Palaeofloods and global change

A great weakness of various international scientific initiatives in global change, earth-system science, and related hydrological assessment of flood hazards is their overemphasis on prediction from idealized conceptual models. The latter are abstract constructs made possible by rapidly increasing computer power but predicated upon often unverified and sometimes unverifiable assumptions. It is now realized that abrupt climate change and extreme events pose more of a global change hazard than do the mean climate phenomena predicted by global climate models (GCMs). For 20 years there has been an overemphasis on developing these models as the principal tool for dealing with threats to habitability of the planet. In contrast to unverified predictions of the future given by GCMs, palaeoflood data provide evidence of real-work cataclysms that people can understand sufficiently to alter their perceptions of hazards, thereby stimulating appropriate action toward mitigation. This issue is particularly important in the world's tropical monsoon areas, which are prone to especially extreme floods and high variability in their magnitude and frequency. These areas, which are inhabited by half of the Earth's human population, also have excellent sources of palaeoflood information, which comprise a natural archive that can appropriately stimulate productive hazard reduction.