Are heatwaves Present in the ocean?

High temperatures and heatwaves across the globe saw records broken in July 2023 on land and in the oceans. The oceans serve as the Earth's heat reservoir, absorbing substantial amounts of thermal energy as a result of their continuous interaction with the atmosphere. Under specific conditions prolonged periods of unusually high temperatures in the oceans are called marine heatwaves much like their atmospheric counterparts.These higher temperatures could be driven by increased heat input from the atmosphere. decreased heat losses from the ocean or the transfer of warmer water masses through currents Over the past two decades these events have become more prevalent and widespread, having been observed in various areas of the global ocean, in both regional and large scales, at the surface of the ocean and at depth

In particular, recent data shows the occurrence of marine heatwaves surged by 34 percent between 1925 and 2016. While the exact mechanisms triggering marine heatwaves vary from region to region. There are two primary factors. In some instances, the atmospheric conditions themselves play a pivotal role. During such episodes, stagnant air masses and prolonged high temperatures in the atmosphere conspire to heat the ocean's surface setting the stage for a marine heatwave event. This pattern was notably evident during a 2012 North Atlantic event, which saw one of the highest sea surface temperatures ever recorded.

In other cases, the main driver is the movement of ocean currents, which transport relatively warm water masses to new areas. When these warm masses converge in specific regions, they cause a rapid and abrupt increase in the sea's surface temperature. This was witnessed in the 2015 Tasman Sea (situated between Australia and New Zealand) event.

As the impacts of marine heatwaves reverberate across the globe, understanding the complex interplay between the oceans and the atmosphere is crucial for predicting the Occurrence of these extreme events. In the face of climate change, conserving and protecting our oceans becomes ever more critical. Therefore improving marine heatwave predictability is crucial to empower communities and ecosystems alike to adapt and build resilience. By better understanding the science behind marine heatwaves and taking collective action, people can work towards a more resilient and sustainable future for the oceans. (With inputs from agencies).

Picture Credit : Google

Is the color of the oceans changing?

The color of over 56 per cent of the worlits oceans larger than Earths total laut eganse, has changed significantly over the last two decades and human-caused dimate change is likely the driver, according to researchers

These colour changes, subtle to the human eye, cannot be explained by natural, year-to-year variability alone. Ocean colour, a literal reflection of the life and materials in its waters, in regions near the equator was found to have steadily turned greener over time, indicating changes in the ecosystems within the surface oceans.

The green colour of the ocean waters comes from the green pigment chlorophyll present in phytoplankton. the plant-like microbes abundant in upper ocean Scientists are, therefore, keen to monitor phytoplankton to see their response to climate change

The researchers from the Massachusetts Institute of Technology (MIT), US, and other institutes in their paper published in the joumal Nature, say that it would take 30 years of tracking chlorophyll changes before climate-change-driven trends would show, because natural, annual variations in chlorophyll would overwhelm those influenced by human activities.

In a 2019 paper, study co-author Stephanie Dutkiewicz and her colleagues showed that monitoring other ocean colours whose annual variations are much smaller than those of chlorophyll, would convey mom dear signals of climate-change-driven changes and that they might even be apparent in 20 years, rather than 30.

"It's worth looking at the whole spectrum, rather than just trying to estimate one number from bits of the spectrum." said lead author B. B. Cael of the National Oceanography Center. Cael and team then statistically analysed all the seven ocean colours recorded by satellite observations from 2002 to 2022 together.

To understand climate changes contribution to all these changes, he used Dutkiewicz's 2019 model to simulate the Earth's oceans under two scenarios-one with greenhouse gases and the other without them. The greenhouse gas model predicted changes to the colour of about 50 per cent of the world's surface oceans in under 20 years close to Cael's conclusions from his real-world satellite data analysis. "This trend is consistent with anthropogenic climate change"

Picture Credit: google

How do oceans play an important role in ecology?

Oceans cover more than two-thirds of Earth. Understandably, they play a vital role in keeping all life forms going. World Oceans Day (June 8-) just went by, reminding us that an important natural resource is in need of our urgent support.

The importance of ocean

Initially, our ancestors were nomads, moving from one place to another. However, they eventually started settling in one place invariably around waterbodies such as rivers, lakes, oceans, etc. For thousands of years, oceans have been the backbone of human survival. But for even longer, they have been inevitable for all life forms, from the tiniest to the largest. All living beings, even those on land, are directly or indirectly dependent on the ocean for their very existence.

