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Research for a university project about seaweed resulted in a woman stumbling upon a method to harness the power of satellite imagery to detect plastic pollution in the ocean. In 2018, Lauren Biermann was scouring a satellite image of the ocean off the coast of the Isle of May, Scotland, searching for signs of floating seaweed for a project at her university. Her eyes were drawn to lines of white dots gently curving along an ocean front.

“It was weird because I was seeing floating things that didn’t look like plants, and I didn’t know what they could be,” Biermann, an Earth observation scientist at Plymouth Marine Laboratory in the U.K., told Mongabay. She said she considered the fact that it could be plastic, but found it hard to believe that Scotland had patches of plastic off its coast. “I spent the first three months trying to prove that it wasn’t plastic, so I went and made a library of all of the things floating, like foam and driftwood.”

During her investigation, Biermann came across a project conducted by the University of the Aegean in Greece, in which a team of academic staff and students used drone and satellite image technology to identify “plastic targets,” such as water bottles, plastic bags and fishing nets, on the sea surface. This data helped Biermann connect the dots in her own research.

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satellite imagery plastic pollution
Satellite view of plastic in ocean near Scotland. Image by Lauren Biermann.

“I went, yes, okay, this is plastic,” Biermann said. “It was the first time I had … data to validate what I had seen in Scotland, and that’s how I could build a spectral signature of plastic, and then go and apply it to other places.”

More than 8.3 billion tons of plastic waste enter the oceans each year, equivalent to a garbage truck dumping its contents into the sea every minute of the day, according to a report by the World Economic Forum. Anything more than 5 millimeters in size, about a fifth of an inch, is generally considered to be “macroplastic,” while anything below that size is “microplastic.”

Biermann and a team of colleagues embarked on their own study of detecting ocean plastic pollution through satellite imagery, and recently published their findings in Scientific Reports. First, they obtained high-resolution optical data from the European Space Agency (ESA), which is gathered by the Sentinel-2 Earth observation satellite. Second, they used the plastic target data from the University of the Aegean to help differentiate plastic debris from natural objects like driftwood and seaweed.

Then the researchers employed an algorithm to develop a “floating debris index” (FDI) that would identify macroplastics, like plastic water bottles and plastic bags, bobbing on the surface of the sea.

“I will read an article or a social media post about marine plastic pollution, and then go and look at that area, using Sentinel-2, and process the data using the floating debris index … and then extract those values and feed it into the machine learning algorithm,” Biermann said.

Biermann and her colleagues have tested these methods on satellite imagery of coastal waters off Accra, Ghana; the San Juan Islands, U.S.; Da Nang, Vietnam; and east Scotland, reporting an 86% accuracy rate.

However, the process of identifying plastic isn’t always straightforward. Cloud cover and rough seas can compromise the data, and macroplastics won’t stay in one place for a long time, particularly in coastal zones, Biermann said. “Things change really quickly, so a Sentinel-2 image that I look at today would have been taken two days ago, and by then anything that I see is gone,” she said.

While plastic tends to get pushed around in the ocean, winds and ocean currents will propel it into clusters that stay in one place. Biermann says she hopes that optical satellite data can help identify these aggregates, and that people and organizations can use this information to work on solutions.

“There will be cleanup operations like the Ocean Voyages Institute, which we’d like to work with. They would then go to where we spotted things, and they would be able to remove tons of plastic at a time,” Biermann said. “This really is the first technical exercise, but we would then like to apply the method, far more broadly … to rivers and open waters.”

Biermann makes an important clarification: this satellite data shouldn’t be seen as a solution to the plastic pollution issue.

“On its own, it can’t do anything to curb the plastic pollution problem,” Biermann said. “The way to curb plastic pollution problem is to address the source. We know that the majority of plastics come from land, so it’s not just addressing the source in terms of the industry, but also in terms of waste management practices on land.”

She says she also hopes this data will help build awareness of the global plastic pollution issue, and inspire action on the issue.

