Abstract
International Environment month is going now. From the beginning of the world, whatever has been the most impactful part of our world is its biodiversity. From then till today, its impact is so huge that no one can even feel its depth and complexity. So to utilize a little of that and our sins, it’s important for us to go through a analysis.
Biodiversity or Biological diversity is a term that describes the variety of living beings on earth. In short, it is described as a degree of variation of life. Biological diversity encompasses microorganisms, plants, animals, and ecosystems, such as coral reefs, forests, rainforests, deserts, etc.
And after going through and analysis, I’ve found us as the most shameless livings on the earth and it let me feel sorry, very very sorry for some days. In this series, I’ll try to touch there in your heart so that you can also feel sorry, be aware. There will be 4 parts of the document and I’ve also tried to create a map of our duties and responsibilities and so I hope every readers will be with us in each part. Carefully, understanding.
What we have done?
The Role of Human Activity: In its Fifth Assessment Report, the Intergovernmental Panel on Climate Change, a group of 1,300 independent scientific experts from countries all over the world under the auspices of the United Nations, concluded there\’s a more than 95 percent probability that human activities over the past 50 years have warmed our planet.
The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels from 280 parts per million to 416 parts per million in the last 150 years. The panel also concluded there\’s a better than 95 percent probability that human-produced greenhouse gases such as carbon dioxide, methane and nitrous oxide have caused much of the observed increase in Earth\’s temperatures over the past 50 years.
It\’s reasonable to assume that changes in the Sun\’s energy output would cause the climate to change, since the Sun is the fundamental source of energy that drives our climate system.
Indeed, studies show that solar variability has played a role in past climate changes. For example, a decrease in solar activity coupled with an increase in volcanic activity is thought to have helped trigger the Little Ice Age between approximately 1650 and 1850, when Greenland cooled from 1410 to the 1720s and glaciers advanced in the Alps.
But several lines of evidence show that current global warming cannot be explained by changes in energy from the Sun:
Since 1750, the average amount of energy coming from the Sun either remained constant or increased slightly.
If the warming were caused by a more active Sun, then scientists would expect to see warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere, and a warming at the surface and in the lower parts of the atmosphere. That\’s because greenhouse gases are trapping heat in the lower atmosphere.
Climate models that include solar irradiance changes can’t reproduce the observed temperature trend over the past century or more without including a rise in greenhouse gases.
Causes for rising emissions
- Burning coal, oil and gas produces carbon dioxide and nitrous oxide.
- Cutting down forests (deforestation). Trees help to regulate the climate by absorbing CO2 from the atmosphere. When they are cut down, that beneficial effect is lost and the carbon stored in the trees is released into the atmosphere, adding to the greenhouse effect.
- Increasing livestock farming. Cows and sheep produce large amounts of methane when they digest their food.
- Fertilisers containing nitrogen produce nitrous oxide emissions.
- Fluorinated gases are emitted from equipment and products that use these gases. Such emissions have a very strong warming effect, up to 23 000 times greater than CO2.
2011-2020 was the warmest decade recorded, with global average temperature reaching 1.1°C above pre-industrial levels in 2019. Human-induced global warming is presently increasing at a rate of 0.2°C per decade.
An increase of 2°C compared to the temperature in pre-industrial times is associated with serious negative impacts on to the natural environment and human health and wellbeing, including a much higher risk that dangerous and possibly catastrophic changes in the global environment will occur.
For this reason, the international community has recognised the need to keep warming well below 2°C and pursue efforts to limit it to 1.5°C.
Threats to biodiversity: TEMPERATURE SPIKES:
A number of species will be affected physiologically by climate change. There is evidence that some species are physiologically vulnerable to temperature spikes. For example, the green ringtail possum, an endemic species of Queensland’s tropical rainforests, cannot control its body temperature when the ambient temperature rises above 30°C. An extended heatwave in north Queensland could kill off a large part of its population.
CORAL BLEACHING
Warmer sea surface temperatures are blamed for an increase in a phenomenon called coral bleaching. This is a whitening of coral caused when the coral expels their zooxanthellae, a symbiotic photosynthesising algae that lives within the coral tissues and provides it with essential nutrients. The zooxanthellae also give corals their spectacular range of colours.
