For example, it could be the result of a reduction in the northward transport of heat in the Atlantic Ocean, possibly caused by freshening of the surface waters of the northern North Atlantic. Further investigation of this possibility is needed. But there is equally convincing, though equally speculative, evidence to suggest that there may be a link with global warming. While the link between Sahel rainfall and the temperature contrast across the equator is well-established, the evidence concerning the initial cause of the temperature contrast, whether that be natural or human in origin, must be considered circumstantial. Varying degrees of uncertainty surround the linkages between climate change and desertification and desiccation.
Further work is needed to clarify the relative role of the various factors.
Nevertheless, uncertainty should not be allowed to obscure the fact that there are intrinsic links that cannot be ignored. Flowchart showing linkages between desertification, climate change, management failure and related factors. The flowchart summarizes the complex links between the various factors considered in this article. The solid lines indicate causal relationships about which we can be confident. The dotted lines indicate relationships about which there is uncertainty with regard to their precise importance or even existence.