Estimation of the carbon sink of rock weathering by remote sensing and analysis of its spatiotemporal variations
As a type of natural carbon sink,rock weathering plays a critical role in the global carbon cycle by storing atmospheric carbon dioxide(CO2).This process is particularly significant in mitigating climate change,although its contributions are often underestimated or overlooked in broader carbon calculation practices.The present study focuses on Guizhou Province,China,a region that is characterized by extensive karst landforms.These landforms are of particular interest because they are highly effective in capturing atmospheric CO2 through rock weathering.This study aims to explore the spatiotemporal dynamics of the carbon sink of rock weathering from 2001 to 2020.This study integrates various data sources,including remote sensing data,meteorological records,and lithological information,to estimate the carbon sink capacity with the GEM-CO2 model.This study also employs advanced analytical techniques such as Dynamic Time Warping(DTW)and statistical methods to analyze the spatiotemporal evolution of carbon sink.The findings of this study reveal that the rock type is a primary factor influencing the rate of rock weathering and CO2 consumption,followed closely by annual precipitation.The temperature also plays a significant role,although the responses of its effects are observed to be lagged.This indicates that changes in temperature may affect CO2 absorption rates several years after the initial temperature fluctuation occurred.This study identifies that the regions with the highest CO2 consumption through rock weathering are predominantly concentrated in the northeastern,southwestern,southern,and southeastern parts of Guizhou Province.These areas are characterized by widespread formations of carbonate rocks and higher precipitation levels,which can jointly enhance the weathering process and increase carbon sequestration.In contrast,the northwestern regions,which are dominated by silicate rocks and receive lower levels of precipitation,exhibit the lowest levels of CO2 consumption.This discrepancy underscores the importance of both lithological composition and climatic conditions in determining the effectiveness of natural carbon sink.From 2001 to 2020,the annual average karst carbon sink in Guizhou Province ranged from 0 to 1.04×103 t C·km-2·a-1.Although there was a general trend of fluctuation,the overall pattern showed an increase in carbon sequestration capacity.However,the analysis did not reveal any significant single trend over the two decades.This lack of a clear trend suggests a complex interplay between geological and climatic factors that influence carbon sequestration in karst landforms.The variability in carbon sink capacity observed in this study highlights the sensitivity of natural carbon sink to the changes in environmental conditions,particularly in precipitation and temperature.The spatial distribution of carbon sink closely mirrors the distribution of carbonate rocks in Guizhou Province.This correlation emphasizes the critical role that carbonate rocks play in the global carbon cycle due to their high solubility,which can accelerate the process of CO2 absorption.Areas with more annual precipitation were found to have a greater capacity for carbon sequestration,and this result reinforces the importance of hydrological factors in the weathering process.This finding is particularly relevant for the regions that are expected to experience changes in precipitation patterns due to climate change,as it suggests that shifts in hydrological conditions could have a significant impact on the efficacy of natural carbon sink.In addition to these findings,this study also highlights the importance of both geological formations and climatic conditions when the carbon sequestration potential of different regions are estimated.The application of the GEM-CO2 model in this study provides a robust framework for estimating the carbon sink at a regional scale.The effectiveness of this model in this context offers critical data that can be used to guide the development of carbon trading mechanisms and environmental policies aimed at enhancing the natural carbon sink.By integrating geological and climatic data,this model allows a more nuanced understanding of the factors that contribute to the carbon sequestration in karst landforms.The insights gained from this study are invaluable for informing carbon management strategies,particularly in regions with similar geological and climatic conditions.The findings of this study suggest that the carbon sequestration through rock weathering could be a viable component of mitigation efforts for climate change in a wider range.However,the fluctuating nature of carbon sink over the study period indicates that the natural carbon sink is highly sensitive to changes in environmental conditions.This sensitivity underscores the need for adaptive management strategies that can respond to changes in climate and ensure the continued effectiveness of natural carbon sink.Furthermore,this study lays the groundwork for future research to explore the further implications of rock weathering in global carbon cycles.It advocates a more integrated approach that considers both natural and human factors of mitigating climate change.As the climate change continues altering global weather patterns,understanding the role of natural processes like rock weathering in the carbon cycle will be increasingly important for us to develop effective strategies to manage and mitigate the impacts of climate change.
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