Imagine a rich, beautiful, complex tapestry with a myriad of colors and textures. Each little thread combined together makes the tapestry the amazing artwork that it is. The earth is very much like that, filled with an assortment of elements - large and small - alive or inanimate. Biological diversity or biodiversity refers to the totality of all living beings on the planet and the interactions of these living beings, from the biggest animal to the tiniest phytoplankton and bacteria, to their habitats and ecosystems. Rich as it may seem, humans do yet know the full extent of biodiversity in the planet. It is estimated that around 86% of all life forms on earth are yet undiscovered. And at the rate of change the planet is going through, we might no longer discover many species before they become extinct.
Biodiversity balances life on the planet. The silent symbiosis among species speaks multitudes of the importance of each animal, plant, and bacteria. Apex predators like tigers ensure that smaller species do not over-populate the land, while microscopic phytoplankton keep fishes and whales alive. Four essential elements make up biodiversity, one as important as the other, completing and complementing each other, like pieces of a complex puzzle. Genetic diversity refers to the generic variability within species such as the variety of apples and different kinds of beetles. On the other hand, ecosystem diversity points to the number of ecosystems in a given area, including the diversity of biotic and abiotic properties and their interactions. Molecular diversity is the variations of molecules found in all life on earth, without which life itself would not exist. Species diversity indicates the number of each species, as well as their richness (number of species) and abundance (number of individuals of each species) in a particular location. Although we will touch on the loss of all four elements of biodiversity, our main focus will be species diversity and loss.
Biodiversity loss simply refers to loss of a species, but in its hyper mode means large-scale destruction of life and ecosystems in the planet. Massive loss of biodiversity already occurred a number of times in the earth’s history. In fact, scientists say that more than 99 percent of all living beings that ever lived in the planet are already extinct. However, five distinct extinction epochs have been identified by paleontologists.
Around 444 million years ago, during the Ordovician Period, diversity of species grew, but the rise of the Appalachian Mountains and its covering greens sucked carbon dioxide from the atmosphere causing the planet to cool and kill around 85 percent of all life forms.
Some 375 million years ago in the late Devonian period, a great volcanic eruption that formed what is now Siberia could have caused a massive extinction. Emergence of new plants might have also contributed to the massive loss of life in the oceans. These plants were robust and grew deeper roots which caused nutrients to spill out into the ocean triggering algal bloom and die off. This eventually suffocated marine life, especially bottom dwellers. An asteroid impact that created the Siljan crater might have also contributed to the annihilation of 75 percent of all species in that period.
In the Permian period, life was thriving on earth. But in the blink of an eye, actually a few million years in geologic time, everything changed. The late Permian period 250 million years ago killed almost all life on earth. Also called ‘The Great Dying”, more than 95 percent of all species perished in the global warming caused by the eruption of the Siberian Traps, a massive volcanic complex. The catastrophic eruption discharged 14.5 trillion tons of carbon-trapping greenhouse gases in the atmosphere creating a domino effect that resulted to hellish climate on earth. Sea surface temperature went as high as 104 degrees Fahrenheit. No marine life survived waters near the equator at that time.
The earth took millions of years to recover from the End Permian extinction. But when it did, life diversified rapidly. At the end of the Triassic period around 200 million years ago, another massive extinction occurred. Scientists are still baffled about the cause of this extinction period. Asteroid impacts might be one of the causes of the extermination of about 80 percent of all species at that time. Another theory is the series of volcanic eruptions in the Central Atlantic Magmatic Province before the supercontinent Pangea started to split. The ancient lava flows of that period can now be found across eastern North America, eastern South America, and West Africa. This gradual yet colossal change left room for dinosaurs to thrive.
The last great extinction occurred some 66 million years ago called the End Cretaceous period. This was caused by an asteroid impact that created the Chicxulub crater at the Yucatán Peninsula. The impact caused the destruction of many terrestrial organisms and rapid acidification of oceans killing three quarters of all life on earth. However, the extinction also resulted in adaptive radiation, a process wherein organisms diversify into a multitude of new forms due to alterations in the environment, resources, and biotic interactions. Mammals evolved new forms, as well as all birds, fish, and lizards.
Scientists now propose that the Anthropocene, the Age of Man, for some starting at the Industrial Revolution, starting at the Atomic Age for others, is unfolding as the sixth great mass extinction. It claims that human activities are causing this massive loss of biodiversity. Experts assert that never in the history of the planet has a single species caused the demise of so many other life forms. There is a danger of losing more than 50 percent of all life on earth by 2050 should humans fail to address the climate crisis and massive destruction of habitats and ecosystems, and if there is no radical change to protect them in the present.
In this sixth great extinction period, the rich and colorful tapestry of biological diversity starts to fade before our very eyes. Each element of the tapestry of life is important and if these are removed piece by piece, the tapestry would eventually unravel, making life on earth hang on a thread.
2020 marks the end of the UN Decade for Biodiversity, instituted to maintain biodiversity at all levels. However, the Decade did not meet its targets and instead saw continued loss of biodiversity. It is succeeded by the Post-2020 Biodiversity Framework and the UN Decade on Ecosystem Restoration to help meet the unmet targets, towards the 2050 Vision of Living in Harmony with Nature. The vision states that biodiversity is valued, conserved, restored and wisely used, maintaining ecosystem services, sustaining a healthy planet and delivering benefits essential for all people. The vision itself seems problematic with its unsurprisingly anthropocentric take.
Can this vision be achieved, or will the speed of biodiversity loss continue to accelerate? How would the earth look like a generation from now? How would this great change impact various aspects of human life? How will it interact with the many other changes and challenges happening in the planet? Will technology be the panacea? Will humans survive this great mass extinction or will we also be annihilated? These questions and more will be explored further.
© Shiela R Castillo 2021