There’s no ‘garbage patch’ in the Southern Indian Ocean, so where does all the rubbish go?


File 20190401 177175 1wvztzj.jpg?ixlib=rb 1.1
Plastic waste on a remote beach in Sri Lanka.
Author provided

Mirjam van der Mheen, University of Western Australia; Charitha Pattiaratchi, University of Western Australia, and Erik van Sebille, Utrecht University

Great areas of our rubbish are known to form in parts of the Pacific and Atlantic oceans. But no such “garbage patch” has been found in the Southern Indian Ocean.

Our research – published recently in Journal of Geophysical Research: Oceans – looked at why that’s the case, and what happens to the rubbish that gets dumped in this particular area.

Every year, up to 15 million tonnes of plastic waste is estimated to make its way into the ocean through coastlines (about 12.5 million tonnes) and rivers (about 2.5 million tonnes). This amount is expected to double by 2025.




Read more:
A current affair: the movement of ocean waters around Australia


Some of this waste sinks in the ocean, some is washed up on beaches, and some floats on the ocean surface, transported by currents.

The garbage patches

As plastic materials are extremely durable, floating plastic waste can travel great distances in the ocean. Some floating plastics collect in the centre of subtropical circulating currents known as gyres, between 20 to 40 degrees north and south, to create these garbage patches.

The Great Pacific Garbage Patch.
National Oceanic and Atmospheric Administration

Here, the ocean currents converge at the centre of the gyre and sink. But the floating plastic material remains at the surface, allowing it to concentrate in these regions.

The best known of these garbage patches is the Great Pacific Garbage Patch, which contains about 80,000 tonnes of plastic waste. As the National Oceanic and Atmospheric Administration points out, the “patches” are not actually clumped collections of easy-to-see debris, but concentrations of litter (mostly small pieces of floating plastic).

Similar, but smaller, patches exist in the North and South Atlantic Oceans and the South Pacific Ocean. In total, it is estimated that only 1% of all plastic waste that enters the ocean is trapped in the garbage patches. It is still a mystery what happens to the remaining 99% of plastic waste that has entered the ocean.

Rubbish in the Indian Ocean

Even less is known about what happens to plastic in the Indian Ocean, although it receives the largest input of plastic material globally.

For example, it has been estimated that up to 90% of the global riverine input of plastic waste originates from Asia. The input of plastics to the Southern Indian Ocean is mainly through Indonesia. The Australian contribution is small.

The major sources of riverine input of plastic material into the Indian Ocean.
The Ocean Cleanup, CC BY-NC-ND

The Indian Ocean has many unique characteristics compared with the other ocean basins. The most striking factor is the presence of the Asian continental landmass, which results in the absence of a northern ocean basin and generates monsoon winds.

As a result of the former, there is no gyre in the Northern Indian Ocean, and so there is no garbage patch. The latter results in reversing ocean surface currents.

The Indian and Pacific Oceans are connected through the Indonesian Archipelago, which allows for warmer, less salty water to be transported from the Pacific to the Indian via a phenomenon called the Indonesian Throughflow (see graphic, below).

Schematic currents and location of a leaky garbage patch in the southern Indian Ocean: Indonesian Throughflow (ITF), Leeuwin Current (LC), South Indian Counter Current (SICC), Agulhas Current (AC).
Author provided

This connection also results in the formation of the Leeuwin Current, a poleward (towards the South Pole) current that flows alongside Australia’s west coast.

As a result, the Southern Indian Ocean has poleward currents on both eastern and western margins of the ocean basin.

Also, the South Indian Counter Current flows eastwards across the entire width of the Southern Indian Ocean, through the centre of the subtropical gyre, from the southern tip of Madagascar to Australia.

The African continent ends at around 35 degrees south, which provides a connection between the southern Indian and Atlantic Oceans.

How to follow that rubbish

In contrast to other ocean basins, the Indian Ocean is under-sampled, with only a few measurements of plastic material available. As technology to remotely track plastics does not yet exist, we need to use indirect ways to determine the fate of plastic in the Indian Ocean.

We used information from more than 22,000 satellite-tracked surface drifting buoys that have been released all over the world’s oceans since 1979. This allowed us to simulate pathways of plastic waste globally, with an emphasis on the Indian Ocean.

