In years with hotter weather pupils are likely to perform less well in exams, says a major study from researchers at Harvard and other US universities.

哈佛等美国大学的研究人员开展的大型研究指出，在天气炎热的年份，学生们的考试成绩会变差。

There is a "significant" link between higher temperatures and lower school achievement, say economic researchers.

这些经济学研究员称，高温天气和考试成绩下降之间有“重大”关联。

An analysis of test scores of 10 million US secondary school students over 13 years shows hot weather has a negative impact on results.

这项研究在分析了1000万名美国中学生13年间的考试成绩后发现，炎热天气对考试成绩有负面影响。

The study says a practical response could be to use more air conditioning.

研究指出，比较实际的应对措施就是多开空调。

Students taking exams in a summer heatwave might have always complained that they were hampered¹ by the sweltering weather.

在酷暑天考试的学生可能总是抱怨考不好是因为天太热。

But this study, from academics at Harvard, the University of California Los Angeles (UCLA) and Georgia State University, claims to have produced the first clear evidence showing that when temperatures go up, school performance goes down.

哈佛大学、加州大学洛杉矶分校和乔治亚州立大学的学者开展的这项研究声称，首次有明显证据表明，气温升高时，学生考试成绩会下降。

Researchers have tracked how secondary school students performed in tests in different years, between 2001 and 2014, across the different climates and weather patterns within the US.

研究人员追踪了2001年到2014年间这些中学生在不同年份的考试成绩，这些中学位于美国不同的气候带，天气模式也不同。

The study, published by the US National Bureau of Economic Research, found that students were more likely to have lower scores in years with higher temperatures and better results in cooler years.

美国国家经济研究局发布的这项研究发现，气温高的年份里学生的考试成绩更差，而天气凉爽的年份里学生的考试成绩更好。

This applied² across the many different types of climate - whether in cooler northern US states or in the southern states where temperatures are typically much higher.

这一结论适用于美国不同气候带的学校，无论是在凉爽一些的北部州，还是在气温通常高得多的南部州。

The study, Heat and Learning, suggested that hotter weather made it harder to study in lessons in school and to concentrate on homework out of school.

这项名为“高温与学习”的研究指出，天热的时候，学生在学校上课更困难，在校外做作业时也更难以集中注意力。

Researchers calculated that for every 0.55C increase in average temperature over the year, there was a 1% fall in learning.

根据研究人员的计算，一年的平均气温每升高0.55摄氏度，学习成绩就会下降1%。

Colder days did not seem to damage achievement - but the negative impact began to be measurable as temperatures rose above 21C.

冷天似乎不会影响学习成绩，但是当气温升到21摄氏度以上时，负面影响就开始显现。

The reduction in learning accelerated once temperatures rose above 32C and even more so above 38C.

一旦气温升到32摄氏度以上，学习成绩的下滑速度就加快，气温升到38度以上后更是如此。

Joshua Goodman, associate professor at the Harvard Kennedy School of Government, and his co-authors provide evidence that the "heat's disruption of instruction or homework time is responsible for the observed drop in test scores".

哈佛大学肯尼迪政府学院的副教授乔舒亚·古德曼和他的合著者提出了证据，证明“高温对上课和作业时间的影响导致了考试成绩的明显下降”。

He says students were incrementally³ more likely to be "distracted, agitated⁴ and find it harder to focus".

他说，学生更可能“分心、躁动、难以集中注意力”，这一现象会随着温度升高而加剧。

Mr Goodman says the findings also raise bigger questions about whether climate change and global warming will have implications for school achievement.

古德曼说，研究结果还提出了一个更大的问题，即气候变化和全球变暖是否会影响学生的成绩。

Mr Goodman says the researchers also want to examine the long-term consequences of a hot year on a cohort of students.

古德曼说，研究人员还想调查高温年份对同一届学生的长期影响。

If students happen to take important exams in a heatwave year, does that mean they are more likely to miss out on exam results and university places?

如果学生碰巧在高温年份参加重要考试，这是否意味着他们更可能考试失利，错过大学入学机会呢？

Mr Goodman says that policymakers and parents have under-estimated the significance of temperatures in schools and overheated classrooms.

古德曼说，决策者和家长们都低估了学校温度以及教室温度过高的影响。

"Teachers and students already know it's a problem - because they've had to live it," he said.

他说：“老师和学生们早就知道这是个问题——因为他们不得不忍受。”