Increased Risk of Obesity
· Desert Biomes Desert biomes cover about one-fifth of Earth’s land surface. Deserts form due to the low level of rainfall in an area. A primary characteristic of all deserts is low species diversity, including reptiles and small mammals like field mice and gophers. Four major types of deserts exist in this biome: hot and dry, semiarid, coastal, and cold. Hot and dry deserts include the Sahara, the Arabian Peninsula, central Australia, and the Mojave Desert in the American Southwest. Semiarid deserts can be found in areas of Utah, Montana, and the Great Basin. Coastal deserts include the far northwestern Sahara where it borders the Atlantic Ocean, and the Atacama Desert of Chile, which borders the Pacific Ocean. Cold deserts are found in places like Antarctica and Greenland. We’ll return to this topic later, as we consider the nature and extent of desertification in general as well as within our current era of climate change and global warming.
· Tundra Biomes Tundra biomes are the coldest of all the biomes. The word “tundra” comes from the Finnish word tunturia, which means “treeless plain.” Frosty landscapes, extremely low temperatures, and little precipitation characterize tundra. Tundra biomes are poor in nutrients and follow short growing seasons. There are two types of tundra: arctic tundra and alpine tundra. Arctic tundra refers to the Arctic region in the northern hemisphere, around the North Pole. Alpine tundra refers to mountain regions at high altitudes. In these areas, trees can’t grow and nighttime temperatures are below freezing.
· Aquatic Biomes Aquatic biomes fall into two groups: freshwater and oceanic (marine). Freshwater biomes include lakes, ponds, streams, rivers, and marshes or wetlands. Oceanic biomes cover about 75 percent of Earth’s surface, making them the largest biomes on the planet. The five main ocean biomes include the Pacific, Atlantic, Indian, Southern, and Arctic Oceans. Together, they link a huge number of ecosystems. Lesser oceanic sub-biomes include bays, gulfs, and estuaries. Life on Earth began in the oceans. For about a billion years, Earth’s surface was sterile. Surface life only began as plants spread inland and pumped oxygen into the atmosphere. Eventually, the ratio of oxygen to nitrogen in the atmosphere reached 21 percent. This ratio allowed amphibians to come ashore and air-breathing creatures to evolve. (Did you know that the ion balance in human blood serum is roughly identical to the ion balance of ancient oceans? That’s why it’s recommended that people switch from iodized salt to sea salt.) Earth’s oceans are critical to survival of all life on the planet. They regulate global climate patterns. They’re also the source of the water cycle, which is initiated as the surface evaporates. Of course, oceans are also home to millions of fish species, aquatic mammals (dolphins, whales), plankton, phytoplankton, mollusks, jellyfish, and so on. Phytoplankton provides most of the oxygen in the air through photosynthesis. Indeed, these tiny organisms are the basic foundation of the oceanic food chain—not to mention the foundation for all life on Earth.
