Water staircases in seas:-
Internal waves, which move vertically through the ocean, can sometimes pass through “water staircases,” which are steplike variations of density of water, in such as manner as to churn up the underlying warm, salty water, thereby increasing the temperature of the top, cooler layers. This suggests a possible mechanism by which the upper layers of the Arctic Ocean warm up, causing the ice to melt.
Water staircases are steplike variations of density of water due to steplike changes in temperature and salinity. Though internal waves exist where the density gradually increases with depth, they cannot propagate where the density is uniform, for instance, within the steps of the staircase.
Ocean warming
The Arctic Ocean has inflows coming from the Pacific Ocean and Atlantic Ocean. In this, the top layers consist of cooler and less saline water and below that is a layer of water coming from the Atlantic Ocean which is more saline and warmer, too. The effect of salinity wins over that of temperature and so, though the water below is warmer, it is heavier than the cooler, less saline layer on top..
“Warm, but salty water — ultimately originating from the Atlantic Ocean resides near the bottom of the Arctic Ocean. If turbulence could somehow mix this water with that above, then, eventually, the surface could warm more rapidly, and this would increase the rate of sea-ice melt.
The internal movement of water within seas from cold, dense regions to warmer, lighter ones constitutes the largest observable waves. These can stretch to wavelengths of over a hundred metres and travel from top to bottom.
Like normal water waves, these propagate due to a variation of density of the water and not when there is constant density. In a staircase-like formation, though the density is constant within the step, there is a jump in density from one step to another. Hence, the wave’s energy can be transmitted from one interface to another.
Though not predominant, thermohaline staircases do occur in many places. “As well as the Arctic, they are persistent in the Caribbean Sea. This is due to surface heating and evaporation resulting in warm salty water overlying colder fresher water. They do not exist where there are strong currents, as in the Antarctic, which have enough energy to stir up any staircases that might form.
Selective filtering
So the scenario is that when an internal wave strikes a density staircase, a part of its energy may be transmitted through the staircase. In other words, density staircases in the ocean can act to reflect short wavelength internal waves and transmit longer wavelength waves. This is analogous to the selective transparency of glass windows on modern buildings that have multilayered coatings designed to reflect red light (long wavelength light) and allow green-blue (shorter wavelength) light through
On reaching the ocean floor, the long-wavelength waves which have been transmitted cause turbulence and mix up the water. The warm waters then rise to the top and warm the top layers.
“Strong storms passing over the Arctic typically generate waves on the order of 10-100 km horizontal scale. As sea-ice retreats and storms passing over the increasingly non-ice-covered ocean generate more and more waves, it seems that still a substantial fraction of this energy can transmit to depth, and this may consequently cause mixing at depth that could bring those deep warm (but salty) waters closer to the surface. The filtering that my theory predicts suggests that the energy transmitted to depth might be moderately smaller than one would expect in the absence of density staircases. But, for the most energetic waves — those transmitted by storms — the decrease is not substantial.
40 million Indians at risk from rising sea levels: UN report
Nearly 40 million Indians will be at risk from rising sea levels by 2050, with people in Mumbai and Kolkata having the maximum exposure to coastal flooding in future due to rapid urbanisation and economic growth, according to a UN environment report.
The ‘Global Environmental Outlook (GEO-6): Regional Assessments’ said the worst impacts of climate change are projected to occur in the Pacific and South and South-East Asia.
It said focussing on the population at risk from sea-level rise by 2050, seven of the 10 most vulnerable countries worldwide are in the Asia Pacific region.
India tops chart
India tops the chart with nearly 40 million people in the country projected to be at risk from rising sea levels, followed by more than 25 million in Bangladesh, over 20 million in China and nearly 15 million in the Philippines.
It said changes in settlement patterns, urbanisation and socio-economic status in Asia have influenced observed trends in vulnerability and exposure to climate extremes.
The report said in many coastal areas, growing urban settlements have also affected the ability of natural coastal systems to respond effectively to extreme climate events, rendering them more vulnerable.
“Some countries, such as China, India and Thailand, are projected to face increased future exposure to extremes, especially in highly urbanised areas, as a result of rapid urbanisation and economic growth,” it said.
It listed Mumbai and Kolkata in India, Guangzhou and Shanghai in China, Dhaka in Bangladesh, Yangon in Myanmar, Bangkok in Thailand, and Ho Chi Minh City and Hai Phong in Vietnam as projected to have the largest population exposure to coastal flooding in 2070.
The report, published ahead of the UN Environment Assembly taking place in Nairobi next week, said the worst impacts of climate change are projected to occur in the Pacific and South and Southeast Asia.
In 2011, six of the ten countries most vulnerable to climate change worldwide were in Asia and the Pacific.
