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SSP1-2.6“双碳”路径下不同土地利用变化对我国近地面气温的生物物理影响

The Biogeophysical Impact of Different Land Use Changes on Near-Surface Air Temperature in China under the SSP1-2.6 "Double Carbon" Pathway

  • 摘要: 近百年来土地利用和土地覆盖变化主要通过生物地球化学和生物地球物理过程影响气候变化,但其对我国未来气温的生物物理影响存在不确定性。因此,我们利用6个第六次国际耦合模式比较计划的模式数据,预估了共享社会经济路径SSP1-2.6下“双碳”时期不同土地利用变化(即SSP3-7.0情景和SSP1-2.6情景的土地利用)对我国气温的生物物理影响,并定量解析各因子。结果表明,(1)SSP1-2.6“双碳”时期两个情景的土地利用在我国的主要差异为森林覆盖在秦岭—淮河以南增加、以北减少,且在碳中和时期(?10~10%)大于碳达峰时期(?8%~5%);我国西部森林覆盖差异小。(2)全国平均而言,该土地利用差异在碳达峰时期降温贡献为5%,大于碳中和时期(?1%)。(3)土地利用变化在不同区域影响温度变化的因子不同:我国东部北方地区碳达峰时期的降温贡献(?3.2%)到碳中和时期的增温贡献(0.4%),是土壤热通量、晴空长波辐射和感热通量的增温作用增强以及地表反照率和潜热通量降温作用增强的综合结果。中国东部南方地区在两个时期均为降温贡献(?4.1%和?1.8%),主要是云辐射效应的降温作用。中国西部地区在碳达峰时期的增温贡献(4.9%)到碳中和时期的降温贡献(?1.8%),主要是土壤热通量和晴空辐射增温作用转为降温作用。总体上,相比于SSP1-2.6情景,SSP3-7.0情景的土地利用在SSP1-2.6“双碳”时期对我国整体起降温作用,但存在区域差异。

     

    Abstract: In the past century, changes in land use and land cover have affected climate change mainly through biogeochemical and biogeophysical processes, and the biogeophysical effects on air temperature in China are still uncertainty. Thus, this study utilizes data of six models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to project the biogeophysical influence of different land use and land covers (i.e., under SSP3-7.0 and SSP1-2.6) on temperature in China during the "double carbon" period under Shared Socioeconomic Pathway (SSP) SSP1-2.6, and quantitatively analyzes the factors involved. Results indicate that: (1) During the "double carbon" period under SSP1-2.6, the difference of land use and land covers under two scenarios is that forest cover increases in the south of the Qinling-Huaihe River regions and decreases in the north, with greater differences in the carbon-neutral period (?10% to 10%) than in the carbon peak period (?8% to 5%). Differences in forest cover in western China are minimal. (2) National mean, its contribution to future warming during the carbon peak period is ?5%, and it is greater than that during the carbon-neutral period (?1%). (3) This contribution also exhibits regional disparities. In north eastern China, there is a transition from a negative contribution during the carbon peak period (?3.2%) to a positive contribution during the carbon-neutral period (0.4%). This is attributed to the combined results of increased warming effects of ground heat fluxes, clear-sky longwave radiation, and sensible heat fluxes, as well as enhanced cooling effects of surface albedo and latent heat fluxes. South eastern China exhibits negative contributions (?4.1% and ?1.8%) throughout the “double carbon” period, resulting from the cooling effects of cloud radiation and the enhanced warming effects of ground heat fluxes, clear-sky longwave radiation, and sensible heat fluxes. In western China, the positive contribution during the carbon peak period (4.9%) shifts to a negative contribution during the carbon-neutral period (?1.8%), primarily due to the transition of warming effects from ground heat fluxes and clear-sky radiation to cooling effects. Overall, the results suggest that forest cover in the ssp126-ssp370Lu experiment generally has a cooling effect during the "double carbon" period under SSP1-2.6, partially mitigating the impacts of greenhouse gases; however, regional disparities exist.

     

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