气候变化影响的最新认知

政府间气候变化专门委员会（IPCC）第二工作组于2007年4月6日正式发布了第四次评估报告，该报告客观、全面而审慎地评估了气候变化已有的和未来的可能影响。现有观测证据表明，人为增暖可能已对许多自然和生物系统产生了可辨别的影响，但由于适应以及非气候因子的作用，许多影响还难以辨别。21世纪中期，某些中纬度和热带干旱地区年平均河流径流量和可用水量会减少10%～30%；如果全球平均温度增幅超过1.5～2.5℃，目前所评估的20%～30%动植物物种可能面临灭绝的风险会增大；从全球角度看，局地平均温度增加1～3℃，预计粮食生产潜力会增加，但若超过这一范围，则会减少。兼顾适应和减缓的措施能够降低气候变化相关风险。

Updated Understanding of Climate Change Impacts

"Climate Change 2007? Impacts, Adaptation and Vulnerability", the Working Group II contribution to the IPCC Fourth Assessment Report (AR4) was launched on April 6, 2007. This report summarize the newest peer-reviewed and comprehensive findings from international scientific communities on impact and adaptation. The observed evidence shows that it is likely that anthropogenic warming has had a discernible influence on many physical and biological systems, but many are difficult to discern due to adaptation and non-climatic factors. By the mid-21th century, annual average river runoff and water availability are projected to decrease by 10%~30% over some dry regions at mid-latitudes and in the dry tropics; Approximately 20%~30% of plant and animal species assessed so far are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5~2.5℃; Globally, the potential for food production is projected to increase with increases in local average temperature over a range of 1~3℃, but above this it is projected to decrease. A portfolio of adaptation and mitigation measures can diminish the risks associated with climate change.