“What I don’t want to see is my work being used to greenwash the problem — now we can see it from space, so we know where to go and fetch it,” she said. “That’s not the case at all. And I think if anything, it’s just to say there that there’s enough of it now that it can be seen from space, [and we should] take that message to heart. The individual is not the problem here, and our individual behavior is not generating plastic on such a scale that it can be seen from space. Really, it is an industry problem.”

This article was originally published on Mongabay, written by Elizabeth Claire Alberts, and is republished here as part of an editorial partnership with Earth.Org. 

Through modern innovation in the current age, satellites and space stations are integral for space exploration, scientific discovery, communications, and remote sensing. However, producing and implementing orbital systems is incredibly costly, both financially and environmentally. New technological advancements increasingly require the use of satellites, but with the mounting global ecological crisis, how essential are they?

Over 2 200 active satellites are orbiting Earth, with the US leading with the most satellites per country, followed by China and Russia. In 1966, only six states were participating in the ‘space race’; now, there are 72 countries with active programmes or satellites in orbit. Many satellites are controlled by governing bodies and institutions that cover individual states or trade blocs, such as the National Aeronautics and Space Administration (NASA) in the US and the European Space Agency (ESA), or by national military departments. However, the vast majority of satellites are currently owned and controlled by private firms, an industry that has rapidly expanded in the past decade. The private space sector is experiencing a new uptick in scientific- or business-related endeavours, causing the number of active satellites in orbit to increase by the month. 

Elon Musk, founder and CEO of SpaceX, is launching one such endeavour, called Starlink, a network of low Earth orbit (LEO) satellites that will eventually create a global communications system capable of high-speed broadband internet connections. By the end of 2020, SpaceX is set to launch over 1 400 new satellites to ensure global coverage by 2021, and over 12 000 satellites over the next eight years. Latest reports suggest that number will increase to as many as 42 000 satellites in total, meaning that one single enterprise – SpaceX – will launch and have control of more satellites than have ever been launched since 1957. Starlink purports to be a ‘clean’ satellite constellation, whereby the LEO satellites will de-orbit to keep space clean once their lifespan is complete. However, it is debatable as to how clean the production and launches of thousands of satellites will be in reality. 

SpaceX is not the only new commercial space-venturing company. OneWeb, based in the UK, Blue Origin, founded by Amazon founder, Jeff Bezos, and the Luxembourg-based SES, which is already one of the largest satellite operators in the world, are among many firms looking to the stars to expand into the highly lucrative sector. These enterprises, along with other new government-led and research-based programmes, suggest a recent boom in the space economy that shows little signs of slowing down. Aside from the economic worth of the global satellite industry, which was estimated to be US$360 billion in 2019 (both commercial and government-led), there are many other advantages for society from utilising outer space.

The Role of Satellite in Climate Change

Satellites have a wide range of benefits. However, there are several important uses in the frame of the climate change. From the International Space Station (ISS) to hundreds of other observational satellites, remote sensing allows for climate and environmental monitoring. These imaging satellites are an incredible source of data for climate change research, enabling us to see the global changes on the planet that are happening more frequently, and with data freely available for anyone to view and use. For example, changing oceanic temperatures, currents and rising sea levels can be monitored by space-based research instruments. ISS measurements have indicated that global sea levels have increased by an average of 3.3 millimetres per year since 1993, due to melting glaciers and sea ice, and from thermal expansion within the oceans. Additionally, satellite imagery can show the changing sizes of glaciers and sea ice, which show that after 2017, 2019 had the second-lowest sea ice extent in the Arctic since 1978, with a similar situation in the Antarctic’s sea ice extent and coverage.

