From its most basic atoms and molecules to the ecosystems that make it up, is a living, changing Earth. Being perhaps the only planet that is life-sustaining in our entire galaxy, this makes ours and other organisms’ places within it extremely precarious. Preserving biodiversity, or the variety of organisms, is one goal of environmental policy. Once our Earth’s biodiversity can be understood, the venture of environmental studies will then be one step closer to being understood. The other natural capitals of chemical and energy cycling that maintain biodiversity, the human activity that affects them all, and more, will also be explored.
Starting at the most basic are the atoms and molecules that make up the matter of life and, depending on the composition of the matter, give way to basic compounds that then make up the organic carbon-based molecules that make up all life. When those organic molecules grow in complexity, this leads to the rise of DNA molecules which code the amino acids which make up the organelles of cells, which make up all living organisms on Earth. Of course this explanation is extremely simplified, but the basic idea is that all living organisms on Earth are made up of similar building blocks. All living creatures are also composed of cells, plant or animal, that are composed of organelles also coded by DNA and RNA in complex processes that make them out of the building blocks of proteins called amino acids. Biodiversity happens when these organisms adapt to different climates, geography, and more.
There are three main properties that sustain life. One is incoming solar radiation, or high-quality energy that goes through the environment and eventually is lost as heat, or low-quality energy. A second property that sustains life is the cycling of nutrients through parts of the biosphere, like nitrogen or phosphorus. Finally, gravity sustains life on Earth by holding on to the atmosphere and allowing for every one of the processes of life to happen. We will go more in depth to the first two later.
As a side note, the atmosphere is also vital in sustaining life although it is not technically a main property of life sustenance. It provides climates for organisms to live in through the greenhouse effect, as well as a life-allowing mix of gasses such as nitrogen and oxygen. One way humans impact the atmosphere is by adding greenhouse gasses through the burning of fossil fuels. Although the greenhouse effect is a natural phenomenon that stabilizes our climate, anthropogenic causes have been linked to the increase in concentration of the gases, which have steadily changed climates and cause biodiversity to decline. Greenhouse gas emission is a main problem that environmental policy must combat, but is not something that will be addressed here.
Before we talk about solar radiation, its important to understand energy. Energy, or the capacity to do work, can come in the form of potential, or stored energy, and kinetic, or moving energy in the natural environment.
Another division of energy that is commonly used to describe types of energy is low versus high-quality energy. High-quality energy has the capacity to do work because it is concentrated. Solar radiation, high-speed wind and the energy released when we burn gasoline or coal are examples of high-quality energy. In contrast, low-quality energy is dispersed so it has little capacity to do useful work. Low-temperature heat in the atmosphere or ocean is an example of low-quality energy. The cycling of energy through the environment relies on two laws of Thermodynamics. The first law states that energy cannot be created or destroyed and the second that energy goes from more useful, or higher-quality to less useful, or lower-quality energy. Much of this energy that organisms use primarily originates in the sun.
Returning to nutrient cycles, we will now see how they affect the environment and organisms that live in it. The hydrologic, or water cycle is pretty self-explanatory. Basically the water in large reservoirs such as oceans evaporates with the rays of the sun in the form of heat, condenses, and then precipitates to flow back into the reservoir. As the main supporter of life on Earth, water is vitally important.
The nitrogen cycle is a little more complicated but basically involves Nitrogen in the air being “fixed” by bacteria that exist in particular legumes and fungus into a usable form. The fixed nitrogen is then used by organisms to grow-being a great fertilizer of plants. When the organisms decompose the cycle begins again.
The sulfur cycle is a cycle that begins in ocean sediments and rock. With volcanic eruptions and tectonic plate movement, the sulfur enters the atmosphere and deposits on land. Sulfur in the form of salts is present in rainfall or soil and is then absorbed by plants. They then use them to create important proteins.
Finally, the phosphorus cycle is begun when the reserves of phosphorus in ocean sediments and rocks erode and are utilized by marine life. They are brought on land when birds consume fish and subsequently excrete guano in coastal regions. Human activity affects all of these cycles, as environmental science proves. When fertilizer is used and is taken out of the phosphorus and nitrogen cycle, fossil fuels are burned and speed up the hydrologic cycle. Sulfate is also created from combusted fossil fuels and creates acid deposition in the form of sulfuric acid, which harms life on land. Environmental policy is extremely concerned with rectifying the effects humans have on the cycles.
All life on Earth can be broken down into three categories: heterotrophs, autotrophs and chemotrophs. Basically heterotrophs consume other organisms, autotrophs create their own food from the sun’s rays and chemotrophs create food from inorganic molecules in nutrient cycles. There are various breakdowns of these categories within the study of Ecology, the science of how organisms interact with each other, but they are not relevant to our main focus of study-environmental science. What’s most important to remember is a continuance of one of the basic laws of energy conservation, energy is lost to the environment as excess heat in a food chain, for example, which with each succeeding level loses energy from the original source of the sun to autotrophs then heterotrophs.
Biodiversity is broken down into four major components: species, genetic, ecological and functional diversity which are all necessary to maintain it. One major contribution to biodiversity is evolution, which is the process by which a population changes over time by splitting to two or more new species that can no longer have viable offspring with the original population. Biomes, regions with distinct climates and species, such as chapparals, deserts, deciduous forests and tropical rainforests are so different from each other that they also contribute to the biodiversity of the planet. Because they are formed around different climates it is only natural that particular species will survive there and nowhere else.
Biodiversity can be stunted by nutrient overloads such as excess nitrogen from fertilizer runoff causing deoxygenation in bodies of water which kills off many species of marine life. Global warming is also a contributor to declining biodiversity, as many species exist within niches, or places in the food chain, that may be lost with a rapid change in climate. We will go into more of the causes of biodiversity in a later discussion. This is not, however, a comprehensive look into those problems but an overview of the overall topic.
One easy cause and effect scenario with declining biodiversity is the case study of the endangerment of sharks. A keystone species, or a species that if extinct would cause an ecosystem collapse, in many marine biomes; it is killed for its fins and other body parts. Massive overfishing of sharks causes many negative effects, as its absence causes an imbalanced food chain. What people also don’t realize is that animals such as sharks have amazing attributes that haven’t been fully researched-such as the fact that they are cancer-resistant. If sharks go extinct, we may lose this valuable source of possible cancer prevention research.
With the loss of any species we lose valuable assets that we may not even know about. We cannot take Earth’s flora and fauna for granted and instead should protect them with policies and institutions-a key part of environmental policy.