原文：

A majority of the world’s climate scientists have convinced themselves, and also a lot of laymen, some of whom have political power, that the Earth’s climate is changing; that the change, from humanity’s point of view, is for the worse; and that the cause is human activity, in the form. of excessive emissions of greenhouse gases such as carbon dioxide.
    A minority, though, are sceptical. Some think that recent data suggesting the Earth’s average temperature is rising are explained by natural variations in solar radiation, and that this trend may be coming to an end. Others argue that there is no conclusive evidence that modern temperatures are higher than they used to be.
    We believe that global warming is a serious threat, and that the world needs to take steps to try to avert it. That is the job of the politicians. But we do not believe that climate change is a certainty. There are no certainties in science. Prevailing theories must be constantly tested against evidence, and more evidence collected, and the theories tested again. That is the job of the scientists.

点评：

此次英译汉内容非常清晰，一共三段，一段写科学家和政客等门外汉是如何相信全球变暖这一现象，另一段写反对者的观点。这符合外刊作者的一贯写作手法：即引述各方观点后再在最后引出自己的观点。

词汇梳理：

convince：确信

laymen：外行

sceptical：怀疑的

solar radiation：太阳辐射

conclusive evidence：确凿的证据

prevailing：盛行的  

参考译文：

世界上大部分气候学家已经使他们自己及许多普通民众（包括一些政界人士）确信，地球的气候正处于变化之中；对人类而言，这一变化正日趋严重；罪魁祸首是人类活动，其表现形式为过量排放二氧化碳之类的温室气体。
    但是，仍有一小部分人对此持怀疑态度。一些人表示，虽然近期的数据表明地球的平均气温正在升高，但其原因是太阳辐射的自然波动，这一趋势可能临近结束。另一些人认为并没有决定性证据表明近现代的地球温度高于古代。
    我们认为，全球变暖是人类面临的严重威胁，世界各国需要采取措施，竭力避免这一问题。这是政治家的职责。但是我们也相信气候变化并不是必然的。科学无绝对。盛行的理论必须不断得到实际证据的检验。一旦搜集到了新的证据，就需要进行再次验证。这是科学家的任务。