Zooxanthellae are expelled when the coral is under stress from environmental factors such as abnormally high water temperatures and/or pollution. Since the zooxanthellae help coral in nutrient production, their loss can affect coral growth and make coral more vulnerable to disease. Major bleaching
events took place on the Great Barrier Reef in 1998, 2002 and 2006, causing a significant die-off of corals in some locations. Ocean acidification poses yet another challenge for corals because it makes it harder for corals to build their skeletons.
Bleached coral, caused by environmental stress. Image source: Paul / Flickr. INCREASES IN EXTREME EVENTS
Predicted changes in the intensity, frequency and extent of disturbances such as fire, cyclone, drought and flood will place existing vegetation under stress and favour species able to rapidly colonise denuded areas. In many cases this will mean the spread of alien ‘weed’ species and major changes in the distribution and abundance of many indigenous species. Heatwaves may affect the biodiversity of marine ecosystems, as seen in the summer of 2010–11 in south western West Australia. Extended periods of warmer sea temperatures resulted in the shut-down of the abalone industry, and the migration of whale sharks and manta rays further south and east than usual.
CHANGES IN RAINFALL
Australia is a dry continent. Its plants and animals are mostly well adapted to drought and have developed a wide range of strategies for coping with the country’s climatic extremes. The marginal nature of the environment,
however, means that even minor changes in rainfall patterns could have major impacts on wildlife. The Murray-Darling Basin (Australia’s largest water catchment) and southwest Western Australia are already threatened by salinity and other environmental problems. Predicted decreased rainfall and consequent lower river flows in both regions would have a major impact on aquatic biota. Freshwater wetlands such as the Macquarie Marshes in the central west of New South Wales—and the frogs, waterbirds, turtles and other aquatic life dependent on them—are also at risk because of a change in water quality and quantity.
Changes in rainfall patterns can damage land, plants and animals. Image source: Willem van Aken / CSIRO Science Image.
INCREASED CO2 AND PLANT GROWTH
The basic ingredients for photosynthesis include carbon dioxide and water. Increased carbon dioxide in the atmosphere causes increased growth rates in many plant species. This is good news for farmers, but only if this carbon dioxide ‘fertilisation’ effect is matched by adequate soil moisture and other nutrients. Leaf-eating animals like koalas may not be so lucky: increased concentrations of carbon dioxide could diminish the nutritional value of foliage.
A lot of CO2 that has been emitted into the atmosphere has been absorbed by the oceans. This has resulted in a decrease in the ocean’s pH, which in turn affects the rate at which many marine organisms build skeletons, meaning that reefs damaged by bleaching or other agents would recover more slowly.
SEA-LEVEL RISE
According to the most recent IPCC report, sea level is predicted to rise by 26– 98 centimetres by 2100, due to the thermal expansion of the oceans and the melting of polar ice-caps and ice sheets. Coupled with the effects of storm surges, which are expected to be of a greater magnitude in a warmer world, this increase in sea level could threaten many coastal ecosystems. Also at risk are mangrove forests and low-lying freshwater wetlands in Kakadu National Park.
mangroves and wetlands in Kakadu National Park are some of the areas under threat from rising sea level. Image source: Paul Morrison / Flickr.
What would rapid species extinction mean for Australia?
Climate change is predicted to take place faster in the next century than at any time for at least the last 10,000 years. Coupled with other factors, such as continued land-clearing, this could mean the extinction of species at a rate even greater than when the dinosaurs disappeared around 65 million years ago. Some species not under immediate threat of extinction might nonetheless suffer decreases in population size, diminishing intra-species’ genetic diversity (and therefore face increased vulnerability).
Does it really matter if many species go extinct? The world would certainly be a less interesting place with less biodiversity, but would it affect us?
A diversity of species increases the ability of ecosystems to do things like hold soils together, maintain soil fertility, deliver clean water to streams and rivers, cycle nutrients, pollinate plants (including crops), and buffer against pests and diseases—these are sometimes called ‘ecosystem functions’ or ‘ecosystem services’. A loss of species could reduce this ability, particularly if environmental conditions are changing rapidly at the same time. It is possible that as the climate changes and as species are eliminated from an area we will see a change in some ecosystem functions; this could mean more land degradation, changes in agricultural productivity and a reduction in the quality of water delivered to human populations.
Overharvesting: Overexploitation—which is the harvesting of game animals, fish, or other organisms beyond the capacity for surviving populations to replace their losses—results in some species being depleted to very low numbers and others being driven to extinction.