Global simulated concentration of floating waste after 50 years.
Mirjam van der Mheen, Author provided

We found that unique characteristics of the Southern Indian Ocean transport floating plastics towards the ocean’s western side, where it leaks past South Africa into the South Atlantic Ocean.

Because of the Asian monsoon system, the southeast trade winds in the Southern Indian Ocean are stronger than the trade winds in the Pacific and Atlantic Oceans. These strong winds push floating plastic material further to the west in the Southern Indian Ocean than they do in the other oceans.

So the rubbish goes where?

This allows the floating plastic to leak more readily from the Southern Indian Ocean into the South Atlantic Ocean. All these factors contribute to an ill-defined garbage patch in the Southern Indian Ocean.

Simulated concentration of floating waste over 50 years in the Indian Ocean.

In the Northern Indian Ocean our simulations showed there may be an accumulation of waste in the Bay of Bengal.




Read more:
‘Missing plastic’ in the oceans can be found below the surface


It is also likely that floating plastics will ultimately end up on beaches all around the Indian Ocean, transported by the reversing monsoon winds and currents. Which beaches will be most heavily affected is still unclear, and will probably depend on the monsoon season.

Our study shows that the atmospheric and oceanic attributes of the Indian Ocean are different to other ocean basins and that there may not be a concentrated garbage patch. Therefore the mystery of all the missing plastic is even greater in the Indian Ocean.The Conversation

Mirjam van der Mheen, PhD Candidate in Oceanography, University of Western Australia; Charitha Pattiaratchi, Professor of Coastal Oceanography, University of Western Australia, and Erik van Sebille, Associate Professor in Oceanography and Climate Change, Utrecht University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisements

Forget turning straw into gold, farmers can turn trash into energy


Bernadette McCabe, University of Southern Queensland and Craig Baillie, University of Southern Queensland

Mention agriculture to many Australians and it conjures up images of mobs of cattle in the dusty outback, or harvesters gobbling up expanses of golden wheat. In reality, much of our high-value agriculture is near the coast, and close to capital cities. Think of the Adelaide Hills, the Lockyer Valley west of Brisbane, Victoria’s Gippsland region and Goulburn Valley, and Sydney’s Hawkesbury Valley.

These centres are where a lot of our agricultural processing happens – near big, eco-conscious populations ready to put their hands in their pockets for quality products.


Read more: Why consumers need help to shift to sustainable diets


But besides feeding us, farming can also potentially help us with the move towards cleaner energy. While it’s unclear how agriculture will factor into the federal government’s proposed National Energy Guarantee, it’s obvious that the farming sector can do plenty to reduce Australia’s emissions. An Industry Roadmap released this week by the Carbon Market Institute forecasts that by 2030 carbon farming will save the equivalent of 360-480 tonnes of carbon emissions, generate between A$10.8 billion and A$24 billion in revenue, and create 10,500-21,000 jobs.

One extremely promising area is turning agricultural waste and by-products into energy. This reduces emissions, makes farmers less vulnerable to variable energy prices, and adds value for consumers.

Using waste for energy

In Queensland and northern New South Wales, some sugar mills are making electricity by burning bagasse (sugarcane waste) as a biomass energy source. Other plants in Victoria, like Warrnambool Butter & Cheese, are using whey to produce biogas, thus reducing their spending on natural gas.

Other kinds of waste from viticulture and horticulture are also potentially useful. Even the trash produced when cotton lint fibres are removed from the seed is a largely untapped source of environmentally friendly energy.


Read more: Explainer: why we should be turning waste into fuel


The agricultural sector should be aiming to close the loop: to reclassify waste as a resource. Turning trash into treasure is a step towards energy independence, an idea that is gaining momentum overseas. An energy-independent farm seeks to cater for its own energy needs, creating a self-sustaining environment that buffers against fluctuating energy prices.

Australian farms should largely be able to achieve this. The trend towards renewable energy sources, and equipment that can run on biofuels, demonstrates an appetite for sensible, sustainable technology.

