In 2015, 193 parties signed the Paris Agreement. In doing so, they agreed to pursue efforts to limit the average global temperature increase to 1.5° Celsius - or 2.7 degrees Fahrenheit -above pre-industrial levels. To be clear, our planet is already 1.1 degrees hotter than it was 150 years ago. But most scientists agree that an increase of just .4 more degrees will drastically change the world. However, it would continue to be livable. Things do get murky, though, as the projections increase above that.