· Forest Biomes Forest biomes include three main types—tropical rainforests, temperate forests, and boreal forests (also called taiga). These three kinds of forests once occupied about 70 percent of the planet’s surface. Today, due largely to deforestation, pollution, and industrial and agricultural activities, forests occupy only about one-third (30 percent) of Earth’s land area. Tropical forests are confined to regions near the equator. These forests harbor the largest array of species of all kinds. They’re also a significant source of atmospheric oxygen. The largest of the tropical forests on Earth is the Amazon basin. This area is sometimes called our planet’s “lungs” because of the volume of atmospheric oxygen it supplies. Other major tropical forest areas include the Guyana Shield of northern South America (from Guyana to Venezuela to Colombia and Ecuador), as well as regions of Indonesia, Malaysia, Vietnam, Cambodia, Thailand, and southernmost India. They also include Africa’s Congo Basin (“the Congo”) in Central Africa. This region includes the Democratic Republic of the Congo and extends into highland regions of Uganda, Rwanda, and Burundi, where we find the threatened domain of the mountain gorilla. The deforestation of tropical rainforests in Brazil and Southeast Asia is a problem. Deforestation deprives the planet of precious resources found only in rainforests. This includes amazing species diversity, an unknown number of medicinal herbs (many pharmaceutical drugs originated from tropical medicinal herbs), and, of course, the oxygen pumped into the atmosphere. Subtropical forests constitute a subdomain of tropical forests. They represent a transition zone from tropical forests to higher-latitude temperate forests. In the United States, Florida and the Gulf Coast states are thought of as subtropical climate regions. However, in most of this region, subtropical forests are mainly noticeable by their absence. In much of this region, forests and wetlands have been destroyed for urban residential development as well as agricultural and industrial development. Of course, the same may be said of temperate forests worldwide. Temperate forests, as suggested by their name, occupy Earth’s temperate latitudes. These are the regions from 40 to 60 degrees latitude in the northern and southern hemispheres. In Europe, temperate forests can be found from northwestern Europe to the Arctic Circle in Scandinavia. North American temperate forests include the temperate rainforests of the U.S. Pacific Northwest and Canada’s British Columbia. Otherwise, temperate forests remain in the eastern United States and portions of southeastern Canada. In Asia, temperate forests exist in western Russia, northeast China, and Japan. In the southern hemisphere, temperate forests cover much less territory. They can be found in southern Chile, Tasmania in Australia, and South Island in New Zealand. In general, temperate forests include both coniferous and deciduous species. (Coniferous trees produce cones and evergreen needles. Deciduous trees produce leaves that fall off seasonally.) Temperate rainforests are home mainly to coniferous (evergreen) species. In general, deciduous trees are those that produce leaves that change colors in the fall, drop to the ground, and sprout new leaves in the spring. Coniferous trees bear needles and cones and stay green all year round. However, not all trees or shrubs fall neatly into these categories. Some trees that grow needles and cones are actually deciduous trees. Some broadleaf trees and shrubs are neither coniferous nor deciduous. Examples include rhododendron and mountain laurel. Both are broadleaf evergreens that stay green all year long. They reproduce in the same manner as other angiosperms (flowering plants). Taiga is the Russian name for forest, although in southerly regions they are called boreal forests. The taiga represents the world’s largest connecting terrestrial biome, making up about 30 percent of all of Earth’s forests. In Asia, the taiga covers much of northern Russia and Siberia. Taiga forests are also found in northern Mongolia and Kazakhstan as well as on the Japanese island of Hokkaido. In Europe, taiga forests cover an area that includes northern Norway, Sweden, and Finland. In North America, boreal forests occupy most of the land area of the Canadian interior as well as a portion of Alaska. Spring and fall are barely noticeable in the taiga. Instead, there’s a short summer season that’s warm and humid. This is followed by a much longer season during which the closely packed coniferous trees are covered in frost and snow. If this season had a message on a sign, it might read, “Hostile to life. Enter at your own risk.” On the other hand, during the brief summer, the taiga is a haven for insects, which attract many species of birds. The birds build nests as they feast on the insects. A number of animal species are also adapted to life there. The snowshoe rabbit, for example, changes color from beige to white. Other year-round animals find ways to adapt to arctic temperatures. These include moles that tunnel under the snow, as well as bears, mice, badgers, wolverines, squirrels, and reindeer (in Eurasia).
