Human's mindless plunder can accelerate 'sixth extinction'
Most of us know that the Earth shows a great diversity of living organisms — from the microscopic to the gigantic, found in a range of habitats — from the hot deserts of the Sahara to the cold mountain tops of the Tibetan plateau. What do we know of this biodiversity? What threatens it?
The raging COVID-19 pandemic has claimed many lives and there is no sign of it abating, at least in certain parts of the world. Man’s quest for creature comforts and a cruel disregard for the complex and interconnected ecosystems have given birth to multiple challenges. Notably, the potent pandemics of the recent past are zoonotic [diseases transmitted from animals to humans]. This is testimony to man’s wanton incursions into pristine habitats.
In this two-part series, The Federal examines equitable and ethical ways to proceed in the coming years so that the impact on the environment and our own habitat is minimal. For, our actions will determine our place in the fragile world.
Most of us know that the Earth holds a great diversity of living organisms — from the microscopic to the gigantic, found in a range of habitats — from the hot deserts of the Sahara to the cold mountain tops of the Tibetan plateau. What do we know of this biodiversity? What threatens it?
The Earth is approximately 4.5 billion years old and it has supported life for the past 3.5 billion years. From microscopic single-celled cells, life has evolved over this time, responding to changing environmental factors, adapting into complex multicellular life forms. The Earth is not a static system, nor is the life it supports. The natural living world we see around us today is the result of millions of years of evolution that is still ongoing, changing as we speak, hurtling into an unknown future.
Life on Earth is spectacular, complex, entangled, and enduring. Yes, Earth is very biodiverse. But exactly how many species are there?
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It is not easy to count all the species on Earth. As of today, over 1.3 million species have been scientifically documented, including nearly 6,500 mammals; 10,000 birds; 3,00,000 plants, and one million species of insects!
Very few microorganisms have been documented thus far (bacteria, viruses among others) as these are difficult to isolate and grow. Despite this seemingly large number of species, scientists are of the opinion that nearly 80% of the earth’s biodiversity (specifically smaller organisms) still remain undescribed to science. But can we reliably say how many more species are on Earth?
Biodiversity is more than just numbers
Scientists estimate the number of species based on the number of species currently known. A 2011 estimate pegged the number of eukaryotic species on earth at 8.7 million. [Eukaryote is an organism of a cell or cells wherein the genetic material is DNA in the form of chromosomes contained within a distinct nucleus. Eukaryotes include all living organisms other than the eubacteria and archaebacteria.]
This estimate leaves out prokaryotic organisms such as bacteria, and viruses, about which we have so little information. If you include these groups, the diversity is likely to be even higher. It is no surprise that we continue to ‘discover’ and describe new species to science even to this day including insects, amphibians, oceanic and freshwater fish, fungi, microorganisms among many others.
Biodiversity is a household term, and most of us understand it as the number of species on earth or in any region. But it is more than just a number. It refers to all the various life forms on earth (including taxonomic and genetic variation), and the interactions that they show. It is these ecological interactions that make biodiversity more than just the number of species in a region.
Ecological interactions between species are fundamental properties of all ecosystems and influence the functioning of ecosystems. These interactions can occur between individuals of the same species, or between individuals of different species. One example of ecological interaction that we all may be familiar with is that of pollination, where insects and flowering plants show intricate and complex interdependence. Predation is another example of an ecological interaction, where one species consumes another. A species may be part of many ecological interactions with different species, some positive, some antagonistic (or negative). There are different types of ecological interactions, each of which build the complex web that is an ecosystem, entangling species into relationships that are persistent, and at the same time changing, as each species responds to the external world individually.
‘No man’s an island,’ said John Donne. I think it is fair to say that no species is an island.
We are in the midst of an ecological or a biodiversity crisis. For the last few decades, we have been witnessing a loss of biodiversity, largely due to human impact. Called the sixth extinction event, we are losing thousands of species every year according to some estimates. Habitat loss and fragmentation, diversion of land for development, and hunting and poaching are some of the causes of biodiversity loss. Some of the largest threats to biodiversity come from deforestation for infrastructure projects such as hydroelectric schemes, mining and other resource extraction work, and timber extraction. Much of this is driven by consumption and demand from rapidly growing economies far away from the forests?
What does the future hold?
It is not just species that we are losing, we are losing whole networks of interconnected systems, within which we are embedded. And these have consequences.
Human societies are embedded within ecological systems, even if it does not appear to us like that. We depend on natural processes for everything — our food, air, water. Called ecosystem services, the natural world provides for us, regulates the climate, and supports life on earth. When we lose biodiversity, and hence ecological interactions, we are at risk of disrupting these ecosystem services. This is not hypothetical; we are already seeing the impacts of environmental degradation and biodiversity loss on almost all aspects of human civilization — agriculture, fishing industry, our oceans turning into dead zones, our climate, and our health and lives, to name a few.
This ecological or biodiversity crisis is not the same as the climate crisis, nor is it independent of it. Destruction of ecosystems and loss of biodiversity impact climate. The changing climate, in turn, impacts biodiversity and ecosystem health. When crises become entwined, the change is far more intense and unpredictable.
Take the tropical forests of Asia. Deforestation in large parts of Asia, including India, has a profound impact on biodiversity, climate, and our own well-being. One of the main drivers of deforestation in many parts of tropical Asia, especially island southeast Asia, is palm oil plantations. Palm oil has come to dominate our lives, invading our food, our cosmetics, and the orangutan’s home. India is one of the leading consumers of palm oil; from the processed food (biscuits, chips, chocolates) we eat to the shampoo we use, most of these have palm oil. To reduce dependence on other countries for palm oil, the Indian government is promoting widespread cultivation of oil palm. This can have a significant impact on the extent of forests, on biodiversity, and on the water table. Destroyed rainforests do not fade gently into the night, they have consequences that impact the whole world. The earth’s climate system is complex and the rainforests are important cogs in the climate wheel. Its disappearance has consequences on our climate and it is being witnessed across the globe, including in India.
There is hope. There is an increasing awareness among people of these connections and impacts. They are engaging with issues, changing lifestyles, and questioning governments. In the past few years, local communities and organisations have been at the forefront of protecting our valuable natural resources. Apart from making changes as individuals, we should continue to demand better policies from our governments. We should continue to ensure that our governments do everything to protect biodiversity, and the rights of forest-dwelling peoples.
(This is the first article of the two-part series, ‘Celebrating Biodiversity.’)
(Krishna Priya Tamma is an ecologist whose interest spans tropical forest diversity, dynamics, and bio-geography. She teaches at Azim Premji University and her current areas of research include forest recovery in northeast India and the influence of human activity on the recovery and bio-geography of birds).