Greenhouse Effect and Global Warming/Global Climate ChangeThe greenhouse effect may be the primary cause of global warming. This effect, so named because the Earth's atmosphere retains heat similarly to how a greenhouse does, occurs due to energy being trapped as part of a natural cycle.
According to Global Issues, when the sun heats the Earth, the Earth radiates some of the sun's energy into space. However, some energy is trapped by atmospheric gases such as carbon dioxide and water vapor. As this energy builds up in the Earth's atmosphere, the Earth gradually becomes hotter.
Man-Made Contributions to the Greenhouse Effect?The greenhouse effect is not necessarily problematic. Without any energy trapping, the Earth might be too cold to support human or animal life. However, human activity can accelerate the greenhouse effect, causing the planet to become too hot to remain inhabitable.
Natural Cycle? Is global warming a natural cycle? Or is global warming affected by human influence? What does the science say? Both are true. In the natural cycle, the world can warm, and cool, without any human interference. For the past million years this has occurred over and over again at 100,000 year intervals. About 80-90,000 years of ice age with about 10-20,000 years of warm period.
The difference is that in the natural cycle CO2 lags behind the warming because it is mainly due to the Milankovitch cycles. Now CO2 is leading the warming. Current warming is clearly not natural cycle. The earths natural cycles, if human
industrial output had not been involved, would have us near or slightly below thermal equilibrium, possibly slightly cooling.
Differences Between Natural Climate Change and Human-Induced Climate ChangeThe Earth's climate has always changed over time, and the greenhouse effect has always been with us. However, in the past such changes have been entirely natural. Human activity, especially the burning of fossil fuels such as oil or gasoline, may accelerate this global warming.
Carbon DioxideThe primary source of carbon dioxide is combustion of fossil fuels, and it is the largest contributor to greenhouse gases. Approximately one-third of the carbon dioxide in the atmosphere was placed there by combustion engines. Trees remove carbon dioxide from the air, and widespread deforestation removes trees (usually by burning, which increases carbon dioxide even more); as such, it is a contributor to global warming.
MethaneMethane traps heat more than 20 times as efficiently as carbon dioxide and is considered an important greenhouse gas. Primary sources of methane include flooded rice paddies, melting permafrost, coal mining, natural gas and bovine flatulence.
Ozone
Ozone can occur at two levels in the Earth's atmosphere--in the troposphere (low in the atmosphere) and in the stratosphere (higher up). Ozone in the troposphere is created when oxygen is struck by ultraviolet radiation, which turns the regular oxygen molecule into an ozone molecule and occurs with the combustion of engines. Tropospheric ozone is considered to be the third most powerful greenhouse gas, following only carbon dioxide and methane.
Other PollutantsNitrous oxide is also a greenhouse gas that is generated during the use of fertilizers and the combustion of fossil fuels. CFC
(chlorofluorocarbons) can also be considered greenhouse gases but are not as great a threat as some of the others mentioned. The problems that CFCs cause are twofold. They break down the ozone layer, which allows more radiant heat to enter the earth's atmosphere, and they are extremely efficient at holding this heat in.
Ozone Depletion What is ozone depletion?
Ozone depletion, on the other hand, is the disappearance of ozone. The ozone layer is a dynamic protective layer above the earth; it's a layer approximately nine to 30 miles above the earth in the stratosphere (upper atmosphere). It constantly builds and destroys itself. When the rate of destruction surpasses the rate of construction, the ozone depletes. The ozone layers filter ultra-violet rays (UV rays). UV rays can be harmful to all life on earth in strong doses, including plant, animals and humans. The disappearing ozone may affect the rate of cataracts and skin cancer in humans.
Global Warming's Effects on Ozone Depletion
Global warming isn't the direct cause of ozone depletion, but they share many similarities. The man-made CFCs like Freon are mostly responsible for the depletion of the ozone layer. The gases may also act as a greenhouse gas that traps the heat on earth, but to a lesser degree. Many gases that heat up the earth also tear down the ozone layer. In addition, CFCs may still influence the ozone because those gases stay in the atmosphere for a long time.
