Planet Earth Weekly

Climate Change and Renewable Energy: Saving Our Planet for Future Generations


Climate Change and Human Population Growth Precipitated the Pleistocene Mass Extinction

climate change and species extinction

Climate change and extinction of species

“Extinction is the rule. Survival is the exception!”

By John J. Hidore

May 19, 2018—-Changes in climate can and do result in the elimination of species of plants and animals. Evolutionary adaptation and ecological equilibrium may not take place as rapidly as the climate changes. Adaptation by plant and animal species to environmental change may take years, centuries or thousands of years.

Different species respond at different rates and in different forms to climate change. Plants are always producing hybrids and individuals with mutations. In any plant species, there are those individuals better suited to the extremes of the range of the plant. These individuals may thrive under changing conditions while the majority perish. In this manner, the optimum conditions for the species changes to those of the new environment. Animals may also come under more and more stress with changing environmental condition and some species become extinct.

Mass extinction and climate change

Mass extinction throughout time

The Paleozoic/Mesozoic Mass Extinction

At intervals through geologic time, events have taken place that resulted in the demise of many if not most living species. Extreme cases are called extinctions or mass extinctions. A current definition of a mass extinction is a widespread and unusually rapid decrease in the number of species of plants or animals. There have been at least 13 mass extinctions since life became abundant on the planet. As a result of these mass extinctions 99 percent of all species that have existed on the planet no longer exist.

The most extensive mass extinction of all time happened at the boundary between the Paleozoic and Mesozoic Eras. Ninety percent of all living species died out and very drastic changes took place in the fauna of the planet with a major collapse of marine fauna, especially those living in shallow water on the continental shelves.

Among the organisms that perished were the trilobites. Trilobites were one of the dominant organisms of the seas. They survived the previous two extinctions but couldn’t withstand the changes that mark this period in earth’s history. While many land species disappeared, there was no parallel to the mass extinction of marine animals. The changes were so drastic that the life of the following Mesozoic Era was quite different from that of the Paleozoic Era.

climate change and mass extinction

Survival or mass extinction

The Pleistocene Mass Extinction was a Global Event

In the recent history of the earth there have been two periods of accelerated extinction of biota during which the extinction rates were greater than evolutionary causes would predict. These two periods are the end of the Pleistocene Epoch and the modern period.

The Pleistocene extinction, took place over a period of a few thousand years, at the end of the last glacial advance (l8,000 to 8000 BCE). In a relatively short period of time, whether measured in either geologic time, evolutionary time or in terms of human history on earth, a large number of species of mammals and birds disappeared without being replaced. The period of greatest species loss was from 13,000 to 8000 BCE. During this time there was a rapid warming of the planet. Especially impacted species were the larger animals weighing more than 40 kg (88 lbs)The spacing of the extinctions over several thousand years makes it difficult to ascribe to climate events alone. Furthermore, most of the extinct animals were large enough to be conspicuous and edible.

The rate of extinction varied from place to place and through time. The rate of extinction was lowest in Sub-Saharan Africa where modern humans coexisted with the large animals the longest. The rate of extinction increased as distance from the African region increased. The highest rate of extinction occurred in South America.

mass extinction of species

Climate change and mass extinction

To some extent the rate of extinction paralleled the spread of modern humans. It was long believed that large mammals were too powerful for humans to hunt. Perhaps this was true for the individual hunter with spear or bow and arrow, but when hunters went out in groups, it is quite possible they could have been very successful hunters of large animals, even using only simple tools.

In Africa, pygmies hunted elephants with primitive tools. The Plains Indians of North America demonstrated they could successfully hunt large animals with primitive weapons. Herds of animals were driven off cliffs or into water by the use of fire and were either subsequently destroyed in the fall or drowned, or at least made far more vulnerable to attack. Modern humans became more sophisticated hunters as they spread from their place of origin in Africa. Places that were isolated from human migration for a longer period of time, such as some islands, suffered less species loss.

The Mass Extinction in North America

The largest North American mammals were hardest hit. Seventy percent of existing species became extinct. Horses and camels, which had evolved in the New World, became extinct on this continent, as did mammoths and mastodons, which had migrated into the New World over the once dry land of the Bering Strait. The ground sloth, saber toothed tiger, dire wolf, giant buffalo, antelope, and the giant beaver also disappeared, and yet there was no concomitant loss of small mammals, plants or aquatic organisms.

The spread of the human species and the state of the cultural development at the end of the Pleistocene suggests that humans were a major factor in this accelerated extinction. A surprising number of the fossilized bones of extinct animals and birds were discovered associated with charcoal and stone tools, such as arrowheads or spear points. Some of the sharpened tools were still embedded in the bones. Humans appeared in North America rather suddenly from Asia, occupied the continent, and began hunting animals that had never had a chance to adapt to this special type of predator.

