Global stock markets and commodity prices have been on a downward trajectory over the past month. Why? Markets have been spooked by mixed economic signals coming from the US and more hawkish sentiment from central banks (interestingly central bankers have rowed back on this following the turbulence - click here). They have also been concerned by the state of the Eurozone, with even Germany entering the economic doldrums. The Ebola scare has even been blamed for the turbulence of the past few weeks. However, the greatest fear in financial markets is of a slowdown in China. A slowdown in China means a fall in demand for commodities (hence the fall in commodity prices) and a fall in demand for other goods and services (even university education!). Could China's debt-fuelled construction and economic boom be coming to an end?
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.