Most of the refugees are not fleeing combat or other violence but poverty. There has been a recent surge that’s (finally) drawn attention but literally millions have fled poverty in Africa and the Middle East for years. That is why the Muslim population of Europe has become so large: in 2010, there were about 13 million foreign born Muslims in Europe (which excludes Turkey, of course, and those born in Europe). The number should look relatively familiar: it’s in the same ballpark as the Latino/Hispanic migrants come to the US and generally for the same reasons: poverty at home, lack of opportunity at home, sometimes violence at home. As I said, the latest surge has caught attention but this has been going on for years. There are a half million Muslims in Sweden and a few places, notably Malmo, are now over 20% Muslim.
Note the recent surge is not people fleeing violence now but, for reasons that are obscure, people who were already displaced. The reporting on this from the Middle East, meaning by local sources, indicates that factors involved include: a) belief that the various wars will continue (in Syria, Libya, Iraq), b) reports from people who have gone to Europe have been disseminated among family, clan, etc. and c) that there is a general sense that people can go to certain countries (notably Germany) and receive a lot of government support, including medical care and education and housing allowances. In other words, there is now little hope the situation at home will improve for a long enough time that people see more value in relocating. The picture I draw is a fairly classic information cascade in which people see x leaving so they also leave because what if Germany closes the doors and they get in but your family doesn’t? That seems to have put a large mental premium on acting now.
As to root causes, yes the US played a big part in destroying Iraq and I’d say we were extraordinarily naive and obtuse to believe a thin caste of Westernized Libyans, Syrians, etc. could take over their nations and lead them Western-style. That completely misunderstood the region, the cultures, the religion and pretty much everything else I could list. But in the end, Syrians have destroyed Syria. Libya has enough oil money to keep all Libyans relatively happy but they’ve only succeeded in wrecking the country and devolving into a somewhat more refined version of gang rule than Somalia.
(As an aside, we are so naive about other cultures we can’t even see that Russia, for example, has direct interests in keeping Assad in power: they face Sunni Islamist rebellions and terrorism inside Russia and its republics so the last thing they want is a Sunni-dominated Syria and, worse, a Sunni Islamist dominated Syria wanting to export that to Russia. That is a big reason why the Russians are selling to Iran: not Israel but Shia bulwark against the Sunni. So when people were talking about how we needed to support the Syrian rebels, the Russians heard that as a direct threat to their own internal security and propped up Assad and his allies. And now, I have to say do people doubt that weapons sent to the “Syrian moderates” would have ended up in Islamist hands? We have this weird idea that everyone is like us and that with just a bit of push that will all come out. It just isn’t the way the world works.)
If you look at economic figures, the Arab world - not counting oil states - was slightly better off than the Asian nations in the early to mid-1970’s. (Same is almost true, btw, of N. Korea versus S. Korea: they were about even.) Since then, these Asian nation have leaped ahead and the non-oil Arab world has quite literally stagnated. As a note, Syria was actually somewhat of an exception: it had decent public health and education systems, actually made an effort to incorporate Palestinians into the economy (as opposed to isolating them from work, from the health and education system as Lebanon has) and under Bashir Assad liberalized the economy somewhat and saw reasonable though not outstanding growth.
One can say something similar about a handful of countries in Africa - they were on a par with Asia and Arab states - but they actually slid backwards until recent years. There’s a chance that parts of Africa now have a reasonable economic future, but much of it is still a disaster by most measures. That’s why people leave.
It’s important to note that each country has its own connections to migrants. French migrants tend to come from French-speaking countries. Many came from Algeria, despite the memory of the civil war with France, because the self-inflicted violence there became unbearable, with large scale massacres in the 90’s scaring everyone. Now migrants from there are economic. British migrants have tended to come from Pakistan and other former colonial areas. German migrants were mostly Turk, which is one reason the information in that region about Turkey seems most well known. (Note that the 1998 Maastricht Treaty finally allowed Turkish Germans born in Turkey to become German citizens.)