Joel doesn't spend much time on this, but the future act of God in showering His Spirit on all His people is associated with portents of the end times:

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          I will show wonders in the heavens and on the earth,
                 blood and fire and billows of smoke.
          The sun will be turned to darkness and the moon to
                 blood
                 before the coming of the great and dreadful day
                 of the Lord (Joel 2:30-31).

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          And also:

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          The sun and moon will be darkened,
                 and the stars no longer shine (Joel 3:15).

         

Joel foretells a dual manifestation: God's Spirit sent upon the people, and natural catastrophes. The mention of "survivors" in Joel 2:32 means that there must also be casualties, people who did not survive.  The promise of deliverance points to the prior condition of widespread oppression.  We can infer that it is to be a time of suffering on earth, of chaos and torment, perhaps persecution, as well as natural disasters.

        

And yet, God is not only above the chaos of that age, He is in the midst of it, and active in history.  It is those very people who witness the signs and endure the suffering who will experience the Spirit in a powerful way.  The pouring of His Spirit upon them is not just a sign to console them, but it is to accomplish His purpose among mankind.  In the midst of the disorder, God is at work tearing down and building up.  What He is tearing down is the rule of the nations -- civilization, the political powers that rule the world, but oppose His purposes.  What He is building up is His kingdom among men, the fulfillment of His original promise to Abraham, to multiply his descendants as the stars of heaven, and to bless all nations through him.