Climate Change

The implications of climate change on the coastal environment are an issue which is currently at the forefront of coastal management. Through sea level rise, increased risk of flooding (from increased storminess), and the effects of coastal squeeze many of our coastal areas are increasingly subjected to greater rates of erosion and flooding. In the past ad hoc approaches to flood defence and erosion where adopted in an effort to protect effected areas from inundation and loss of land. Defences employed along one section of coastline constrained natural coastal processes and aggravated the risk of flooding and erosion in neighbouring coastal areas. In recent years a more sustainable approach to coastal management has been adopted. A number of strategies have been developed for the coasts and estuaries of England . These strategies are designed to meet the needs of flood management, through the development of a coherent strategy which minimises future pressures on the estuary development and addresses coastal squeeze issues in these environmentally sensitive area. The aim of these strategies is to ensure that the measures devised to facilitate the impacts of climate change will enable coastal processes to operate in a sustainable manner whilst reducing the risk of erosion and flooding induced by climate change.

The East Anglian coast is particularly susceptible to the effects of climate change. The East Anglian coast is rapidly loosing its sand to high energy coastal processes. The removal of this natural coastal defence places the cliffs, dunes and sea walls under even greater pressure. The hinterland of the East Anglian Coast is low-lying. In the event of a breach of sea defences, flood water would propagate quickly through the hinterland causing extensive damage to significant assets. The effects of climate change and the increased risk of flooding represents a substantial threat to these areas.

The development of coastal and estuarine strategies for East Anglia will ensure the most sustainable options for flood management are used to deal with the effects of climate change.

Sea Level Rise
Global sea levels rise and fall throughout time on an irregular basis in response to changes to the environment, which results in either an emergence (regression) or submergence of the coastline (transgression).

Changes in global sea level rise today have been attributed largely in response to changes in the worlds climate due to global warming, resulting in the phenomena becoming a major concern both globally and nationally.

However it should be understood that global sea level rise is not only attributed to the changing sea levels but also to vertical changes of the land brought about by geological processes that occur locally (isostatic adjustment).

Currently at a regional level, East Anglia is faced with a sea level rise of 4.5mm/yr and an isostatic adjustment (sinking of the land) of 1.5mm/yr, giving what is called a relative sea level rise of 6mm/yr, for the East Anglian coast.

This problem in East Anglia has arisen in response to events that occurred during and after the last ice age (which ended between 10,000 and 15,000 years ago), where large ice sheets covered much of central and northern Britain.

The huge weight of this ice pressed the land downwards as it advanced across the country. Once the ice began to retreat, the weight of the ice was removed causing the land in Scotland and Northern England, once covered in ice, to rise again. The land in Southern England however began to sink into the sea, this process is still continuing in both areas of the country today.

Climate Change
There is growing scientific agreement (Intergovernmental Panel on Climate Change) that human activities are having an impact on the world’s climate. The main cause is the release of Greenhouse gases (GHG's) such as methane and carbon dioxide, which help warm the atmosphere.

Global warming causes three main effects on our planet, which are and will continue to bring about changes to the environment in which we live.

Melting of glaciers and ice caps
One effect that climate change has is to warm up places that were very cold. The ice at the North and South Poles is starting to melt more quickly. As the ice melts, freshwater is released into the oceans and contributes to the volume of water.

Increased Storminess & Wave Activity
Climate change affects the weather. This may mean more stormy weather resulting in increased wave activity. One way in which waves form at sea is when the wind blows over the water. The energy in the wind is passed onto the wave and the wave moves in the direction that the wind is blowing. As the wave reaches the shore it will break against whatever is in its path. This could be a beach, a saltmarsh, mudflat, cliff or a sea wall, for example. The energy that is in the wave is then transferred to the shore.

Waves can be extremely powerful and can cause a lot of damage. The damage is called erosion and when we have big storms and powerful waves a lot of the coast can be eroded very quickly. We need to help the coast to stand up to erosion and many organisations work together to prevent the coast being washed away. Waves cause serious damage to flood defences and if large enough can over-top them causing flooding behind defence walls.

Thermal Expansion
If you imagine a kettle boiling, it is a very similar process, but on a much larger scale. As water is heated up the heat causes all the molecules of the water to move faster and collide. In the sea the water is nowhere near boiling, however imagine how much water there is in the oceans and seas. A very small increase in temperature will cause a slight increase in 'expansion' so the sea level will rise a little.

Taking into account The UK Climate Impacts Programme predicts,

• Increases in sea level rise around our coasts.
• Weather patterns will change to wetter winters and increases in storm strengths.
• This will increase wave height and frequency.

In summary the effects of climate change will mean a change in the weather that we experience and the environment that we live in.

Coastal Squeeze
Salt marsh and mudflats are both important habitats for wildlife, which are rapidly eroding in response to a process called coastal squeeze.

Coastal squeeze occurs as the salt marsh and mudflats become trapped between the sea walls and the rising sea. The seawall prevents these habitats moving upwards and landwards within the changing tidal frame and so become reduced in their extent.

The creation of salt marsh is very important from a flood management point of view as salt marsh significantly reduces wave energy.

The reduction of wave energy is important as waves are extremely erosive and are responsible for damage to flood defences, scouring of beaches and overtopping of sea walls. By reducing wave energy, the salt marshes allow for smaller defences further inland.

This reduces the cost of construction and hence reduces the cost to the tax payer. It also creates important amenity areas for the public, and wildlife havens for animals and plants thus helping us to meet legal targets set by the EU Habitats Directive regarding the replacement of intertidal habitat.