Just this morning I saw some tweets about how Global Warming is a "A marketable but mostly inaccurate name for something very very important." I fully agree. I would communicate the problem like this: The climate changes. Which is not a surprise because the climate always changes. Alas, it seems the direction the climate moves have dire consequences on humanity -- some places (affecting hundreds of millions at least) will have severe droughts and other places, like huge cities on ocean coasts might get flooded.