Search

Southeast Asian peatlands represent a globally significant carbon store that is destabilized by land-use changes like deforestation and the conversion into plantations, causing high carbon dioxide (CO2) emissions from peat soils and increased leaching of peat carbon into rivers. While this high carbon leaching and consequentially high DOC concentrations suggest that CO2 emissions from peat-draining rivers would be high, estimates based on field data suggest they are only moderate. In this study, we offer an explanation for this phenomenon by showing that carbon decomposition is hampered by the low pH in peat-draining rivers. This limits CO2 production in and emissions from these rivers. We find an exponential pH limitation that shows good agreement with laboratory measurements from high-latitude peat soils. Additionally, our results suggest that enhanced input of carbonate minerals increases CO2 emissions from peat-draining rivers by counteracting the pH limitation. As such inputs of carbonate minerals can occur due to human activities like deforestation of river catchments, liming in plantations, and enhanced weathering application, our study points out an important feedback mechanism of those practices.

Satellite gravimetry is a key component in the investigation of groundwater depletion on the Indian subcontinent. Terrestrial mass loss by sediment transport in rivers is assumed to be below the detection limit of current satellites like GRACE-FO. Thus, it is not considered in the calculation of terrestrial water budgets. However, the Indian subcontinent is drained by the Ganges and Brahmaputra rivers, which constitute one of the world’s most sediment rich river systems. We find that the impact of sediment mass loss within the combined Ganges-Brahmaputra-Meghna catchment accounts for (4±2)% of the long-term gravity decrease currently attributed to groundwater depletion. For erosion-prone Himalaya regions, the correction for sediment mass loss reduces the local trend in equivalent water height by 0.22 cm/yr, which is 14% of the observed trend., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

To assess realistic climate change mitigation strategies, it is important to research and understand the global carbon cycle. Carbon dioxide (CO2) and methane (CH4) are the two most important anthropogenic greenhouse gases. Their atmospheric concentrations are affected by anthropogenic emissions as well as exchange fluxes with oceans and the terrestrial biosphere. For the prediction of future atmospheric CO2 and CH4 concentrations, it is critical to understand how the natural exchange fluxes respond to a changing climate. One of the factors that impact these fluxes is the changing hydrological cycle. In our project, we combine information about the hydrological cycle from geodetic satellites (e.g. GRACE & GRACE-FO) with carbon cycle observations from other satellites (e.g. TROPOMI & OCO-2). Specifically, we plan to investigate the impact of a changing water level in soils on CH4 emissions from wetlands and on the photosynthetic CO2 uptake of plants. Details of our approach and first results will be presented.

This chapter provides background information on peat and more specifically on Indonesian peatlands and their role in the global carbon cycle and summarizes information on human-induced CO2 emissions caused by peat oxidation and fires. In contrast to these so-called on-site CO2 emissions, not much was known about off-site CO2 emissions prior to the joint Indonesian–German project Science for the Protection of Indonesian Coastal Ecosystems (SPICE). Off-site CO2 emissions are CO2 emissions caused by the mobilization of peat carbon along the land–ocean continuum, which were studied by us in the framework of SPICE. Our results allowed us to establish comprehensive carbon budgets showing that peatland preservation and restoration are crucial measures to combat global warming and mitigate climate change impacts caused. e.g., by sea level rise. Furthermore, we conducted socioeconomic experiments and used the established carbon budget to demonstrate the economic conflict that arises between restoration and transformation of peatlands into plantations. Abstrak Bab ini memberikan informasi mengenai gambut dan lebih khusus lagi tentang lahan gambut di Indonesia dan peranannya dalam siklus karbon global, serta merangkum informasi mengenai emisi CO2 yang disebabkan oleh aktivitas manusia sehingga mengakibatkan terjadinya oksidasi dan kebakaran lahan gambut. Terkait emisi CO2 yang terdapat di tempat ini telah banyak di ketahui, namun hal yang kontras dengan informasi terkait emisi CO2 di luar lokasi masih kurang diketahui sebelum program kerjasama riset SPICE antara Indonesia dan Jerman dilakukan. Emisi CO2 di luar lokasi merupakan emisi CO2 yang disebabkan oleh mobilisasi karbon yang berasal dari gambut di sepanjang kontinum darat hingga laut, yang diteliti dalam kerangka kerja program SPICE. Riset ini menunjukkan hasil pengukuran karbon budget yang komprehensif dimana aspek pelestarian dan restorasi lahan gambut merupakan upaya yang sangat penting untuk memerangi pemanasan global dan mitigasi perubahan iklim yang ditimbulkan, misalnya akibat kenaikan permukaan laut dan meningkatnya emisi CO2. Lebih lanjut, dalam riset SPICE ini dilakukan juga eksperimen sosial ekonomi dan menggunakan pengukuran karbon budget yang telah ditetapkan untuk menunjukkan potensi konflik ekonomi yang mungkin terjadi antara aktivitas restorasi dan transformasi lahan gambut menjadi perkebunan, pertanian atau tujuan lainnya.

Southeast Asian peatlands represent a globally significant carbon store that is destabilized by deforestation and the transformation into plantations, causing high carbon dioxide (CO2) emissions from peat soils and increased leaching rates of peat carbon into rivers. While global model studies assumed that CO2 emissions from peat-draining rivers would be high, estimates based on field data suggest they are only moderate. In this study we offer an explanation for this phenomenon and show that carbon decomposition is hampered by the low pH in peat-draining rivers, which limits CO2 production in and emissions from these rivers. We find an exponential pH limitation that shows good agreement with laboratory measurements from high latitude peat soils. Additionally, our results suggest that enhanced input of carbonate minerals increase CO2 emissions from peat-draining rivers by counteracting the pH limitation. As such inputs of carbonate minerals occur due to human activities like deforestation of river catchments, liming in plantations and enhanced weathering projects, our study points out an important feedback mechanism of those practices.