Unit 4
Energy and Future
Listening and speaking
Listening
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1-4 F T F T
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1)concentration
2)blanket
3)humanity
4)enhanced
5)underground
6)cycle
7)methane
8)exhausts
9)melt
10)more extreme
Transcript
In the video we will learn how the burning of fossil fuels has added extra carbon dioxide to the atmosphere, and we will see how this leads to climate change, human-induced climate change, or global warming.
We need to understand something about burning fossil fuels. Fossil fuels, like oil, coal and
natural gas are the remains of the living things for millions of years ago. They’re mainly composed of carbon with varying amounts of hydrogen. If you collect all the exhaust gases from your car during a journey and squash them into a bottle so that they can be weighed, compared with the weight of petrol burned, the exhaust gases will weigh much heavier, because oxygen from the air has been added.
Here’s a bit of a petrol molecule ‒ H2CCH2. It joins with six oxygen atoms or three molecules to build up hydrogen oxide or water vapor and carbon dioxide, another two molecules.
Before the world became industrialized by burning fossil fuels, carbon dioxide concentration in the atmosphere was about 0.28%, tiny compared with oxygen at 21% and nitrogen at 78%, but enough to keep us warm. Without this natural blanket of insulating gas, the earth would be too cold to support life as we know it. But this carbon dioxide released when fossil fuels burn adds to the existing carbon dioxide levels which are now nearly 50% higher than in pre-industrial times.
Although we get a daily supply of heat from the sun, the earth normally loses this at night and in the cool seasons, so that the average temperature of the earth remains constant. But this status quo is starting to change. As humanity adds carbon dioxide into our atmosphere, it is as if we’re putting a sweater around the planet. The extra layer isolates the heat and it cannot escape as easily. While it’s easy to take off your sweater, the earth cannot lose its greenhouse gases as quickly, and we keep adding to them.
By putting our planet in a sweatbox, we’re causing wide-ranging consequences for our climate. Some people think that living things contribute to the enhanced greenhouse effect, as they breathe out carbon dioxide. But this carbon has come from their food, and that’s come from plants, which took carbon from the atmosphere.
Even burning wood doesn’t contribute to the enhanced greenhouse effect, as long as the trees you cut down are replanted. However, the carbon in fossil fuels has remained trapped underground for hundreds of millions of years, so it is extra carbon that’s been added to the natural cycle.
We’re also throwing away other gases into the atmosphere which help trap infrared radiation and so also enhance the natural greenhouse effect. They’re methane, especially from paddy fields and from cows, and nitrous oxide from car exhausts.
Why does this rise in temperature cause our climate to change? Well there’s extra energy trapped on (the) earth, already causing glaciers and ice caps to melt. With more energy in the atmosphere, weather becomes more extreme, so there are more floods, droughts, and storms. We have recorded record global temperatures at the start of the 21st century.
So in summary, we recalled that the natural greenhouse effect is a good thing and keeps the earth warm enough for life to exist. However, burning fossil fuels containing carbon that’s remained underground for hundreds of millions of years has extra carbon dioxide ‒ a greenhouse gas to the atmosphere. We have polluted the atmosphere with other greenhouse gases too such as methane. All these gases enhance the natural greenhouse effect and cause global warming and climate change.
Speaking
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1 Iceland gets 85% of the country’s electricity from the earth’s heat. Iceland’s electricity supply is 100% renewable and depends on geothermal energy and hydropower.
2 Stanford professor Mark Jacobson has concluded that US can meet its 100% of energy demand through renewables by 2050 through concentrated solar power, utility-scale and rooftop photovoltaic, onshore and offshore wind, tidal and conventional hydropower and geothermal wave.

Extensive rdeductibleeading
Integrated exercises
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1-5:        7 1 6 7 5
6-10:    3 2 5 6 4
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1)boom
2)reduced
3)cost-efficient
4)fuel
5)jobs
6)trade deficit
7)energy-intensive
8)diminished
9)Middle Eastern
10)get in the way
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