Outside Looking In: Satellites in the Climate Crisis
NASA Satellite images of the sea ice extent changes between 1979 and 2015 in the Arctic, showing a massive decline as a result of climate change and anthropocentric activities around the globe (Source: NASA

Remote sensing satellites, such as NASA’s Global Precipitation Measurement (GPM) satellite, can determine the changing precipitation patterns and flooding. Rainfall changes indicate that globally, more extreme weather events are happening, with more droughts, flooding and hurricanes. Vegetation cover changes are also observable, even with the naked eye from space. Along with NASA’s GPM, ESA’s Copernicus Sentinel-2 satellite enables spatial mapping of biodiversity and biomass, agricultural impacts, soil degradation, forestry cover and deforestation (and afforestation). Understanding this is essential for understanding the bigger picture for better ground-level mitigation and management of degradative land uses, such as intensive agricultural practices.

Observations of how widespread wildfires have been would not have been possible without a satellite’s viewpoint, showing worsened conditions of increasing fire risk, frequency, and magnitude as a result of climate change, which also feedbacks to increase carbon dioxide emissions. In the recent (and ongoing) Australian bushfire crisis, satellite imagery has shown the extent of burnt land in the country, and the distance the smoke travelled at the peak of the fire season, reaching as far away as South America. More recently, satellite images have shown that nitrogen GHGs have dropped in areas affected by COVID-19 quarantine measures, such as in China and Italy.

Greenhouse gases (GHGs) and temperature changes are also monitored from satellites, making them essential in modelling past, present and future differences to understand the atmospheric, terrestrial and oceanic implications from climate change. Instruments such as NASA’s Atmospheric Infrared Sounder (AIRS) satellite can measure GHG increases, such as CO2. Carbon dioxide levels are regularly monitored from space, showing that atmospheric CO2 levels have reached 413 parts per million (ppm). This is the highest concentration of CO2 that our planet has experienced in 3 million years. Satellites can also detect other GHGs, such as methane and nitrous oxide, which often come from industrial leaks or oil and gas fields. Satellites are integral for compliance with international environmental treaties such as the Paris Agreement. In aiming to keep within the Agreement’s target of mitigating global warming to 1.5°C above pre-industrial temperatures by the end of the century, satellites show we are already at 0.98°C above, a number that fluctuates annually.

Aside from the fundamental need to understand climatic changes from space, satellites are useful for early warning systems for natural disasters, the increased occurrences of extreme weather events, or ‘human disasters’. Satellites can monitor weather events in case of necessary evacuations, such as hurricane or flooding events, which are usually in conjunction with land-based monitoring systems and institutions (e.g. National Oceanic and Atmospheric Administration (NOAA) in the US). For natural disasters such as earthquakes, tsunamis or landslides, satellites are just as important in answering disaster events. Satellites have even been able to detect minute changes in human-made infrastructures, such as monitoring changes in road surfaces before a bridge collapse.  

However, despite the array of advantages of satellites in the climate crisis, what are the implications and costs of utilising the space beyond our immediate atmosphere?

Space exploration and entrepreneurship are very costly ventures. Sourcing the parts for satellites is expensive due to the amount of rare and valuable materials within them; production, engineering and software costs are similarly very high, often upward of US$100 million per satellite. Consequently, only states, companies, and individuals with significant disposable capital (or those with sponsorship from state or private funds) can viably finance space programmes. As a result, there is a disproportionate allocation of control over space from entities and institutions that can financially support such ventures, prohibiting many countries from accessing the benefits of satellite control. 

The pollution crisis of the Earth’s waterways is well-documented. This notion is reflected beyond our atmosphere. Space debris is an issue that is not often talked about; apart from the International Space Station (ISS), most people will never have contact with outer space, and therefore it is not often an immediate concern. 

Old shuttles and satellite parts enter the planet’s atmosphere on a reasonably regular basis, estimated at 200-400 pieces a year. While these parts frequently burn up upon re-entry and have minimal direct impact on terrestrial regions, they do not disappear completely. By burning up, due to the intense friction of travelling from a vacuum to an atmosphere full of gases, noxious chemicals and GHGs are released in the upper atmosphere. These gases, while negligible in amount, are generally more potent than CO2, and can deplete the ozone layer or retain more thermal radiation. 

