They boarded the boat in search of a better life for themselves and their families, the step that would finally get them to freedom and safety in Europe. But around midnight on April 18, as many as 800 migrants died when the boat capsized in Libyan waters in what the United Nations has called the deadliest month ever recorded for migrants fleeing by sea. There were 28 survivors.

Years of war, oppression and human rights abuses in countries like Syria, Libya, Eritrea and Somalia, are the main reason for the mass seabound exodus across the Mediterranean. 

Between January 1 and April 21 this year, 36,390 migrants, including children and pregnant women, entered Europe by sea, according to the United Nations refugee agency (UNHCR). While there has only been a slight increase on the number of arrivals during the same period in 2014, there has been a staggering rise in the number who are dying. In April of last year, 96 migrants died, while so far this month more than 1,200 migrants have died in the Mediterranean. In the five years since the Arab Spring uprising, Italy has consistently received the largest number of migrants each year, but the Southern European country is often just the first step on a journey to Northern Europe.

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This scale of mass migration hasn’t been seen since the aftermath of the Vietnam War, when more than 1 million Vietnamese refugees were resettled in Western countries, said Kathleen Newland, head of humanitarian protection work and co-founder of the Washington, D.C.–based Migration Policy Institute.

“You only have to look at the countries of origin of the people who are taking to these boats to understand the basic dynamic of it. The largest single group are people from Syria, which is entering its fifth year of civil war,” said Newland.

The Syrian migrants see no end in sight for their country’s brutal civil war and have likely used up most of their savings, said Newland. That kind of desperation is driving people to make a risky sea voyage in order to earn a living and put their children in school in a foreign, but safe, land.

Eritreans are the second largest group of migrants. A country with one of the most repressive governments on Earth, its young people are fleeing a life of indefinite conscription. While “national service” is supposed to be limited to 18 months, many serve for most of their lives.  

Others fled Afghanistan, Mali and Gambia. Increasing numbers are leaving Iraq and Newland predicts some migrants from Yemen will soon make the voyage away from airstrikes, shelling and a humanitarian crisis. While a small number are people who could be classified as economic migrants hailing from countries like Ivory Coast or Senegal, there’s “no question” that the majority are refugees, said Newland.

The smuggling enterprise across North Africa is extremely complex, with different sections of the routes controlled by different militias and tribes. Sub-Saharan Africans pay less to the smuggler—around $400 to $500— simply because they don’t have the means to pay more, but are subject to rougher conditions like being put in the ship’s hold and not be given life jackets, said Newland. Middle-class Syrians families are expected to pay more, into the thousands.

 A police officer holds an EU flag at the entrance of the European Commission office, splattered with red paint thrown by demonstrators to raise awareness for the deaths of immigrants in the Mediterranean, in Athens on April 23. Kostas Tsironis/Reuters

It’s cheaper to travel in the winter than in the summer, when the weather and seafaring conditions are better, and it costs less to travel in an unsafe rickety boat. While more people crossed the Mediterranean this winter than last, the death rate has been much higher due to a number of boat disasters involving vessels that each carried hundreds of people.

“The spike in April certainly comes from calmer seas and warmer weather, but what was unusual this year is that you didn’t see a quiet January and February, which you usually do. Starting in the Christmas season, the boats tend to dry up,” said Newland.

As the summer months beckon, more migrants will make the journey, mistakenly seeing safety in the calm seas and sunshine.

“We cannot wait for bad seas to stop migrants. Anyway, they will take a ship and come to Italy or Spain,” said Alfonso Giordano, professor of sustainable development and migration flows at LUISS Guido Carli University in Rome.  

Mare Nostrum, the Italian Navy’s year-long search-and-rescue operation that saved the lives of more than 168,000 migrants in just over a year, shut down last December and was replaced by Operation Triton. In its first two months Triton, an initiative of the European border agency Frontex, saved 11,000. It is under-funded and under-resourced and considered weak and inefficient, and it was never intended to be a search-and-rescue operation like Mare Nostrum. Commercial ships and private companies are increasingly stepping in to save lives and a reduced Italian Navy still responds to distress calls.

This year has already been particularly deadly. The 1,796 deaths occurring since the beginning of the year pushed European leaders to hold a meeting on Thursday to decide how to deal with the full-blown crisis.

The European Council released a 10-point plan of immediate action on Tuesday ahead of the meeting in Brussels. The plan includes reinforcing the EU’s maritime patrol operations and extending the area it covers, as well as fingerprinting all migrants and creating a pilot project on resettling refugees. All countries in Europe must share responsibility, said Giordano.

“This is not a problem for Italy, Spain [or] Malta, but a European problem,” said Giordano. “At the end of the day, the problem is for all countries.”

UNHCR welcomes the 10-point plan but wants to see a robust search-and-rescue mission like Mare Nostrum be reinstated, said Brian Hansford, spokesman for UNHCR. Establishing credible means to resettle in Europe, creating humanitarian visas and encouraging family reunification are also steps that can be taken.

But whatever Europe’s leaders decide during Thursday’s meeting, the top priority should be keeping people alive, says Hansford.

“We can’t simply let people die,” he said.