, and disturbance patterns. Generally, older, more mature forests store more carbon per unit area than younger or recovering forests, therefore emissions are higher when these forests are completely removed.
Retention in the ocean and aquatic ecosystems
The seas contain large amounts of dissolved CO2, and phytoplankton, like trees, use photosynthesis to extract it, forming part of the oceanic food chain. Plankton and marine living organisms use dissolved CO2 to form their skeletons and shells based on Calcium Carbonate (CaCO3). This mechanism manages to eliminate CO2 in the water and favors the dissolution of what it contains from the air. The calcareous skeletons, shells, and organic carbon of these organisms eventually fall to the seafloor, where sediments form rocks over time.
25% of the greenhouse gasses emitted are reabsorbed by the oceans through other living beings such as plankton, corals, fish, algae, and photosynthetic bacteria. Coastal marine systems are also extremely important in carbon sequestration. Coastal wetland and mangrove forest systems capture and store about 34 metric tons of carbon annually, equivalent to 24 million cars in one year. The ocean is considered the main global carbon sink, however, it is saturated and in acidification processes which has affected all organisms important in carbon sequestration.
Carbon Sinks in Guatemala
Guatemala has large areas of forest that have historically been a sink for greenhouse gasses. Forests make up 34.19% of the country’s coverage and mangrove coverage is estimated to be 18,839 hectares, 17,670 ha of which are found on the Pacific coast and 1,169.2 ha in the Caribbean. However, these sinks are highly threatened by deforestation and degradation, caused by changes in land use, extensive livestock farming, demand for firewood as an energy source, and illegal wood extraction. It is estimated that in 2010, forests captured more carbon dioxide than was emitted. It is not until the last decade that the trend has reversed to the point that the conversion of areas with natural vegetation to pasture or crops has become the main source of emissions for the country. According to the Global Forest Watch Organization, in the last two decades there has not been a single year in which the country did not lose forest cover. As of 2016, about 1% of natural forests have been lost each year.
The coastal marine zone of Guatemala covers 19 municipalities in seven departments and 26% of the population depends and lives in these areas. The marine territorial extension is 120,299 km2, which represents 53% of the country’s total area. In turn, the country belongs to the Mesoamerican Barrier Reef System (MBRS) which is a barrier reef that extends for approximately one thousand kilometers along Mexico, Belize, Guatemala and Honduras. This barrier reef plays an important role in the carbon cycle and climate change mitigation. To improve carbon sequestration processes in the ocean, the cultivation of seaweed, ocean fertilization, artificial outcrops, mineralization and sedimentation of deep waters are proposed.
- Te has preguntado alguna vez qué pasa con todo el CO2 que generamos?
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