Responses to climate change

It is widely accepted that, even with complete compliance towards current objectives in greenhouse gas emissions and strong steps towards future reduction, the changes which have already taken place in the atmosphere will continue to alter conditions in the oceans for many decades to come. These changes will be considerable, however there may well be management approaches, and technological efforts that could mitigate at least some of these impacts.
Changing temperatures. These have already begun to bring changes to ecosystems such as coral reefs, and may bring further changes to the distribution of fish-stocks. It will become increasingly important to track and even predict these changes so that management of fisheries and designation of marine protected areas will support the maintenance of stocks, allow for recovery, and perhaps even utilise new fish stocks in particular areas

Coastline defence UNEP/ Topham Picturepoint

Sea level rise. In urban areas, sea defences are a widespread solution to the threat of sea level rise. There are even cases of increasing land areas in places such as Key West in Florida where sea level rise has been combined with natural subsidence of the land, thanks to heavy and extensive land reclamation. Highly sophisticated barriers such as the Thames Barrier in London have already been erected in some areas. This barrier, built in 1983 at a cost of 530 million (then approximately US$840 million), has been lifted 1-10 times a year since its construction, during the highest tides, to prevent flooding in London. For the remainder of the year it remains lowered and allows shipping traffic. Across wider areas, the costs of coastal defence can be considerable, and one further response which is being considered in many areas is that of managed retreat or managed realignment of coasts. This is where the sea is deliberately allowed to flood into land areas where it was previously held back by sea walls. Under controlled conditions such flooding will support the development of salt-marshes (or mangroves in tropical regions) which are themselves highly efficient and protecting coasts from more rapid erosion. Apart from allowing the maintenance of areas of highly important and productive natural habitats, such realignment leads to substantial savings in the production and maintenance of sea walls.