Overexploitation from hunting and harvesting also has adversely affected many species. For example, according to research from Fishlab.com, about 20 million tropical fish and 12 million corals are harvested annually for the aquarium trade, depleting natural populations in some parts of the world.
Overharvesting refers to harvesting a renewable resource to the point of diminishing returns. Ecologists use the term to describe populations that are harvested at a rate that is unsustainable, given their natural rates of mortality and capacities for reproduction. The term applies to natural resources such as wild medicinal plants, grazing pastures, game animals, fish stocks, forests, and water aquifers. Sustained overharvesting can lead to the destruction of the resource, and is one of the five main activities – along with pollution, introduced species, habitat fragmentation, and habitat destruction – that threaten global biodiversity today.
All living organisms require resources to survive. Overharvesting these resources for extended periods of time can deplete natural resources to the point where they are unable to recover within a short time frame. Humans have always harvested food and other resources they have needed to survive; however, human populations, historically, were small and methods of collection limited to small quantities. Exponential increase in human population, expanding markets, and increasing demand, combined with improved access and techniques for capture, are causing the exploitation of many species beyond sustainable levels.
Effects of overharvesting
As mentioned above, sustained overharvesting is one of the primary threats to biodiversity. Overharvesting can lead to resource destruction, including extinction at the population level and even extinction of whole species.
Depleting the numbers or amount of certain resources can also change their quality; for example, the overharvesting of footstool palm (a wild palm tree found in Southeast Asia, the leaves of which are used for thatching and food wrapping) has resulted in its leaf size becoming smaller.
Overharvesting not only threatens the resource being harvested, but can directly impact humans as well – for example by decreasing the biodiversity necessary for medicinal resources. A significant proportion of drugs and medicines are natural products which are derived, directly or indirectly, from biological sources. However, unregulated and inappropriate harvesting could potentially lead to overexploitation, ecosystem degradation, and loss of biodiversity; further, it can negatively impact the rights of the communities and states from which the resources are taken.
Invasive species:
In biology, an exotic species refers to a plant species or an animal species that is non-native. It is introduced into an area where it does not occur naturally.
An invasive species is defined as a non-native species that causes disruption in the local ecosystem. Therefore, it is a type of exotic species but it particularly became a nuisance because it “invaded” and outcompeted the native species in the local ecosystem. In other words, the species has become a “pest” to its new location. For instance, an animal is introduced as a biocontrol that will kill the pests on a particular ecosystem. After some time, the biocontrol exotic species did not just kill the pest but also outnumbered other species not regarded as pests as their population grew exponentially.
The term exotic species has a wider scope and the invasive species is one of its subsets; some of the other subsets are “naturalized species” (i.e. exotic species that have become established and are able to sustain their population even without human help) and “acclimatized species” (i.e. exotic species that have physically and behaviorally adjusted to the new environment).
Invasive species cause harm to wildlife in many ways. When a new and aggressive species is introduced into an ecosystem, it may not have any natural predators or controls. It can breed and spread quickly, taking over an area. Native wildlife may not have evolved defenses against the invader, or they may not be able to compete with a species that has no predators.
The direct threats of invasive species include preying on native species, outcompeting native species for food or other resources, causing or carrying disease, and preventing native species from reproducing or killing a native species\’ young.
There are indirect threats of invasive species as well. Invasive species can change the food web in an ecosystem by destroying or replacing native food sources. The invasive species may provide little to no food value for wildlife. Invasive species can also alter the abundance or diversity of species that are important habitat for native wildlife. Aggressive plant species like kudzu can quickly replace a diverse ecosystem with a monoculture of just kudzu.
Additionally, some invasive species are capable of changing the conditions in an ecosystem, such as changing soil chemistry or the intensity of wildfires.
CAUSES OF INVASIVE SPECIES
There are two key causes of invasive species introduction that are intentional and unintentional anthropogenic activities.
- Intentional Causes of Invasive Species Introduction: Intentional causes are listed below with a brief description.
- Controlling Pests: Exotic species are introduced in an area to control pests that are ruining the standing crops.
- Import Pets: Some people import various kinds of animals and keep them as pets. These imported animals are nonnative and often considered alien species.
- Trading Alien Species: This point represents the economic situation. People are intentionally involved in the international trade of animals, plant species for economic benefits.
- Unintentional Causes of Invasive Species Introduction: Unintentional causes also include human activities.
- Natural Migration: This is also included among many other reasons. Invasive species migrate to new environments where they don’t have competitors/predators.
