“I WONDER whether in this situation it makes sense to remain within the European Union,” said Italian foreign minister Roberto Maroni recently, in a crude attempt to blackmail other EU countries into taking more of Italy's illegal immigrants.

But the time may come when Italy's northern neighbours will be quite happy to see Italy leave the Union. In fact, they may even close their borders with all the EU's Mediterranean members.

The current fuss has arisen because Italy, the closest EU country to Tunisia, was hit by a wave of Tunisian 'refugees' after the recent revolution there. They are not really fleeing from persecution and repression: the revolution largely ended that. They are economic migrants taking advantage of the fact that the chaotic new regime, unlike the Ben Ali dictatorship, no longer patrols the beaches to stop them from leaving for Italy.

Ben Ali had an unwritten deal with several EU countries to control the migrant flow in return for financial and diplomatic support. Since his regime collapsed in January, an estimated 25,000 Tunisian 'refugees' have flooded into Italy, mostly in boats that dump them on the shores of the nearby Italian island of Lampedusa.

This is profoundly unpopular in Italy, a country with a severe allergy to immigrants from the wrong parts of the planet. Prime Minister Silvio Berlusconi, who is currently fighting charges of bribery, abuse of power and paying for sex with underage girls, is certainly not going to defy that popular mood.

Indeed, Berlusconi is on record as saying that Milan “seems like an African city” because of the number of foreigners in the streets. (Actually, only four per cent of Italy's population are non-citizen foreign residents, and more than half of them are European.) So when Lampedusa was inundated with Tunisians, Berlusconi came up with a sneaky way of getting rid of them.

Most of the 'refugees' from Tunisia would rather be in France anyway, because many of them have relatives there and most of them speak some French. So Berlusconi's government just made it easy for them to go to France.

Early this month, Italy began issuing six-month temporary residence certificates to the Tunisian refugees. Once they were Italian residents, however temporary, they were legally free to go anywhere else in the Schengen group of countries, an area with no internal border controls. Most of the Tunisian refugees immediately headed for France.

Which is why, last Saturday, the French authorities began stopping the trains that normally cross the border from Italy into France without any identity checks. Now fast forward 30 years, and assume that the average global temperature is 2°C higher than it was in 1990. That's a reasonable assumption if there is not a drastic cut in global greenhouse gas emissions in the next 10 years.

This is a scenario in which not tens of thousands but millions of people are fleeing the drought-stricken countries of North Africa, trying to get into Europe. But it's also a scenario in which millions of Italians, Spanish, Greeks and citizens of other EU members in the Mediterranean take advantage of the Schengen rules on free movement to move somewhere cooler that still has enough food. Like France, for example.

Will France (and Germany and Poland and Sweden) let all these 'climate refugees' from the Mediterranean countries in? Not very likely, is it? And are strategists in the more northerly EU countries aware that this problem is coming their way? Of course they are.