A think tank in Germany has played out five scenarios for the migrant crisis, with the best case being 1.8 million migrants entering the country this year and the worst case 6.4 million.

German think tank SAT from Freiburg has simulated what the flow of migrants headed to Europe might look like in several scenarios and none of them is a total halt to migration. Even if the European Union (EU) summit with Turkey succeeds they say the problem cannot be solved so easily.

SAT calculated five scenarios for German paper Die Welt of how they expect to see the migrant crisis develop in 2016. The best case scenario would see Germany take in 1.8 million migrants by the end of the current year and at worst they could see upwards of 6.4 million new arrivals. The CEO of SAT, Thomas Arzt, told the German paper: “There is no switch that lets one merely turn off the flow of refugees.”

The think tank believes that the governments negotiating with Turkey do not understand the scale and depth of the problem. The current negotiations, they claim, only look at a narrow part of the overall picture. The closure of migrant routes only causes new ones to form, in much the same way that water flows when it meets an obstacle. Other external factors may also cause migration from other parts of the world.

Scenario one is where the EU is able to make a deal with Turkey at the summit. The simulation sees that in this case there would still be 2.1 million migrants heading for Germany via new routes like the Caucus countries and Poland. The agreement also hasn’t solved the primary factor for Syrian migrants: the Syrian civil war. The estimate seems high but Arzt said that you always have to plan for the worst case in anything.

Scenario two is more optimistic and factors in the end of the current Syrian civil war. The results of 1.8 million people are slightly smaller but Arzt says that because it is likely the Balkan route would re-open if the Syrian war ended, migrants from Iraq and Afghanistan would still come.

The third scenario sees a closed Balkan route and many migrants merely changing course and going through Italy via Albania. The Albanian army is already preparing for this and have asked neighbouring countries to help them prepare for what they see as an inevitable advance of migrants through their borders.

Scenario four is more speculative but looks at what might happen if new conflicts arise in Africa. Nigeria especially could tilt toward civil war with the growing presence of Boko Haram and the terror threat they pose. Other African countries are in open conflict or on the verge of it like Chad, Sudan or the Congo. European Union border agency Frontex believes that this area is where many future migrants will come from. In total this scenario lists 3.7 million migrants.

The final situation envisioned by the think tank is the worst case. It imagines all of the African conflicts, continued migration from the Middle east and central Asia, and the total opening of borders that agitator groups like “No Borders” are calling for. This would see a gigantic 6.4 million migrants in Germany by the end of 2016, far more than the Federal Republic could ever cope with and likely a recipe for civil unrest.