Vox have just released an e-book entitled Secular Stagnation: Facts, Causes and Cures. The list of contributors is impressive - Larry Summers, Paul Krugman, Barry Eichengreen, Edward Glaesar, Nick Crafts, Joel Mokyr are just some of the authors. The book's summary is here. The workable definition of secular stagnation which emerges from the book is "that negative real interest rates are needed to equate saving and investment with full employment." The main concern of the authors is "that secular stagnation makes it harder to achieve full employment with low inflation and a zero lower bound on policy interest rates."
The Berkeley Earth Project , an independent study of global warming, has found that the earth has become a degree warmer over the past half century. However, the statistical uncertainty surrounding pre-1920 estimates makes it very hard to say much about long-term trends - click here for graph . This is one of my concerns with the global warming debate - we simply don't have trustworthy long-run data which looks at temperature changes over the last millennium (or two). My second concern with the global warming debate is that it is very hard to prove any sort of casual link between global warming and human activity. The scientists may be able to show correlation between global warming and our production of carbon dioxides etc., but correlation is not causation. My third concern with the debate is that those who are sceptical or agnostic are stereotyped as flat-earthers or intellectually-challenged crackpots. This only stifles debate and the progress of science itself.