Wednesday March 21, 2018
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Rising sea level may become a serious threat in the coming decades

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By Nithin Sridhar

A latest study by NASA scientists using satellite data suggests that a rise of up to 1 meter in the global sea level may become inevitable. NASA scientists used a series of highly sensitive altimeters to measure the ocean height from the space.

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The study further reveals that there has been an average increase of 8 centimeters in the sea levels since 1992. Scientists add that the sea levels have been rising at a faster rate than they were half a decade ago and this rate is going to further increase over coming decades.

Previously, United Nations Intergovernmental Panel on Climate Change (IPCC) had predicted in 2013 that the sea level rise would be in the order of 0.3 to 0.9 meters by the end of the century.


If these predictions turn out to be true, then they may lead to serious disasters across the world. Let us try to understand why sea level rises and what are its likely consequences.

Why does the sea level rise?

A sea-level basically refers to the average level of the surface of water in the ocean. Many factors like ocean currents, ocean density, and water and ice mass exchange between land and ocean influence the sea-level. But, the major factors behind sea level rise are thermal expansion of water and melting of ice caps and glaciers.

Thermal expansion of water refers to the property of water to expand, i.e. increase in volume when there is an increase in temperature. Therefore, even a slight increase in temperature can cause a large increase in the volume of water resulting in sea level change.

The melting polar ice-caps and glaciers are another contributing factor. Melting of polar ice caps and glaciers during summer season is a natural phenomenon. This used to be more or less compensated by the re-formation of ice caps and the falling snow during winter seasons. But, the ever increasing global temperature has induced a rapid melting of ice during summer and a decreased falling of snow during winter. This has in-turn led to an increase in the net quantity of water in the ocean. This phenomenon has occurred even in case of ice-sheets of Greenland and West Antarctica. The ice-sheets are melting at a very faster pace with each passing year.

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One report on sea level change states: “Observations since 1971 indicate that thermal expansion and glaciers (excluding Antarcticglaciers peripheral to the ice sheet) explain75% of the observed rise (high confidence). The contribution of theGreenland and Antarctic ice sheets has increased since the early 1990s, partly from increased outflow induced by warming of the immediately adjacent ocean.

Therefore, global warming that leads to increase in temperature across the world (causing both increased thermal expansion and the melting of ice caps) is the main culprit behind sea level rise. In other words, all those human actions that contribute toward global warming and heat-stress also contribute towards sea level rise.

What are the consequences of sea level rise?

Increase in sea level may have wide change of consequences. Various small island nations and low-lying islands are especially at risk. For example, an estimate released by Copenhagen International Climate Congress has forecasted that many of the islands in the Maldives may get swallowed by the sea by 2100, making the whole country of small islands uninhabitable. Therefore, many low-lying islands are at the risk of getting completely submerged. Other Islands may face severe floods and storms as well.

The coastal areas across the world including India may face various risks. Increased sea-level may cause erosion of soil, increased risks of flooding, cyclones, contamination of agricultural soil, pollution of fresh-water sources etc. Further, people living along the coastline will face increased threat to their life and property. In case of India, sea-level increase may induce cyclones in Bay of Bengal and may cause severe damage to islands like Andaman apart from causing various damages along the coastal area.

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It is high time that the efforts at fighting global warming and climate change are escalated to prevent massive natural crisis that may result from climate change.

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Arctic permafrost may unleash carbon within decades: NASA

Plants remove carbon dioxide from the air during photosynthesis, so increased plant growth means less carbon in the atmosphere

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  • Permafrost in Northern Arctic can potentially become a permanent source of Carbon
  • It was previously thought to be safe from the effects of Global Warming
  • Rising temperature in the Arctic can cause severe carbon emissions

Permafrost in the coldest northern Arctic — formerly thought to be at least temporarily shielded from global warming by its extreme environment — could thaw enough to become a permanent source of carbon to the atmosphere in a few decades, warns a NASA-led study. This will happen in this century, with the peak transition occurring in 40 to 60 years, said the study.

Permafrost in Northern Arctic can become a permanent source of carbon in this century itself, according to NASA. Wikimedia Commons
Permafrost in Northern Arctic can become a permanent source of carbon in this century itself, according to NASA. Wikimedia Commons

Permafrost is soil that has remained frozen for years or centuries under topsoil. It contains carbon-rich organic material, such as leaves, that froze without decaying, NASA said in a statement on Tuesday.

As rising Arctic air temperatures cause permafrost to thaw, the organic material decomposes and releases its carbon to the atmosphere in the form of the greenhouse gases carbon dioxide and methane.

The researchers calculated that as thawing continues, by the year 2300, total carbon emissions from the coldest northern Arctic will be 10 times as much as all human-produced fossil fuel emissions in 2016.

Warmer, more southerly permafrost regions will not become a carbon source until the end of the 22nd century, even though they are thawing now, said the study led by scientist Nicholas Parazoo of NASA’s Jet Propulsion Laboratory in Pasadena, California.

That is because other changing Arctic processes will counter the effect of thawing soil in these regions.

The finding that the colder region would transition sooner than the warmer one came as a surprise, according to Parazoo. The researchers used data on soil temperatures in Alaska and Siberia and a numerical model that calculates changes in carbon emissions as plants grow and permafrost thaws in response to climate change.

They assessed when the Arctic will transition to a carbon source instead of the carbon-neutral area it is today — with some processes removing about as much carbon from the atmosphere as other processes emit.

World is under threat due to Global Warming. Wikimedia Commons

They divided the Arctic into two regions of equal size, a colder northern region and a warmer, more southerly belt encircling the northern region. There is far more permafrost in the northern region than in the southern one.

Over the course of the model simulations, northern permafrost lost about five times more carbon per century than southern permafrost.

The southern region transitioned more slowly in the model simulations, Parazoo said, because plant growth increased much faster than expected in the south.

Also Read: Global warming portends ill for India’s flourishing Dairy sector: Experts

Plants remove carbon dioxide from the air during photosynthesis, so increased plant growth means less carbon in the atmosphere.

According to the model, as the southern Arctic grows warmer, increased photosynthesis will balance increased permafrost emissions until the late 2100s. IANS