In discussions of global warming, we often hear about the effects of a 2-degree rise in temperature or a 1-degree rise in temperature. For most of us, such changes seem pretty insignificant. Of course, in our daily lives, a one-degree temperature change is not particularly noticeable. But in the context of climate change, we are talking about a change in average temperature over time, not the temperature on a particular day or at a particular time.
The average global temperature is one degree Celsius above pre-industrial levels. There has long been a goal to limit global warming to no more than 2 degrees above those levels. But the Paris climate conference has set a more ambitious goal of limiting global warming to 1.5 degrees. What difference would that half a degree make?