Global Warming  is often viewed as a major negative, but there could be a few positive impacts. One positive may be the increase of productivity in the colder parts of the world as the temperature rises meaning growing seasons in places such as the Northeast United States could increase.  Another possible positive is the decrease in energy use towards heating since there would be warmer winters.

Global Warming has many major negative impacts.  One impact would be the 1 to 4 foot sea level rise by 2100, which would increase flooding around the world, specifically the South Pacific.  Although the amount of storms would not necessarily increase the severity of storms likely would.  Another negative would be the increase of rain in some areas which would increase flooding.  This goes along with drought would show up in more areas as well. All in all, the side effects of global warming are vastly more negative than the few positives.

http://climate.nasa.gov/effects/

http://www.ncpa.org/sub/dpd/index.php?Article_ID=23746

http://www.nytimes.com/interactive/2015/11/28/science/what-is-climate-change.html?_r=0