When you speak of the world coming to an end, it is important to clarify that the world will not cease to exist; it will simply undergo a radical change from what it presently is. This will begin to happen when Jesus returns to earth. He was asked about the signs that would precede His return in Matthew 24. His answer included the following: There will be much deception; there will be many wars between nations; there will be earthquakes and killer diseases all over the earth; and there will be severe persecution of true believers. He also indicated that a temple will be erected in Jerusalem. Just before His return, the earth will be pludged into utter darkness. In the past century we have seen more people killed in wars than in all previous wars combined. We have also witnessed a rapid increase in the number of serious earthquakes, only recently in Haiti and Chile. We have also seen that in spite of medical advances, killer diseases continue to spring up killing thousands. These are a few of the signs that we are witnessing today.
Keep in mind that Jesus called these signs 'birth pangs.' Like a woman in labor, the sign that something new is about to come forth is when the birth pangs become stronger and more frequent. As we see this happening, we will know His coming is drawing near.