Our Say: What do wetlands and seaweed farming have in common?

By Jane Burns
Education Outreach Manager


Eco solutions

Naturally occurring biological, chemical or physical processes have mitigated or deferred global warming for millions of years by accumulating and storing carbon dioxide (CO2) from the atmosphere in the process known as carbon sequestration. However, depletion of the natural world and an over accumulation of human generated carbon sources have produced dangerous levels of carbon dioxide, the greenhouse gas responsible for most of the global warming.

Slowing global warming is essential to avoid dangerous climate change, and while there are several types of greenhouse gases humans are adding to the atmosphere, carbon dioxide released from burning fossil fuels (coal, natural gas, and oil) and methane (currently the third most prevalent greenhouse gas after carbon dioxide) and water vapor are the biggest sources of emissions globally. In addition, the atmosphere is not the only reservoir for emissions of carbon as over a longer time scale, most of the carbon emitted today will end up in the ocean and disrupt the ocean’s balance.


Acknowledging the problem

The United nations conference on climate change known as COP21 held in Paris in November 2015, resulted in the Paris Agreement adopted by 195 countries. This is the first universal, legally binding global climate agreement and it sets out a global action plan to limit global warming to well below 2°C and try to avoid dangerous climate change.

Current emissions are already halfway towards this threshold and based on the climate modeling scientists use, surface temperatures could rise between 2°C and 6°C by the end of the 21st century. According to NASA Observatory, the modeling predicts that as the world consumes even more fossil fuel, greenhouse gas concentrations will continue to rise, and Earth’s average surface temperature will rise with them. These projections correlate with the Intergovernmental Panel on Climate Change (IPCC) which is regarded by some scientists as conservative, indicate temperature increases of between 4-5°C. At 5-6°C, continued human existence on earth is widely regarded as untenable.

Despite this there is much to be hopeful for if the UN climate agreement fosters a commitment to end the carbon-reliant, fossil-fuel electricity generation and work begins to achieve a net zero-carbon world by the end of the century.

According to Earthwatch, to achieve this we must reduce our carbon output but also improve our carbon stores, that are our forests, oceans and soils.


Carbon storage – an age-old solution

Carbon dioxide is captured in natural systems and held in soils and vegetation, peat bogs, forests, wetlands, geological reservoirs, and river and seabed sediments. Carbon capture and sequestration (CCS) can also occur artificially through a suite of technology options to reduce CO2 emissions from power plants or industrial processes such as from coal and gas-fired power plants or from industrial process such as cement production and natural gas processing facilities.

In helping to mitigate the effects of climate change, the capture and sequestration of carbon in natural systems can be maintained and improved upon. For example, moving away from intensive farming to increase the amount of carbon held in soils through practices such as no till, cover cropping, returning biomass to soils and replacing herbicides, particularly glyphosate-based herbicides with non-chemical inputs.

In addition to improving the management of natural systems, the essential move away from a carbon-reliant, energy-intensive future through deploying renewable energy, such as from solar, wind, hydropower and bioenergy sources will have a significant impact on reducing CO2 emissions into the atmosphere. And reassuringly, wind and solar is today outpacing investments in fossil fuels for three years running and offering electricity at a cost close to or equal to that of fossil fuels.


Scaling up CCS in natural systems

According to the United Nations Environment Programme (UNEP) tens of billions of dollar are being earmarked for a technology that aims to remove greenhouse gases from smoke stacks and bury it deep underground. In the UNEP-commissioned Rapid Assessment report, carbon capture and storage through a Green Economy lens outlines the potential in terms of natural systems – systems from forests to grasslands that have been doing the job in a tried and tested way for millennia.

One of these natural systems is wetlands. A scientific paper published by the Australian government’s Department of Sustainability, Environment, Water, Population, and Communities, states wetlands cover about 6 to 9% of the earth’s surface and have sequestered approximately 35% of the global terrestrial carbon.

Wetlands capture and store carbon in several ways including accumulating organic matter in soils and photosynthesis and in an environment where water is the primary factor, control and support plant and animal life. In addition, the water depth in wetlands is usually no more than six feet, meaning the water table tends to be near the ground surface. Wetland soils tend to remain in a “waterlogged” state, thereby inhibiting diffusion of oxygen and water filtration into sediment profiles found at the bottom. As such, decomposition rates slow down leading to accumulation of large amounts of carbon within wetland sediment profiles. At the same time, some wetlands have the unique ability of distributing carbon horizontally to adjacent wetland environments.

Some wetlands capture and store more carbon than others such as peatlands which according to estimates from Wetlands International, cover about 3% of the earth’s surface area but currently store about 30% of the world’s terrestrial carbon. Other wetland ecosystems that play a key role in carbon sequestration include seagrass meadows and mangrove swamps.

Sadly, human activities are increasingly degrading wetlands globally leading to the release of carbon trapped underneath their sediment profiles and degradation of water quality. Urban areas have also played a key role in the destruction of some 60% of wetlands worldwide, and up to 85% in Australia have been destroyed in the past 100 years, principally due to drainage for agriculture but also through pollution, dams, canals, and urban development.


A new hope: Third way technologies

Along with preservation and restoration of wetlands and other natural systems worldwide, technologies to engineer the climate by carbon dioxide removal (CDR) and scaling up CCS in natural systems are emerging.