- International Trade of Goods: Trading goods inside or outside has also resulted in invasive species introduction.
- Transportation Vehicles: Transportation vehicles carry invasive species such as ships. They carry aquatic invasive species to new environments.
Over-exploitation of natural resources: Overexploitation is one of the main threats to global biodiversity.[2] Other threats include pollution, introduced and invasive species, habitat
fragmentation, habitat destruction,[2] uncontrolled hybridization,[34] climate change,[35] ocean acidification[36] and the driver behind many of these, human overpopulation.[37]
One of the key health issues associated with biodiversity is drug discovery and the availability of medicinal resources.[38] A significant proportion of drugs are natural products derived, directly or indirectly, from biological sources.
Marine ecosystems are of particular interest in this regard.[39] However, unregulated and inappropriate bioprospecting could potentially lead to overexploitation, ecosystem degradation and loss of biodiversity.[40][41][42]
Endangered species
It is not just humans that overexploit resources. Overgrazing can be caused by native fauna, as shown in the upper right. However, past human overexploitation (leading to elimination of some predators) may be behind the situation.
Overexploitation threatens one-third of endangered vertebrates, as well as other groups. Excluding edible fish, the illegal trade in wildlife is valued at $10 billion per year. Industries responsible for this include the trade in bushmeat, the trade in Chinese medicine, and the fur trade.[43] The Convention for International Trade in Endangered Species of Wild Fauna and Flora,
or CITES was set up in order to control and regulate the trade in endangered animals. It currently protects, to a varying degree, some 33,000 species of animals and plants. It is estimated that a quarter of the endangered vertebrates in the United States of America and half of the endangered mammals is attributed to overexploitation.[2][44]
All living organisms require resources to survive. Overexploitation of these resources for protracted periods can deplete natural stocks to the point where they are unable to recover within a short time frame. Humans have always harvested food and other resources they have needed to survive. Human populations, historically, were small, and methods of collection limited to small quantities. With an exponential increase in human population, expanding markets and increasing demand, combined with improved access and techniques for capture, are causing the exploitation of many species beyond sustainable levels.[45] In practical terms, if continued, it reduces valuable resources to such low levels that their exploitation is no longer sustainable and can lead to the extinction of a species, in addition to having dramatic, unforeseen effects, on the ecosystem.[46] Overexploitation often occurs rapidly as markets open, utilising previously untapped resources, or locally used species.
The Carolina parakeet was hunted to extinction.
Today, overexploitation and misuse of natural resources is an ever-present threat for species richness. This is more prevalent when looking at island ecology and the species that inhabit them, as islands can be viewed as the world in miniature. Island endemic populations are more prone to extinction from overexploitation, as they often exist at low densities with reduced reproductive rates.[47] A good example of this are island snails, such as the Hawaiian Achatinella and the French Polynesian Partula. Achatinelline snails have 15 species listed as extinct and 24 critically endangered[48] while 60 species of partulidae are considered extinct with 14 listed as critically endangered.[49] The WCMC have attributed over-collecting and very low lifetime fecundity for the extreme vulnerability exhibited among these species.[50]
As another example, when the humble hedgehog was introduced to the Scottish island of Uist, the population greatly expanded and took to consuming and overexploiting shorebird eggs, with drastic consequences for their breeding success. Twelve species of avifauna are affected, with some species numbers being reduced by 39%.[51]
Where there is substantial human migration, civil unrest, or war, controls may no longer exist. With civil unrest, for example in the Congo and Rwanda, firearms have become common and the breakdown of food distribution networks in such countries leaves the resources of the natural environment vulnerable.[52] Animals are even killed as target practice, or simply to spite the government. Populations of large primates, such as gorillas and chimpanzees, ungulates and other mammals, may be reduced by 80% or more by hunting, and certain species may be eliminated altogether.[53] This decline has been called the bushmeat crisis.
Overall, 50 bird species that have become extinct since 1500 (approximately 40% of the total) have been subject to overexploitation,[54] including:
-
- Great Auk – the penguin-like bird of the north, was hunted for its feathers, meat, fat and oil.
- Carolina parakeet – The only parrot species native to the eastern United States, was hunted for crop protection and its feathers.