· Grassland Biomes Two main types of grassland biomes exist: savannas and temperate grasslands. Species diversity, rainfall patterns, climate zones, and soil types distinguish these biomes from each other. Savannahs feature scattered individual trees separated by grasses. Africa is one example. The savanna covers nearly half the surface of central Africa, south of the Sahara. A key feature of the savanna is the alteration of dry and rainy seasons. During the rainy season, vegetation flourishes. Food can be gathered and stored. This is followed by a dry season, during which the land once again becomes parched and dry. Natural or human-set fires reduce the desiccated vegetation to ash. The ash revitalizes the soil with nutrients, and vegetation returns. Cattle and native species can graze the lush landscape. Other species can gather food. In any case, savannas like this are called climatic savannahs, as they depend on alternating seasons of wet and dry. Another kind of savanna is the derived savannah. This occurs when land is cleared to make room for farming or cattle ranching. Downed trees and shrubs are burned to produce ash. This ash creates viable soil—at least for a few seasons—after which new land must be cleared for the process to continue. Derived savannahs have overall negative environmental impact. For example, this is true of the Sahel that crosses Africa just south of the Sahara. Temperate grasslands include a rich mixture of perennial grasses (grasses that live more than two years) and flowering plants. These plants are called forbs. Temperate grasslands presently occupy about 25 percent of Earth’s land surfaces. The mixture of grasses and forbs produces some of the most fertile soils on the planet. As a result, most grassland has been converted for agricultural purposes (farming). The semi-arid climate of the temperate grasslands varies by region. That’s because grasslands extend over a wide range of latitudes. Imagine the distance from Kansas to northern regions of Alberta, Manitoba, and Saskatchewan in Canada. Over that range of area, summers may be warm or hot, depending on latitude. However, in much of this range, winter precipitation arrives as snow. So, on the plus side, the spring melt provides a steady source of moisture for the growing season. On the downside, rapid melting may result in serious flooding. In North America, grasslands include the high plains of the prairie states into Canada. In the United States, grasslands can be found in eastern Washington, parts of California, and in semi-arid regions of the Southwest. Globally, temperate grasslands can be found in Argentina, Uruguay, and the Veld region of South Africa. In Eurasia, the steppes are a type of grassland. The steppes can be found from the Ukraine west across central Russian to parts of Mongolia. The steppes played a major role in advancing humanity, as people there were the first to domesticate horses. The domestication of horses changed transportation and the conduct of wars forever. Typically, grassland fauna are low in diversity, especially as compared to tropical forests and savannas. In North America, native species included bison, pronghorn antelopes, and rodent herbivores such as pocket gophers, ground squirrels, and prairie dogs. Badgers and coyotes are still around as predators and scavengers.
To learn more about Earth’s major biomes, check out this video:
https://courses.ashworthcollege.edu/content/enforced/10698-SO245_21_1/Images/SO245V%20Lesson%204%20Image%205.jpg?_&d2lSessionVal=Ailknb0zPMmFVbH2d0YvJK7G3&ou=10698Earth from Space (NASA public domain image)
Let’s look at some of the ecological challenges facing the world. These issues are all related to climate change and global warming in various ways. As you learn about them, consider their origin and impact. Think about how they contribute to climate change and global warming.
Pollution is the process of making land, water, or air unsafe for life. Pollution of the air, water, and soil is a problem for everyone. For example, in 2014 toxic chemicals were unintentionally spilled into the water supplies of nine counties and the city of Charleston in West Virginia. The culprit was a toxic chemical called 4-methylcyclohexane. The spill may have been an accident but it was still a catastrophe. The government issued a ban on the use of tap water for nine days, which barely made an impact on the ongoing problem. Several hundred people had to be treated in hospitals for chemical exposure over the following weeks. Tap water continued to have a peculiar, lingering licorice odor for some time afterward.
Pollution comes from many sources. For example, water pollution can come from oils spills, acid rain, and industrial and farm runoff. These issues also cause problems with soils. Farms that rely on petroleum-based fertilizers, pesticides, and herbicides, for instance, have destroyed organism-rich topsoil. Meanwhile, air pollution comes from emissions from internal combustion engines. Think about the brown clouds that are often seen over urban centers. (California has been a recent exception; in that state, regulatory action has made urban air more breathable.)
