Most discussions that involve global warming tend to focus on the amount that the sea level will rise. The thinking goes that if the polar ice caps melt it will cause the sea level to rise. Even a slight rise in the sea level will cause all sorts of problems that we will have to deal with.
Sea level is an important issue when it comes to global warming, but in the context of human security it tends to miss some important points. Placing too much emphasis on sea level causes us to focus on island communities and shorelines that will have to be evacuated and where the refugees will go. These problems would certainly be large, but in terms of human security the problem of rising temperatures will be much larger.
The image above from Cline, 2007 shows the projected changes in agricultural production in 2080 due to global warming. You can see from the image that regions that are in warmer climes will have drastic changes in their agricultural output. In many cases, agricultural production will decrease by as much as 50 percent. This will have a huge impact on human security.
There will be far less food available for people in warmer countries to consume. They will either have to import food from colder climates or migrate to other locations. The map above shows that the impacted areas will be home to the majority of the population of the world.
Wealthy nations should be able to handle the gradual shift in agricultural output. Poor nations that are located in warmer climates like those in Africa are going to have a very rough go of it. People in these developing nations will have to worry about food security as their primary issue. People in positions of power will use food to manipulate their countries.
The number of climate refugees due to rising temperatures will far exceed the number that have to evacuate islands and shorelines due to a rise in sea level. When looking at global warming we should try to focus on the biggest problems.