经济学人下载:气候变化的不确定性(2)

Building models is also made hard by lack of knowledge about the ways that carbon—
由于缺乏关于碳在环境中移动方式的知识，建立模型也很困难—

the central atom in molecules of carbon dioxide and methane,
碳是二氧化碳和甲烷分子中的中心原子，

the main heat-capturing greenhouse gases other than water vapour—moves through the environment.
是除了水蒸气外的主要吸热温室气体。

Understanding Earth's carbon cycles is crucial to understanding climate change.
了解地球碳循环是理解气候变化的关键。

But much of that element's movement is facilitated by living organisms,
但这些元素的大部分运动都是由活的生物体推动的

and these are even more difficult to understand than physical processes.
并且这些甚至比物理过程更难理解。

Plants absorb carbon from the air during photosynthesis and then return it during respiration. Animals that eat those plants also respire.
在光合作用下，植物从空气中吸收碳，然后在呼吸过程中将其返回。吃这些植物的动物也呼吸。

Bacteria and fungi similarly break down dead plants and animals to pillage materials and energy from them,
细菌和真菌也会分解死去的动植物，从它们身上掠夺物质和能量

releasing carbon dioxide and methane into the atmosphere as they do so.
并在此过程中将二氧化碳和甲烷释放到大气中。

Some organic matter, nevertheless, gets buried rather than broken down, and is thus removed from climatic consideration.
然而一些有机物质会被掩埋而不是分解，因此要将它们从气候的考虑中移除

But, over time, this buried material is transformed by heat and pressure into oil, gas and coal—
但随时间消逝，这种掩埋材料通过加热和压力转化成石油、天然气和煤炭—

substances pertinent to the climate in the context of one particular biological agent, Homo sapiens.
在特殊的生物媒介—智人的背景下，这些物质和气候有关。

This species uses them to power its civilisation,
这一物种利用它们强大了其文明，

taking mere decades to fill the air with carbon that took hundreds of millions of years to accumulate underground.
仅仅用了几十年就使空气充满了碳，而这些碳在地下积累了数亿年

Organic matter may also be trapped in ice: on land in areas of permafrost, and at the bottom of the sea in molecular structures called clathrates.
有机物质或许也被困在冰里：在陆地上的永久冻土地区，在海底被称为笼形化合物的分子结构中。

On top of all this, the oceans themselves contain vast amounts of dissolved carbon dioxide,
最重要的是，海洋本身含有大量的溶解二氧化碳，

and many sea creatures draw on that reserve to build themselves shells and carapaces out of calcium carbonate.
并且很多海洋生物利用这个保护区，用碳酸钙为自己建造贝壳和甲壳。

Not all of this material is recycled. Some ends up on the seabed and eventually turns into limestone.
并不是所有这种物质都可回收。一些会沉入海床，最终变成石灰岩。

Changes in temperature are also a consideration.
温度变化也是一个考虑因素。

The relationship between warmth and carbon-dioxide concentration in the atmosphere is a two-way street.
气温和大气中二氧化碳浓度之间的关系是双向的。

Warm water holds less of the gas than cold water.
温水所含的气体比冷水少。

During past ice ages, oceans therefore drew carbon dioxide out of the atmosphere as they cooled, amplifying the process of cooling.
在过去的冰河时代，海洋在冷却过程中从大气中吸收二氧化碳，放大了冷却过程。

Today's warmer oceans still act in aggregate as sinks for CO2. The warmer they get, however, the less that will continue to be true.
如今更加温暖的海洋仍是二氧化碳的吸收池。然而，海洋变得越暖，这种情况越不可能持续下去。