By Laurence Peter BBC News 19 August 2015 From the section Europe
Italy has brought thousands of rescued migrants to Sicily
Migrant tragedy
Some 2,000 migrants have drowned in the Mediterranean this year, amid a surge in overcrowded boats heading for the coasts of Greece and Italy.
The flow of desperate migrants from Syria and North Africa hoping to reach Europe is already much higher than in the same period in 2014.
Germany, which receives by far the most asylum applications in the EU, is expecting 800,000 refugees to arrive this year.
How big is the migration challenge affecting Europe now?
The number of migrants reaching Europe by boat has risen dramatically this year, compared with the same period in 2014. The number arriving in Greece, in particular, has soared.
The EU's border agency said that almost 50,000 migrants had arrived on the Greek islands in July alone, most of them Syrians.
The number of migrants reaching Greece by sea had reached 158,000 by mid-August, according to the UN, overtaking the 90,000 who arrived in Italy by sea.
The majority heading for Greece via the eastern Mediterranean route take the relatively short voyage from the Turkish mainland to the islands of Kos, Chios, Lesvos and Samos.
Fifty thousand people arrived on the shores of the Greek islands in July
The voyage from Libya to Italy is longer and more hazardous.
Migrant deaths at sea this year passed 2,000 in August, the International Organization for Migration (IOM) reported. And of those, 1,930 died trying to reach Italy.
A shipwreck off Italy's Lampedusa island on 19 April took an estimated 800 lives.
So, more migrants - Syrians especially - are trying to reach Greece now, instead of risking the Libya route.
Since the beginning of the year some 340,000 migrants have been detected at Europe's external borders, Frontex says.
That compares with 123,500 in the same period last year.
One of the biggest surges happened on 6-7 June, when nearly 6,000 people were plucked from the sea and taken to southern Italy, in a major international operation.
Survivors often report violence and abuse by people traffickers. Many migrants pay thousands of dollars each to the traffickers, and robbery of migrants is also common.
Record numbers have been arriving on Kos and Lesvos, packed on to flimsy rubber dinghies or small wooden boats, putting a huge strain on local resources.
Mainland Greece remains a major transit point - many migrants travel up through the Balkans, hoping to reach northern Europe.
Another pressure point is Hungary. In July alone, 34,000 migrants were detected trying to cross from Serbia into Hungary.
Faced with that influx, Hungary has urged its EU partners not to send back migrants who have travelled on from Hungary. And it plans to fence off the whole border with Serbia.
Where do they come from?
The largest migrant group by nationality in 2015 is Syrians - followed by Afghans. Then come migrants from Eritrea, Nigeria and Somalia.
The vicious civil war in Syria has triggered a huge exodus. Afghans, Eritreans and other nationalities are also fleeing poverty and human rights abuses.
In Italy new migrants from Eritrea form the biggest group, followed by those from Nigeria.
But in Greece migrants from Syria are the biggest group, then Afghans, the IOM says.
Last year, some 219,000 refugees and other migrants crossed the Mediterranean, and at least 3,500 lives were lost, the UNHCR reports. In 2013 the total reaching Europe via the Mediterranean was much lower - about 60,000.
Back in 2011 the big challenge was thousands of Tunisians arriving on Lampedusa. Far fewer Tunisians are making the voyage now, but Lampedusa remains a migrant bottleneck.
Data from Frontex records detections of illegal entries - it does not include the many migrants who manage to get in undetected.
What is the EU doing about it?
In November 2014 Italy ended its search-and-rescue mission, called Mare Nostrum. It was replaced by a cheaper and more limited EU operation called Triton, focused on patrolling within 30 nautical miles of the Italian coast.
Aid organisations say the scaling down of the rescue effort has put more migrants' lives at risk.
After much argument EU leaders agreed to triple funding for Triton, to some €120m (£86m) - taking it back to the spending levels of Italy's Mare Nostrum.
In April EU leaders pledged to beef up maritime patrols in the Mediterranean, disrupt people trafficking networks and capture and destroy boats before migrants board them.
However, any military action would have to conform with international law. The chaos in war-torn Libya remains a huge problem.
Championing the rights of poor migrants is difficult as the economic climate is still gloomy, many Europeans are unemployed and wary of foreign workers, and EU countries are divided over how to share the refugee burden.
