QUES . Describe the causes and consequences of sea-level changes.

HINTS:

Sea-level changes:

Rising or lowering of sea level for a longer period[ not like tides] is called sea-level changes or Eustatic Changes. There are two types of sea-level changes:

1 . Sea Level Rise

2 . Sea Level decrease

1 . Sea Level Rise:

The following are the two major reasons for the sea level rise: (a) Isostatic adjustment of land and ocean
and (b) Global warming

(a) Isostatic adjustment of land and ocean:

Due to the overloading of glacial ice, large parts of the land sink into the ground, due to which the sea level rises.

Sea level rises because of the huge sedimentary deposition from continents by rivers or winds.

(b) Global Warming:

Global warming causes two major problems:

The melting of glacial ice increases the amount of water in the ocean, due to which the sea surface rises.

The increase in sea surface temperature leads to the thermal expansion of water leading to a rise in sea level.

Sea Level fall:

Sea level fall due to two major reasons: (a) Global cooling and (b) Upliftment of landmass

(a) Global cooling

In the Global cooling period, there is a reduction of insolation due to various reasons such as large-scale volcanic eruptions, or spread of space dust, or the reduction of Green Houses Gases; which leads to the thermal contraction of ocean water and the formation of glacial ices at higher latitudes; which cause fall in sea level.

Carboniferous and Pleistocene times was global cooling time.

(b) Upliftment of landmass:

The melting of ice glaciers on landmass also causes the sea level to fall as it releases the loads from the land; that causes the rising of the landmass and an apparent fall in sea level.

For example,

1 . Scandinavia is still rising due to the release of glacial ice.

2 . The formation of lofty mountains leads to an apparent fall in sea level.

Impact of sea-level fall:

A drop of 1 degree in global temperature results in a 2-meter drop in sea level.

There is an increase in the land area in the coastal areas.

Changes are seen in the erosion and deposition processes

At present, we are experiencing a global warming phenomenon, and the sea level rising.