极端天气气候事件变化对荒漠化、土地退化和粮食安全的影响

土地是人类赖以生存的重要资源,在受气候变化影响的同时其状况变化也在气候系统中起着关键作用。IPCC最新发布的气候变化与土地特别报告（SRCCL）系统反映了关于荒漠化、土地退化、可持续土地管理、粮食安全和陆地生态系统碳通量方面的最新科学认知,并探讨了如何进行更加可持续性的土地利用和管理以应对与土地相关的气候变化问题。文中从极端事件变化及其影响的角度,结合SRCCL与其他相关文献,予以分析和总结。结果表明,在全球变暖的背景下,极端天气气候事件的变化已经并将继续影响荒漠化和土地退化进程并对粮食安全造成冲击;而土地对气候系统的反馈作用,又会加剧气候变化并提高极端事件发生的概率和严重程度。面对气候变化尤其是极端事件给土地带来的巨大压力,必须坚持可持续的土地管理,通过减少包括土地和粮食系统在内的所有行业的排放,才有可能实现到21世纪末将全球平均升温控制在相对工业化前水平2℃以内的目标,以减轻气候变化对土地和粮食系统的负面影响。

Impacts of extreme weather and climate events on desertification,land degradation and food security

Land is a critical resource supporting human livelihoods. Land is substantially affected by climate change, whereas changes in land conditions also play a key role in the climate system. The latest IPCC special report climate change and land(SRCCL) presents the latest scientific understandings of climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems, and further assesses how to implement more sustainable land use and management in response to land-related climate change issues. This paper focuses on changes in extreme weather and climate events as well as their impacts on land with the combination of the major conclusions of SRCCL and other relevant studies. We show that in the context of global warming, changes in weather and climate extremes have impacted and will continue to impact desertification and land degradation processes, and threaten food security;the feedback from land to the climate system will exacerbate climate change and increase the occurrence probability and severity of extreme events. Given that land is under the enormous pressures brought by climate change, especially by extreme events, adhering to sustainable land management and reducing greenhouse gas emissions from all sectors including land and food systems, is essential to make it possible to limit the global mean surface temperature rise to within 2 ℃ and mitigate the negative impacts of climate change on land and food systems.