By 1958, when people in lab coats started to pay attention to it, it had risen to 315 parts per million. Today it is over 360 parts per million and rising by roughly one-quarter of 1 percent a year. By the end of the twenty-first century it is forecast to rise to about 560 parts per million.
到1958年实验室人员开始重视这个问题的时候，那个数字已经上升到百万分之三百一十五。今天，那个数字已经是百万分之三百六十以上，而且还在以每年大约百分之零点二五的速度继续攀升。据预测，到21世纪末，这个数字会达到大约百万分之五百六十。

So far, the Earth's oceans and forests (which also pack away a lot of carbon) have managed to save us from ourselves, but as Peter Cox of the British Meteorological Office puts it: "There is a critical threshold where the natural biosphere stops buffering us from the effects of our emissions and actually starts to amplify them." The fear is that there would be a runaway increase in the Earth's warming. Unable to adapt, many trees and other plants would die, releasing their stores of carbon and adding to the problem. Such cycles have occasionally happened in the distant past even without a human contribution. The good news is that even here nature is quite wonderful. It is almost certain that eventually the carbon cycle would reassert itself and return the Earth to a situation of stability and happiness. The last time this happened, it took a mere sixty thousand years.
到目前为止，地球上的海洋和森林（森林也带走了大量的碳）成功地挽救了我们自我毁灭的命运。但是，正如英国气象局的彼得·考克斯所说：“有一条临界线。到了那个时候，大自然的生物圈已经无法缓解我们排放的二氧化碳对我们自身所产生的影响，实际上还开始起增大作用。”人们担心，全球变暖的情况将会迅速恶化。由于无法适应，许多树木和别的植物将会死去，把储存的碳释放出来，使问题变得更加严重。这种循环在遥远的过去也偶尔发生过，即使在没有人类参与的情况下。然而，即使到了那种地步，大自然还在创造奇迹，这是个好消息。几乎可以肯定，碳循环最后会东山再起，还地球一个稳定而美好的环境。上一次发生这类事，只花了6万年时间。