Problems - Loss of Species. Problem: Extinction of Plant and Animal Species. Massive extinctions have occurred five times during the earth's history, the last one was the extinction of the dinosaurs, 6. Scientists are calling what is occurring now, the sixth mass extinction. The loss of species is about losing the very web of life on Earth. People trying to save critical habitat have been dismissed or ridiculed as sentimental “tree- huggers” who want to save the “spotted owls,” even if it costs jobs. Most Americans have little idea of the magnitude of the problem. Although they are uncertain of the numbers, most scientists believe the rate of loss is greater now than at any time in the history of the Earth. Within the next 3. Dr Leakey, author of "The Sixth Extinction," believes that 5. Homo sapiens, (the species responsible for the crisis.) The problem is not just the loss of species. There is also the loss of the genetic diversity within species, as well as the loss of diversity of different types of ecosystems ,which can contribute to or hasten whole species extinction. Preserving the wider gene pool diversity in subdivisions of species, such as subspecies and populations, offers the raw material for the evolution of new species in the future. Every day, an estimated 1. Problem: Extinction of Plant and Animal Species. Massive extinctions have occurred five times during the earth's history, the last one was the extinction of the.
A conservative estimate of the current extinction rate indicates that about 2. National Wildlife Federation Causes of the Extinction of Species Scientists have identified the key causes of the crisis. In particular, the loss of species is caused by as the growing size of human populations, and the rate at which humans consume resources and cause changing climate. Global Warming and the Loss of Species At the end of the Permian period, 2. That time a six- degree C. Earth. This extinction is called the "Great Dying." Gigantic volcanic eruptions caused this warming by triggering a "runaway greenhouse effect" that nearly put an end to life on Earth. Conditions in what geologists have termed a "post- apocalyptic greenhouse" were so severe that only one large land animal was left alive, and fewer than one in 1. Michael Benton, Professor of vertebrate paleontology and Head of the Department of Earth Sciences at the University of Bristol, in When Life Nearly Died: the Greatest Mass Extinction of All Time . It took 1. 00 million years for species diversity to return to former levels. In this case, the carbon dioxide buildup which created this greenhouse effect came from massive volcanic eruptions. Today the build up of carbon dioxide is coming from our life style and industrial activity. An increase of 6°C is the upper end of what the IPCC is forecasting for this century, the range that will occur if we do not make severe changes soon. If 9. 5% of the species on Earth die out—one of them will be Homo sapiens. Global warming is already affecting species: migration is accelerating, the timing of the seasons is changing, and animals are migrating, hatching eggs, and bearing young on average five days earlier than they did at the start of the 2. In addition, some butterflies have shifted northward in Europe by thirty to sixty miles or more, species’ ranges are shifting toward the poles at some four miles a decade, amphibians were spawning earlier, and plants are flowering earlier. In a major report in Nature, the lead author, Terry Root said: “There is a consistent signal. Animals and plants are being strongly affected by the warming of the globe.” She later said that, “It was really quite a shock, given such a small temperature change. If we’re already seeing such dramatic changes among species, it’s really pretty frightening to think what we might see in the next 1. For if one link in nature's chain might be lost, another might be lost, until the whole of things will vanish by piecemeal." Thomas Jefferson. Habitat Loss as a Cause of the Loss of Species Other than global warming, the greatest threat to biodiversity is habitat loss and fragmentation by deforestation and urbanization. Urbanization has dramatically increased the rate of habitat loss and change. Sprawling development is consuming land at a rate of five or more times the rate of population growth, destroying wildlife habitat and degrading water quality. Dredging, draining, bulldozing, and paving the land for housing developments, malls, business parks, and new roads, all destroy habitat. For example, in Maryland, 1. Biological resources are degraded and lost through “development” activities like large- scale clearing and burning of forests, over- harvesting of plants and animals, use of pesticides, draining and filling of wetlands, destructive fishing practices, air pollution, and the conversion of wildlands to agricultural and urban uses. Humans create all of these causes. Humans have altered nearly half of Earth’s land mass over the past 1. United Nation. These alterations include farming, logging and urban development. Deforestation is also one of the leading causes of habitat loss. For centuries, humans have altered landscapes, through deforestation, fire and over- use. Already, around half of the world's original forests have disappeared, and they are still being removed at a rate 1. As tropical forests contain at least half the Earth's species, the clearance of some 1. Habitat loss is identified as a main threat to 8. IUCN's Red Lists (those species officially classified as "threatened" and "endangered.” ICUN is the World Conservation Union"). Invasive Alien Species Cause the Loss of Species An "alien" or "exotic" species is one that occurs in an area outside its historically known natural range, as a result of either intentional or accidental dispersal by human activities. For millennia, oceans, mountains, rivers and deserts served as natural barriers to the movement of certain plants and animals, providing the isolation essential for unique species and ecosystems to evolve. In just a few hundred years, however, international trade and the expansion of global travel, accompanied by intentional introductions, have ended millions of years of biological isolation. When alien animal and plant species spread to non- native habitats, they alter habitats, and crowd out native species through predation, competition, disease and hybridisation. Hundreds, possibly thousands of extinctions have been caused by alien invasive species. Pollution Leads to a Loss of Species Pollution is found everywhere in the world- -chemicals have been found in animals even in the Arctic and Antarctic. Chemicals can cause mutations and fertility problems, already seen in the reproductive organs of fish, alligators, and polar bears. The city and industry sewage treatment plants that lack advanced technology, dump nutrients and pathogens in the water. When the treatment plants discharging into Tampa Bay were upgraded, the sea grasses, 8. A recent EPA report noted that nearly 4. Fifty percent of freshwater species populations, from fish and frogs to river dolphins, are declining from pollution by pesticides, fertilizers and other agricultural chemicals. Everything that happens on land affects the waterways; storm water picks up contaminants from roads, vehicles, lawns, and construction sites and then dumps it in the nearest stream. In pushing other species to extinction, humanity is busy sawing off the limb on which it is perched." Paul Ehrlich. Bycatch Causes the Loss of Species Bycatch is unwanted species, juveniles, and other marine wildlife, that fishers catch unintentionally. Commercial fishing is grossly wasteful: in the process of harvesting 8. According to a new study submitted to the International Whaling Commission (IWC), nearly 1,0. Scientists believe that death in fishing gear is the leading threat to the survival of the world’s 8. Bycatch is also the greatest threat to seabirds and sea turtles. Illegal Wildlife Trade causes the loss of species Trade in some animal and plant species is high, and is capable of heavily depleting their populations and even bringing some species close to extinction. Live animals are taken for the pet trade, or their parts exported for medicines or food. Thousands of species including African and Asian elephants, Tibetan antelopes, rhinos, birds of paradise, parrots, and orchids are part of the illegal international wildlife trade. This trade is worth billions of dollars annually and has caused massive declines in the numbers of many species of animals and plants. The scale of over- exploitation for trade is a major threat to the survival of species.
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