首先,地球系统的碳循环槽无关的讨论大气变化{有限公司}_2 \文本集中美元或海洋酸化。以同样的方式,水的体积循环过滤系统的一个游泳池池的水平是无关紧要的。重要的是水的净输入和输出。让我们看看这张图的地球碳储存,通过碳循环通量。[![在这里输入图像描述][1]][1]图(Dave蓝冰)[2]的[卡尔顿学院][3]。碳的总量的确是巨大的,和总通量加起来每年近700吨二氧化碳排放。注意,只有~ 400 Gt传输文本\{有限公司}_2美元,其余是有机物。图中的数字不精确,但他们是很好的近似。给出的图在图中对人类燃烧化石富乐是6吨的碳,对应于22日Gt \文本{有限公司}_2,美元的添加到其他人类排放可能加起来类似于29 Gt的参考引用。 The amount of $\text{CO}_2$ released by volcanic activity varies widely in time, but the amount given in the figure is an average value, and amounts to 0.6 Gt of Carbon, equivalent to 2.2 Gt of $\text{CO}_2$. **But pretty much the same amount is removed by subduction. Therefore, volcanic activity is not a significant LONG TERM source of $\text{CO}_2$.** And by long term I mean millions of years. So you can argue that natural emissions are larger than human emissions. Sure. The respiration of plants produce 8 times more $\text{CO}_2$ than humans, but plants take it back (and more) through photosynthesis. Atmospheric $\text{CO}_2$ have varied widely through Earth's history, but in the last several thousands years it have been pretty stable, because all the sources were in balance with the sinks, leading to a very small net change in $\text{CO}_2$ concentration in the atmosphere and oceans (there in the form of carbonic acid). However, this balance was disrupted by the industrial revolution and human emissions, mostly due to the use of fossil fuels. Going back to the swimming pool analogy: evaporation might be tiny compared with the volume of water turned around by the filtering system, but give it long enough time and your swimming pool will be dry. We added a source of carbon in the carbon cycle, and if we don'r remove it or add an equivalent sink ([carbon sequestration][4]), the concentration of $\text{CO}_2$ in the atmosphere and carbonic acid in the oceans will keep rising. [1]: https://i.stack.imgur.com/rqQsg.png [2]: https://serc.carleton.edu/integrate/teaching_materials/earth_modeling/bice_story.html [3]: https://serc.carleton.edu/integrate/teaching_materials/earth_modeling/student_materials/unit9_article1.html [4]: https://en.wikipedia.org/wiki/Carbon_sequestration