What do the Saudis care about global warming?
It would only make it easier to move through those northern parts of the Middle East, while they are establishing THEIR version of the Great Caliphate. There shall still be the struggle with Shi’ite factions, Iran mostly, but battles fought in warmer conditions are usually much more conclusive more quickly than those fought under really cold conditions.
Consider the US Marines being turned back by the North Koreans and the winterized Chinese Communist troops at Chosin Reservoir in 1950 and 1951, or the German Nazis crippled by the winter at the assault on Stalingrad, where the Germans finally surrendered in early 1943.
The advancing troops could have used a little “global warming” right about then.
I notice Egypt is not in the mix.
I think it’s mainly Sunni forces (much smaller than the figures given) preparing for a Shia-led assault.
And I don’t think the forces employed (other than from Jordan and Pakistan) are really ready to fight a first-class war.