Today it is not a scientific issue but a political one. The question can be answered from a humanitarian, security, logistics and many other points of view. From a business point of view, the question can be asked "what kind of answer the dear customer wants to hear?"
What kind of answer do You want to read? I can write You based on humanitarian, defence (of the refugees and of the incontry citizens as well), lor ogistical viewpoint. The other viewpoints are out of my scientific knowledge.
The humanitarian dimension also has two parts: the human rights of migrants and of citizens. Every human being has the same right to life as to safety and to all first and second generation human rights, because they are linked to the person's identity, not to citizenship, nationality or belonging to any group. It follows that the rights of every human being must be respected, whether in their home country, while traveling abroad or in the other state where they are authorized to settle. Settlement in another country must be authorized by that country, since the state must protect the same rights of those who have already lived there. There are countless examples in history that newcomers (migrants) to the country have violated the rights of those who live there (citizens), and that those who live there have violated the fundamental rights of migrants. In my opinion, this question can be found in the intensive and solution-oriented dialogue between the leaders of the parties involved (issuing and receiving countries and the migrant community).
Economic and financial crises, military crises and the growing climate crisis occurring in developing countries and the lowest income countries, advancing unfavorable climate changes and the effects of these climate changes, such as the more and more frequent droughts and pest infestations on farmlands, drying out wells, and soil sterilization, the decline in the biodiversity of natural ecosystems, etc., are key factors that will result in an increasing scale of international population migration. Therefore, it is necessary to develop social welfare systems for refugees, support in adapting to new realities, develop social solidarity, accept and tolerate other cultures and value systems, etc.
This is a very thorny issue. In my view, the EU is not doing enough to face this problem. I also believe that all the international communities should collaborate to curb the inflow of irregular migrants.