We all breathe easy because all oceans together produce at least 50% of the planet's oxygen. Due to their sheer size, oceans distribute heat from the Equator to the Poles, regulating the world's climate. Without this, different regions will constantly experience only extreme weather. Marine life is a good source of food for both humans and animals the world over. In addition, some also have medicinal properties. Oceans are also crucial for global economy since they help in transport and tourism.

What is ailing them?

Oceans face several threats today. Thanks to global warming, our oceans are warming too. This affects marine life since many cannot survive warmer waters. When a few species struggle, they can affect others that are dependent on these species, and this can result in ecosystem collapse. Further, warming waters can increase sea levels, resulting in natural disasters. Human activities such as overfishing, plastics, polluted wastewater discharged into the oceans, etc. affect the natural balance in a marine ecosystem.

According to the U.N., "With 90% of big fish populations depleted, and 50% of coral reefs destroyed, we are taking more from the ocean than can be replenished." The U.N. calls for us to work together in such a way that we not just take less from the oceans but help these natural resources flourish.

The theme for 2023

The theme this year is "Planet Ocean: tides are changing". The United Nations will work with people from different walks of life - from policy-makers, indigenous leaders, and scientists to private sector executives, citizens, and youth activists to turn the spotlight on oceans.

What is the 30 X 30 target?

At the 2022 United Nations Climate Change Conference or Conference of the Parties of the UNFCCC, more commonly COP27, held in Egypt last November, as many as 112 nations took an important pledge. They promised to take steps for protecting at least 30% of Earth's land and ocean by 2030 to help curtail biodiversity loss and climate change.

Did you know?

  • The ocean is key to our economy with an estimated 40 million people being employed by ocean-based industries by 2030.
  • Oceans absorb about 30% of carbon dioxide produced by humans, buffering the impacts of global warming.

Picture Credit : Google 

Why was the Arctic Ocean, the smallest of all oceans, in the news recently?

The Arctic Ocean, which is the smallest of the world's oceans, lies close to the North Pole. Along with its marginal seas the Chukchi, East Siberian, Laptev, Kara, Barents, Greenland, and Beaufort, the Arctic Ocean has the least-known basins and bodies of water in the world's oceans due to its remoteness, difficult weather, and perennial or seasonal ice cover.

About four million people live in the Arctic region. Many of them are indigenous groups that have thrived in this harsh climate for hundreds of years. They rely mostly on the ocean resources for surviving this harsh climate and generate livelihood through these activities. Fishing, sealing, whaling, and other activities are their livelihood means. The U.S., Canada, Greenland, Iceland, Norway, and Russia all have territories that reach into the Arctic Ocean.

The Arctic Ocean is in the news these days because of its effects on global warming. Rising temperatures in the Arctic are expected to cause large amounts of fresh melt-water to enter the north Atlantic, an event that will possibly disrupt global ocean current patterns. This will lead to drastic changes in the Earth's climate. When the extent of sea ice diminishes and the sea level rises, the effect of storms (such as the Great Arctic Cyclone of 2012) on open water increases. Reduced sea ice also leads to increased human-animal conflicts. It will, for example, cause polar bears to search for new sources of food, forcing them to move into human territories. Since December 2018, the archipelago of Novaya Zemlya has been under a mass invasion of polar bears, and in February 2019, a state of emergency was declared there. Dozens of polar bears were entering homes, public buildings, and inhabited areas in search of food. All this led to the Arctic Ocean being in the news.

Picture Credit : Google 

What is the record held by the Mariana Trench?

The Mariana Trench is not only the deepest oceanic trench on Earth but also holds the two lowest points on the planet. This crescent- shaped trench is located in the Western Pacific, east of the Mariana Islands near Guam. The region around the trench is known for many unique environments, such as vents bubbling up liquid sulfur and carbon dioxide, active mud volcanoes, and marine life adapted to pressures 1,000 times more than at sea level.

