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Why is it hot if we were supposed to be in a cold period?

The stabilization of Antarctica in the South Pole and the closing of the North Pole in the continents around it were supposed to allow us to cool down, but human activity is stronger


Pangea map. From Wikipedia
Pangea map. From Wikipedia

The Paleozoic Era lasted for about 300 million years - from 550 million years ago to about 250 million years ago. This era is considered a time when great changes took place, including geological, climatic, as well as the appearance of plants and vertebrates on land. The beginning of the era in the separation of the Rodinia supercontinent, Rodinia to Gondwana in the south, and pieces of land that later joined to form the northern continent (Eurasia + North America.

The Paleozoic era is divided into sub-periods: the Cambrian, which lasted about 50 million years and is known mainly because of what was called the "Cambrian explosion", a concept that describes the accelerated development of many diverse species, including the development of arthropods, the ancestors of today's molluscs and insects, and the chordates (chordates with a primary backbone).

After the Cambrian comes the Ordovician period, which lasted about 45 million years, and is recorded in fossil layers characterized by an abundance of marine invertebrates. The best known among them is the trilobite, an armored arthropod that lived on the sea floor for about 250 million years until it became extinct.

The next period of about 30 million years is the Silurian, in which jawless fish appeared, molluscs and corals that thrived in the oceans, but the innovation and uniqueness of the celery is that it lives on land. This is the period when the first organisms that carried out photosynthesis - lichens - evolved.

The developed plants appeared in the next period, the Devonian, the ferns and the primitive trees. At the same time, tetrapods, the first vertebrates, inhabit the land. They resembled a lizard and appeared in a variety of shapes and sizes. Among the vertebrates, the first terrestrial arthropods also appeared.

About 360 million years ago, the Carboniferous period began, which lasted about 60 million years. This is the period that provides us with the types of mineral fuel - oil, coal, gas and the like. The trilobites began to disappear while more and more fish species appear at the same time. Conifers appear on land and giant dragonflies in the sky.

Two new groups evolved from the lizards: marine reptiles such as snakes and lizards, and a group of ancient lizards, archosaurs, from which the dinosaurs, crocodiles and birds later evolved. The more successful group that began its existence in this period was (Archimylacris eggintoni), the one from which the cockroaches evolved.

The last period in the Paleozoic era was the Permian, which began about 300 million years ago. The warm days abounded in life, and coral reefs provided shelter for fish and shells. The best known shells are the nautilus and the ammonite. On land, more developed conifers and ginkgo trees grew. The developed flora allowed terrestrial vertebrates to evolve as herbivores, and where there are vegetarians there are also carnivores.

About 250 million years ago, 99% of life disappeared from the surface of the land (and the seas) and the Paleozoic era ended with what is considered the greatest known extinction (the Permian extinction).

In the background of all the development described above, the continents are moving, and the climate is changing. The Cambrian period is characterized by a warm climate that alternates with an ice age. During the Ordovician period, glaciers that form cause the sea level to drop. Gondwana migrates south, while the small continents to the north begin to connect. In Salur, the continents get closer, the sea level rises (again) and intracontinental seas (salty lakes) are formed.

In Devon, the continents join in the north and form Laurasia, in the south there is Gondwana which, towards the end of the Paleozoic era, joins the continents in the north to Laurasia and creates the famous and well-known supercontinent, Pangaea, surrounded by a huge ocean, called Panthalassa. The interior of the giant continent was dry and because of its size no clouds could reach the far coast. So about 250 million years ago, at the end of the Paleozoic era, our world was a huge ocean and a mostly desert supercontinent.

Pangea later breaks up into continents that spread across the oceans. About 50 million years ago, Antarctica was located at the South Pole; North America, Europe and Asia hug the North Pole, and at the (cold) poles that are cut off from the warm ocean currents, ice accumulates.

This combined with the effect of the Milankiewicz cycle puts our world into an ice age. The Milankiewicz cycle allows for slight warming, from time to time, which gives interglacial periods, one of which we entered about 20 thousand years ago. The same cycle is supposed to cause a gradual cooling in our time, but we worry and make it warmer and thus change world orders.

2 תגובות

  1. What is the relationship between the article and the title? Just one paragraph at the end which is mostly opinion.

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