Global Lords: I Have Information System

In the warm forests, animals were thriving and evolving into new forms such as herbivores, carnivores, and omnivores. However, during the high temperatures of the PETM period, the size of some animals began to shrink, which is similar to phenomena observed in modern mammals by biologists. For instance, in cold climates, a moose tends to weigh around 80 pounds (approximately 36.28 kilograms) more than its southern counterparts.

This is because the larger the animal, the stronger its ability to retain heat internally. Relative to their overall mass, the proportion of their body surface exposed to the natural environment is smaller, so animals lose heat more slowly. But in hot seasons, retaining warmth is not as important—expelling excess heat becomes vital for survival. Small creatures with a higher surface area-to-weight ratio can dissipate heat more easily. For example, an early horse known as Sifrhippus sandrae shrank by nearly one-third during the PETM period, while an early primate known as Cantius abditus reduced its size by about 10% from the middle to the end of the PETM period.

Insect diversity increased in the ”struggle for survival”

Unlike mammals, for insects, the PETM period was undoubtedly a good time, as the warm climate encouraged dry tropical forests to spread northward. Since many insects are cold-blooded (their body temperature and physiological needs relate to the climate of their habitat), the warming climate opened new doors for a large number of tiny organisms to emerge.

Climate change opened new doors for a large number of tiny organisms to emerge, provided by Red Star News

These proofs are preserved in the fossils from this period. Scientists claim that more than 5,000 plant fossils from before, during, and after the PETM period show an increase in the quantity and diversity of insect damage. At the same time, a study on the Big Horn Basin in Wyoming, USA, shows that more than half of the leaves in fossils from this period were damaged by insects, 20% higher than before or after the PETM period.

And now, some insects, such as certain mosquitoes and ticks, have already adapted to new climate environments and are expanding into new living domains. A 2019 study estimated that by 2080, the number of people worldwide exposed to mosquito-transmitted diseases might increase by nearly one billion.

Rapid ”replacement” speed of species

On Earth, changes occur every minute and second, with some species heading toward extinction while others evolve. Paleontologists refer to the speed at which new species replace old ones as ”replacement.” Fossils from the Paleocene ocean relics indicate that near the surface, the ”replacement” process occurred at extremely rapid speeds during the PETM period.

Fossils from the Paleocene ocean relics indicate that near the surface, the ”replacement” process occurred at extremely rapid speeds during the PETM period, provided by Red Star News

In the shallow water areas near the coast, snails and clams died in succession, but were quickly replaced by similar mollusks, which played the same ecological roles—filtering sand, eating algae. The changes in other species were even more dramatic. For example, after undergoing a major extinction, it took the triggerfish and pufferfish nearly 20 million years to evolve enough new species to restore their lost diversity.

Near the equator, coral polyps similar to those surviving today disappeared and were replaced by disc-shaped organisms known as ”large foraminifera,” which filled their ecological niche and became reef constructors—until millions of years later when the ocean cooled again.

Precipitation caused global climate extremes

During the PETM period, the rise in temperatures caused changes in global rainfall patterns, providing necessary assistance for the spread of subtropical canopies and resulting in polar swamp forests.

The majority of Earth’s weather patterns: the circulation method of air and water in the ocean and sky is influenced by the temperature difference between the hot equator and cold poles, provided by Red Star News

Before Paleocene-Eocene, water evaporating near Earth’s center formed rain clouds, leading to precipitation in tropical and polar latitude regions. However, climate warming caused changes in air currents, making more equatorial moisture reach the distant polar regions before returning to Earth. This is one reason ancient Arctic regions were able to support the growth of hickory and cypress trees, which provided climbing places for lemurs and primates.

The study shows that by the end of this century, the soil in the southwestern United States will be 10% to 20% drier than now, while the risk of drought will increase by at least 20%, provided by Red Star News

But falling rain must have somewhere to go; in some parts of the world, increased wet weather means that moisture in arid regions will evaporate more. Now, similar impacts may have resulted from current climate change, as wetter winters have already increased the frequency of destructive floods in northwestern Europe. Meanwhile, the southwestern United States grows drier year by year. Studies show that by the end of this century, the soil in the southwestern United States will be 10% to 20% drier than now, while the risk of drought will increase by at least 20%.

Hundreds of global waters may revert to the PETM period

At the beginning of the PETM period, ocean temperatures were already high. For instance, before warming occurred, the equatorial temperature of the Ancient Atlantic was 36.6 degrees, about 8.8 degrees higher than the current Atlantic Ocean temperature. The unbearably hot seawater caused deep seas to lose cooling sources, reducing oxygen levels in the water. At the same time, global warming led to the co-absorption of a large quantity of carbon dioxide by the oceans, causing a sharp increase in ocean acidity, making it difficult for life to survive in such suffocating places.