The Challenger Deep, the southern end of the Mariana Trench, is the deepest spot in the ocean. The National Oceanic and Atmospheric Administration, in 2010, used sound pulses sent through the ocean and calculated the Challenger Deep to be 10,994 metres deep even though it was considered almost impossible to measure its depth. In 2021, pressure sensors were used to calculate its depth and it was discovered that the deepest spot in Challenger Deep was 10,935 m. The ocean's second-deepest place is also in the Mariana Trench. The Sirena Deep, which lies 200 kilometres to the east of Challenger Deep, is 10,809 metres deep.

Picture Credit :Google

What are the specialities of the giant kelp?

The longest species of seaweed is the giant kelp Macrocystis pyrifera. It is found near the Californian shore and in different parts of the world near the Pacific Ocean. The longest specimen that has been verified is 60 metres long but unofficial reports say that even longer specimens have been found.

They form large and dense kelp forests, which become habitats for a number of different marine species. They are often located in cold and clear waters, where they resemble tall grass although they are not part of the grass family. It is a type of brown alga and belongs to the large kingdom of Protista. Since kelp is not a plant, it does not have roots and obtains its nutrients from a structure called a holdfast by which it attaches itself to the rocky bottom of the ocean. But kelp are similar to plants by the fact that they use photosynthesis to harvest the Sun's energy and do not feed on other organisms to keep themselves alive. They are also one of the fastest growing species and are known to grow up to 60 centimetres in a single day when given perfect conditions. Strikingly, when the kelp reaches the sea surface, it grows horizontally and floats as large mats that shade the water column and the sea floor below it.

The kelps also become a source of nutrition once they decompose in the sea bed. Sea otters even use these giant kelps to avoid being floated away while they sleep.

Picture Credit : Google

What are the specialities of the Great Barrier Reef?

The Great Barrier Reef covers an area of 348,000 square kilometres, and is the longest and largest reef complex of the planet. In fact, this remarkable site is one of the seven wonders of the natural world. Located on the north-east coast of Australia, the Great Barrier Reef is home to a huge diversity of species and habitats. This ecosystem is intricately interconnected, making it one of the richest and most complex natural ecosystems on earth.

It is home to over 1,500 species of fish, 400 species of corals, and 4,000 species of molluscs. It also hosts 240 species of birds along with a number of sponges, anemones, marine worms, crustaceans, and other species. This giant marvel is also home to many endemic and threatened species listed by the International Union for Conservation of Nature (IUCN). These features make it a very popular tourist destination and thus contribute to the economic development of the country.

In order to safeguard and preserve the reef, it was declared as the Great Barrier Reef Marine Park in 1975, and the supervision of the park was handed over to the authorities of the Marine Park.

Owing to its significance in the ocean ecosystem, the Great Barrier Reef was added to UNESCO’s World Heritage List.

Picture Credit : Google 

WHERE IS THE HAWKSBILL TURTLE FOUND?

The hawksbill gets its name because its mouth resembles the sharp beak of a hawk. The turtle, which has a beautifully coloured and patterned shell, lives among the coral reefs of the Pacific, Indian and Atlantic Oceans. It can grow to about 1.14 m, more than half the length of a full-size bed, and weigh almost 70 kg.

Hawksbill turtles often nest in small numbers, and usually on remote beaches. The largest populations of hawksbills are found in the west Atlantic (Caribbean), Indian, and Indo-Pacific Oceans.

The largest nesting populations of hawksbill turtles occur in Australia and Solomon Islands. Approximately 2,000 hawksbills nest annually on the northwest coast of Australia and 6,000 to 8,000 nest annually in the vicinity of the Great Barrier Reef. The largest rookery for hawksbill turtles in the South Pacific Ocean is in the Arnavon Islands of the Solomon Islands, where approximately 2,000 hawksbill nest each year. Arnavon hawksbills have been heavily exploited for their shell for centuries, but two decades of conservation and monitoring efforts are showing encouraging signs of recovery. Around 2,000 hawksbills nest each year in Indonesia and 1,000 in the Republic of Seychelles. 

In the Atlantic, the greatest number of hawksbill nests are laid in Mexico, Cuba, and Barbados, but nesting occurs throughout the Insular Caribbean. The most significant nesting within the United States occurs in Puerto Rico and the U.S. Virgin Islands. Each year, about 500 to 1,000 hawksbill nests are laid on Mona Island, Puerto Rico and another 100 to 150 nests on Buck Island Reef National Monument off St. Croix. In the continental United States, nesting is rare and is restricted primarily to the southeast coast of Florida and the Florida Keys. 

