Change In Sea Level Definition: Long term changes in sea-level are brought about by Climate change. This not only affects the type of processes but also rates at which they operate.

How and why is the sea level changing? England and Wales are vulnerable to an increase in flood risk from a rise in sea levels and other potential changes in storm frequency and intensity. Over 8% of the land area of England are protected by river and coastal defenses. Two processes contribute to sea level rise as a result of global warming. As the temperature of the atmosphere increases: 1) ice on land will melt and run into the sea 2) total volume of seawater will expand The greatest effect is from this thermal expansion of the oceans as they warm. Sea level rise by thermal expansion will continue for many centuries after the climate has been stabilized because of the large heat capacity of the ocean.

Areas at risk of flooding in England and Wales

How and why is the seal level changing? The sea level is changing because there is expansion and contraction of ice sheets. The two different ways of expansion are: 1)Eustatic – this is where sea level changes are due to a hydrological cycle caused by water held in storage on land in ice sheets. 2)Isostatic adjustment – a more local change in sea level resulting from the depression of the earth’s crust by the increased weight imposed upon it by growing ice sheets. Isostacy - The balancing of the downward force of the Earth's crust and the upward force (buoyant force) of the Earth's mantle.

Features of emergent coastlines Raised coasts Common in areas that were glaciated during the last ice age. Several ports now lie several kilometres inland and now out-ports have had to be built as a result.

Continued : Coastal plains The most typical raised coastlines are lowlands or former coastal plains that emerged. As a result of emergence, a gently shelving smooth and wide coastal plain develops. Coastal plains form rich farming land as a result of the thick marine deposits that cover it. Offshore, in the shallow water, lagoons and offshore bars may be common. E.G. south eastern coast of USA

Continued : Barrier Islands Barrier islands are a natural sandy breakwaters that form parallel to flat coastlines. Between the islands which may extend several kilometres and the mainland is a tidal lagoon. Barrier islands make up 13% of the world’s coastline. They develop on coasts with relatively high energy waves and a low tidal range.

Features of submerged coastlines Fjords ~ they are located where glaciers were able to erode below sea level. ~when the ice has melted valleys surrounding them were flooded by the rising sea to form long, deep, narrow inlets with precipitous sides and hanging valleys. ~Example is North-west Scotland, Alaska, Norway, British Columbia in Canada and south island of New Zealand. ~ Description= Long, narrow inlets with high, cliff like sides, very deep except at the shallow entrance.

Rias During the ice age, when the ice melted and sea level rose the valleys cut by rivers and its tributaries were drowned to produced sheltered, windy inlets, called Rias. Description= Long, Winging inlets with low,gently sloping sides. They are generally shallow, with their depth increasing towards the sea. Examples= Parts of south-west england, Walse and Ireland, also Brittany in France and north-west spain. Fjards They are low land areas which have been glaciated and drowned.

Global warming The earth is being warmed by short wave radiation during the day from the sun During the night it is cooled by longer wave infrared radiation. We need a balance between these two. However, incoming radiation is passing out through the atmosphere but outgoing radiation is trapped by a blanket of trace gases. As they trap heat like a greenhouse, they are called greenhouse gases.

Continue…. Global warming During the twentieth century, global temperatures increased by 0.6ºc. A further increase of between 1.6ºc and 4ºc is expected by It has caused the sea level to rise by cm in the last 100 years. The Intergovernmental panel on climate change (IPCC) forecasts a further rise of 50 cm by These changes will increase the hazards of coastal flooding and erosion. 100 million people are living in low lying coastal areas and could be at risk.

Continue…. Global warming During the twentieth century, global temperatures increased by 0.6ºc. A further increase of between 1.6ºc and 4ºc is expected by It has caused the sea level to rise by cm in the last 100 years. The Intergovernmental panel on climate change (IPCC) forecasts a further rise of 50 cm by These changes will increase the hazards of coastal flooding and erosion. 100 million people are living in low lying coastal areas and could be at risk.

Response Miami, Florida, suffer hurricanes every 7 years. People have responded by spending 30 million pounds to make Miami beach hurricane proof. This includes a widen beach, evacuation routes, artificial mounds 6 metres above sea level for all new buildings. As Japan and Hawaii are prone to tsunamis they have developed seismographs to detect shock waves. These can be used to warn people of danger and so evacuation can take place.

Past, Present and future references This is not the first sea level change, it is occurring constantly all over the world. It usually occurs over long period of time. When there is a new change new cliffs and beaches are created.