Sleep N H, Zahnle K, Neuhoff P S
Department of Geophysics, Stanford University, Stanford, CA 94305, USA.
Proc Natl Acad Sci U S A. 2001 Mar 27;98(7):3666-72. doi: 10.1073/pnas.071045698. Epub 2001 Mar 20.
In the beginning the surface of the Earth was extremely hot, because the Earth as we know it is the product of a collision between two planets, a collision that also created the Moon. Most of the heat within the very young Earth was lost quickly to space while the surface was still quite hot. As it cooled, the Earth's surface passed monotonically through every temperature regime between silicate vapor to liquid water and perhaps even to ice, eventually reaching an equilibrium with sunlight. Inevitably the surface passed through a time when the temperature was around 100 degrees C at which modern thermophile organisms live. How long this warm epoch lasted depends on how long a thick greenhouse atmosphere can be maintained by heat flow from the Earth's interior, either directly as a supplement to insolation, or indirectly through its influence on the nascent carbonate cycle. In both cases, the duration of the warm epoch would have been controlled by processes within the Earth's interior where buffering by surface conditions played little part. A potentially evolutionarily significant warm period of between 10(5) and 10(7) years seems likely, which nonetheless was brief compared to the vast expanse of geological time.
最初，地球表面极其炎热，因为我们所知的地球是两颗行星碰撞的产物，那次碰撞还形成了月球。在这个非常年轻的地球内部，大部分热量在表面仍然相当热的时候就迅速散失到太空中了。随着地球冷却，其表面单调地经历了从硅酸盐蒸汽到液态水甚至可能到冰的每一种温度状态，最终与阳光达到平衡。不可避免地，表面经历了一个温度约为100摄氏度的时期，现代嗜热生物就生活在这个温度下。这个温暖时期持续了多久，取决于来自地球内部的热流能维持浓厚的温室大气多长时间，热流要么直接作为日照的补充，要么间接通过其对新生碳酸盐循环的影响来维持。在这两种情况下，温暖时期的持续时间都将由地球内部的过程控制，而表面条件的缓冲作用很小。一个在10^5到10^7年之间的、可能具有进化意义的温暖期似乎是有可能的，不过与漫长的地质时间相比，这仍然很短暂。