In the U.S. Pacific, hawksbills nest primarily in Hawaii where 10 to 25 females nest annually on beaches along the south coast of the island of Hawaii and the east coast of the island of Molokai. This population may constitute one of the smallest hawksbill nesting populations in the world, but is the largest in the Central North Pacific Ocean. In the Eastern Pacific, approximately 700 females nest annually from Mexico to Peru.

Credit : National oceanic and atmospheric administration

Picture Credit : Google 

HOW ANTARCTIC FIN WHALE CAME BACK FROM EXTINCTION?

Often, within the pages of wildlife conservation stories lies that one spark, idea, or action that spawns dramatic positive changes. Here's one such story on how one decision has resulted in a huge impact, practically bringing back a key species from the brink of extinction.

The recent filming of southern fin whales in Antarctic waters thrilled scientists, researchers, and conservationsists  no end.  And, why not? It's a deeply encouraging sign that not only have these marine mammals returned to their historic feeding grounds but their numbers have increased too, albeit gradually. The species was earlier reduced to less than 2% of its original population, thanks to the usual suspect-unsustainable hunting for decades. And then came the whaling ban towards the last quarter of the 20th Century, positively impacting the course of the animal's fate over decades. Slowly but surely fin whales have rebounded; slowly because fin whales give birth to only one calf at a time.

Over the last few years, researchers have recorded a hundred groups of these whales, including large ones comprising up to 150 animals. "Using data from their surveys, the authors estimate that there could be almost 8,000 fin whales in the Antarctic area." Listed as "vulnerable" by the International Union for Conservation of Nature, fin whales have a tremendous impact on the environment. In fact, they are called "ecosystem engineers" because after consuming iron-rich krill, they excrete nutrients that help the "growth of tiny phytoplankton, the foundation of the marine food web". In addition, the increasing number of this marine mammal - the world's second largest animal-is also an indicator of the ocean's good health.

While other threats cannot be ruled out for these ocean giants, the "increasing numbers of southern fin whales is an encouraging sign that conservation measures can work".

Picture Credit : Google 

IS THERE UNDISCOVERED LIFE IN OCEANS?

So much of our oceans is still unexplored and remains a mystery. In fact, it is safe to presume we know more about the surface of Mars than about Earth's seafloors! But whatever  we little know of life in ocean depths is intriguing, fascinating, and incredible. The deep oceans are low on sunlight and plants but high on pressure, and yet, several creatures call this space home. Here's a glimpse of how they have adapted to life in unforgiving conditions.

Colours that help

 Since they dwell in open waters without plants or rocks to hide under to safeguard themselves from predators, many creatures benefit from disguise. Some of them are red. rendering them difficult to spot since red light does not penetrate those depths. Some others are transparent, again tough to spot. Many others are bioluminescent, a good tool to confuse predators.

Heard of sea snow?

Since ocean depths hardly have any plant, finding "live meal" is a tough task. Apparently, the duration between two live meals can be even up to three weeks for a marine creature! That's where marine snow or sea snow comes into play. When no live meal is available, the next best thing to turn to is the dead. Organic particles from the surface waters - disintegrated bodies of animals and plants, mingling with fecal matter-drift down in what is known as "marine snow".

What is chemosynthesis?

At the cracks between oceanic plates are hydrothermal vents - these are the hot springs on the ocean floor. These vents send out chemical compounds such as hydrogen sulphide. These chemical compounds are used for preparing food - much like sunlight is used in photosynthesis. This process used by microorganisms such as bacteria to create food (such as glucose), is called chemosynthesis.

Though humans still don't have a complete understanding of ocean depths, we're definitely leaving our mark there- and, sadly, not in a good way. With global warming, over-fishing, and pollution, we're changing the composition of the oceans they are acidifying, and hosting crustaceans with microplastics, as far deep as the Mariana Trench, the deepest location on Earth.

Picture Credit : Google 

WHY IS DENMARK'S BUBBLING REEF UNIQUE?