Other species affected by overexploitation include:
-
- The international trade in fur: chinchilla, vicuña, giant otter and numerous cat species
- Insect collectors: butterflies
- Horticulturists: New Zealand mistletoe (Trilepidia adamsii), orchids, cacti and many other plant species
- Shell collectors: Marine molluscs
- Aquarium hobbyists: tropical fish
- Chinese medicine: bears, tigers, rhinos, seahorses, Asian black bear and saiga antelope[55]
- Novelty pets: snakes, parrots, primates and big cats
Cascade effects
Overexploiting sea otters resulted in cascade effects which destroyed kelp forest ecosystems.
Overexploitation of species can result in knock-on or cascade effects. This can particularly apply if, through overexploitation, a habitat loses its apex predator. Because of the loss of the top predator, a dramatic increase in
their prey species can occur. In turn, the unchecked prey can then overexploit their own food resources until population numbers dwindle, possibly to the point of extinction.
A classic example of cascade effects occurred with sea otters. Starting before the 17th century and not phased out until 1911, sea otters were hunted aggressively for their exceptionally warm and valuable pelts, which could fetch
up to $2500 US. This caused cascade effects through the kelp forest ecosystems along the Pacific Coast of North America.[56]
One of the sea otters’ primary food sources is the sea urchin. When hunters caused sea otter populations to decline, an ecological release of sea urchin populations occurred. The sea urchins then overexploited their main food source, kelp, creating urchin barrens, areas of seabed denuded of kelp, but carpeted with urchins. No longer having food to eat, the sea urchin
became locally extinct as well. Also, since kelp forest ecosystems are homes to many other species, the loss of the kelp caused other cascade effects of secondary extinctions.[57]
In 1911, when only one small group of 32 sea otters survived in a remote cove, an international treaty was signed to prevent further exploitation of the sea otters. Under heavy protection, the otters multiplied and repopulated the depleted areas, which slowly recovered. More recently, with declining numbers of fish stocks, again due to overexploitation, killer whales have experienced a food shortage and have been observed feeding on sea otters, again reducing their numbers.
Pollution: All forms of pollution pose a serious threat to biodiversity, but in particular nutrient loading, primarily of nitrogen and phosphorus, which is a major and increasing cause of biodiversity loss and ecosystem dysfunction. Atmospheric nitrogen deposition represents a major threat to European biodiversity and a serious challenge for the conservation of natural habitats and species. In addition, nitrogen compounds can lead to eutrophication of ecosystems. The main pollution sources are from transport and agriculture. It is the only air pollutant for which concentrations have not decreased in Europe following the implementation of legislation.
For many European ecosystem types, studies have concluded that nitrogen deposition results in loss of species richness. Peatland ecosystems provide an example of how species replacement, resulting from nitrogen deposition, may alter ecosystems functionality. For example, the carbon sequestration capacity of rain fed (ombrotrophic) bog ecosystems decreases when subjected to elevated nitrogen inputs.
Figure 1 Exceedance of critical loads for eutrophication due to the deposition of nutrient nitrogen in 2010
The critical load of nutrient nitrogen is exceeded by more than 1 200 equivalents nitrogen per ha and year in western France, some parts of Belgium and the Netherlands, and the North of Italy.
Pollution continues to be a major problem affecting most of the European seas, in spite of the reduction in point sources (e.g. sewage outfall pipes or fish farm effluents) of nutrients in some areas. Nitrogen and phosphorus enrichment can result in a chain of undesirable effects, starting with excessive growth of planktonic algae, which increases the amount of organic matter settling to the seabed. This accumulation may be associated with changes in species composition and altered functioning of the food web.
Wildlife and plant life have evolved over millions of years, but they are struggling to adapt to life on a polluted planet. The impact of humans is increasing all the time in line with a population set to reach over 10 billion by the end of this century. The fact is, the majority of pollution will affect wildlife in a negative way, whether directly (e.g breathing in toxic chemicals from the air) or indirectly
(e.g habitat loss due to climate change caused by an increase in certain air pollutants). Types of pollution that might affect wildlife include, air pollution, water pollution, plastic pollution, soil pollution, light pollution, and noise pollution.
Air pollution
Air pollution is any substance suspended in the air that can have adverse effects on the health of humans and the wider ecosystem. This could be solid particles such as dust or soot from a coal-fired power station, or it could be gases that are invisible to the naked eye such as ammonia or carbon dioxide.
These pollutants can affect biodiversity in a direct way, i.e by impacting health due to inhalation or they can affect biodiversity indirectly by altering the wider environmental conditions.
(To be continued…)