degrees or more during this century, which might be dangerous. Melting polar ice could raise sea levels, while global warming might cause more intense storms and disrupt the weather patterns that bring rain to agricultural regions. Computer models are just a guess, of course, but when the farming areas that we all depend upon for food rely on current temperatures, rolling the dice (骰子) with the climate cannot be wise. Yet today the United States has no national law regulating greenhouse gases.

　　There are methods to reduce global warming. For instance, individuals can make lifestyle changes. Replace an SUV with a regular car; an SUV gives off 100 tons of greenhouse gases over its lifetime, which is far more than a car does. Moderate your use of home heating and air conditioning, most of which is powered by fossil fuels, and upgrade appliances to energy-saving models. Besides, emissions (排放) trading is a good measure. In 1990, rising levels of acid rain were considered an emergency problem. Congress passed an emissions-trading program, which allowed industrial managers to buy and sell permits to emit a limited amount of pollutants that cause acid rain. The acid-rain trading program created a financial motivation to invent technology to reduce acid rain; if a factory or power plant cut its emissions below the limit, it could sell the extra credits at a profit. Once there was money to be made by reducing acid rain, human creativity came into play. The results were spectacular.

　　 Stages of Environment 　　Present 　　Future 　　 We are faced with the greenhouse effect which causes global warming. And if all the people in the world don't 2. ________ in the fight against it, the problem can't be solved. If environmental trends continue in a positive way, there will be no 5. ________. The possible effects of global warming Possibilities The global temperature might 6. ________ by 5 degrees or more.