Canada’s extreme wildfires dominate the decline in global land carbon sinks in 2023

Terrestrial land carbon sinks are strongly influenced by climate extremes, and 2023 is the warmest year on record, accompanied by an El Niño event, extreme wildfires, and extreme precipitation and drought, but their impact on global land sinks in 2023 remains unclear. Here, we used the Global Carbon Assimilation System, version 2, to estimate recent global land sinks by assimilating the OCO-2 ACOS v11.1 XCO2 retrievals. We estimate the global land sink to be -1.63 ± 0.52 PgC/yr in 2023. Compared to 2017-2022, it decreases by 0.59 PgC/yr, in which net ecosystem exchange decreases by only 0.14 PgC/yr, but wildfire emissions increase significantly by 0.45 PgC/yr, mainly in Canada. Our findings suggest that extreme wildfires are an important threat to land sinks under global warming., We generate this dataset using the Global Carbon Assimilation System, version 2 (GCASv2) by assimilating OCO-2 ACOS v11.1 XCO2 retrievals. GCAS v2 was developed to estimate gridded surface carbon fluxes by assimilating primarily satellite XCO2 retrievals, which consists of the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4) and the ensemble square root filter (EnSRF). It has good performance in assimilating GOSAT and OCO-2 XCO2 retrievals, revealing the response of terrestrial ecosystems to extreme climate events, and has participated in the inversion of the Global Carbon Budget 2023.
For this dataset, GCASv2 was run from 6 September 2014 to 6 January 2024 with a DA window of 1 week. Only the terrestrial net ecosystem exchange (NEE) and the atmosphere-ocean carbon exchange (OCN) were optimized, and the carbon emissions from fossil fuels and cement (FFC) and from wildfires were prescribed. Usually, the choice of a priori NEE has an important impact on the inversion of ..., , # Canada’s extreme wildfires dominate the decline in global land carbon sinks in 2023

[https://doi.org/10.5061/dryad.83bk3jb1h](https://doi.org/10.5061/dryad.83bk3jb1h)

## Description of the data and file structure

There are 6 zip files in this dataset, including (1) monthly and annual prior and posterior NEE and OCN fluxes, and prescribed wildfire and fossil fuels and cement emissions in a global spatial resolution of 1°×1° from the 4 experiments (Global prior and posterior fluxes at 1deg resolution.zip); (2) globally (Global_Carbon_Budget.zip), latitudinally (Lat_Zones.zip), and regionally (Transcom_regions.zip, Canada.zip) aggregated annual fluxes of NEE, wildfire emissions, and NBE from the 4 experiments; (3) adjusted fluxes for Canada and different latitudinal zones using different thresholds because of the compensating effect between NEE and wildfire emissions (Adjusted.zip). Details about these zip files are as follows:

**1) Global prior and posterior fluxes at 1deg resolutio...

陆地碳汇受气候极端事件的强烈影响，2023年为有记录以来最热年份，伴随厄尔尼诺（El Niño）事件、极端野火、极端降水与干旱，但上述事件对2023年全球陆地碳汇的影响仍不明确。本研究采用全球碳同化系统第2版（Global Carbon Assimilation System, Version 2, GCASv2），通过同化轨道碳观测卫星2号（OCO-2）的ACOS v11.1版XCO₂反演产品，估算近期全球陆地碳汇。经估算，2023年全球陆地碳汇为-1.63±0.52 拍克碳每年（PgC/yr）。相较于2017-2022年平均值，该碳汇减少了0.59 PgC/yr，其中净生态系统交换（Net Ecosystem Exchange, NEE）仅减少0.14 PgC/yr，而野火碳排放显著增加0.45 PgC/yr，主要发生在加拿大。本研究结果表明，极端野火是全球变暖背景下陆地碳汇的重要威胁。
本数据集通过同化OCO-2 ACOS v11.1版XCO₂反演产品，依托全球碳同化系统第2版（GCASv2）生成。GCASv2旨在通过主要同化卫星XCO₂反演产品来估算网格化地表碳通量，其核心包含臭氧及相关化学示踪物模式第4版（MOZART-4）与集合平方根滤波（Ensemble Square Root Filter, EnSRF）。该系统在同化温室气体观测卫星（GOSAT）与OCO-2的XCO₂反演产品时表现优异，能够揭示陆地生态系统对极端气候事件的响应，并参与了2023年全球碳预算（Global Carbon Budget 2023）的反演工作。
本数据集的GCASv2运行时段为2014年9月6日至2024年1月6日，数据同化窗口为1周。仅对陆地净生态系统交换（NEE）与大气-海洋碳交换（OCN）进行优化，而化石燃料与水泥生产碳排放（FFC）及野火碳排放采用预设值。通常，先验NEE的选取对反演结果具有重要影响……，# 加拿大极端野火主导2023年全球陆地碳汇下降

[https://doi.org/10.5061/dryad.83bk3jb1h](https://doi.org/10.5061/dryad.83bk3jb1h)

## 数据与文件结构说明

本数据集共包含6个压缩包文件，具体如下：(1) 4组试验中分辨率为1°×1°的全球月尺度与年尺度先验、后验NEE及OCN通量，以及预设野火、化石燃料与水泥生产碳排放数据（压缩包名：Global prior and posterior fluxes at 1deg resolution.zip）；(2) 4组试验中全球尺度（Global_Carbon_Budget.zip）、纬度带尺度（Lat_Zones.zip）与区域尺度（Transcom_regions.zip、Canada.zip）聚合后的NEE、野火碳排放与NBE年通量数据；(3) 由于NEE与野火碳排放存在补偿效应，基于不同阈值针对加拿大及不同纬度带调整后的通量数据（Adjusted.zip）。各压缩包的详细说明如下：

**1) Global prior and posterior fluxes at 1deg resolutio...**