Current debate about reducing climate change tends to focus on two paths for limiting greenhouse gas emissions or ‘Geoengineering’ which is a broad definition for both managing solar radiation and removing carbon dioxide from the atmosphere.

But a “third way” to combat climate change is possible for capturing the carbon dioxide already in the atmosphere, and storing it for reuse.

Author, Climate Councillor and Professorial Fellow at the Melbourne Sustainable Society Institute, Tim Flannery, argues that ‘these strategies will be necessary to combat climate change, but cannot substitute completely for reducing emissions.’ Flannery says there are two routes within the third way – biological and chemical. Biological methods involve the removal of CO2 from the atmosphere or oceans via photosynthesis, and then storing the captured carbon in a variety of forms – from living forests to charcoal and plastics, or locking it deep in the Earth’s crust. Chemical removal options use the weathering of rocks, or artificial means, to capture atmospheric carbon, then sequester the carbon in a variety of places.

In his recent book “Atmosphere of Hope: Searching for Solutions to the Climate Crisis,” Flannery proposes that seaweed farming is one such third way approach and a viable biological asset that humans can use to capture and store carbon, and the technologies required to do so already exist. The potential for this biological approach is being taken seriously at a research level and Flannery refers to one analysis that shows “that if seaweed farms covered 9% of the ocean they could produce enough biomethane to replace all of today’s needs in fossil fuel energy, while removing 53 gigatonnes of CO2 (about the same as all current human emissions) per year from the atmosphere. It could also increase sustainable fish production to provide 200kg per year, per person, for 10 billion people. Additional benefits include reduction in ocean acidification and increased ocean primary productivity and biodiversity.”

This analysis comes from Dr. Antoine De Ramon N’Yeurt , a leading proponent for large-scale seaweed farming and supporter of Ocean Algal Afforestation (OAA) – a Negative Emission Technology utilizing the world’s oceans to reduce atmospheric carbon dioxide concentrations through expanding natural populations of large seaweeds (macroalgae), which absorb carbon dioxide through photosynthesis like terrestrial forests.Atmosphere of Hope: Searching for Solutions to the Climate Crisis

Scientists also find seaweed attractive because it grows at up to 30-60 times faster than the growth rate of land-based plants meaning it can draw carbon from the atmosphere at a faster rate.


Seaweed farming in Australia

Australia is one of the world’s leading emitters of greenhouse gases and relies on coal to generate more than 80% of its electricity which accounts for about 35% of Australia’s carbon emissions per year. Australia could be well placed to roll out seaweed farming and utilise carbon sequestration strategies to help reduce its carbon footprint.

In a novel approach to aquatic applications, research projects from James Cook University’s School of Marine and Tropical Biology and Centre for Sustainable Tropical Fisheries are the first in Australia to demonstrate the use of freshwater and marine macroalgae for the development of renewable fuels and bioproducts. They are also the first to have integrated the production of macroalgae into waste waters for aquaculture, agriculture, energy generation and the mining and mineral processing industries. The intensive culture of macroalgae can be used to produce renewable fuels (biocrude), biomass energy, algal meal as an animal feedstock, functional food and feeds, as well as biochar and fertilisers.

The South Australian Government has welcomed a new research project to examine the feasibility of farming seaweed in association with existing ocean-based fish aquaculture.

Scientists from UTS and Deakin University have carried out the ‘first investigation of how a diverse range of coastal plants and seaweed (macroalgae) can contribute to “blue carbon” stocks, the carbon in leaves, sediments and roots that is naturally captured, or sequestered, by plants in coastal habitats’.

According to co-lead author Stacey Trevathan-Tackett, a PhD candidate in the UTS Plant Functional Biology and Climate Change Cluster (C3 ), these blue carbon systems are recognised as being more efficient than land-based systems for long-term carbon storage, and “there is enormous seaweed biomass in our oceans and understanding where that all ends up and how much of it is locked away is the next big area of research to pursue.”

The study forms part of a large coastal carbon accounting project being undertaken by researchers in eight Australian institutions under the CSIRO Marine Geochemistry Coastal Carbon Cluster initiative. The project was co-funded by Deakin University Centre for Integrative Ecology within the School of Life and Environmental Sciences.

The Future

Tim Flannery predicts addressing climate change will “define the lives of generations”. He is optimistic about the “clutch of innovative technologies and strategies he labels a “third way” to address climate change” but there are no silver bullets, but together they provide grounds for optimism about humanity’s capacity to deal effectively with global warming. Flannery says, perhaps with hope, “It is possible the next decade will astonish us with the solutions that we discover to safeguard our planet for our grandchildren and their grandchildren.”

If we are to address the environmental challenges ahead that could help avoid climate catastrophe, many initiatives are required. The need for education for sustainability (EfS) is well established and strengthening the environmental education sector with the resources and capabilities for EfS will help to educate young people and adults to contribute to more sustainable patterns of living and take positive action on climate change. Education, leadership from all sectors of society and a raft of innovative, low-carbon technologies can provide grounds for optimism about humanity’s capacity to deal effectively with global warming.

Image sources:
Wetland – www.weekendnotes.com
Seaweed – University of NSW 2014

By CERES Education – Outreach Team|2017-11-06T18:33:55+10:00April 18th, 2016|0 Comments
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