North American Blue Carbon Scoping Study
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Background paper North American Blue Carbon Scoping Study September 2013 Commission for Environmental Cooperation Please cite as: CEC. 2013. North American Blue Carbon Scoping Study. Montreal, Canada. Commission for Environmental Cooperation. 49pp. This report was prepared by Samantha D. Sifleet for the Secretariat of the Commission for Environmental Cooperation. The information contained herein is the responsibility of the author and does not necessarily reflect the views of the CEC, or the governments of Canada, Mexico or the United States of America. Reproduction of this document in whole or in part and in any form for educational or non-profit purposes may be made without special permission from the CEC Secretariat, provided acknowledgment of the source is made. The CEC would appreciate receiving a copy of any publication or material that uses this document as a source. Except where otherwise noted, this work is protected under a Creative Commons Attribution Noncommercial-No Derivative Works License. © Commission for Environmental Cooperation, 2013 Publication Details Publication type : Background paper Publication date : September, 2013 Original language : English Review and quality assurance procedures : Final Party review: August, 2013 QA12.30 Disponible en français: (Sommaire de rapport) Disponible en español : ( Resumen ejecutivo) Cover photo: Jessica Sypher For more information: Commission for Environmental Cooperation 393, rue St-Jacques Ouest, bureau 200 Montreal (Quebec) H2Y 1N9 Canada t 514.350.4300 f 514.350.4372 [email protected] / www.cec.org North American Blue Carbon Scoping Study Table of Contents Executive summary Key Findings .................................................................................................................... iv Introduction ....................................................................................................................................3 What is Blue Carbon? ...................................................................................................... 3 Mangroves in North America .......................................................................................................4 Annual carbon sequestration in mangrove forests in North America ...................... 4 Carbon stocks in mangrove sediments of North America ......................................... 6 Carbon content of mangrove forest biomass in North America ................................ 7 Mangrove extent and overlap with MPAs in North America ...................................... 9 Emissions from mangrove loss in North America ..................................................... 12 Salt Marshes in North America ..................................................................................................13 Annual carbon sequestration rates in salt marshes in North America ................... 13 Carbon stocks in salt marsh sediments of North America ....................................... 15 Carbon content of salt marsh biomass in North America ........................................ 17 Salt marsh extent and overlap with MPAs in North America .................................. 18 Emissions from salt marsh loss in North America .................................................... 20 Seagrasses in North America ......................................................................................................21 Annual carbon sequestration in seagrass meadows of North America ................. 21 Carbon stocks of seagrass sediments in North America ......................................... 23 Carbon content of seagrass biomass in North America .......................................... 25 Seagrass extent and overlap with MPAs in North America ..................................... 28 Emissions from seagrass loss in North America ....................................................... 29 Key Data Gaps & Recommendations .........................................................................................30 Literature Cited ...........................................................................................................................31 Appendix: Additional Tables and Figures .................................................................................35 Commission for Environmental Cooperation iii North American Blue Carbon Scoping Study Executive Summary Coastal wetlands store large amounts of carbon in their vegetation and soils. The development of carbon markets creates the potential for carbon offset payments for coastal wetland conservation and restoration. A careful accounting of both the long-term storage of carbon and annual greenhouse gas fluxes in these ecosystems is needed before carbon payments can begin. Additionally, the geographic location of blue carbon ecosystems, namely mangrove forests, salt marshes, and seagrass meadows, must be accurately documented prior to enrollment on the carbon offset markets. This report examines the extent and carbon sequestration dynamics of blue carbon ecosystems in North America. The overlap of existing marine protected areas in North America with these coastal wetlands is explored in an effort to assess the current size of the blue carbon market in North America. Key Findings 1. A lack of accurate geospatial data for salt marsh and seagrass ecosystems is the greatest hurdle for the blue carbon market in North America. Mangrove forests are the best mapped of all the systems and the most ready for inclusion in current carbon offset programs. 2. Variability in soil carbon stores, for both carbon density and depth, within a given ecosystem type also presents issues in calculating total carbon sequestered. While default mean or median values can be used initially, more accurate measurements will be needed in the future. Depth measurements of the organic-rich peat soils lying underneath these habitats in North America are sparse. A concerted effort to measure the depth and the carbon density of these soils should be pursued. 3. Ecosystem stressors, such as nutrient loading and sea level rise, can shift the overall greenhouse gas balance of blue carbon habitats. Therefore, habitat quality monitoring and measurements should be included in the development of blue carbon offset standards. Commission for Environmental Cooperation iv North American Blue Carbon Scoping Study RESUMEN EJECUTIVO Los humedales costeros almacenan grandes cantidades de carbono en la vegetación que albergan y en sus suelos. Con el desarrollo de los mercados de carbono se genera la posibilidad de establecer sistemas de pagos por compensación de emisiones de carbono para la conservación y restauración de los humedales costeros. Antes de poder iniciar e implementar estos sistemas, es preciso cuantificar minuciosamente tanto el almacenamiento de carbono a largo plazo como los flujos anuales de gases de efecto invernadero en estos ecosistemas. Asimismo, deberá documentarse con toda precisión la ubicación geográfica de los ecosistemas de carbono “azul”, principalmente manglares, marismas salobres y lechos de pasto marino, antes de proceder a inscribirse y tomar parte en los mercados de compensación de emisiones de carbono. En el presente informe se examina el alcance y la dinámica del secuestro de carbono de los ecosistemas de carbono “azul” a escala de América del Norte. Asimismo, en un esfuerzo por evaluar la dimensión que alcanza actualmente el mercado del carbono “azul” en la región, se explora el traslape entre las áreas marinas protegidas existentes en América del Norte y estos humedales costeros. Principales conclusiones 1. La falta de datos geoespaciales precisos relacionados con los ecosistemas de marismas salobres y lechos de pasto marino constituye el mayor obstáculo para la creación de un mercado de carbono “azul” en América del Norte. Los manglares, por su parte, además de ser los sistemas mejor cartografiados, son los que más prontamente pueden incluirse en programas de compensación de emisiones de carbono en vigor. 2. La variabilidad en las reservas de carbono en el suelo dentro de un tipo de ecosistema dado, lo mismo en términos de densidad de carbono que de profundidad, supone otro de los problemas para poder calcular el total de carbono captado y almacenado. Aunque inicialmente pueden emplearse valores medianos o promedio por omisión, en el futuro se requerirán mediciones más precisas. Sin embargo, aún son escasas las mediciones de la profundidad de los suelos de turba ricos en materia orgánica que subyacen estos hábitats de América del Norte. Por lo tanto, deberán procurarse iniciativas concertadas encaminadas a medir la profundidad de estos suelos y la densidad del carbono en ellos almacenado. 3. Ciertos factores de presión ambiental, como la carga de nutrientes y el aumento en el nivel del mar, pueden modificar el equilibrio global de los gases de efecto invernadero en los hábitats de carbono “azul”. Por ello habrán de incluirse actividades de monitoreo y medición de la calidad de los hábitats cuando se establezcan estándares en materia de compensación de emisiones de carbono “azul”. Commission for Environmental Cooperation 1 North American Blue Carbon Scoping Study Sommaire de rapport De grandes quantités de carbone sont stockées dans la végétation et le sol des terres humides côtières. Les marchés du carbone pourraient financer les activités de conservation et de restauration des terres humides côtières avec les crédits de compensation de carbone. Il faut cependant déterminer avec exactitude le stockage à long terme du carbone