Battle with the sea
result, and many smaller coastal communities have had to plan for total relocation.
Many low-lying islands, including entire countries such as Kiribati, are likely to be uninhabitable by 2100 due to ocean changes, but habitability thresholds remain extremely difficult to assess. Coastal areas, including most big cities, will need to invest heavily in coastal protection measures within the next few years to plan for the next few decades, the report says.
Land reclaimed from the sea is at particular risk, such as lowlying South Dunedin, and the Wellington CBD.
That means more sea walls, as in Nelson and Dunedin, but also dykes, surge barriers, early warning systems, and floodproof buildings. Even where that infrastructure already exists, much of it will need to be backed up or improved. Globally, that’s going to run up a bill of hundreds of billions of dollars a year.
For big global cities, many of which already have some form of coastal protection infrastructure in place, that might be a costeffective solution. But poorer areas, and rural ones with smaller populations, will find it harder to afford, and in many cases it is the very people with the highest exposure who have the least financial ability to adapt, either by moving or by building reinforcements.
The report urges that restoring coastal vegetation is crucial. Not only is it a carbon sink, but ecosystems such as seagrass meadows and mangroves are effective in providing storm protection and improving water quality.
While the sea is a looming threat, it could also be a solution. Azura, a device developed in
New Zealand, has the capacity to generate electricity from wave power. Oil rigs can be converted into offshore wind farms, and research into algae-based biofuels has been promising.
Victoria University of Wellington Professor James Renwick said the only guaranteed solution was ‘‘’unprecedented transitions in all aspects of society’’.
‘‘If the wholesale transition to renewable energy does not start by 2020, we will be well on the way to two degrees [Celsius] of warming and beyond. Such a warm future would bring serious disruption to global food security and water availability and would displace hundreds of millions of people. The economic and human costs are virtually incalculable.’’