土地变化,火灾和气候变化削弱了美国的碳沉
Jinxun Liu1, Benjamin M Sleeter1, Zhiliang Zhu1
1US Geological Survey, Reston, VA 20192, USA.
Science advances
|November 12, 2025
概括
美国土地碳汇正在减弱,土地利用变化是主要的驱动因素. 自2000年以来,美国成为净碳来源的频率超过了沉水器.
科学领域:
- 环境科学 环境科学
- 气候科学 气候科学
- 生态生态学 生态生态学
背景情况:
- 陆地生物圈在调节大气中二氧化碳 (CO2) 水平方面发挥着至关重要的作用.
- 准确评估土地碳汇对于了解全球碳循环和为气候政策提供信息至关重要.
- 之前的研究表明,美国的碳排放量持续下降,但土地变化动态的影响需要进一步调查.
研究的目的:
- 使用详细的建模框架,从1985年到2020年评估美国的陆地碳汇.
- 量化土地覆盖变化,气候,野火和侵蚀对碳预算的贡献.
- 确定碳损失的主要驱动因素及其对国家碳核算的影响.
主要方法:
- 采用了自下而上的建模框架,整合了30米的土地变化数据.
- 利用跨规模,跨景观和跨系统的方法来追踪部分土地覆盖的变化.
- 应用区域模型校准以提高准确性,并考虑到空间异质性.
主要成果:
- 据估计,陆地和水中的平均碳汇量分别为每年+110±37和+19±0.5千克的碳.
- 陆地碳汇没有明显的趋势,在20世纪90年代达到顶峰,自2000年以来,碳源的年数比碳汇的年数多.
- 土地变化是影响碳平衡的主要因素,导致每年碳损失70±5.5千克,超过了气候和野火的影响.
结论:
- 土地利用变化对美国的碳预算产生了重大影响,通常作为碳来源.
- 二氧化碳施肥效应不足以抵消土地变化的碳损失.
- 这些发现挑战了先前的国家和全球评估,并强调需要将详细的土地变化动态纳入碳预算估计和政策制定.
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