The most recent extinction is that taking place today. How severe it will be is yet to be determined.

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Climate change and mass extinction


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Climate Change through Early Geologic Time

The Earth's Atmosphere: Increased Oxygen over time.

The Earth’s Atmosphere has changed over time.

“There is still much work to be done to stop global warming and its resulting effects–the possible mass extinction of many of Earth’s species!”!

By Dr. John J. Hidore

November 27, 2015—When the subject of climate change or global warming comes up people immediately think of what is happening around us now. The time in which we live is not typical of past conditions. Neither the climatic environment nor current living organisms are typical of those in the past.

The Earth’s Eras

The earth was formed approximately 4.6 billion years ago. Not much is known about the early history of the planet because little evidence remains of this time period, but geologists have divided the history of the Earth into four time periods called eras. They are the Precambrian, Paleozoic, Mesozoic and Cenozoic. Each of these eras were unique in many ways, including climate and the life forms that were dominate. Each boundary between eras created a point in time when there was a drastic change in the global environment.

Climate Change and Mass Extinction

Extinction of Species

The earliest, and longest, geological era is the Precambrian which spans 88% of Earth’s history, approximately four billion years. Most of us have difficulty in comprehending such a long period time! If we consider the age of the earth on a scale of a single year, the Precambrian Era covers the first 321 days. Using this scale this places the end of the Precambrian Era in mid-November. Evidence of what took place on the planet in the Precambrian is skimpy but today we know some of the most important events. During this long span of time Earth changed drastically. In the beginning it was a hot molten mass without atmosphere, ocean, or land. It was only after a long time that the mass cooled enough for the solid crust to form.

The Primitive Atmosphere

As the Earth cooled and a solid crust formed, gases such as water vapor, carbon dioxide, and nitrogen formed. It may have had a composition of 60-70% water vapor, 10-15% carbon dioxide, and 8-10% nitrogen. Temperatures near the surface were much higher then than now being in the range of 85-110oC (185-230o F).

By 3.8 billion years ago, continued cooling caused the water vapor to condense, clouds to form, and frequent, intense, and widespread rain to occur. The large amount of water vapor in the atmosphere must have caused rains that went on continuously for thousands of years. Eventually the ocean basins filled with water. Water began to cycle through the environment as it changed from liquid in the ocean to gas in the atmosphere and back to liquid precipitation again. By 3.5 billion years ago the distribution of water was pretty much the same as today. Sea levels were similar to that of recent times.

Climate Change and Mass Extinction

Mass extinction could happen again-do we care?

The Origin and Demise of Early Life Forms

The most important event of the Precambrian Era is the appearance of living organisms. Exactly when or where life first appeared on the planet is not known, but several aspects of the appearance of life are certain:
1. All the chemical elements essential to life were present before life appeared and were present in sea water. Early forms of life were bacteria that thrived in a carbon dioxide rich environment.
2. The next step in the process of evolution was the development of organisms capable of photosynthesis. Photosynthesis removes carbon dioxide from the atmosphere. The process takes carbon dioxide and water, and in the presence of sunlight, produces oxygen.
3. Between three and a half and four billion years ago crude forms of algae appeared. They were oxygen-producing bacteria that lived in an oxygen-poor environment. These oxygen producers began to change the atmosphere from carbon-rich to oxygen rich.
4. Most organisms that thrived in a carbon dioxide rich atmosphere perished. This resulted in the first great mass extinction, an event in which the majority of existing life forms disappeared

Unusual cooling result in ice ages

Throughout most of the history of the Earth, the planet has been much warmer than it is today. There have been times however, when the climate became much cooler than now.
At times the atmosphere got cold enough for massive amounts of ice to develop on the surface. Such periods are known as ice ages. The earliest ice age took place two billion years ago. A second ice age took place from 800 to 600 million years ago and was more widespread than the previous one. Ice collected first in the Arctic and Antarctic regions and then expanded outward. The glaciers repeatedly scoured the continents, creating what was possibly the most extensive glaciation period ever to occur on our planet.

The Precambrian Era

This glaciation period also correlates with the boundary between the Precambrian Era and the Paleozoic Era approximately 750 million years ago. The climate changes, which took place during the Precambrian Era, were massive and dwarfed the climate changes taking place today. The Precambrian Era also resulted in mass extinctions. However, environmental changes are now taking place so rapidly that some scientists predict these changes will lead to another mass extinction. Some studies indicate that more than half of all species that existed since humankind first appeared on the planet are already extinct. If this is the case than we are indeed may be responsible for another mass extinction.

There is still much work to be done to stop global warming and the resulting effects–possible mass extinction of many of Earth’s species!

There is still much work to be done to avoid climate change