Biodiesel, wind and solar energy, and electricity and gas generated from biogas are being implemented globally. From an international perspective, farmers’ consideration for using or increasing renewable energy seems to be independent of the size of their operations but rather stem from their desire for farms to be energy-independent.


Read more: Biogas: smells like a solution to our energy and waste problems


La Bellotta farm in Italy, a mixed-energy farm, is a prime example. It’s using a concept tractor powered by methane generated from on-farm waste.

Closer to home, Westpork, WA’s largest pork producer, is about to add wind power and battery storage to its existing solar arrays, and possibly biogas too, as part of a plan to go 100% renewable energy and slash production costs.

The right policy settings

Agriculture was responsible for about 16% of Australia’s greenhouse gas emissions in 2013, trending down to 13% in 2015.

The National Farmers Federation is looking to the Government’s 2017 Review of Climate Policy to deliver policy settings that will enable the sector to remain competitive and grow production at the same time as meeting international obligations.

We particularly need policy to encourage investment in agriculture research. Climate-smart practices and technologies can simultaneously reduce emissions and improve productivity and profitability.

Meanwhile, improving the design of carbon-offset markets (like the federal government’s Emissions Reduction Fund) to make them more accessible to farmers could unlock the full carbon potential of Australian farms.


Read more: Farming in 2050: storing carbon could help meet Australia’s climate goals


A recent report from Powering Agriculture, produced with international backing, showed that while food production across the world is increasing, the energy required for each unit of food is falling.

With Australia’s relatively small population, huge area and extreme temperatures, it’s hard to compare apples with apples, but the adoption of renewable energy in Australian agriculture is helping to make us look like more efficient food producers too.

Mixing renewable energy sources gives farmers a plausible path to becoming energy independent. Bioenergy, such as biogas, gives flexibility to intermittent power like solar and wind, while reducing waste and creating a home source of biofertiliser.

When you boil it down to basic science, food and fibre are just stored energy. Beyond the animals and crops farmers bring to market, the Australian agricultural sector produces massive amounts of energy – they just need the tools to monetise it.


The ConversationThe topic of Farm Energy Independence will be discussed at the upcoming TropAg Symposium.

Bernadette McCabe, Associate Professor and Principal Scientist, University of Southern Queensland and Craig Baillie, Director (National Centre for Engineering in Agriculture), University of Southern Queensland

This article was originally published on The Conversation. Read the original article.

Switzerland: Space Junk Garbage Collector


The link below is to an article that reports on plans by Switzerland to clean up space junk.

For more visit:
http://inhabitat.com/cleanspace-one-to-clear-the-planets-orbit-of-370000-pieces-of-hazardous-space-junk/

Pacific Ocean: The World’s Largest Garbage Tip


The link below is to an article reporting on a growing and very disturbing problem in the Pacific Ocean.

For more visit:
http://news.mongabay.com/2013/0506-lloyd-pacific-pollution.html

The Great Pacific Garbage Patch


The link below is to an article reporting on that section of the Pacific Ocean known as the Great Pacific Garbage Patch.

For more visit:
http://boingboing.net/2012/08/09/the-eighth-continent-searchin.html

Article: The North Pacific Gyre


The following link is to an article reporting on the North Pacific Gyre, the so-called Pacific garbage patch. It’s an interesting read and may clear up some misconceptions on the region.

For more visit:
http://io9.com/5911969/lies-youve-been-told-about-the-pacific-garbage-patch

Mount Everest to be Given a Clean Up


The world’s highest mountain, Mount Everest, is to be given a clean up. Everest, which was first climbed by Edmund Hillary in 1953, has become something of a garbage tip. Everything from climbers rubbish to dead bodies has been left on the mountain. Now a Nepalese expedition made up of twenty Sherpa mountaineers and eleven support crew is seeking to remove some of the garbage left behind since that first ascent.

The government of Nepal wants to clean up the popular tourist attraction, bringing down rubbish that includes old tents, climbing equipment and the odd body. Global warming has led to much of the rubbish (and several bodies) no longer being covered by snow and ice.

Over 300 people have been killed attempting the climb to the top of the world, the Mount Everest summit.

For more on this story, see the Reuters article at:

http://af.reuters.com/article/worldNews/idAFTRE63I0XE20100419