Final answer:
Significant climate changes over time include the warming during the Medieval Climate Anomaly, the cooling of the Little Ice Age, and the sharp increase in temperatures during the last 150 years. The end of the last ice age marked the beginning of the current warmer interglacial period. Earth has experienced many long-term changes in climate throughout its history, some leading to the evolution or extinction of species.
Step-by-step explanation:
Relating present temperatures to various historical time periods shows a vast range of climatic changes on Earth. Over the last 150 years, especially since the Industrial Era, temperatures have risen dramatically, reflecting a much steeper increase than in previous millennia. Going further back, during the Medieval Climate Anomaly (900-1300 AD), temperatures were slightly warmer, by about 0.10 °C to 0.20 °C, which facilitated Viking colonization in Greenland due to decreased ice cover. The subsequent period, known as the Little Ice Age, lasting until around 1850, saw a cooling in the Northern Hemisphere.
Looking back approximately 12,000 years, the last ice age ended, and we entered a warmer inter-glacial period. Over the last million years, Earth has experienced cycles of glacial (cold) and interglacial (warm) periods, with the last glacial maximum being 20,000 years ago and with ice covering much of the Northern Hemisphere, including parts of North America and Europe. Extending to 5 million years ago and beyond, Earth's climate has seen even longer-term fluctuations between warmer and cooler states, hugely influencing the evolution and distribution of life on our planet. The climate 180 million years ago was drastically different, with likely much warmer global temperatures during the Jurassic period of the Mesozoic Era, long before human influence.