Freedom of speech is an achievement of the American people guaranteed by the American Constitution of 1787. This guarantee protects people from free thought and political criticism, but does not exempt people from being held responsible when they commit crimes in expressing themselves. For example, a person cannot be racist and justify this as free speech. Likewise, newspapers should publish their publications freely and based on facts and values, but in accordance with the democratic legal system, which will penalize acts considered criminal when necessary.
A push factor would be something like war or famine or something. A pull factor would be something like a job or new opportunity, its usually for financial reasons in my opinion. Hope this helped!
The greenhouse gas raises the temperature by trapping the earth radiant heat inside the atmosphere and warming also increases the accumulation of the atmospheric water and most abundant in the greenhouse gases. And this accelerates the greenhouse effects.