A dip in the waters in the Hirsholm islets off the northern shores of Denmark is like diving into a giant aquarium. Amidst the dazzling colours of its vibrant marine life, tiny bubbles from the seabed soar to the surface like clear blobs. The unique phenomenon is caused by the presence of methane gas. The gas was probably formed due to the microbial decomposition of plants deposited thousands of years ago under the sea. As the gas seeped up through funnels in the floor, chemical reaction with underwater microbes hardened the sand particles into sandstone structures. Water currents washed away the surrounding loose sand, leaving behind solid stone columns, arches and slabs, which became thriving hubs of plant and animal life. The methane constantly bubbles out through vents in these columns, resembling air bubbles in a fish tank. The site is an important centre of marine biology.

Picture Credit : Google 

WHY IS THE FORESTS OF THE MARINE WORLD UNDER THREAT?

A type of algae, kelp is crucial for thriving ecosystems the world over. However, kelp forests are shrinking. But, why? Let's find out

Most types of seaweed or marine algae grow along the coasts in shallow waters, where they can attach themselves to rocks, shells, or the sea floor. A root-like part called holdfast anchors them firmly and prevents them being washed away by strong waves or currents. A soft, flexible stem-like frond with outgrowths similar to leaves emerges from the holdfast. Though they carry out photosynthesis, algae are not plants as they don't have true roots, stems, leaves, or flowers. Marine algae can be green, brown, or red in colour. Red algae are delicate and feathery and prefer warm tropical seas. Small green algae are found everywhere in shallow waters. Brown algae called giant kelp grow in cool waters at depths ranging from 15 to 40 mt.

Extraordinary ecosystem

A kelp forest is one of the most valuable and productive: ecosystems on Earth. Kelp forests are found all over the world-the west coasts of North and South America, the southern tip of Africa and Australia, and off islands near Antarctica. In North America, kelp forests are found on the Pacific Coast from Alaska to California. A forest of kelp is home to a variety of creatures. They live and forage for food among its broad blades. The kelp provides shelter not only from predators. but also from storms. Mammals and birds that thrive in kelp forests include seals, sea lions, whales, sea otters, gulls, terms, egrets, and herons. Sea otters have an especially beneficial bond with kelp. Mother otters wrap their babies in kelp to keep them from drifting away while they go hunting. Adult otters also find the dense kelp canopies a secure place to snooze. The otters return the favour by eating sea urchins that dine on kelp. Kelp forests can shoot up in no time, growing up to 30 cm a day. Some species attain heights of over 45 mt!

Kelp farming is a big part of the billion-dollar global seaweed-farming industry. Kelp renders sea water less acidic. This enables kelp farmers to raise shellfish, which require low acidity. Kelp and mussels are grown on floating ropes, which also support baskets of scallops and oysters. One kelp farm can produce 40 metric tonnes of kelp and a million shellfish per hectare per year! As with other species of seaweed, kelp is used in many products,) including shampoos and toothpastes, as well as a wide range of foods such as salad dressings, puddings, cakes, dairy products, and ice cream. It is also employed in pharmaceuticals and in the manufacture of fireproof and waterproof textiles.

Urchin attack

The waters off the coast of northern California are home to lush forests of bull kelp. Since 2013, the population of purple sea urchins that feast on the kelp, has exploded, destroying almost 90 % of the kelp forest. Sea stars prey on purple urchins and keep their numbers in check. However, a mysterious disease killed off huge numbers of sea stars, leaving sea urchins to thrive. Sea snails (called red abalone) and red sea urchins, both of which are raised for meat and feed on bull kelp, died from starvation. Commercial red sea urchin and red abalone fisheries located on America's northwestern coast have closed down as a result.

Fact file

• Kelp forests are the ocean's lungs just as trees are the Earth's lungs. They absorb carbon dioxide and give out oxygen.

• Warming seas along the Australian coast have wiped out huge swathes of kelp forest.

•Extremely hot weather is harmful to kelp forests. Strong storms can wipe out large areas by uprooting the plants from the sea floor.

• There are 18 species of edible kelp, including kombu widely used in Japanese cuisine.

•Kelp is rich in calcium and Vitamin K.

Picture Credit : Google 

WHAT IS ZOOPLANKTON?

Zooplankton is an aquatic microorganism that drifts with water currents. It is one of the two types of plankton, the other being phytoplankton, a plant variety. Zooplankton and other small marine animals consume phytoplankton. They themselves become food for fish, crustaceans, and other larger creatures. As an intermediary species, zooplankton plays a crucial role in the aquatic food chain. As ocean waters warm, studies suggest zooplankton is travelling towards the Poles, which could end in an ecological collapse.

