1 . Population and climate
The human population on Earth has grown to the point that it is having an effect on Earth’s atmosphere and ecosystems. Burning of fossil fuels, deforestation, urbanization, and cultivation of rice and cattle are increasing the concentration of carbon dioxide, nitrogen oxides and dust in the atmosphere. About 70 percent of the Sun’s energy passes through the atmosphere and strikes Earth’s surface. This radiation heats the surface of the land and ocean, and these surfaces then reradiate infrared radiation back into space. This allows Earth to avoid heating up too much. However, not all of the infrared radiation makes it into space; some is absorbed by gases in the atmosphere and is reradiated back to Earth’s surface. A greenhouse gas is one that absorbs infrared radiation and then reradiates some of this radiation back to Earth. Carbon dioxide and nitrogen oxides are greenhouse gases. In fact, without greenhouse gases in the atmosphere, scientists calculate that Earth would be about 33℃ cooler than it currently is.
The current concentration of carbon dioxide in the atmosphere is about 360 parts per million. Human activities are having a major influence on atmospheric carbon dioxide concentrations, which are rising so fast that current predictions made by scientists are that atmospheric concentrations of carbon dioxide will double in the next 50 to 100 years.
Some scientists predict that a doubling of carbon dioxide concentration will raise global temperatures anywhere between 1.4℃ and 4.5℃. The increase in temperature will not be uniform, with the smallest changes at the equator and changes two or three times as great at the poles. The local effects of these global changes are difficult to predict, but it is generally agreed that they may include alterations in ocean currents, increased winter flooding in some areas of the Northern Hemisphere, a higher incidence of summer drought in some areas, and rising sea levels, which may flood low-lying countries.
1. It can be inferred from the passage that one positive aspect of greenhouse gases is that they _______.| A．remove pollutants from Earth’s atmosphere and ecosystems |
| B．absorb 70 percent of the Sun’s energy |
| C．help keep Earth warm |
| D．double atmospheric concentrations of carbon dioxide |
| A．The rapid rise of atmospheric carbon dioxide concentrations is mostly caused by human activities. |
| B．Human activities will no longer have an influence on atmospheric carbon dioxide concentrations in the next 50 to 100 years. |
| C．Some scientists predict that atmospheric carbon dioxide concentrations will not increase in the next 50 to 100 years. |
| D．Some scientists recently predict that atmospheric carbon dioxide concentrations that are largely influenced by human activities will double in the next 50 to 100 years. |
| A．different |
| B．identical |
| C．comparable |
| D．changeable |
| A．Sea levels will fall. |
| B．The effects will not occur in some regions of the world. |
| C．The local plants and forests will be permanently damaged. |
| D．It is hard to know exactly what form the local effects will take. |
| A．Raising livestock and growing rice are the actions of humans. |
| B．The surface of the land and ocean can help decrease the temperature of Earth. |
| C．Although carbon dioxide concentration may double in the future, temperatures at the North Pole and South Pole may not change. |
| D．Nitrogen oxides absorb infrared radiation that can increase the temperature of Earth. |
2 . SYDNEY —Australian scientists have designed a system which uses microwaves to break down plastic into an environmentally friendly by-product.
Head of Electrical Engineering at Australia’s James Cook University, Prof. Mohan Jacob revealed on Thursday that by using microwaves, plastic waste can be converted into biochar(生物炭), charcoal that can be used as a soil conditioner.
“We are developing a processing room, which could process many kinds of plastic materials, up to 5 kilograms of waste,” Jacob said. “It will be a typical example system for the development of biochars from different types of plastics under various conditions.” Jacob explained that microwave energy is used to heat the plastic waste above 600 degrees centigrade within the custom-made room, where it ends up as a biochar, which can then be used to improve the properties of soil.
Currently underway is step one of the project, testing the room, after which, step two will involve improving the energy efficiency of the system and maximizing the yield of by-products. If all goes to plan, step three will be to construct a medium scale waste processing system which is customizable and can be installed remotely.
Jacob said that with the average person using 130 kg of plastic every year, there is an urgent need for developing better ways of processing it.
“Perhaps contrary to popular opinion, plastic is an indispensable material in modern life. It is cheap, competent, lightweight, and has many benefits like maintaining food quality and safety and preventing waste,” he said.
However, “abandoned plastics endanger our marine wildlife, and have begun to enter the food chain. There is an urgent need for developing technologies to recover plastic waste.”
1. How does the system function?| A．Microwaves are used to produce plastic. |
| B．Plastic waste is heated in the microwaves. |
| C．Plastic waste is cut into pieces and buried into the soil. |
| D．Microwaves change plastic waste into biochar by heating. |
| A．Plastic consumption now is acceptable. |
| B．Plastic should be abandoned in our life. |
| C．The system of processing plastic has come into use. |
| D．Finding better ways to deal with plastic waste is urgent. |
| A．Make up for a loss in time. |
| B．Find or regain lost possession. |
| C．Extract or recycle an energy source for reuse. |
| D．Return to a normal state of health, mind or strength. |
| A．3 steps of processing plastic waste. |
| B．A way of producing plastic products easily. |
| C．A new system of breaking down plastic waste. |
| D．A program designed for plastic use in the daily life. |