Ozone is actually a greenhouse gas, contributing to trapping heat in the stratosphere. If the ozone layer depletes, it affects the temperature of the earth. The depletion contributes to a
global cool down and significant weather changes in higher areas near the stratosphere.
Acid RainAcid rain is caused by certain types of pollution that release carbon, sulfur dioxide and similar particles into the air. These particles mix with water vapor and give it an acidic quality that continues as the water vapor is gathered into clouds and falls as rain. This higher acidic content has been linked to several hazardous effects.
Human StructuresSome of the greatest damage from acid rain occurs on human structures. This is seen in the well-
known examples of rapid wear on stone buildings and outdoor statues made from marble or other calcite materials. The acid interacts with this stone and eats it away, which neutralizes the dangerous effects the acid may have on wildlife, but also ruins the artistry and usefulness of certain stonework. This also holds true for certain kinds of paint, especially automotive paints, in which etching and wear have been noted.
Water Rain naturally seeps into groundwater and runs through soil to surface water, such as
streams and lakes. On its way toward groundwater, the acid rain is often neutralized by the minerals it encounters, but runoff into surface water can pose more dangerous problems. First of all, all lakes and streams have a general pH level (often between 6 and 8) that allows natural organisms to survive in the local area. If this balance is made too acidic, it can kill some kinds of smaller organisms,
which in turn affects the entire food chain. Additionally, acidic rain can expose certain metals in the surrounding stone and wash them into the water. Some metals, such as aluminum, are toxic to surrounding wildlife.
Forests The damage acid rain can cause to forests depends on
the buffering abilities of the soil. Soil that can neutralize acid rain well will protect the trees from significant damage, while soil with low buffering qualities will allow the acid rain to be absorbed by trees or will release toxic metals into the earth that can damage plant life. Acid rain can also cause damage to leaves on broadleaf trees,
inhibiting their ability to photosynthesize. While this rarely kills trees outright, the combined factors can halt growth and slowly destroy forests.
Loss of BiodiversityDespite knowing about biodiversity’s importance for a long time, human activity has been causing massive extinctions. As the Environment New Service, reported back in August 1999 (previous link): “the current extinction rate is now approaching 1,000 times the background rate and may climb to 10,000 times the background rate during the next century, if present trends continue [resulting in] a loss that would easily equal those of past extinctions.”
A major report, the Millennium Ecosystem Assessment, released in March 2005 highlight a substantial and largely irreversible loss in the diversity of life on Earth, with some 10-30% of the mammal, bird and amphibian species threatened with extinction, due to human actions. The World Wild Fund for Nature (WWF) added that Earth is unable to keep up in the struggle to regenerate from the demands we place on it.
Biological diversity is the resource upon which families, communities, nations and future generations depend. It is the link between all organisms on earth, binding each into an interdependant ecosystem, in which all species have their role. It is the web of life.
The Earth’s natural assets are made up of plants, animals, land, water, the atmosphere AND humans! Together we all form part of the planet’s ecosystems, which means if there is a biodiversity crisis, our health and livelihoods are at risk too.
But we are currently using 25% more natural resources than the planet can sustain As a result species, habitats and local communities are under pressure or direct threats (for example from loss of access to fresh water).
Endangered Species
An endangered animal is a species that will only survive for a short period of time unless actions are taken to save it. These animals are usually assigned a status based on the length of time the species is expected to survive under current conditions, so a species that is being hunted, is living on land that is being destroyed or is disappearing quickly is considered to be in more danger than other animals.
Why are they endangered?
Introduced Species
One of the biggest threats to ecosystem diversity is the increasing introduction and spread of invasive species. After habitat lost, invasive species are the biggest threat posed to biodiversity and many biological experts agree that invasive species are a growing and serious problem. In addition, the impacts of invasive species are costing billions of dollars around the world every year. Management of invasive species
can, however, reduce the impacts of invasive species and possibly save native species and global biodiversity.
