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  3. Global Warming and Climate Change What Are Global Warming and Climate Change? Global warming and climate change refer to

Global Warming and Climate Change What Are Global Warming and Climate Change? Global warming and climate change refer to

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问题                   Global Warming and Climate Change
    What Are Global Warming and Climate Change?
    Global warming and climate change refer to an increase in average global temperatures. Natural events and human activities are believed to be contributing to an increase in average global temperatures. This is caused primarily by increase in "greenhouse" gases such as Carbon Dioxide (CO2).
    What Is the Greenhouse Effect?
    The term greenhouse is used in conjunction with the phenomenon known as the greenhouse effect.
    Energy from the sun drives the earth’s weather and climate, and heats the earth’s surface;
    In turn, the earth radiates energy back into space;
    Some atmospheric gases (water vapor, carbon dioxide, and other gases) trap some of the outgoing energy, retaining heat somewhat like the glass panels of a greenhouse;
    These gases are therefore known as greenhouse gases;
    The greenhouse effect is the rise in temperature on Earth as certain gases in the atmosphere trap energy.
    Six main gases considered to be contributing to global climate change are carbon dioxide (CO2), methane (CH4) (which is 20 times as potent (强有力的) a greenhouse gas as carbon dioxide) and nitrous oxide (N2O), plus three fluorinated industrial gases: hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). Water vapor is also considered a greenhouse gas.
    Many of these greenhouse gases are actually life-enabling, for without them, heat would escape back into space and the Earth’s average temperature would be a lot colder. However, if the greenhouse effect becomes stronger, then more heat gets trapped than needed, and the Earth might become less habitable for humans, plants and animals. What Are the Impacts of Global Warming?
    For decades, greenhouse gases, such as carbon dioxide have been increasing in the atmosphere. But why does that matter? Won’t warmer weather be nicer for everyone? Rapid Changes in Global Temperature
    A documentary aired on the National Geographic Channel in Britain on August 9, 2003 was titled What’s Up with the Weather. it noted that the levels of carbon dioxide, for example, were currently at their highest levels in the past 450,000 years.
    Increased greenhouse gases and the greenhouse effect is feared to contribute to an overall warming of the Earth’s climate, leading to a global warming ( even though some regions may experience cooling, or wetter weather, while the temperature of the planet on average would rise).
    However, it is the rapid pace at which the temperature will rise that will result in many negative impacts to humans and the environment and this is why there is such a world-wide concern. Extreme Weather Patterns
    Most scientists believe that the warming of the climate will lead to more extreme weather patterns such as:
    More hurricanes and drought;
    Longer spells of dry heat or intense raja (depending on where you are in the world);
    Scientists have pointed out that Northern Europe could be severely affected with colder weather if climate change continues, as the arctic begins to melt and send fresher waters further south.
    It would effectively cut off the Gulf Stream that brings warmth from the Gulf of Mexico, keeping countries such as Britain warmer than expected;
    In South Asia, the Himalayan glaciers (冰川) could retreat causing water scarcity in the long Super-storms
    Mentioned further above was the concern that more hurricanes could result. The link used was from the environmental organization WWF, written back in 1999. In August/September 2004 a wave of severe hurricanes left many Caribbean islands and parts of South Eastern United States devastated. In the Caribbean many lives were lost and there was immense damage to entire cities. In the U.S. many lives were lost as well, some of the most expensive damage resulted from the successive hurricanes.
    Interviewing a biological oceanography professor at Harvard University, IPS notes that the world’s oceans are approaching 27 degrees C or warmer during the summer. This increases the odds of major storms.
    When water leaches such temperatures, more of it evaporates, priming hurricane or cyclone formation.
    Once born. a hurricane needs only warm water to build and maintain its strength and intensity.
    Furthermore, "as emissions of greenhouse gases continue to trap more and more of the sun’s energy, that energy has to be dissipated (消散), resulting to stronger storms, more intense precipitation (降水量) and higher winds."
    There is abundant evidence of an unprecedented (前所未有的) number of severe weather events in the past decade. In 1998. Hurricane Mitch killed nearly 20,000 people in Central America, and more than 4,000 people died during disastrous flooding in China. Bangladesh suffered some of its worst floods ever the following year, as did Venezuela. Europe was hit with record floods in 2002 and then a record heat wave in 2003.
    More recently, Brazil was struck by the first-ever recorded hurricane in the South Atlantic last March.
    "Weather records are being set all the time now. We’re in an era of unprecedented extreme weather events," said McCarthy, professor of biological oceanography at Harvard University.
    Historical weather patterns are becoming less useful for predicting the future conditions because global warming is changing ocean and atmospheric conditions.
    "In 30 to 50 years’ time, the Earth’s weather generating system will be entirely different." he predicted.
Ecosystem Impacts
    With global warming on the increase and species’ habitats on the decrease, the chances for various ecosystems to adapt naturally are diminishing.
    Many studies have pointed out that the rates of extinction of animal and plant species, and the temperature changes around the world since the industrial revolution, have been significantly different to normal expectations.
    An analysis of population trends, climate change, increasing pollution and emerging diseases found that 40 percent of deaths in the world could be attributed to environmental factors.
    The ongoing accumulation of greenhouse gases causes, increasing global warming. This is a global self-reinforcing vicious circle (恶性盾环) accelerating the global warming.
Rising Sea Levels
    Water expands when heated, and sea levels are expected to rise due to climate change Rising sea levels will also result as the polar caps begin to melt.
    The World Watch Institute reports that "The Earth’s ice cover is melting in more places and at higher rates than at any time since record keeping began". (March 6, 2000).
    Rising sea levels will impact many coastlines, and a large mass of humanity lives near the coasts or by major rivers.
Increase in Pests and Disease
    An increase in pests and disease is also feared.
    A report in the journal Science in June 2002 described the alarming increase in the outbreaks and epidemics of diseases throughout the land and ocean-based wildlife due to climate changes.
    One of the authors points out that, "Climate change is disrupting natural ecosystems in a way that is making life better for infectious diseases."
    The Guardian summarizes a United Nations warning that, "One in six countries’ in the world face food shortages this year because of severe droughts that could become semi-permanent under climate change."
    Drought and desertification (沙漠化) are starting to spread and intensify in some parts of the world already.
    If some of this does get worse, it is likely that the poorest regions and people are likely to suffer the most, as they would have the least resources at hand to deal with the effects.
Environmental factors attribute __________ deaths in the world.
选项
答案40 percent
解析 在Ecosystem Impacts中可找到答案。
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