Have you ever stood by the sea and wondered at its never ending vastness? Now, behold that sight, because, few years later, you may witness a different sea --- one that would have further risen by a few inches and taken over a bit of the coast, caused a flood or two, displaced hundreds of people and overturned the marine ecosystem.

Sea level is rising – more rapidly than ever. In a report released in February, scientists have noted that Global sea level rose by about 5.5 inches, between 1900 and 2000. And the rise over the last two decades has been even faster, with the annual rate being 0.13 inches. This is twice the speed of the rise in the preceding 80 years.

According to a study, the oceans will continue to rise, given the current rate of warming, and it could be anywhere between 2.5 and 6.5 feet by 2100. The number may seem minuscule, but the impact can be irreversible.

The prediction for India is grim too. The Intergovernmental Panel on Climate Change (IPCC) has forecast that the sea levelsin India will rise at the rate of 2.4 mm a year and by 2050, the total increase will be 38 cm. In the ranking of countries that would be most affected due to sea level rise, in terms of population, India stands four.

Why is the Global Mean Sea level rising?

Sea Level Rise is an indicator of climate change and the primary cause is global warming. Oceans observe 80 per cent of the heat added to the atmosphere. As the sea water warms, it expands in volume. The melting of land ice (glaciers, ice caps, and ice sheets) due to increase in Earth’s surface temperature, also contribute to the rise.

Impact

The coastal settlements will be the first to get affected and even a small increase can have a destructive effect on the habitats. Sea level rise cause erosion and push salty water upstream in coastal areas. Coastal flooding will grow more frequent and damaging. Low-lying islands will be at the risk of getting submerged completely and storms can get powerful. All these can ultimately lead to displacement of thousands of people and loss of livelihood.

What can we do about it?

We are not in immediate danger, it can take a few decades to manifest. But the cause of the risk is happening now. Unless we do something about global warming now, a serious threat awaits us in the future. In the long term, if emissions continue to rise unchecked, the melting of polar ice caps can flood most of the world’s coastal cities.

The primary way to stop sea level rise is to cut emission of CO2, methane and soot. The main human activity that emits CO2 is the combustion of fossil fuels (coal, natural gas, and oil) for energy and transportation.

* Reduce fossil fuel combustion

*Reduce carbon footprint

* Save power, switch to energy efficient lights, appliances; turn off lights when not in use

* Use public transport/ walk or cycle

* Try to harness solar energy and other renewable energy

* Create awareness among others

How is sea level measured?

The sea level is measured using Tide Gauge and satellites.

Did you know?

The two ice sheets on Earth today cover most of Greenland and Antarctica.

Greenland’s ice sheet is melting faster than ever before.

There is enough water stored in the East Antarctic ice sheet to raise sea levels by 164 feet (50 meters).

In a nutshell

With the current rate of emission, the Earth could heat up to anywhere between 0.3 degree Celsius to 4.8 degree Celsius on an average during the 21st century. Burning of fossil fuels and cutting down of trees have increased the concentration of heat-trapping gases. The temperature rise has led to warming of oceans, their expansion and the melting of ice, adding water to the world's oceans and raising the sea level.

Activity:

1. In the one month that you are going to be at home during the summer vacation, try and keep all electric appliances switched off, whenever not in use. Get your parents' help to compare power consumption before and after this activity. Write to us about the experience at the end of the month at school@thehindu.co.in with the subject: Electricity.