To really see the danger, you need to think about how just a little change in temperature is a pretty big deal. Last summer, a heat wave that killed off most of the grass in our yards and the local farmers were hit pretty hard by it. Many others crops were fine and we survived although wounded. What if this happened every season, around the world. Food shortages would be extreme among many other horrible problems. Nature is extremely delicate in terms of what mankind can do. We also rely entirely upon nature and are just as delicate.
There isn't much we can do to stop it until we find a perfect solution. We however can make tiny changes in our daily routines to prolong the effects. Get energy efficient light bulbs, turn off the lights, invest in properly insulating your home, and plant some trees.