Estimates by ESA put the number of space junk objects in Earth’s orbit at approximately 900 000 objects over 1cm in size, of which around 5 400 of those are larger than one metre (including over 2 000 active satellites). Roughly 70% of these pieces are in LEO. Space debris can be anything from bolts, paint chips and instrument parts, to entire defunct satellites and rocket bodies. Any object 10cm in size or larger can have a significant effect on active spacecraft due to the high speeds that objects orbit at; most modern satellites and stations are fitted with debris shields for smaller pieces. 

Outside Looking In: Satellites in the Climate Crisis
Space junk image projection by ESA, of pieces larger than 1mm in size in Earth’s orbit (Source: ESA).

Historically, space junk has destroyed active satellites, creating more debris in the process. In the future, a chain reaction of colliding space debris, known as the Kessler syndrome, could render LEO unusable. Such a reaction could inhibit the possibility of communication and essential remote sensing satellites that many people and organisations around the world rely on every day. It could also dissuade future space programmes from taking place due to the threat of extra-terrestrial debris. The implications of adding Starlink’s potential 42 000 new space instruments into orbit over the next decade or so, not to mention others, are innumerable in terms of impacting the already-fragile environment.

More positively, there have been several operations seeking to remove such debris from space. In 2018, British satellite RemoveDEBRIS was launched and deployed from the ISS to test new technologies that were successful in capturing space debris. Alternatively, another way to mitigate space debris in altitudes where satellites typically orbit is to move them to a ‘graveyard orbit’, where instruments near the end of their lifespan are sent to altitudes of 225 miles from Earth’s surface and higher, although this does not entirely solve the space junk crisis.

Unsurprisingly, the requirements for constructing a satellite make them incredibly resource-intensive. An immense array of elements and raw materials are used to create space structures; kevlar, aluminium, silicon, titanium or composite alloys such as nickel-cadmium and aluminium-beryllium are often essential. This is without considering the many resources necessary for electrical systems onboard the satellite, and the methods of building the space-faring instruments. The mining of metals alone is highly energy-intensive and degradative to the surrounding environment, including atmospheric and groundwater pollution. Following extraction, deoxidation or purification of the resources also contribute to the total emissions, along with transportation of the materials to production facilities. 

The effects of launch emissions from solid rocket fuel are not well understood and are difficult to measure. The majority of satellite launches produce a negligible amount of CO2, especially in comparison to other industries. However, particulates produced in the launch interact in the stratosphere and have a significant impact on ozone depletion. For instance, alumina particles are emitted from the launch and absorb sunlight, enabling thermal heating in the upper stratosphere and causing positive feedback and further latent warming. The effects of other gases and particles’ interactions with upper atmospheric environs have yet to be modelled, meaning every new rocket launch has unknown and potentially critical implications for climate change. 

Some reports state that liquid hydrogen, an alternative rocket fuel to solid propellants, is almost carbon neutral with 28 tons of CO2 per launch, alongside water vapour. However, the impacts of initially creating the specialised liquid fuel are estimated to be upward of 672 tons of CO2 per launch due to the industrial-scale amount of energy needed to produce the fuel, meaning the supposedly ‘clean’ fuel type is not as green when taken at face value. Ironically, satellite imaging will likely be the most effective tool in understanding the upper atmosphere’s composition and the impact of space programmes’ launch emissions on the atmosphere. 

Satellites are incredibly important in understanding and combating climate change. Understanding the climate crisis and its related issues are integral to combating it- if we cannot measure it, we cannot mitigate it. Without satellite capabilities, the knowledge and data on global warming and climate change today would not be anywhere as close to what we have available now, even with land-based sensing equipment. Nevertheless, there are implications and costs associated with satellites. When considering the Starlink programme, the overall impacts caused by one single private firm will be vast. There will be knock-on effects well into the future, such as production pollution, launch emissions from tens of thousands of satellites, and space debris. It is debatable as to how necessary a slightly higher coverage and faster internet speed will be in light of the ever-imminent climate crisis. 

