这种变化表现在树木的年轮中。
有些年轮可以追溯到近一万年前的冰河时代末期。
Some of the rings go back almost ten thousand years to the end of the Ice Age.
史蒂文森博士正在分析一种元素——活树和死树年轮中的碳-14。
Doctors Stevenson is analyzing one element—carbon-14 in ring from both living and dead trees.
一万年的树木年轮显示，碳14水平大约每420年上升和下降一次。
Ten thousand years of tree rings show that the carbon-14 level rises and falls about every 420 years.
爬行动物的骨骼生长在本质上是周期性的，在骨头上产生一系列的同心圆，就像树木的年轮一样。
Bone growth in reptiles is periodic in nature, producing a series of concentric rings in the bone, not unlike the growth rings of a tree.
替换可能是一个令人惊叹的精确过程，因此贝壳纹饰的细节，树木的年轮和骨的微妙结构都被准确地保存。
Replacement can be a marvelously precise process, so that details of shell ornamentation, tree rings in wood, and delicate structures in bone are accurately preserved.
在开始有记录之前，我们只有主要根据年轮和冰芯重建的“代理记录”，还有一些不完整的书面记录作为补充。
For the time before records began, we have only "proxy records" reconstructed largely from tree rings and ice cores, supplemented by a few incomplete written accounts.
在地球上，人们认为，表明太阳黑子周期最可靠的迹象之一是树木的生长速度，就像树干横截面上可见的年轮一样。
On Earth, among the surest indications of sunspot cycles are believed to be the rate that trees grow, as seen in the rings visible in the cross sections of their trunks.
通过查找某一年年轮中的元素，科学家可以知道那一年空气中的元素是什么。
By looking up the elements in the rings for a given year, scientists can tell what elements were in the air that year.
你可以通过数年轮来判断树木的年龄，但是作为树木生命的记载，年轮能说明的东西远不止于此。
You can tell the age of a tree by counting its rings, but these records of trees' life really say a lot more.
年代最古老的年轮最靠近树心。
The oldest rings are those closest to the center of the tree.
这是因为树木每年都会产生新的年轮。
我们比较了木炭和年轮对火灾的记录。
所有学校每年轮流举办运动会。
All the schools take turns to hold the sports meet every year.
树的年轮是最明显但又最有争议性的一个例子。
Tree rings are the obvious, and most controversial, example.
我们这些年来分享得太多了，就像树的年轮一样。
一些树变成了木炭，它们的年轮因此被保存下来。
Some of those rings are in wood that has been preserved as charcoal.
他们交叉着腿坐成一个个同心圆…就像树上的年轮。
They sit cross legged, in concentric circles... like growth rings in a tree.
但是年轮很小，表明那些树木的生长是极其缓慢的。
But the rings were very small, showing that the trees grew extremely slowly.
年轮未能捕捉最近的变暖，更添加对该纪录价值的怀疑。
The fact that tree-ring records do not capture recent warming adds to the scepticism about the value of such records.
每年各队互相交手一次，主场则是每年轮换一次。
Each team plays each other once, with home advantage alternating on a yearly basis.
这些木炭沉积物的年代与年轮火伤痕迹记录的年代高度契合。
The chronology of charcoal deposits closely matches the tree-ring chronology of fire scars.
同树木一样，石笋通常也有能显示其年生长周期的年轮。
Like trees, stalagmites are often composed of concentric layers that represent annual growth periods.
研究小组也将年轮记录的火灾历史与沼泽草甸中沉积的木炭进行了比较。
The team also compared charcoal deposits in boggy meadows within the groves to the tree-ring fire history.
其它的一些技术则使得他们可以精确的判断出每条年轮所代表的具体年份。
Other techniques allowed them to figure out exactly which year each ring represented.
所以，在这里挖出的冰核都能像树木年轮那样按季节数出年份来。
The ice cores pulled up at WAIS will be dated by counting back these seasonal layers as if they were tree rings.
为了对年轮进行研究，研究人员通常会从树木取出一块铅笔大小的核心部分。
To study tree rings, researchers generally take a pencil-sized core from a tree.
不幸的是，今年轮到我了，我在最坏的情况下遇到了最重要的比赛。
Unluckily for me, this year mine came when I arrived at the most important tournaments in the worst possible condition.
尽管树木年轮表明当时发生了气候剧变，却没有任何数据解释这次剧变的原因。
But while the tree rings show variability, there is no data for why these climate changes occurred.
尽管树木年轮表明当时发生了气候剧变，却没有任何数据解释这次剧变的原因。
But while the tree rings show variability, there is no data for why these climate changes occurred.
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