Body size has been defined as a "master trait" for plankton as it is a morphological characteristic shared by organisms across taxonomy that characterises the functions performed by organisms in ecosystems. It has a paramount effect on growth, reproduction, feeding strategies and mortality.One of the oldest manifestations of the biogeography of traits was proposed over 170 years ago, namely Bergmann's rule, in which field observations showed that larger species tend to be found at higher, colder latitudes

Zooplankton are generally larger than phytoplankton, mostly still microscopic but some can be seen with the naked eye.Many protozoans (single-celled protists that prey on other microscopic life) are zooplankton, including zooflagellates, foraminiferans, radiolarians, some dinoflagellates and marine microanimals. Macroscopic zooplankton include pelagic cnidarians, ctenophores, molluscs, arthropods and tunicates, as well as planktonic arrow worms and bristle worms.

Zooplankton is a categorization spanning a range of organism sizes including small protozoans and large metazoans. It includes holoplanktonic organisms whose complete life cycle lies within the plankton, as well as meroplanktonic organisms that spend part of their lives in the plankton before graduating to either the nekton or a sessile, benthic existence. Although zooplankton are primarily transported by ambient water currents, many have locomotion, used to avoid predators (as in diel vertical migration) or to increase prey encounter rate.

Ecologically important protozoan zooplankton groups include the foraminiferans, radiolarians and dinoflagellates (the last of these are often mixotrophic). Important metazoan zooplankton include cnidarians such as jellyfish and the Portuguese Man o' War; crustaceans such as cladocerans, copepods, ostracods, isopods, amphipods, mysids and krill; chaetognaths (arrow worms); molluscs such as pteropods; and chordates such as salps and juvenile fish. This wide phylogenetic range includes a similarly wide range in feeding behavior: filter feeding, predation and symbiosis with autotrophic phytoplankton as seen in corals. Zooplankton feed on bacterioplankton, phytoplankton, other zooplankton (sometimes cannibalistically), detritus (or marine snow) and even nektonic organisms. As a result, zooplankton are primarily found in surface waters where food resources (phytoplankton or other zooplankton) are abundant.

Just as any species can be limited within a geographical region, so are zooplankton. However, species of zooplankton are not dispersed uniformly or randomly within a region of the ocean. As with phytoplankton, ‘patches’ of zooplankton species exist throughout the ocean. Though few physical barriers exist above the mesopelagic, specific species of zooplankton are strictly restricted by salinity and temperature gradients; while other species can withstand wide temperature and salinity gradients. Zooplankton patchiness can also be influenced by biological factors, as well as other physical factors. Biological factors include breeding, predation, concentration of phytoplankton, and vertical migration.The physical factor that influences zooplankton distribution the most is mixing of the water column (upwelling and downwelling along the coast and in the open ocean) that affects nutrient availability and, in turn, phytoplankton production.

Through their consumption and processing of phytoplankton and other food sources, zooplankton play a role in aquatic food webs, as a resource for consumers on higher trophic levels (including fish), and as a conduit for packaging the organic material in the biological pump. Since they are typically small, zooplankton can respond rapidly to increases in phytoplankton abundance, for instance, during the spring bloom. Zooplankton are also a key link in the biomagnification of pollutants such as mercury.

Zooplankton can also act as a disease reservoir. Crustacean zooplankton have been found to house the bacterium Vibrio cholerae, which causes cholera, by allowing the cholera vibrios to attach to their chitinous exoskeletons. This symbiotic relationship enhances the bacterium's ability to survive in an aquatic environment, as the exoskeleton provides the bacterium with carbon and nitrogen.

Credit : Wikipedia 

Picture Credit : Google 

WHAT IS SEA LEVEL RISE AND WHY IS IT HAPPENING?

As our planet warms, oceans across the globe absorb a large portion of the heat generated. In the process, the water expands, resulting in universal sea-level rise. In addition, the rise is also caused by the melting of glaciers and icebergs. Usually such melting during warmer months and freezing during colder months is a natural phenomenon. However, with global warming, there's more of the former than the latter, leading to alarming sea-level rise, threatening to submerge several cities within just a few decades.

Why does sea level change?