Across the globe, the overconsumption of resources has created a crisis associated with waste—garbage—disposal. Developed countries in particular produce an enormous amount of garbage. This garbage is dumped into the oceans or buried in landfills. The disposal of nuclear waste poses a tremendous health hazard. The radiation from nuclear waste dumps can remain toxic and lethal for centuries.
Waste disposal is one of our most serious environmental problems.
Here are examples of a few waste disposal dangers:
· Chemical spills pose danger to water supplies.
· Landfills and incinerators dump carcinogens and pollutants into the air. This increases the risks for cancer, asthma, and respiratory disorders.
· Landfills attract rats, flies, and other carriers of a variety of communicable diseases.
· Burning waste contributes to the number of greenhouse gases in the atmosphere. These gases promote global warming and climate change.
Let’s focus on that last item for a moment. According to one source, “Asia, Latin America, and Africa alone are to blame for about 40 percent of methane emissions every year. That 40 percent is equal to about 37 million metric tons of carbon dioxide.” Further, experts believe that industrialized nations produce considerably more waste than this. Specifically, “In the United States, each American produces an average of .75 tons of trash every year.” That’s the most waste per person per capita in the world. Europeans are estimated to dispose of about half a ton of trash annually. In Asia, an average person produces .2 tons of trash each year.
Pollution affects everyone, everywhere. Environmental problems in Asia can and do affect North America, Europe, and Africa. For this reason, cooperation among nations is needed to deal with the waste problem.
Consider, for example, Europe leads in the development of environmental technologies. In fact, about 60 percent of environmental discoveries and technologies originate in Europe. Thus, Europeans can play a major role in raising awareness and helping other nations to apply workable solutions. China and India are both high on the list of Asian countries with major pollution problems, including water and air pollution, deforestation, and the loss of biodiversity. Other countries can work with their governments to find workable solutions.
Urban sprawl refers to the uncontrolled expansion of urban living areas. Urban sprawl means one thing in developed countries and quite another in developing or underdeveloped countries. In this lesson, we’ll focus on urban sprawl issues as they apply in the United States. The complex issues related to urbanization in the developing world will be considered in future lessons.
In developed countries, urban sprawl occurs when populations move from high-density cities into lower-density surrounding areas. The era of urban sprawl in the United States began during the period of economic prosperity following World War II. It was made possible in large part by the progressive reforms initiated under President Franklin Roosevelt’s “New Deal.” Labor unions were strong, and corporations embraced fair labor practices. There were plenty of good jobs with benefits. The G.I. Bill allowed a whole generation of young men to obtain a college education, and the future looked bright. Consumer demand soared. The philosophy of consumerism soared. The “American Dream” was linked to owning a home, sophisticated appliances, and the latest model of automobile. The rush to the suburbs became a stampede, which came at a serious cost. Let’s look more closely.
Increased Air Pollution
According to the Sierra Club, the typical annual commute from the suburbs to the workplace involves about eight workweeks of 55 hours each. That’s 440 unpaid hours sitting behind the wheel of an automobile. More driving leads to an increase in air pollution, in addition to health risks due to inhaling exhaust fumes and smog.
Overconsumption of Water
Urban sprawl means a larger ecological footprint for people. As people spread out and population density increases, water distribution problems arise. One of these problems is the result of a demand for water to landscaping. According to the EPA, about 30 percent of daily water in the United States is used outdoors. People water their lawns and golf courses, grow flowers and plants, and fill their outdoor pools. Review this site for more details: Understanding Your Own Water Use
Increased Risk of Obesity
According to the Ontario College of Family Physicians and the American Planning Association, life in the suburbs is associated with higher rates of obesity. This can partially be blamed on the consumption of processed foods and fast-food restaurants. However, experts also agree that obesity has risen due to overuse of automobiles for traveling even short distances.
In many places, people in the suburbs must drive to go anywhere. They spend too much time sitting in the car instead of walking where they need to go. In short, too little exercise can lead to an excess of weight on the body.
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