Book review: High Tide on Main Street

The additional tag line for this book, “Rising Sea Level and the Coming Coastal Crisis“, pretty much describes the story that unfolds even from the very early pages, although this book charts a somewhat different course, at least in the first half. With recent events such a Hurricane Sandy in mind, there is a tendency to focus on sea level rise as a short term or even “now” event.  But our descendants may see vast changes in the shape of the coastline and the viability of the great cities for hundreds and perhaps thousands of years to come as a result of the change in atmospheric CO2 that today’s society will hand on to them. That is what this book is really about.

HTOMS 

The author of this book, John Englander, takes the reader on a tour of the recent few million years, where sea level has shifted by tens of metres in response to relatively modest changes in global temperature and CO2 levels. These are changes that sit within the range that CO2 levels have moved in the last century  or are similar to the temperature swing that is expected to play out over the coming century (even the hoped for 2°C limit). Englander builds a strong case that rising sea level is the single aspect of the current warming that will profoundly impact civilization. This is a message that very few people really get, given the myopic view we tend to have on events.

We hear much about the current 3+ mm rise in sea level per annum and the forecasts of 0.3 metres to 1 or 2 metres change over this century, but according to Englander this is just the beginning. The slow changes in ice sheet coverage in response to small shifts in global temperature have caused sea levels to rise and fall by up to 100 metres. The last ice age saw sea level some 125 metres lower than today (for a 5 deg.C lower global temperature) and the warming peak during the previous inter-glacial some 125,000 years ago had sea level topping out some 8 metres above current levels. Estimates vary, but there is good evidence to indicate that sea level and global temperature move together at about 10-20 metres per degree C. It’s just that sea level, because of the size of the ice sheets, moves on a millennial rather than annual time scale and takes a very long time to equilibrate.

This is interesting material and Englander does a great job of sharing the evidence and explaining the dynamics, but fifty pages or so into the story and it starts to run out of steam. It’s not a difficult case to make with the wealth of paleoclimate data that is available, but once made that is pretty much it. The book then turns its attention back to this century and the remainder of the story looks at individual cities, immediate government responses (or lack of them) and threats to infrastructure, population bases and low lying countries. It is solid stuff, but not up there with the first half.

One interesting teaser is some speculation about mega-projects that may arise in the centuries to come, for example damming the Straits of Gibraltar to protect the coastline of the Mediterranean and Black Sea. Built across the shallowest part of the straits, such a project doesn’t defy imagination.

 Gibralter dam

Gibralter dam cross section 

The book is an interesting read and worth having a look at, if for no other reason than to better understand the real legacy that we may well be leaving our descendants.