科学家通过多个完整的温度数据集来追踪全球气温变化。[1]三个最完整的温度记录始于1880年，分别由美国Goddard太空研究所、美国国家环保信息中心和英国气象局哈德利中心维护。[1]除了仪器观测数据，研究人员还依靠冰芯记录进行长期气候对比，其中最完整的冰芯记录来自南极，可追溯超过一百万年。[1]气候学家Friedrike Otto指出，这些冰芯"保存了关于过去温度、降雨和大气条件的信息，可追溯数千至数百万年"。[1]
当前全球气候变暖的特征显著不同于历史模式。NASA指出，当今气候变化主要由人类燃烧化石燃料引起，其发生速度远快于过去一百万年左右。[1]历史上也曾出现极端气温事件，约5600万年前，大量碳进入大气，可能来自火山活动和海洋沉积物释放的甲烷，引发了一个全球变暖时期。[1]
对于极端热浪的评估，科研机构采用定量标准来确认其严重程度。世界天气归因组织对2026年6月欧洲热浪的分析显示这是该地区有记录以来最严重的热浪。[1]衡量热浪影响的关键指标是湿球温度，当其持续在35摄氏度（95华氏度）左右时，即使在阴凉处或补充水分，人体也可能过热。[1]
Understanding whether a heat event truly represents a record requires examining multiple lines of evidence spanning vastly different timescales. Three of the most complete instrumental temperature datasets begin in 1880 and are maintained by the U.S. Goddard Institute for Space Studies, the U.S. National Centers for Environmental Information, and the UK Met Office Hadley Centre [1]. For deeper historical context, the most comprehensive ice core records come from Antarctica and extend back more than one million years [1]. According to climatologist Friedrike Otto, these frozen archives preserve information about past temperatures, precipitation, and atmospheric conditions dating back thousands to millions of years [1].
Today's rapid warming is fundamentally different from natural temperature variations in Earth's history. About 56 million years ago, large quantities of carbon entered the atmosphere, possibly from volcanic activity and methane released from ocean sediments, triggering a global warming period [1]. NASA has determined that current climate change is primarily caused by human burning of fossil fuels and is occurring far faster than comparable warming events over the past million years or so [1]. Recent analysis by the World Weather Attribution organization found that a heat wave affecting Europe in June 2026 was the most severe on record for that region [1]. The dangers of extreme heat become acute when wet-bulb temperatures persist around 35 degrees Celsius (95 degrees Fahrenheit), at which point the human body risks overheating even in shaded areas or with water intake [1].