THE WEATHER this summer in southern England, where I live, has been brutal(残酷的；极其恶劣的): exceptional heatwaves and record-breaking(破纪录的) spells without rain. Tracks have buckled(弯曲变形), disrupting transportation, and crop yields are down substantially, with farmers warning of food shortages next year.
今年夏天，我居住的英格兰南部天气异常恶劣：极端热浪和创纪录的无雨期。铁轨因高温弯曲，交通中断，农作物产量大幅下降，农民警告明年将出现粮食短缺。
Some experts tell us that this is merely what we can expect based on(基于，根据) long-standing(长期存在的) climate-change predictions of “hotter drier summers”. But such predictions do not explain what we experienced this summer and it is important—and urgent—to understand why not, at least if we are to be prepared for next summer and those immediately after.(但此类预测无法解释今夏经历，理解原因至关重要且紧迫。)
一些专家告诉我们，这只是基于长期气候变化预测“更热更干的夏季”所预期的情况。但这样的预测并不能解释我们今年夏天的经历，而理解其中的原因至关重要且紧迫——至少如果我们想为明年及之后的夏天做好准备的话。
The perhaps familiar predictions of “warmer wetter winters, hotter drier summers” describe what is called the “thermodynamic(热力学的)” aspect of climate change: the generic(一般的，普遍的) consequence of the fact that global surface temperatures are warming from greenhouse-gas emissions, and that a warmer atmosphere necessarily contains more water vapour(水蒸气). With more humid air, the standard low-pressure systems that bring rain to the British Isles in winter will bring even more rain under climate change. In summer, by contrast(相比之下), where such low-pressure systems are suppressed(被抑制，被压制) by the reduced equator-to-pole temperature gradient(梯度，坡度) (a consequence of the Sun moving northward), the warmer air will dry the land, reducing rainfall further. We understand this thermodynamic signal extremely well—not least because(尤其是因为) the underlying physics is simple.
那些或许耳熟能详的预测——“冬季更暖更湿，夏季更热更干”——描述的是所谓气候变化的“热力学”方面：这是全球地表温度因温室气体排放而变暖，以及更温暖的大气必然含有更多水蒸气这一事实的普遍后果。由于空气更加潮湿，冬季给不列颠群岛带来降雨的标准低压系统在气候变化下将带来更多降雨。相比之下，在夏季，由于赤道到极地的温度梯度减小（这是太阳北移的结果），此类低压系统受到抑制，更温暖的空气将使土地变干，进一步减少降雨。我们非常理解这种热力学信号——不仅仅是因为其背后的物理学原理很简单。