The central argument of the climate change paper we released today is that the right place to start an analysis of where climate change is going to hit hardest is by looking not at the places where climate will change most or fastest, but rather by looking at the places where vital systems are already stressed. These are the places where even a small amount climate change can potentially precipitate a collapse of the economy, the public health system, civil order, or all of the above. By contrast, places with resilient vital systems are likely to be able to accommodate mild change and even quite drastic change.
Consider the contrast between the Netherlands and Bangladesh. Here are two countries that, on the face of the climate evidence alone, would seem equally vulnerable to climate change: both are densely populated countries, at or below sea level, and at risk of violent storms. Yet Bangladesh is far more vulnerable to climate change, and the results of climate change, as they unfold, are likely to be much more dramatic there than in the Netherlands. How do we know that? We know not because the climate science has improved dramatically in its ability to forecast regional impacts of climate change in South Asia versus Northwest Europe. Rather, we know this because we know that the Netherlands's various vital systems -- communications infrastructure, public health system, water delivery system, food supply system, transportation infrastructure, public security, and so on -- are in much better shape than Bangladesh's. Although an acute, climate-change-driven weather event may impact any one of those systems in either country (and you can't predict exactly when or how that will happen), Bangladesh with its many stressed vital systems, is far more likely than the Netherlands to experience not only the failure of a single vital system, but also a cascading series of failures across vital systems. And we know this not by looking at the climate science, but by looking at the social science.
When Peter says that 60 to 100 million people may be displaced in the Bangladesh, he's not kidding. Check out this image from the LA Times:And the line on that map represents merely the place where the new permanent shoreline will be. Keep in mind that the water level will be far further inland during a big storm surge. When some Katrina-style typhoon roars in from the Bay of Bengal, the amount of land under water will be vastly greater. This is why Peter's estimation is not only not exaggerated, it's almost inevitably going to happen.
The next step is to imagine what a displacement of 60m people looks like. What kind of a humanitarian mission gets mounted? Where do the refugees go? Do the Indians let them in? Do they stay? How does the worldwide Muslim community react to the crisis? This is why a publication as sober as The Economist labels climate change one of the three greatest security challenges of the 21st century, alongside terrorism and failed states.