Causes sea level to rise because water expands as it warms up; melting of the world’s ice sheets. A large ice mass, which flows over hills and valleys and occupies a large portion of a continent. The world has only three major ice sheets today (Greenland, West Antarctica, and East Antarctica).

 In Greenland and Antarctica;  melting of smaller around the world; and decrease in the amount of water held on land, for example, in groundwater beneath the land and in reservoirs above the land. Ocean warming accounts for around half of the observed change in sea level (this is often called “thermal expansion”), with the melting of thousands of small glaciers accounting for the other half of the increase in sea level. Since the 1800s, the melting ice sheets in Antarctica and Greenland have contributed relatively little to sea level change. But, these ice sheets are starting to melt faster due to global warming and may push sea level up much more in the future.

How much could sea level rise?

Because of global warming, the thermal expansion of the ocean and glacier melting will continue to play a role in the rise of sea level in the future . If all of the planet’s remaining as small glaciers were to melt, sea level would rise about 50 cm. The amount that thermal expansion can raise sea level in the future will depend on the continued warming of sea water. The largest possible contribution to sea level rise in the future comes from the world’s large ice sheets in Greenland, West Antarctica, and East Antarctica. If these ice sheets melted completely, the level of the oceans would rise about 7 m from the Greenland ice sheet, 5 m from the West Antarctic ice sheet, and 53 m from the East Antarctic ice sheet. This is why many glaciologists (scientists who study ice) focus on how Greenland and Antarctica are changing because of global warming.

How will sea level rise affect the countries of the world?

The effect of ice sheet melting on sea level is different across the world.

So, when the sea level rises, people will be affected in different ways, depending on where they live. The UK is used to occasionally dealing with rising sea level for short periods of time, particularly when there are storms at the same time as when the tides higher than usual. If the IPCC predictions are correct, we must consider the possible increase in sea level on top of natural tidal surges. This will cause dangerously high tides to occur more often in the coming decades, and these future tides might be more destructive than we are used to.

In farming regions near the coast, seawater flooding on land can contaminate the soils with salt, making them less able to support the growth of crops. The salty water may also get into underground stores of fresh water (known as groundwater), which is the source of important drinking water and also for farmers to grow crops.

In coastal cities, sea level rise will cause more flooding to houses, businesses, and while it may seem sensible to consider moving cities away from harmful floods, especially as we know it will likely happen in the future, our cities cost so much to develop that we are more likely to simply try to protect them from rising sea levels. A vision of our cities near the sea involves them with walls facing the ocean several meters high, with the street level of the cities themselves being below the level of the ever rising sea.

Credit : Frontiers for young mind 

Picture Credit : Google 

WHAT IS PELAGIC ZONE?

The pelagic zone is the open region of any lake, sea, or ocean that is away from any part of land, be it the coast or the sea floor. Marine life-from microscopic plankton and tuna to sharks - dominates this area. Due to the abundance of marine creatures, it is a critical space for producing oxygen, regulating climate, and economic activity.

Pelagic Zone Facts

The pelagic zone plays many critical roles that make it essential to life on Earth. Factors that make the pelagic zone unique include:

It covers more than 50% of the Earth in water, more than 3.2 kilometers (2 miles) deep.
It makes up more than 99% of the inhabitable space on our planet.
The deepest part of the ocean, the Mariana Trench, is about 11,000 meters (7 miles) deep.
The open ocean produces more than 50% of the world's oxygen.
It is a critical carbon sink, storing 50 times more carbon dioxide than the atmosphere.
Many of its inhabitants never experience sunlight.

The open ocean provides food, medicine, and economic opportunities for people worldwide. In addition to seafood, ocean harvests provide ingredients for foods like peanut butter and soy milk. Medications for Alzheimer's disease, cancer, heart disease, and arthritis use materials extracted from the ocean, and the United States alone produces $282 billion in ocean-dependent goods and services.

Layers of the Pelagic Zone

The pelagic realm is divided into five distinct regions based on average depth and sunlight availability. Moving from the surface to the ocean floor, the zones are labeled:

Epipelagic
Mesopelagic
Bathypelagic
Abyssopelagic
Hadopelagic

Sunlight, oxygen, and temperature decrease with depth while pressure increases. The organisms in each zone have adapted to live in these conditions.

Credit : Study.com

Pucture Credit : Google