Factbox: Why does Europe have a migration crisis and how does it compare with others worldwide?

By Alex Whiting LONDON (Thomson Reuters Foundation) - A sudden surge in the numbers of people seeking refuge in Europe this year has European leaders grappling for answers to the crisis, and triggered both fear and compassion among European publics. Why have the numbers suddenly increased this year, how large is the crisis, and how does it compare with similar crises around the world? WHY ARE MORE PEOPLE COMING TO EUROPE THIS YEAR? Although the number of people making the dangerous journey by sea from Libya to Italy has not changed significantly, according to the International Organization for Migration (IOM), there has been a surge in numbers crossing the Mediterranean from Turkey to Greece - a much shorter and less treacherous journey. So far more than 250,000 migrants and refugees have arrived in Greece this year, compared with 34,000 in the whole of 2014, according to IOM data. The majority are Syrian. Other nationalities include Afghans, Albanians, Pakistanis and Iraqis. Many are fleeing worsening conflict in Syria, some have left squalid refugee camps in countries bordering Syria where this year the World Food Program had to halve the amount of food aid because of funding cuts. Syrians are now less likely to travel via Libya because of the deepening conflict there. The majority of those risking their lives to reach Europe via Libya are fleeing poverty, conflicts or oppressive governments in countries like Eritrea, Somalia, Sudan, Nigeria and Mali. Refugees have been forced to flee their countries because of war or fear of persecution, and have protection under international law. Migrants leave a country voluntarily to seek a better life. HOW BIG IS THE EUROPEAN CRISIS? Some 380,000 people have arrived in Europe by sea this year, according to IOM. Those arriving in Greece travel to northern Europe via Macedonia, Serbia and Hungary. The numbers are small compared with the nearly 4 million Syrian refugees hosted by Turkey, Lebanon and Jordan. Lebanon hosts 1.1 million refugees, making up around a quarter of the population. Turkey hosts nearly 2 million, and Jordan 630,000. The European Union is home to more than 500 million people, so the proportion of migrants and refugees to host population is also small. "This is not an emergency in terms of numbers," said Flavio Di Giacomo, spokesman for the IOM in Rome. "This is an emergency because of the way people are forced to arrive in Europe, putting their lives in the hands of smugglers and risking their lives at sea, and then walking through the Balkans in this terrible situation," he added. More than 2,700 people have died making the crossing this year - the majority of deaths occurred in the crossing between Libya and Italy. About 100 of them have died trying to cross from Turkey to Greece. HOW DOES IT COMPARE WITH OTHER REFUGEE CRISES? At the end of last year, there were some 19.5 million refugees worldwide, the U.N. refugee agency UNHCR said. About half of them come from Syria, Afghanistan and Somalia. Turkey hosts the largest number of refugees in the world - nearly 2 million. That's followed by Pakistan which hosts more than 1.5 million, Lebanon 1.1 million, Iran nearly 1 million, Ethiopia nearly 660,000, and Jordan around 630,000, according to UNHCR. Developing countries host the vast majority of the world's refugees - 86 percent of them - and nearly 6 million refugees have found shelter in countries with an average annual income of less than $5,000, UNHCR said. (Reporting by Alex Whiting, Editing by Ros Russell.; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, corruption and climate change. Visit www.trust.org)