On coastal areas highly exposed to cyclones and typhoons, the poor tend to be more exposed to natural disasters because they live on land open to hazards.
Combined impact
Evidence suggests that climate change and climate variability and sea-level rise will exacerbate multi-dimensional poverty in most developing countries.
By 2050, areas of storm surge zones are expected for Bangladesh, China, India, Indonesia, and the Philippines, with a combined total of over 58 million people at risk.
The UN report further said global urban populations are projected to increase by 2.5 billion by 2050, with nearly 90 per cent of the increase in Asia and Africa.
India fifth largest producer of e-waste: study
India, which has emerged as the world’s second largest mobile market, is also the fifth largest producer of e-waste, discarding roughly 18.5 lakh tonnes of electronic waste each year, a study says.
Telecom equipment alone accounts for 12 per cent of the e-waste, a joint study by Assocham-KPMG said.
Matter of concern
The rising levels of e-waste generation in India have been a matter of concern in recent years. With more than 100 crore mobile phones in circulation, nearly 25 per cent end up in e-waste annually, it said.
The Ministry of Environment, Forest and Climate Change has notified e-waste management rules, 2016, in which producers are for the first time covered under extended producers’ responsibility (EPR).
Waste collection target
The rules prescribe a waste collection target of 30 per cent waste generated under EPR for the first two years, progressively going up to 70 per cent in the seventh year of the rule.
The rules prescribe stringent financial penalties for non-compliance. However, the study said the unorganised sector in India is estimated to handle around 95 per cent of the e-waste produced in the country.
Given the huge user base and vast reach of telecom in India, it is practically difficult and expensive for the handset manufacturers to achieve the targets prescribed in the rules from first year, the study added.
ISRO plans to test air-breathing propulsion system
After successfully testing a technology demonstrator of a reusable launch vehicle, Indian Space Research Organisation (ISRO) is planning to test an air-breathing propulsion system, which aims to capitalise on the oxygen in the atmosphere instead of liquefied oxygen while in flight.
Generally, vehicles that are used to launch satellites use combustion of propellants with oxidiser and fuel. The air-breathing propulsion system aims at using oxygen present in the atmosphere up to 50 km from the earth’s surface to burn the fuel stored in the rocket.
Lower lift-off mass
The system, when implemented, would help in reducing the lift-off mass of the vehicle since liquefied oxygen need not be carried on board the vehicle. This would also help increasing the efficiency of the rocket and also make it cost-effective.
The new propulsion system, once mastered, would complement ISRO’s aim to develop a reusable launch vehicle that would have longer flight duration. The system, involving the scramjet engine, would become crucial while sending up the spacecraft.
ISRO is now evolving and testing various technologies to bring down the cost of launch vehicles. The national space agency has earlier developed rockets that can send multiple satellites in a single mission.
Ancient Mars hosted habitable environments: study
Scientists have found evidence for widespread buried deposits of iron- and calcium-rich carbonates on Mars, which suggests that the red planet once hosted habitable environments with liquid water.
Identification of these ancient carbonates and clays on Mars represents a window into history when the climate on Mars was very different from the cold and dry desert of today.
Carbonates beneath the surface of Mars point to a warmer and wetter environment in that planet’s past. The presence of liquid water could have fostered the emergence of life.
Subject of an energetic debate
The fate of water on Mars has been energetically debated by scientists because the planet is currently dry and cold, in contrast to the widespread fluvial features that etch much of its surface.
Scientists believe that if water did once flow on the surface of Mars, the planet’s bedrock should be full of carbonates and clays, which would be evidence that Mars once hosted habitable environments with liquid water.
And the carbon dioxide
Researchers have struggled to find physical evidence for carbonate-rich bedrock, which may have formed when carbon dioxide in the planet’s early atmosphere was trapped in ancient surface waters. They have focused their search on Mars’ Huygens basin.
This feature is an ideal site to study carbonates because multiple impact craters and troughs have exposed ancient, subsurface materials where carbonates can be detected across a broad region, researchers have said.
Outcrops in the 450-km wide Huygens basin contain both clay minerals and iron- or calcium-rich carbonate-bearing rocks.
Carbonate-bearing rocks
The study has highlighted evidence of carbonate-bearing rocks in multiple sites across Mars, including Lucaya crater, where carbonates and clays 3.8 billion years old were buried by as much as 5 km of lava and caprock.
The researchers identified carbonates on the planet using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), which is on the Mars Reconnaissance Orbiter. This instrument collects the spectral fingerprints of carbonates and other minerals through vibrational transitions of the molecules in their crystal structure that produce infrared emission.
Geologic features
The team paired CRISM data with images from the High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) on the orbiter, as well as the Mars Orbiter Laser Altimeter (MOLA) on the Mars Global Surveyor, to gain insights into the geologic features associated with carbonate-bearing rocks.
