The refugee crisis you refer to is actually the second Syrian refugee crisis.
The first refugee was an internal displacement of 1.5 million people (out of a population of 20 million) over the period 2007-2011 during crops failed due to unprecedented drought. Over two hundred villages were completely depopulated, and 40% of Syria's agricultural workforce was lost. Domestic wheat production crashed, and prices skyrocketed as it was replaced by imports.
So you had over a million hungry, unemployed displaced people crowded into cities, when a bad harvest in Russia caused a spike in global wheat prices. Check out the graph in this link labelled "World Monthly Grains Price Index" and note the massive upswing in prices in 2010 - 2011. There was a similar price spike in 2007, but back then Syria produced essentially all the wheat it consumed. In 2010 Syria only produced 80% of what it needed, resulting in underconsumption -- aka "starvation". You can check out the figures here.
Finally note that the so-called "Day of Rage" which critically destabilized the regime took place on March 15, 2011. The timing was not coincidental.
Now you can talk to me about "political struggle" in Syria. The roots of that struggle are of course decades old. But the effects were exacerbated by the worst drought in 900 years.
Without the sarcasm, try to stay on topic lest you continue to be perceived as a shithead Troll.
I have stayed on topic. Shithead troll I guess is a matter of perspective. Syria is exactly the kind of scenario security planners are worried about. And one reason they are worried is that many in the public literally find the idea of climate-driven refugees unimaginable. People who've been paying attention find it all too easy to imagine.