Climate explained: rising carbon emissions (probably) won’t make the Earth uninhabitable


Shutterstock/Jurik Peter

Laura Revell, University of Canterbury


CC BY-ND

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

If you have a question you’d like an expert to answer, please send it to climate.change@stuff.co.nz


Even with all humanity’s carbon emissions to date, there’s a lot less carbon dioxide in Earth’s atmosphere than Venus, and Earth is further away from the Sun. But if carbon emissions continue at the current rate, is there any risk of reaching a tipping point at which a runaway greenhouse effect takes over, making Earth uninhabitable for any form of life?

When sunlight enters the Earth’s atmosphere, some is reflected back to space by clouds, some is reflected by bright surfaces such as ice and snow and some is absorbed by the land surface and ocean.

To maintain a balance, the Earth emits energy back to space in the form of infrared, or longwave, radiation. Some longwave radiation is absorbed in the atmosphere by heat-trapping gases, such as carbon dioxide.

This is the well-known greenhouse effect.




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As is already well established, concentrations of carbon dioxide have increased over the past 250 years, causing the average surface temperature to increase.

One consequence of increasing atmospheric carbon dioxide concentrations is that, as the atmosphere warms, it can contain more water vapour. Since water vapour is itself a greenhouse gas, this can create an amplifying effect.

In general, as surface temperature increases, the Earth emits more longwave radiation to space to maintain the energy balance. But there is a limit to how much longwave radiation can be emitted.

If the atmosphere becomes completely saturated with water vapour, the Earth’s surface and lower atmosphere warm up, but further increases in emission of longwave radiation are not possible.

The runaway greenhouse

This is termed a runaway greenhouse and would mean the Earth would become lethally hot and unable to cool itself by emitting heat to space.

Ultimately, this is the fate of the Earth. In billions of years from now the Sun will become brighter and grow into a Red Dwarf. As the Sun’s luminosity increases, the Earth will become hotter and its oceans will evaporate.

We’re doomed … but not for billions of years.

The hot and steamy atmosphere will ensure the Earth is just as uninhabitable to current life-forms as Venus is today.

But could we bring such a situation about on a shorter timeframe through continued carbon dioxide emissions? The good news is, probably not.

We’re safe, for now

Previous research has found that, due to differences in the properties of water vapour and carbon dioxide as greenhouse gases, adding carbon dioxide to the atmosphere is likely insufficient to trigger a runaway greenhouse.

Atmospheric carbon dioxide is currently around 416 parts per million (ppm) – up from approximately 280 ppm since the first industrial revolution began, some 250 years ago.

In geological terms, this is a very large increase to take place over a short period of time. Yet human emissions of carbon dioxide are considered insufficient to trigger a runaway greenhouse, given the fossil fuel reserves available.

The Earth should be safe from a runaway greenhouse developing for at least another 1.5 billion years.

But then …

The caveat to all the above is that the models scientists use to study future climate are built based on past, known conditions. It is therefore difficult to predict how certain parts of the climate system might operate under extremely high greenhouse gas emissions scenarios.

Clouds hiding the Sun but with rays of light emerging from behind top.
Clouds can reflect sunlight back to space.
Flickr/scheendijk, CC BY

For example, clouds can reflect sunlight back to space, or they can trap heat emitted by the Earth. In a warming world, scientists are still unclear on the role clouds will play.




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While a runaway greenhouse would make Earth completely uninhabitable to life as we know it, the losses that may accrue from just a few degrees Celsius of global warming are serious and must not be discounted.

Sea level rise, increased frequency and intensity of extreme weather events, threats to endangered species and unique ecosystems are just a few of the many reasons we have to be concerned.

The silver lining is we (probably) don’t need to worry about becoming like our neighbour Venus any time soon.The Conversation

We’re not heading this way just yet.

Laura Revell, Senior Lecturer in Environmental Physics, University of Canterbury

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

The European Union wants to impose carbon tariffs on Australian exports. Is that legal?


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Felicity Deane, Queensland University of TechnologyWhat Australian politicians call carbon tariffs, the European Union labels a carbon border adjustment mechanism.

While one sounds bad (the World Trade Organisation has rules that restrict tariffs) the other sounds understandable — if the European Union is imposing a carbon tax on its own products as Australia once did, surely it is reasonable to impose it on products from overseas.

The argument is that if a German steel manufacturer has to pay a tax of, say, $77 a tonne for the carbon it emits while making the steel, an Australian manufacturer should be charged the same when its product enters the country, unless it has already paid the same tax here.

To do otherwise would give the Australian product an unfair price advantage — it would create “carbon leakage” of the kind Australian businesses used to warn about in the leadup to Australia’s carbon price.

The European Union approved the idea in principle on March 10.

The details are less than clear, in part because it is possible that carbon tariffs are not permitted under the rules of the World Trade Organisation to which European nations and most other nations belong.

WTO rules might help Australia…

The rules say taxes or “charges of any kind” can only be imposed on imported products the same way as they are domestically.

That appears to mean that they can be imposed on importers but not on producers, which isn’t quite what the European Union has in mind.

Ideally the World Trade Organisation would be able to provide guidance, but (in part because of the actions of the US Trump administration) it isn’t really in a position to do.

…if only they were enforceable

New World Trade Organisation director general Ngozi Okonjo-Iweala.
Fabrice Coffrini/AP

The WTO has a new director general in Ngozi Okonjo-Iweala who took office this month, but it will remain in an “induced coma” for as long as its appellate body is unable to hear disputes.

