Good news, Mr. Gore, the Apocalypse has been postponed

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Within the first half hour of the film it is clear that Gore does not see global warming merely as a future threat. He states, ?Now we?re beginning to see the impact in the real world.? The example of this impact that made the biggest impression on me was that of Lake Chad in Northern Africa. Gore showed dramatic satellite images demonstrating the rapid shrinking of the once-giant lake to near dryness since the turn of the previous century. He suggested that this water shortage has brought on the conditions that have lead to the tragedy and mass violence in the bordering areas of Niger and Darfur. This made me listen. What would it take for a lake of such magnitude to dry up? The warming must be dramatic indeed. I decided to Google it.

The first site that came up was Wikipedia, where I learned that, indeed, Lake Chad is a critical water source for over 20 million people and its rapid shrinkage is extensively documented. At this point the surface area is about 1,350 km2, down from its all time high of about 400,000 km2 in about 4,000 BC. However, there were also some details that Gore failed to mention. The lake itself is only seven meters deep at its deepest. Its average depth currently is 1.5 ? 4.5 meters (depending on your source). Essentially, it is a large and geo-politically important swamp. For comparison, Lake Champlain covers approximately the same amount of land and has an average depth of 19.5 m and a max depth of 112. Lake George, with one-tenth the surface area, is almost nine times as deep. It turns out Lake Chad has actually been dry multiple times in the past: in 8500 BC, 5500 BC, 2000 BC and 100 BC. Though Wikipedia and a paper in Journal of Geophysical Research on the topic agree that global climate change may have played a role, they also report that the major factors were significant local changes ? a rapidly expanding population drawing water from the lake, the introduction of irrigation technologies and local overgrazing. Yes, these are anthropogenic causes, but they are neither global nor warming, and are utterly independent of CO2. In addition, Africa as a continent experienced a dramatic shift towards dryer weather in the end of the 19th century that is not generally attributed to CO2. (Coe, M.T. and J.A. Foley, Human and natural impacts on the water resources of the Lake Chad basin. Journal of Geophysical Research (Atmospheres) 106, D4, 3349-3356. 2001) Gore might as well have photographed a glass of water on a picnic table, called it a lake, drunk its contents and then attributed the change to global warming.