Feedback Loops

by Edward Hugh

Rising ocean temperatures in key hurricane breeding grounds of the Atlantic and Pacific oceans are due primarily to human-caused increases in greenhouse gas concentrations, this is the key finding of a study published online in the September 11 issue of the Proceedings of the National Academy of Sciences (PNAS). You can find a description of the study here, and an interview with study authors Benjamin Santer and Tom Wigley here.

Why is this news interesting for a blog like Demography Matters? Well quite simply because it shows that a feeback loop exists between human activity, climatic change, and the frequency of hurricanes. And hurricanes, as we know (from, eg, the dramtic case of Katrina) then go on to influence human behaviour, and so we go on.

And the best bet is that there is a tight link between demographic processes, economic growth and climatic change. These loops are extremely complex and unfortunately we have no class of models which even begin to address such issues.

I highlighted this question in an earlier post on some work by the biologist and ecologist Mercedes Pascual. The issue there was health, and how climate changes were affecting mosquito populations in East Africa. As Pascual suggests these changes are obviously implicated in the incidence of diseases such as malaria, and the consequent health impact may then lead to changes in both economic growth and fertility patterns. That the problem is an extensive one, and 'hard' to get to grips with (in the true meaning of hard problem), and that we are still light years away from understanding the compex processes involved I take as evident. As I said at the time, a good first step here will be to understand the demographic processes themselves (call this partial analysis if you will) and how they impact on (and are in turn impacted by) economic growth processes. This seems a 'doable' challenge, and would be a good first step to building out to a much broader class of models which might then begin to address the bigger questions.