从陆地和海洋生态系统角度辨析大气CO_2浓度与全球变暖关系

Relationship between Atmospheric CO_2 Concentration and Global Warming Based on Carbon Storage Dynamics of Terrestrial and Marine Ecosystems

根据古气候记录的温度与大气CO2浓度变化的关系,结合近百年尺度陆地和海洋生态系统碳库对全球变暖的响应模式,探讨大气CO2浓度升高与全球变暖的关系.结果发现,不论是古气候记录的大气CO2浓度升高的时间滞后于升温的时间,还是古气候与近百年来大气CO2浓度升高幅度相近条件下,两者升温幅度存在约10倍差异的事实,均不支持"大气CO2浓度升高驱动了全球变暖"的观点.近百年尺度陆地和海洋生态系统碳汇功能随升温降低从而增大了大气CO2来源,这有可能是"温度升高促进了大气CO2浓度增加"的原因.陆地生态系统碳汇功能降低的驱动机制可能是由于升温降低了陆地生态系统的净初级生产力,增大了异氧呼吸和有机碳分解速率所致;而海洋CO2吸收能力的降低则可能与升温导致CO2溶解度、海水盐度降低以及海洋温盐环流削弱或破坏等有关.

By the investigation of relationship between temperature and atmospheric CO2 concentration of ancient climate record,and the responses of carbon pools in terrestrial and marine ecosystems to recent global warming,relationship of atmospheric CO2 concentration and global warming is re-examined.The result shows that the view of ＂global warming driven by increasing atmospheric CO2 concentration＂ can not be strongly supported by the facts,such as in the ancient climate record atmospheric CO2 concentration often lagged behind the change of temperature,etc.In contrast,it is found that during the past century,both terrestrial and marine ecosystems reduced carbon storage as a response to global warming,thus supporting the view of ＂global warming contributes to the increase of atmospheric CO2 concentration＂.For terrestrial ecosystems,the reduction of carbon storage may be due to the mechanism that global warming decreases total NPP of terrestrial ecosystems;for marine ecosystems,global warming may cause the decrease of the ocean′s carbon absorption,by which the mechanism is very complicated.