Why is Libya such a problem in the current crisis?
Fighting continues to rage between militias in Libya
Two rival governments are battling for control of Libya, and so-called Islamic State militants have entered the country too.
The chaos has given people traffickers freedom to exploit migrants, with inadequate intervention from the authorities.
The EU and UN hope that a political agreement can be brokered to bring some stability to Libya, but so far there are few signs of progress.
There is great reluctance to send in any European military force.
What has caused migrant numbers to rise?
The wars raging in Syria and Iraq are clearly big drivers of migration to Europe. Syria's Middle Eastern neighbours have taken in some three million refugees, while millions more are displaced inside Syria.
But many migrants also continue to make hazardous journeys from the Horn of Africa, often treated brutally by people traffickers and enduring desert heat and unrest in Libya, the main point of departure.
War has ravaged Somalia and Italian officials believe many of the migrants are genuine asylum seekers, fleeing persecution. In the case of Eritrea, it appears many are young men fleeing compulsory military service, which has been likened to slavery. Eritrea is blighted by political repression, human rights groups say.
Many Afghans continue to flee poverty and persecution in their country, as attacks by Taliban insurgents and criminal gangs remain widespread.
Are EU countries sharing the burden?
Rosarno, southern Italy: One of many migrant camps set up to handle the emergency
For years the EU has been struggling to harmonise asylum policy. That is difficult with 28 member states, each with their own police force and judiciary.
More detailed joint rules have been brought in with the Common European Asylum System - but rules are one thing, putting them into practice EU-wide is another challenge.
The Dublin Regulation is a core principle for handling asylum claims in the EU. It says responsibility for examining the claim lies primarily with the member state which played the greatest part in the applicant's entry or residence in the EU. Often that is the first EU country that the migrant reached - but not always, as in many cases migrants want to be reunited with family members, for example in the UK or the Netherlands.
There are tensions in the EU over the Dublin Regulation - Greece complained that it was inundated with applications, as so many migrants arrived in Greece first. Finland and Germany are among several countries that have stopped sending migrants back to Greece.
EU governments argued over a proposal to spread the burden of housing migrants, under a quota system. Eventually they agreed to take 32,500 asylum seekers from Syria and Eritrea over the next two years - that is, genuine refugees. But the original target was 40,000.
Another 20,000 refugees currently in UNHCR camps would also be transferred to the EU, but the details have not been decided.
What about EU migrants?
It is important to remember that huge numbers of EU citizens move from one EU country to another freely. They are also described as "migrants", but they are fully protected by EU law, unless they are fugitive criminals. Their status is quite different from that of non-EU migrants. In some EU countries, including the UK, they have become an issue because of pressure on social services and competition for jobs.
Most EU countries are in the Schengen zone, which has made it much easier to cross borders without having to show a passport or other papers.
How do migrants get asylum status in the EU?
They have to satisfy the authorities that they are fleeing persecution and would face harm or even death if sent back to their country of origin.
The ban on mass "push-backs" - also known as "non-refoulement" - is an EU principle. In some cases it has not been respected, however. Greece, overburdened with asylum seekers, has been accused of refusing to let in some groups of migrants.
Under EU rules, an asylum seeker has the right to food, first aid and shelter in a reception centre. They should get an individual assessment of their needs. They may be granted asylum by the authorities at "first instance". If unsuccessful they can appeal against the decision in court, and may win.
Asylum seekers are supposed to be granted the right to a job within nine months of arrival.
The number of asylum claims in the EU rose to 626,065 in 2014, up from 435,190 in 2013, the European Commission reports. The 2014 figure is the highest since a peak in 1992, though back then the EU had fewer member states.
In 2014 the number of applicants from Syria more than doubled compared with 2013, reaching 123,000. That was 20% of the total, and far above the next biggest group - Afghans, who accounted for 7%.
Migrants from Kosovo were in third place, just above Eritreans. Poor, marginalised Roma account for many of the migrants from Kosovo.
In 2014 asylum was granted to 163,000 people in first instance decisions - that is, nearly 45% of such decisions. Germany granted the most - 41,000 - followed by Sweden (31,000) and Italy (21,000).