With the onset of a ‘new space race’, policymakers need to be taking a serious look at the environmental costs of satellite use and improving research capabilities and regulation in order to mitigate these degradative implications. Future programmes need to invest in reducing or offsetting emissions and taking more responsibility for satellites once they have reached the end of their life. In the case of active satellites, retrofitting them to be less resource- or emission-intensive could be a viable solution in aiding this, depending on future technological and engineering advancements.

Unlike other satellites, PRISMA can read the chemical composition of ground and water based on light refraction. 

The first images captured by PRISMA Earth observation satellite of the Italian Space Agency (ASI) reveal the quality of water in various lakes in Italy. PRISMA mapped the lakes measuring the Nephelometric Turbidity Unit (NTU) of the waters, which assessed to be varying in different areas.

What is PRISMA?

Launched in orbit on March 22 this year with a powerful hyperspectral optical sensor, PRISMA is a first-of-its-kind earth observation tool designed to provide information about environmental monitoring, natural resource management, pollution, and crop health. 

Mapping Lake Trasimeno, the largest lake in Central Italy, PRISMA inferred that the waters are generally less turbid in the south-eastern bay, where communities of aquatic macrophytes thrive on a large scale. Macrophytes have the ability to limit resuspension of bottom sediments in a waterbody. 

Italian National Research Council (CNR-Irea) officials stated that further data processing would reveal in-depth details about the terrestrial ecosystem of Italy and other parts of Europe.

PRISMA operates in a Sun-synchronous orbit, which enables it to circle the Earth in such a way that the Sun is always in the same position as the satellite takes pictures of the planet below.

From its orbit, at about 620 kilometers of altitude, PRISMA (an Italian acronym for Hyperspectral Precursor of the Application Mission) observes the Earth on a global scale with different eyes. It includes a medium resolution camera that can view across all visual wavelengths and a hyperspectral imager that can capture a wider range of wavelengths between 400 and 2500 nanometers.

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The satellite image of Lake Trasimeno shows a turbidity gradient that varies between 3 and 6.2 NTU

“It will be able to offer an unprecedented contribution to the observation of natural resources from space and to the study of main environmental processes,” said an official release from the Italian Space Agency. “It studies the interactions between atmosphere, biosphere, and hydrosphere. It also tracks environmental and climate changes on a global level; the aftermath of anthropic activities on ecosystems.”

Why is PRISMA important?

PRISMA is able to provide valuable information to support the prevention of natural hazards like floods and man-made quandaries like soil pollution. It can also monitor fixed objects and protected areas of cultural or environmental significance, aids actions to humanitarian crises, and explores mineral resources. 

“Unlike the passive satellite sensors currently operating, which record the solar radiation reflected by our planet in a limited number of spectral bands, PRISMA will be able to acquire 240 spectral bands,” said the ISA statement. “This will help us to refine our knowledge concerning natural resources and climate change.”

PRISMA was developed by a consortium led by OHB Italy and Leonardo. 

Cold War-era US reconnaissance satellites have gone out of orbit. But they have left images that reveal the horrifying realities of climate change. A new study based on declassified satellite imagery revealed that the melting of Himalayan glaciers has doubled since the turn of the 21st century, compared to the previous 25 years.

A team of researchers led by doctoral student Joshua Maurer, from Columbia University’s Lamont-Doherty Earth Observatory, analysed Cold War-era spy imagery combining it with modern satellite data and found that 8bn tonnes of ice are being lost every year. Over 650 of the largest glaciers across India, China, Nepal, and Bhutan, which together represent 55% of the region’s total ice volume, have lost the equivalent of a vertical foot and a half of ice each year this century due to global heating caused by human activities.

Earlier, scientists had documented the rate at which the Himalayas had lost ice mass in the course of this century using more sophisticated satellite imagery. But this is the first comprehensive look at the melting rates of the Himalayan glaciers over a 40-year time span.

