Momentum is gathering pace to change the supply chain map of Britain, evinced by a switch to port centric logistics, but is a key factor being overlooked that could make the move disastrous without environmental preparedness? The economics of re-basing logistics parks to port vicinities look cogent. They can eliminate many return empty container trips and allow containers to be fully loaded, and so reduce transport costs and carbon emissions. But a new, insidious threat, incalculably damaging, beckons, albeit still hedged by uncertainties --- rising sea levels.
By the nature of coastal ports they must be at sea level but the port assets, like wharfs and dock cranes, can at least be placed high enough above high spring tide levels so as to make them unlikely to flood in the next 100 years. The problem is their hinterland. These areas around the new London Gateway terminal, due to open this November, Tilbury, further up the Thames, Felixstowe, Southampton and Portsmouth are all low- lying and mostly marshy. There is nothing much that can be done with existing ports, though where they incorporate huge logistics parks, like that at London Gateway, effective bunds may be needed to counter future flood risks and any future ports might need to consider substantially raised roads and railway banks that connect them to the inland sites so that they will not leave the ports marooned by flooding.
Is the risk from rising sea levels, however, strong enough to galvanise authorities around the world into more forceful and inevitably costly action? A look at the facts leaves little room for complacency. For 2,000 years global sea levels barely changed. Then they began to rise in the late 19th century as the Earth started to warm, helped by industrialisation and its consequences for CO2 emissions and other greenhouse gases. At an eighth of an inch a year sea levels are rising twice as fast as they were a few decades ago, and there is no comforting reason why this rate of acceleration should not quicken. Over the past century the planet's temperature has risen one degree Fahrenheit and the sea level by about eight inches. Only in last May the concentrations of carbon dioxide in the atmosphere reached 400 parts per million, the highest in three million years.
Clearly there is a need for a global effort to cut greenhouse gas emissions but even if we stopped burning all fossil fuels tomorrow the existing greenhouse gases would continue to warm the Earth for centuries, so future generations have been irreversibly committed to a warmer world and rising seas. Even so, that does not negate the case for more stringent gas emission controls because without them the future would be even more intolerable. It must be admitted that in the short-term scientists are still uncertain about how fast and how high seas will rise. Estimates vary between 23 inches and six feet by 2100 and the US Army Corp of Engineers recommends that planners consider a high scenario of five feet. But what is certain is that past estimates have been too conservative, and there is a joker in the pack. This is the huge Thwaites Glacier in West Antarctica, underpinned by a 2,000 ft undersea ridge, slowing its slide into the sea. If a rising sea allowed more water to seep between the ridge and glacier the latter could detach. Such a breakaway would be enough to raise sea levels by 10 ft.
To an extent, the damage is done, and a foretaste of things to come was New York's hurricane Sandy storm surge last year that inundated a defenceless city, killing 43 and leaving a US$19 billion bill. Many coastal cities are now at significant risk, including even those like London which have built hitherto effective barrages. If one uses a conservative estimate of a 20 inch sea level rise then according to the OECD estimates some 150 million people in the large port cities will be exposed to risks from coastal flooding, along with US$35 trillion worth of property. The consequences of doing nothing more effective than at present are too nightmarish to contemplate. Rapidly developing countries like China and India who are spending huge sums on military expenditure and who have the most to lose from rising sea levels should abandon such inessentials and redirect their revenues to meet the inevitable, natural calamities to come.