'Outrageous Waves: Global Warming and Coastal Change in Britain through 2000 years' by Basil Cracknell (Philimore and Co., Chichester:2005) was produced at a time when everything being published had to have a slant towards CAGW as the publishing houses seemed to think that otherwise they would not sell. Problem was that this just as likely caused as many people not to buy the book as buy it – so it was a negative policy. I purchased the book as I had an interest in coastal change – already possessing a couple of other books on the same subject. I wasn't disappointed.
CAGW alarmism explains the title of the book (publisher's priority) and the Introduction is an attempt by Cracknell to explain what global warming was all about (also most likely as a result of publisher pressure). He was a geographer and had collected a mass of data on the changing coastline of Britain over 40 years. He retired just as the CAGW storm was in maximum overdrive. How was he to get his lifetime's opus published. He had to embrace the new group-think. However, Cracknell is not into blaming rising levels of co2 as a result of fossil fuel emissions for the warming as he was aware there were other warm periods – as warm if not warmer than the 20th century. No, he was aware that during the last 2000 years there was a Roman Warm Period and Medieval Warm Period (even a Little Medieval Warm Period).
Sea level change, however, does not appear to coincide with warm periods – this much is obvious from his data. It follows on from warm periods and is squarely situated in cooling episodes. Cracknell, keeping the publishers happy (if not ignorant) suggests that sea level rise was as a result of the warm periods (an inevitable follow-on). Melting glaciers and reduced ice caps mean more water flows into the ocean basins. The Alps were ice free in the middle ranges during the Roman era so there is something to say for this view – but could melting glaciers account for a rapid rise in sea levels? The ocean basins are huge in comparison to the glaciers.
Was Cracknell right? Well, the Roman Warm Period was followed by the Romano-British Transgression (on both sides of the North Sea) which he dates roughly AD300-600. We might quibble at those dates but it is worth pointing out there was a very cold blip around AD260 – and another in the 6th century (both ends of the transgression). According to HH Lamb (quoted by Cracknell who regarded him as an authority) there is a time lag between the warming process and the rise in sea levels (which appears to be a reasonable point of view). The lag, he thought, was about 100 years. In contrast we may note the Roman Warm Period began after 200BC – so there was 500 years of stable sea levels prior to the rise.
Cracknell notes that in spite of a lengthy Medieval Warm Period (roughly 950-1200) few records of the coastline show evidence of sea flooding before the 13th century – and sea flooding was a common problem well into the 15th century (when the Little Medieval Warm Period kicked in). He delineates three major transgression events, dating them AD300-600, AD750-850, and AD1200-1500. It may be that the middle one should be 800-950 but that is not what he implies. However, the dating may be skewed by the AD750 event (an influx of C14 into the atmosphere as a result of a heavy CME overload or whatever) but that is neither here nor there as the major sea level changes followed the Roman and Medieval warm periods rather than the short lived Middle Saxon warm period (as he describes it). HH Lamb, he notes, also associated stormy weather in cool periods with sea floods – and tidal surges. This, according to Lamb, was entirely due to cooling (no wonder the CAGW crowd try and distance themselves from Lamb). Low Arctic temperatures can produce heightened thermal gradients – especially between 50 and 65 degrees north (leading to increased storminess). It is known that temperatures in NW Europe were distinctly cooler after AD300 – one only has to look at the archaeological evidence of a change in farming practises (and what was being sown and harvested). The higher sea levels at this time have been described by Steve Mitchell in the pages of SIS journals, and the most prominent part of the evidence was the higher tidal reach of rivers such as the Ouse, the Trent and the Thames (and early Christian churches stranded far from the modern sea shore in Scotland).