Hundreds of millions of people exposed to increased water stress.Remember that these projections are based on IPCC AR4 (2007), which was a compilation of research up to the middle of last decade. A lot has happened in climate science in the last five or six years, and little of it has made the picture any rosier. Crucially, the above projections do not include a variety of feedback mechanisms that were not well understood at the time of publication. And there have also been advances in modeling likely impacts in some areas, notably, sea level rise, which is now thought to be between 0.5 and 1.5 metres by 2100. Of course, if our emissions are towards the upper end of the scenarios, then rises are also likely to be higher than 50 cm. However, I think that it is reduction in cereal production that could be the most significant effect geopolitically in the next few decades.
30–40% of species at risk of extinction around the globe.
About 30% of global coastal wetlands lost.
Increased damage from floods and storms.
Widespread coral mortality.
Terrestrial biosphere tends toward a net carbon source.
Reduction in cereal productions.
Increased morbility and mortality from heat waves, floods and droughts.
For a more up to date assessment of the state of the science, see the recent Australian Climate Commission's publication The Critical Decade, whose three chapters are helpfully summarised by Skeptical Science: one; two; three. Here is the concluding paragraph:
As you’ve read in this report, we know beyond reasonable doubt that the world is warming and that human emissions of greenhouse gases are the primary cause. The impacts of climate change are already being felt in Australia and around the world with less than 1 degree of warming globally. The risks of future climate change – to our economy, society and environment – are serious, and grow rapidly with each degree of further temperature rise. Minimising these risks requires rapid, deep and ongoing reductions to global greenhouse gas emissions. We must begin now if we are to decarbonise our economy and move to clean energy sources by 2050. This decade is the critical decade.Remember, we are not just talking about less ice or a few more days of sunscreen, the likely geopolitical consequences of our current path are dire. It doesn't have to be this way.