The Once-Secret Source

During the 1970s and 1980s, at the height of the Cold War, a US spy programme–Hexagon–had launched 20 satellites into orbit to secretly photograph the Earth.  The satellite missions, run by the National Reconnaissance Office, sought to capture wide-ranging views of what transpired around the globe. Each satellite was the size of a truck and weighed over 15,000 kilograms. In all, they photographed some 877 million square miles of Earth.

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One of the satellites KH-9 Hexagon, commonly known as Big Bird, before the launch

The covert images were taken on rolls of film that were then dropped by the satellites into the atmosphere to be collected by military planes. The films were contained in metal canisters, which deployed their parachutes before being captured by high-flying spy planes. The materials were declassified in 2011, and have been digitised by the US Geological Survey for scientists to use.

Among the spy photographs are the Himalayas–an area for which historical data is scarce.

The photos had lain unused in archives for several years. The Columbia University team developed a computer software to turn these old photos into 3D maps allowing them to digitally explore the Himalayan surfaces as they appeared in 1975. They looked at 650 glaciers and compared them with modern satellite data from Nasa and the Japanese space agency (Jaxa) to create the first detailed, four-decade record of ice along the 2,000km mountain chain.

How fast are glaciers melting?

Researchers found that between 1975 and 2000, the average loss of glacial ice was about 25 cm per year, but this doubled to 50 cm in the 21st century. These are average figures, spread out across the region, and in the worst-hit areas, that ice loss is as much as 5 metres a year.

Warming air temperatures have accelerated ice loss. Inferring data from local weather stations, the team found temperatures in the Himalayas have risen one degree Celsius higher than those from 1975 to 2000.  The rising temperatures are consistent with the observed melting. Further calculations also confirmed that one degree was indeed enough to produce such a massive loss of glacier ice.

The Himalayas contain many different types of glaciers — such as those covered in debris or located near bodies of liquid water lakes — in many different environments.

The study concluded that the rate of melt was consistent across all the glaciers they studied.  “All of the glaciers have lost similar amounts of ice. It indicates there is one overarching factor causing this,” said lead researcher Josh Maurer. “Global temperature rise is the only one that makes sense.”

Map of glacier locations and geodetic mass balances for the 650 glaciers.
Circle sizes are proportional to glacier areas, and colors delineate clean-ice, debris-covered, and lake-terminating categories. Insets indicate ice loss, quantified as geodetic mass balances plotted for individual glaciers along a longitudinal transect during 1975–2000 and 2000–2016. Both inset plots are horizontally aligned with the map view. Gray error bars are 1σ uncertainty, and the yellow trend is the (area-weighted) moving-window mean, using a window size of 30 glaciers.

Why are glaciers important?

Glacier loss at this rate points to an impending threat that might devastate an entire region of South Asia in the near future. Glaciers are a key source of fresh water for both natural ecosystems and nearby human communities, helping to feed mountain streams as they melt during the summer months. More than 800 million people from China, India, Pakistan, and Bangladesh rely on seasonal Himalayan runoff for irrigation, hydropower, and drinking water. The ice and snow in the region are the source for Asia’s mighty rivers including the Indus, the Yangtze, and the Ganga-Brahmaputra. As these glaciers shrink, they could alter the local hydrology and disrupt the water supplies. As a result, densely populated areas in South Asia would face more severe water crisis than ever before.

Melting glaciers pose another unpredictable danger: disastrous floods. Glacial water gets blocked by piles of rubble and forms glacial lakes that can burst and flood villages and cities downstream. These lake outburst floods have killed thousands of people in the Andes, Himalayas, and Alps in the past. In May 2012, one such flood killed over 60 people in villages near Pokhara, Nepal; it also destroyed houses and infrastructure.

Another study published last February projected that, even in the best-case scenario, if the world rapidly decarbonised and was carbon neutral by 2050, limiting global warming to 1.5 degrees Celsius, the Himalayan glaciers are still melting rapidly and stand to lose a third of their total ice, because the peaks are warming at a faster rate than the global average.

