College Essays, College Application Essays - Paper on global warming
The ecosystems may not have recovered from Olson’s Extinction of 270 mya, and at 260 mya came another mass extinction that is called the mid-Permian or extinction, or the , although a recent study found only one extinction event, in the mid-Capitanian. In the 1990s, the extinction was thought to result from falling sea levels. But the first of the two huge volcanic events coincided with the event, in . There can be several deadly outcomes of major volcanic events. As with an , massive volcanic events can block sunlight with the ash and create wintry conditions in the middle of summer. That alone can cause catastrophic conditions for life, but that is only one potential outcome of volcanism. What probably had far greater impact were the gases belched into the air. As oxygen levels crashed in the late Permian, there was also a huge carbon dioxide spike, as shown by , and the late-Permian volcanism is the near-unanimous choice as the primary reason. That would have helped create super-greenhouse conditions that perhaps came right on the heels of the volcanic winter. Not only would carbon dioxide vent from the mantle, as with all volcanism, but the late-Permian volcanism occurred beneath Ediacaran and Cambrian hydrocarbon deposits, which burned them and spewed even more carbon dioxide into the atmosphere. Not only that, great salt deposits from the Cambrian Period were also burned via the volcanism, which created hydrochloric acid clouds. Volcanoes also spew sulfur, which reacts with oxygen and water to form . The oceans around the volcanoes would have become acidic, and that fire-and-brimstone brew would have also showered the land. Not only that, but the warming initiated by the initial carbon dioxide spike could have then warmed up the oceans enough so that methane hydrates were liberated and create even more global warming. Such global warming apparently warmed the poles, which not only melted away the last ice caps and ended an ice age that had , but deciduous forests are in evidence at high latitudes. A 100-million-year Icehouse Earth period ended and a 200-million-year Greenhouse Earth period began, but the transition appears to have been chaotic, with wild swings in greenhouse gas levels and global temperatures. Warming the poles would have lessened the heat differential between the equator and poles and further diminished the lazy Panthalassic currents. The landlocked Paleo-Tethys and Tethys oceans, and perhaps even the Panthalassic Ocean, may have all become superheated and anoxic as the currents died. Huge also happened, which may have and led to ultraviolet light damage to land plants and animals. That was all on top of the oxygen crash. With the current state of research, all of the above events may have happened, in the greatest confluence of life-hostile conditions during the eon of complex life. A recent study suggests that the extinction event that ended the Permian may have lasted only 60,000 years or so. In 2001, a bolide event was proposed for the Permian extinction with great fanfare, but it does not appear to be related to the Permian extinction; the other dynamics would have been quite sufficient. The Permian extinction was the greatest catastrophe that Earth’s life experienced since the previous supercontinent existed in the .
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The Oligocene ended with a sudden global warming that continued into the (c. 23 to 5.3 mya). The Miocene was also the first epoch of the (c. 23 to 2.6 mya). Although the Miocene was , England had palm trees again, Antarctic ice sheets melted, and oceans rose. The Miocene is also called the Golden Age of Mammals. Scientists still wrestle with why Earth’s temperature increased in the late Oligocene, but there is no doubt that it did. As the has demonstrated, many dynamics impact Earth’s climate, and positive and negative feedbacks can produce dramatic changes. For the several million year warm period, carbon dioxide levels do not appear to have been elevated. That data has been seized on by as evidence that carbon dioxide levels have nothing to do with Earth’s temperature, but climate scientists not rarely think that way. Carbon dioxide is only one greenhouse gas, and . But as clouds demonstrate, water is notoriously ephemeral, constantly evaporating and precipitating, and some land can get a lot (rainforests), and some can get very little (deserts). Icehouse Earth temperatures are more variable than Greenhouse Earth temperatures, particularly during the transitions between states, and an Icehouse Earth atmosphere contains less water vapor than a Greenhouse Earth atmosphere.
This paper will describe the nature of global warming, as well as the basic causes and effects of this continuous rise of the Earth’s temperature and explain how people can stop this process contributing to the clean and safe planet not only for the present but also for the future generations....
Global Warming, Spin and Media — Global Issues
Global warming is considered as a byproduct of energy crisis, because as oil continues to burn in the refining process, CO2 is constantly emitted to the atmosphere at a fast rate and in heavy concentrations, which in turn, worsens the global warming situation.
Global warming is the greatest challenge facing our planet
The Cambrian’s global ocean contained far less oxygen than today’s. Being newly and probably inconsistently oxygenated by oceanic currents was only part of the problem. The Cambrian oceans were warmer than today’s oceans, perhaps far warmer, such as 40o C and higher for the . Water’s ability to absorb oxygen declines as it gets warmer. Water heated from 10o C to 40o C will lose 40% of its ability to absorb oxygen. The phenomenon of warmer water absorbing less oxygen contributed to many instances of anoxic waters during the eon of complex life, and particularly in the warmer, earlier periods.
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The first tree forests formed in the late Devonian, and bark is the great innovation that led to forming the Carboniferous’s vast coal deposits. Compared to modern trees, Carboniferous trees seemed to go overboard on bark, at least partly to discourage arthropods. Today’s trees generally contain at least four times as much wood as bark. Those early trees had about . trees dominated the Carboniferous rainforest and could grow 30 meters tall. Because it took more than a hundred million years for life to learn to break down lignin, that early lignin did not degrade via biological processes. The early Carboniferous was warm, even with a small ice cap at the South Pole, and Earth’s first rainforests appeared in the late Devonian and again proliferated in the Carboniferous. The Carboniferous lasted from about 360 mya to 300 mya and was the Golden Age of Amphibians, as the rainforest was largely global in extent and swamps abounded. Amphibians were the Carboniferous’s apex predators on land, and some reached crocodile size and acted like them.
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In recent years, Neogene temperatures have been the focus of intensive research. What appears to be the proximate cause of elevated temperatures was a dramatic change in global ocean currents. The final closing of the , the isolation of Antarctica, the creation of , and the opening and closing of land bridges, such as in the Bering Sea and ultimately the land bridge between North and South America, created dramatic changes in ocean currents and global climate. One result was fluctuating . Its production declined beginning about 24 mya, and its weakness lasted until about 14 mya. Consequently, Earth’s oceans were not stratified as they are today, and warm water extended far lower into the oceans than it does today. Also, it reduced the temperature gradient between the equator and poles, which drives global currents: the greater the differential, the more vigorous the currents. It was still an Icehouse Earth, but the “mid-Miocene climatic optimum” was relatively warm. The past three million years are the coldest that Earth has seen since the that ended 260 mya, but this . While the steadily declining carbon dioxide levels of the past 150-100 million years is the ultimate cause of this Icehouse Earth phase, relatively short-term and regional fluctuations have had their proximate causes rooted in other geophysical, geochemical, and celestial dynamics.