1 million year ago, Canada, North American and N Euro were covered by thousands feet of ice/iceberg, and sea-level was much lower so Alaska and Asia was connected, and Indonesia and Malaysia didn't have so many islands and they were hilly areas, so people can come to Australia and N America. that's Glacial period. Earth became much warmer in recent hundreds of thousands years, and this had nothing to do with Human Being. Recent a few hundreds years climate changes has very little to do with Human, so CO2 reduction, etc. are useless, should not do such thing as "YinYeFeiShi".
3億年到2億五千萬年前的平均溫度比現在高出差不多3度,曾經有1千萬年的時間地球的溫度比現在高出5度。一億年前有一段時間的溫度比現在高出4度。地球現在還在冰河期。在恐龍時代地球沒有冰川,動物,植物都巨大。因為CO2濃度比現在高出太多,植物瘋長,結果是動物也长成巨獸。5千六百萬年前,Greenland 的平均氣溫是85F, 29.4C,那裡是鱷魚的天下。
地球上最热的时期——冥王纪、新元古代晚期、白垩纪热温室、都发生在人类存在之前。 那些古老的气候下的物种人類从未见过。 现代人类文明及其永久的农业和定居点仅在过去一万年左右的时间里发展起来。 该时期通常是低温和相对全球(如果不是区域)气候稳定的时期之一。 与地球历史上的大部分时间相比,今天异常寒冷。 我们现在生活在地质学家所说的间冰期——冰河时代之间的时期。。