Invasive species are able to win over habitat from the native animal, plant or organism species because they often have traits that help them out-compete native species. Invasive species often have faster regeneration or reproduction times, faster growth rates or more aggressive behavior. Some invasive species, especially plant species, can adapt to the changing habitat and are, therefore, more capable of growing in low nutrient or high toxicity soils where many native species cannot survive. Some invasive species, on the other hand, secrete chemicals into the ground making the soil inhabitable for competing species. Invasive species also often lack natural predators and enemies in their new habitats
Human Activities: Over harvesting and poaching
There are several endangered species that are threatened by poaching. Animals such as the black rhinoceros, gorilla, African elephant and tiger are the most at risk due to the practice. In fact, according to Sea World, 90 percent of black rhino deaths are caused by the
poaching of their horns. African elephants are killed for their ivory tusks. Poaching of gorilla meat and tiger fur has also led to the decline of these species.
If the prevalence of poaching continues, the practice will be a
primary cause in the extinction of several species. In fact, according to a 2007 article in London's The Independent, half of the Earth's animal and plant species are expected to disappear by 2100. The result will be destruction of the planet's ecological systems, leading to grave effects on humans' way of life.
Habitat Loss and
Deforestation
Deforestation is clearing Earth's forests on a massive scale, often resulting in damage to the quality of the land. Forests still cover about 30 percent of the world’s land area, but swaths the size of Panama are lost each and every year.
The world’s rain forests could completely vanish in a hundred years at the current rate of deforestation.
Forests are cut down for many reasons, but most of them are related to money or to people’s need to provide for their families. The biggest driver of deforestation is agriculture. Farmers cut forests to provide more room for planting crops or grazing livestock. Often many small farmers will each clear a few acres to feed their families by cutting down trees and burning them in a process known as “slash and burn” agriculture.
Logging operations, which provide the world’s wood and paper products, also cut countless trees each year. Loggers, some of them acting illegally, also build roads to access more and more remote forests—which leads to further deforestation. Forests are also cut as a result of growing urban sprawl.
Not all deforestation is intentional. Some is caused by a combination of human and natural factors like wildfires and subsequent overgrazing, which may prevent the growth of young trees.
Deforestation has many negative effects on the environment. The most dramatic impact is a loss of habitat for millions of species. Seventy percent of Earth’s land animals and plants live in forests, and many cannot survive the deforestation that destroys their homes.
Deforestation also drives climate change. Forest soils are moist, but without protection from sun-blocking tree cover they quickly dry out. Trees also help perpetuate the water cycle by returning water vapor back into the atmosphere. Without trees to fill these roles, many former forest lands can quickly become barren deserts.
Removing trees deprives the forest of portions of its canopy, which blocks the sun’s rays during the day and holds in heat at night. This disruption leads to more extreme temperatures swings that can be harmful to plants and animals.
Trees also play a critical role in absorbing the greenhouse gases that fuel global warming. Fewer forests means larger amounts of greenhouse gases entering the atmosphere—and increased speed and severity of global warming
Biomagnification
"Biomagnification is the sequence of processes in an ecosystem by which higher concentrations of a particular chemical, such as the pesticide DDT, are reached in organisms higher up the food chain, generally through a series of prey-predator relationships."
Every time energy in the form of food moves up a level on the food chain, known as a trophic level, it is 1/10th the value of the previous level. This is not true for chemicals in the flesh of organisms
being consumed. When a predator animal consumes a contaminated organism, it receives nearly all of the chemical contaminant stored in its prey.
High-Risk Environments
The buildup of toxins is especially prominent in food chains with long-lived top predators and organisms with high body-fat contents. In Arctic environments, top predators like whales and polar bears have relatively long lives compared to most of their prey, and they have high body fat to combat the extreme cold.
Water Pollution