The extent of the global distribution of martian carbonates is not yet fully resolved and the early climate on the red planet is still subject of debate.
However, this study is a forward step in understanding the potential habitability of ancient Mars.
Receive Daily Updates
Recent Posts
Steve Ovett, the famous British middle-distance athlete, won the 800-metres gold medal at the Moscow Olympics of 1980. Just a few days later, he was about to win a 5,000-metres race at London’s Crystal Palace. Known for his burst of acceleration on the home stretch, he had supreme confidence in his ability to out-sprint rivals. With the final 100 metres remaining,
[wptelegram-join-channel link=”https://t.me/s/upsctree” text=”Join @upsctree on Telegram”]Ovett waved to the crowd and raised a hand in triumph. But he had celebrated a bit too early. At the finishing line, Ireland’s John Treacy edged past Ovett. For those few moments, Ovett had lost his sense of reality and ignored the possibility of a negative event.
This analogy works well for the India story and our policy failures , including during the ongoing covid pandemic. While we have never been as well prepared or had significant successes in terms of growth stability as Ovett did in his illustrious running career, we tend to celebrate too early. Indeed, we have done so many times before.
It is as if we’re convinced that India is destined for greater heights, come what may, and so we never run through the finish line. Do we and our policymakers suffer from a collective optimism bias, which, as the Nobel Prize winner Daniel Kahneman once wrote, “may well be the most significant of the cognitive biases”? The optimism bias arises from mistaken beliefs which form expectations that are better than the reality. It makes us underestimate chances of a negative outcome and ignore warnings repeatedly.
The Indian economy had a dream run for five years from 2003-04 to 2007-08, with an average annual growth rate of around 9%. Many believed that India was on its way to clocking consistent double-digit growth and comparisons with China were rife. It was conveniently overlooked that this output expansion had come mainly came from a few sectors: automobiles, telecom and business services.
Indians were made to believe that we could sprint without high-quality education, healthcare, infrastructure or banking sectors, which form the backbone of any stable economy. The plan was to build them as we went along, but then in the euphoria of short-term success, it got lost.
India’s exports of goods grew from $20 billion in 1990-91 to over $310 billion in 2019-20. Looking at these absolute figures it would seem as if India has arrived on the world stage. However, India’s share of global trade has moved up only marginally. Even now, the country accounts for less than 2% of the world’s goods exports.
More importantly, hidden behind this performance was the role played by one sector that should have never made it to India’s list of exports—refined petroleum. The share of refined petroleum exports in India’s goods exports increased from 1.4% in 1996-97 to over 18% in 2011-12.
An import-intensive sector with low labour intensity, exports of refined petroleum zoomed because of the then policy regime of a retail price ceiling on petroleum products in the domestic market. While we have done well in the export of services, our share is still less than 4% of world exports.
India seemed to emerge from the 2008 global financial crisis relatively unscathed. But, a temporary demand push had played a role in the revival—the incomes of many households, both rural and urban, had shot up. Fiscal stimulus to the rural economy and implementation of the Sixth Pay Commission scales had led to the salaries of around 20% of organized-sector employees jumping up. We celebrated, but once again, neither did we resolve the crisis brewing elsewhere in India’s banking sector, nor did we improve our capacity for healthcare or quality education.
Employment saw little economy-wide growth in our boom years. Manufacturing jobs, if anything, shrank. But we continued to celebrate. Youth flocked to low-productivity service-sector jobs, such as those in hotels and restaurants, security and other services. The dependence on such jobs on one hand and high-skilled services on the other was bound to make Indian society more unequal.
And then, there is agriculture, an elephant in the room. If and when farm-sector reforms get implemented, celebrations would once again be premature. The vast majority of India’s farmers have small plots of land, and though these farms are at least as productive as larger ones, net absolute incomes from small plots can only be meagre.
A further rise in farm productivity and consequent increase in supply, if not matched by a demand rise, especially with access to export markets, would result in downward pressure on market prices for farm produce and a further decline in the net incomes of small farmers.
We should learn from what John Treacy did right. He didn’t give up, and pushed for the finish line like it was his only chance at winning. Treacy had years of long-distance practice. The same goes for our economy. A long grind is required to build up its base before we can win and celebrate. And Ovett did not blame anyone for his loss. We play the blame game. Everyone else, right from China and the US to ‘greedy corporates’, seems to be responsible for our failures.
We have lowered absolute poverty levels and had technology-based successes like Aadhaar and digital access to public services. But there are no short cuts to good quality and adequate healthcare and education services. We must remain optimistic but stay firmly away from the optimism bias.
In the end, it is not about how we start, but how we finish. The disastrous second wave of covid and our inability to manage it is a ghastly reminder of this fact.