全球荒漠化的现状、未来情景及防治对策

简要介绍了千年生态系统评估（MA）项目针对荒漠化问题编写的《生态系统与人类福祉：荒漠化综合报告》的核心内容。报告表明：① 除南极洲以外的其它各洲均存在荒漠化土地，荒漠化是旱区居民满足基本生存需求的主要障碍，它已被列为当今世界具有局地与全球效应的最为严重的环境问题;② 根据MA构建的4种情景的分析结果，预计荒漠化在未来50年（2000—2050年）内仍会不断加剧，但是在不同情景条件下其发展程度也不相同;③ 荒漠化已成为实现联合国千年发展目标的主要障碍，为了有效地防治荒漠化，必须在局地至全球的各级层次上对当前的生态系统管理方式、习惯行为和政策做出重大调整，同时最好是将工作重点放在预防上，因为试图修复荒漠化区域不仅成本昂贵，而且往往收效甚微;④ 为了更好地认识荒漠化的本质，当前亟待在全球尺度上建立准确一致的荒漠化本底数据库和评估指标体系，并对科学认知方面的一些不确定性进行深入研究。

Desertification: Current State and Trends, Scenarios and Response Options

The synthesis report, ecosystems and human well being: desertification synthesis, was briefly introduced in this paper. This report indicates: ① Desertification is occurring on all continents except Antarctica and affects the livelihoods of millions of people, including a large proportion of the poor in drylands. Therefore, desertification ranks among the greatest environmental changes today and is a major impediment to meeting basic human needs in drylands. ② In all four MA scenarios, desertified area is likely to increase, though at different rates. No scenario indicates a reversal in the threat of desertification. ③ Addressing desertification is critical and essential to meeting the Millennium Development Goals. Effective prevention of desertification requires both local management and macro policy approaches that promote sustainability of ecosystem services, and the pressing task is to initiate a systematic global monitoring program, leading to development of a scientifically credible, consistent baseline and indicators of desertification. Major interventions and shifts in ecosystem management are needed to overcome challenges related to desertification. it is advisable to focus on prevention, because attempts to rehabilitate desertified areas are costly and tend to deliver limited results. ④ To better understand the significance of desertification, it is necessary to reduce uncertainties regarding the relationships among desertification, climate change, biodiversity, ecosystem services, and human well being.