ISIS represents about the highest estimates 50,000 fighters, and likely nowhere near that. They've had about as many casualties throughout rounds of bombing as they've had members.
Insofar as ISIS is a threat, it is only because it might spark a regional or global conflict which would then involve powers with omnicidal capability. Aside from that, ISIS will trash the region and be connected to some horrible terrorist attacks, but will otherwise not do very much.
Global warming threatens every aspect of human life, everywhere.
It threatens billions of people who live near the sea or have their livelihood affected by coastal life. It threatens untold numbers of people who have their lives directly or indirectly connected to coral reefs. It will cause conflicts over everything from water to petrochemical resources. Mass exoduses of people poleward and upward will strain existing systems to handle refugees, likely to the breaking point.
Even very sanguine scenarios for global warming point to it being a catastrophic threat that will cost hundreds of billions.
The fact that, as of this writing, two-thirds of the respondents indicated that a loosely organized regional military threat is even in the same league as a global threat that will drive conflicts everywhere indicates that the priorities of many national media outlets are grotesquely askew.