global warming

The global warming is one of the important issues nowadays. Global warming means that the temperature of the earth is increasing. One of the main reasons of temperature increase is the greenhouse gases. Before the twentieth century there was no increase in temperature, but in the middle of the twentieth century the temperature began to increase because of gases from the factories and cars. It is expected that the temperature over the next fifty or one hundred years will increase; the earth may be hotter than millions of years before. That means the global warming will affect the plants, weather, animals and humans, so why are we cutting down forests? Burning fuels? Although we know this is bad for our planet we still do the same thing. The results of global warming are sea levels are increasing and cities along the coast may be flooded. High temperatures may cause forests to die and food crops to fail.