Since 19th century, human has been changing the earth continuously. They began to use various energies to server themselves. The most important application is electricity. If the electric power is cutted, wo even couldn't do anything. Air conditioner, fridge, wash matchine, computer and oven all need electric power. We use coal,water power,wind,biology and nuclear power to generate electric power. Generally, when we convert a power to another power, the efficiency is not perfect, we will lose some energy. Most of the lost energy is changed as hot energy. So when we touch the machine used electric power, we can feel it's hot.
Except electric power, we also use another kind of power, that is chemical power. We can get it by burning coal and oil. This power is used broadly. For example, the car, the plane and some other traffic tools. But when we generate the chemical power, there will cause lots of waste gas. Some kind gases in the waste gas can let earth become a greenhouse. Then we generate a mass of hot energy but these greenhouse gases prevent it to run away to the universe. The hot energy stays at our planet, and the temperature becomes high little by little.
Now the global warming is obvious, the ice of the south earth pole is melting little by little, the drought and the hurricane appears more and more. Each person can feel the earth is warming now.
Now the big energy countries start to decrease the greenhouse gas releasing and increase the efficiency of power conversion.For example, we use water power, wind, nuclear power to generate electric power as much as possible, but not use coal and oil. Each people has the responsibility to protect our home.