Man-made or natural - climate change is real. The effects on the oceans is real. The effects on national security are real.
Regardless, humans CAN affect climate change through actions or inactions.
No, the world won't end in 12 years. However, if we don't take decisive steps in the very near future, we will have larger and more dire issues to resolve further in the future. Well, our children and grandchildren will have to resolve those, but the danger is still the same.
Are we going to pass the buck to our kids? Or do something about it now? An ounce of prevention is worth a pound of cure. Our time to prevent is running out.