For the last 2 billion years, Earth’s climate has alternate between frigid ice and steaming hot like the world of the dinosaurs. If certain types of rocks like coal which need abundant rainfall forms under climate condition, like rainforest or temperate forest, that tells us method used to determine ancient climates. However, this timeline represents changes in climate throughout geological time.
Early Cambrian Climate ( 540 Million years ago). Early Cambrian climate is not well known, because the climate was not very hot nor very cold and there is no evidence of ice at the pole.
Early Ordovician Climate (480 million years ago) – this is a mild climate that probably covered most of the globe. Then, the continents were flooded by the oceans creating warm, broad tropical seaways. Early Silurian Climate (420 million years ago)- This early Silurian climate has coral reefs that thrived in the clear sunny skies of the southern Arid belt. The coral reefs stretched across North America and Northern Europe.
As the conditions lingered, glacial conditions prevailed near the South Pole.
Early Devonian Climate (400 million years ago)- This early Devonian climate is generally dry conditions that prevailed across much of North America, Siberia, China and Australia during the early Devonian. It was noted that South America and Africa were covered by cool, temperate seas. However, during the late Devonian (360 million years ago), Pangea began to assemble, in the tropical rainforest in the Canadian Artic and Southern China, thick coals beginning to form for the first time. While glaciers covered parts of the Amazon basin, thus was located to the south pole.
Early Carboniferous Climate- Early Carboniferous climate shows why Pangea move northward, and the climate belts move southward. So, tropical rainforests cross from Artic Canada to Newfoundland and Western Europe. Then, the desert regions in the mid-North America begin to contract while Southern Hemisphere begins to cool off.
Early Permian Climate (280 million years ago)- As early Permian climate begin to establish, much of the Southern Hemisphere was covered by ice as glaciers pushed northward, and coal was produced in both Equatorial rainforest and in the Temperate forest. This happened during the warmer “Interglacial” periods. However, in the late and medium Permian climate, the equatorial rainforest had disappear as desert spread across central Pangea. Even after the southern ice sheets were gone, an ice cap still covers the North pole.
Early Triassic Climate- Early Triassic Climate is the interior of Pangea; it was hot and dry. However, warm temperature climates extended to the poles as it was assumed the hottest times in Earth history. At the very end of Permian, rapid global warming may have created a super- “Hot House” world that caused the great Permo-Triassic extinction. Note that 99% of all life on Earth perished during the Permo-Triassic extinction. During late Triassic climate, global climate was warm, there is no ice at either North or South pole. Only warm temperature conditions extended towards the poles.