Present emission trends are putting the world on a path toward 4°C warming within this century. The effects of such warming would not be evenly distributed around the world, nor would the consequences be simply an extension of those experienced at 2°C warming. A 4°C world would be one of unprecedented heat waves, severe droughts, and major floods in many regions, with serious impacts on human systems, ecosystems and associated services.
Projections for a 4°C warmer world show:
- A dramatic increase in the intensity and frequency of high-temperature extremes.
- Dry areas generally becoming drier and wet areas wetter.
- The extinction of entire coral reef ecosystems due to a 150% increase in ocean acidity.
- Sea-level rise of .5 to 1 meter by the end of this century.