Global dimming is the phenomenon of the reduction of sunlight reaching Earth's surface. It's caused by the increase in sulfur contents in our atmosphere.
Global dimming is having a combination of affects with global warming. While global warming heats up the atmosphere, global dimming cools down the atmosphere. So in effect, they're affect cancels out each other. While this is a fact, it is not necessarily a good news. Global dimming actually reduces the amount of sunlight reaching the surface. This means our plants will get less light for photosynthesis, and make us produce less food.