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A Holocene History of Flooding in Great Britain
Macklin, M.G., Johnstone, E. and Lewin, J. 2005. Pervasive and long-term forcing of Holocene river instability and flooding in Great Britain by centennial-scale climate change. The Holocene 15: 937-943.

The authors state that "widespread and economically devastating flooding in Europe during the 1990s and start of the new Millennium has been linked to rapidly changing regional hydroclimates, primarily attributed to global warming [our italics]." But is this attribution correct? Their study was an attempt to answer this question by putting the recent past into "a more reliable longer-term and wider-scale context."

What was done
Macklin et al. "present the first probability-based, long-term record of flooding in Europe, which spans the entire Holocene and uses a large and unique database of 14C-dated British flood deposits," after which they compare their reconstructed flood history "with high-resolution proxy-climate records from the North Atlantic region, northwest Europe and the British Isles to critically test the link between climate change and flooding."

What was learned
The UK researchers determined that "the majority of the largest and most widespread recorded floods in Great Britain have occurred during cool, moist periods," and that "comparison of the British Holocene palaeoflood series ... with climate reconstructions from tree-ring patterns of subfossil bog oaks in northwest Europe also suggests that a similar relationship between climate and flooding in Great Britain existed during the Holocene, with floods being more frequent and larger during relatively cold, wet periods." In addition, they say that "an association between flooding episodes in Great Britain and periods of high or increasing cosmogenic 14C production suggests that centennial-scale solar activity may be a key control of non-random changes in the magnitude and recurrence frequencies of floods."

What it means
In terms of recent flooding in both Great Britain and much of the rest of Europe, it would appear that we ain't seen nothin' yet, especially compared to what occurred during cooler periods of earth's history, when the sun was less active than it is now and allowed more galactic cosmic rays to pass through the atmosphere and create more cloud condensation nuclei that led to more persistent clouds that reflected more solar radiation back to space (see Cosmic Rays in our Subject Index). Hence, it would appear that climate-alarmist claims of increased flooding in Europe and elsewhere in response to continued global warming are likely 180 degrees out of phase with reality, although two of sixteen episodes (12.5%) of increased Holocene flooding did in fact occur during times of lower 14C production when it was warmer. If another such flooding anomaly were to occur, therefore, it could be used to support the climate-alarmist contention that recent flooding has been warming-induced. However, the great bulk of pertinent data produced by Macklin et al. - as well as the host of materials archived under the heading of Floods in our Subject Index - argue strongly against that claim.

Reviewed 29 November 2006