Oceans cover over 70% of the Earth’s surface. They feed us, regulate our climate and are a road that connects us all. Satellite and airborne technology offer enhanced possibilities to monitor with detailed granularity their health. How can we harness the power of satellites to better understand oceans and marine ecosystem management systems?

Plastic Trash Tracking: Story of an Open Ocean Cleanup

The Ocean Cleanup is an ambitious non-profit organisation that develops advanced technologies to rid the world’s oceans of plastic. They have pioneered a passive drifting system comprising of floating tubes that captures plastic debris and trash from the Ocean’s surface by following natural currents. They aim to clean up half the Great Pacific Garbage Patch, located between California and Hawaii, in 5 years’ time.

Pinpointing the location of plastics is one of the major challenges, according to a spokesperson:  “We know more or less where it is, but the stuff is always moving. That’s where remote sensing comes in.”

The team mounted a Hyperspectral Shortwave Infrared Imager onto an aircraft and flew it over the Pacific Ocean to scan the surface. It found that plastics possess uniquely identifying characteristics. Plastics on the ocean surface were in fact “robustly distinguished from algae and other vegetation that contain hydrocarbons”. This makes their detection feasible.

Early results with satellites are also promising. Recently, the European Space Agency (ESA) began developing technology to allow satellites to identify the origin, movement and concentration of plastics across the world’s oceans.

The idea was conceived internally by scientists Paolo Corradi and Luca Maresi at ESA. Their project called OptiMAL (Optimal methods for Marine Litter detection) is primarily focused on detecting microplastics near the ocean surface as well as large pieces along the shorelines.

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using satellites to better understand oceans
Concentrations of plastic in the oceans. Source: European Space Agency (ESA)

So far, the have used images from Sentinel 3 satellite and cross-checked them against ground and aerial surveys. The next step is to assess whether plastics can be identified in the ocean through the reflection of different wavelengths of sunlight.

The team will then collect the spectral signals of plastic at sea and enter them into computer models to simulate how those signals would look through the atmosphere.

While the use of satellites to detect ocean surface plastic litter remains in its infancy, the project’s success would constitute a major technical breakthrough in the adaptation of spatial images applied to marine monitoring.

“We should be able to report our first results by the end of this year,” Corradi said.

Shallow Waters: Remote sensing is quantifying the coral reef crisis

Coral reefs face unprecedented pressures as a consequence of anthropogenic disturbance and climate change.

One-quarter of coral reefs have been destroyed by pollution and climate change, according to WWF.

In some of the worst-hit areas, such as the Maldives and Seychelles islands in the Indian Ocean, up to 90% of coral reefs have been damaged beyond repair in the past two years by an increase in water temperature.

Coral reefs, the “rainforests of the sea” are an anchor for many marine ecosystems and their loss would push thousands of species of fish and other marine life in the abyss of extinction.

Remote sensing can measure the effects of such stresses at appropriately large spatial scales. Applications for of satellite technology in particular to coral reefs are varied, spanning from localisation and mapping to classification and health appraisals as well as tracking human interference.

How do satellites map the ocean floor?

Chlorophyll content in ocean waters is an important indicator of water health because phytoplankton, tiny micro-organisms that are the foundation of the marine food chain, use chlorophyll to carry out photosynthesis, capturing Co2 from the atmosphere.

As chlorophyll in the the ocean changes the way it reflects and absorbs sunlight, scientists can map the amount and location of phytoplankton using satellites. These indicators give us valuable insights into the health of the ocean environment.

Satellites can also help to identify the ocean areas that are most at risk of acidification.

Researchers from the University of Exeter, UK developed an ocean acidity map based on satellite imagery from NASA’s Aquarius satellite and ESA’s Soil Moisture and Ocean Salinity (SMOS) satellite.

Ocean acidification is a phenomenon that results from the enormous increase of carbon dioxide released into the atmosphere. It not only affects corals and marine life, but is also expected to have enormous socio-economic costs, influencing the way humans feed themselves and earn their livings.

It is imperative to use satellites and remote sensing technologies to better understand oceans and how they can be restored.

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