The prophecy begins with the sounding of the alarm on the ram’s horn trumpet. Trouble is coming!
As in chapter 1, the reader is left to wonder whether the cause of the trouble is a real army or a swarm of locusts. Much depends on when Joel was prophesying.
If it was before the Exile in Babylon, Joel could well be describing a real army. If it was afterwards, when Palestine was part of the Persian Empire, then it could be a vivid way of depicting a locust swarm, but apparently locusts seldom come from the north when they attack Israel. Normally they come from the south.
When Joel talks about ‘a day of darkness and gloom, a day of clouds and thick darkness, like blackness spread upon the mountains,’ he makes it sound as though the air is thick with locusts. But when he says, ‘Fire devours in front of them, and behind them a flame burns,’ it sounds more like a human army.
Some commentators think farmers might have lit fires to ward off the locusts, but Joel could be describing a scorched earth policy designed to stop an invading army from living off the land. The army marches through and burns what little the retreating defenders have left. 'Nothing escapes.’ The countryside is ‘desolate’, like a ‘wilderness’.
Joel never says that the invaders are soldiers; instead he says that they’re ‘like a powerful army drawn up for battle.’ When ‘they leap upon the city, ...run upon the walls; ...climb up into the houses, [and] ...enter through the windows like a thief,’ they sound very much like locusts scurrying everywhere, a ‘vast’ and 'numberless’ host.
However, the most unsettlinging thing about this passage is that, whether Joel is describing an army rampaging like locusts across the land or a swarm of locusts devouring the crops like a huge army with cavalry and chariots, the Lord God is their general, coming ‘at the head of his army.’
This implies that whatever's happening, whether it's a human or a natural disaster, the nation is being punished for taking the wrong direction. This, we're told, is the consequence of hubris or false pride and conceit.
Perhaps the nation has made unwise alliances that provoked a military invasion. Or perhaps the locusts are seen as God's punishment for unethical, hypocritical or unjust behaviour. Either way, what Joel is describing is a lot like Brexit, a disaster that the people have brought on themselves.
But, Joel says, it's not too late to stave off complete disaster. “Even now, at this eleventh hour,” says the Lord,”Return to me with all your heart, with fasting, with weeping, and with mourning; rend your hearts and not your clothing.”
In other words, just going through the motions of being sorry won't be enough to avert disaster. The nation needs a genuine change of heart, a new beginning.
‘Return to the Lord, your God,’ says Joel. Then he quotes a famous saying from the Book of Exodus chapter 34 and Psalm 85, 'For [the Lord] is gracious and merciful, slow to anger, and abounding in steadfast love.’ They're words also borrowed by the writer of Job. Joel uses this text because he believes God always wants to ‘[relent] from punishing’ us. Mercy is his default position.
What we have here is a striking contrast. On the one hand we get a picture of a relentless God riding at the head of his terrible and ruthless army, intent on punishing arrogance and disobedience. On the other hand Joel pictures a God who might still ‘turn and relent, and leave a blessing behind him.’ So in Joel's view, all is never lost.
Nonetheless penitence is urgently called for. This is no time for taking a break. Young and old, even infants at the breast and couples getting married, must make repentance a top priority. And the 'ministers of the Lord must say, “Spare your people, O Lord, and do not make your heritage a mockery, a byword among the nations.”’
Those words seem particularly apt when, as one famous comedian put it, we live now in a country whose very name, 'The United Kingdom’, has become a joke. Even newscasters have concluded their bulletins in recent weeks with the words, 'People are laughing at us!’
Joel concludes his prophecy with an appeal to God himself, ‘Why should it be said among the peoples, “Where is their God?”’ As he’s already pointed out, God is longing to help us if only we will open our minds to his love.
One commentator says, ‘Despite the extreme crisis that [Joel sees unfolding around him], [he believes] it is still a time of choice.’  We often hear that we’re living in a constitutional and economic crisis but what the word ‘crisis’ really boils down to is a moment of decision. That's what the Greek word “crisis” actually means.
Even in a crisis, then, 'there remains room for disaster to be averted by ‘a return to the Lord,’ as Joel underlines with his phrase ‘Yet even now’ and his poignant question, ‘Who knows whether [the Lord] will not turn and relent?’
Of course, we face some pretty deep crises - nationally and globally. We’re always being warned that we’re at some tipping point or other beyond which there will be no opportunity to turn back, and that’s the same whether we’re talking about runaway global warming, a chaotic No Deal Brexit, or any number of other smaller crises. In the face of this, Christians are called to hold firmly onto the possibility of hope whilever it might still exist. For those who believe in the resurrection of Jesus, Paul points out that even death cannot take away all hope. And that means, also, that we must advocate the possibility of turning and relenting, back-pedalling perhaps, or at least moderating what we do in the hope of making any crisis less severe and intense. ‘Even now who knows whether the Lord will not... relent?’
 Maggie Guitte in Guidelines, The Bible Reading Fellowship, May 2017