Under Trump, the US kept vetoing appointments to the appellate body until the expiration of terms of its existing members meant it no longer had a quorum.

Disputes can still be initiated by countries such as Australia, forcing consultations, but without final determinations.

Although the European Union says it wants to ensure that its adjustment mechanism complies with the WTO’s rules, it hasn’t ruled out the possibility of relying on provisions that allow exceptions.

Both sides could make a case

Exceptions are allowed for the protection of human, animal or plant life or health or the protection of an exhaustible natural resource.

The catch is these exceptions are not allowed to discriminate between countries and must not be disguised restrictions on trade.

It is arguable that an adjustment mechanism designed to protect the competitiveness of European industries will breach these provisions.




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No point complaining about it, Australia will face carbon levies unless it changes course


The European Union has suggested that border adjustments will be unnecessary when the rest of the world has matched it in committing to achieve net zero emissions by 2050, so long as these commitments are back up by real actions.

But that hasn’t happened yet, and despite talk by Prime Minister Scott Morrison of his “hope” that Australia can get to net zero by 2050, Australia hasn’t made a commitment, and hasn’t backed it with tax-like instrument.

With any World Trade Organisation determination uncertain and perhaps impossible, apart from complaining about carbon tariffs or border adjustments, there may be little Australia can do.The Conversation

Felicity Deane, Associate Professor, Queensland University of Technology

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

No point complaining about it, Australia will face carbon levies unless it changes course


John Quiggin, The University of Queensland

Reports that Britain’s prime minister Boris Johnson is considering calling for carbon border levies at the G7 summit to be held in London in June have produced a predictable reaction from the Australian government.

The levies would impose tariffs on carbon-intensive goods from countries such as Australia that haven’t adopted a carbon price or a 2050 net-zero emissions target.

Appearing to be shocked by the news, Energy Minister Angus Taylor declared that Australia is “dead against” carbon tariffs.

They were a “new form of protectionism designed to shield local industries from free trade”.

In fact they are already the policy of the European Union and the US, where President Joe Biden calls them a “carbon adjustment fee against countries that are failing to meet their climate and environmental obligations”. Canada, which has an economy-wide price on carbon, isn’t worried.

Saying you’re dead against something doesn’t stop it, and nor does asserting that it is anti free trade, when it is just as arguable that it is pro fair trade because it denies exporters from countries that aren’t taking action against climate change an unfair advantage.

Australia not the primary target

The mining industry itself made this point during the Gillard government’s introduction of Australia’s short-lived carbon price.

It would leave Australian exporters at a “disadvantage compared with international competitors”.

Australia isn’t the primary target in any event. The main aim of carbon tariffs would be to encourage China’s leader Xi Jinping to shift his country’s zero emissions date from 2060 to 2050, benefiting the rest of the world.




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If Xi Jinping does it, he’ll be on a level playing field with much of the world, although not with Australia, whose fate, like that of Britain’s Admiral Byng in 1757 would be used “to encourage the others”.

Complaining won’t much help. The International Monetary Fund has endorsed the idea, saying

in the absence of an agreement on carbon pricing – which would be by far preferable – applying the same carbon prices on the same products irrespective of where they are produced could help avoid shifting emissions out of the EU to countries with different standards

The World Trade Organisation, which has in the past has pushed back against environmental considerations in trade, is neutered.

World Trade Organisation powerless

In the late 1990s the WTO struck down a range of environmental restrictions imposed by the United States that required imported tuna to be labelled “dolphin safe” and required shrimp catchers to take action to protect turtles.

These decisions proved disastrous for the WTO, producing bitter hostility from the environmental movement and contributing to mass protests at the 1999 WTO meeting, which became known as the Battle of Seattle and ultimately killed the Doha round of trade negotiations.

Right now the WTO is in the organisational equivalent of an induced coma. By refusing to fill vacancies as they arose, the Trump Administration denied its appellate panel a quorum, forcing it to stop hearing cases.

President Donald Trump, neutered the World Trade Organisation.
AP

The result is that any appeal to the WTO against carbon border tariffs would be left in limbo. US President Joe Biden has agreed to the appointment of a new WTO director general, stalled by Trump, but is in no hurry to re-establish the appellate body.

Instead, he will first try to refashion the WTO into an organisation that supports his own policies, among them stronger environmental measures, carbon tariffs and “Buy American” provisions. When reformed, the appellate body will give complaints from Australia’s government short shrift.

Prime Minister Scott Morrison has shown some signs of recognising these realities, making baby steps towards announcing a 2050 zero emissions target.

But time is short. Morrison will have to either face down the denialists and do-nothingists on his own side of politics, or set himself, and Australia, up for a series of humiliations on the international stage, with real and damaging consequences.The Conversation

John Quiggin, Professor, School of Economics, The University of Queensland

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

Astronomers create 40% more carbon emissions than the average Australian. Here’s how they can be more environmentally friendly



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Adam Stevens, University of Western Australia and Sabine Bellstedt, University of Western Australia

Astronomers know all too well how precious and unique the environment of our planet is. Yet the size of our carbon footprint might surprise you.

Our study, released today in Nature Astronomy, estimated the field produces 25,000 tonnes of carbon dioxide-equivalent emissions per year in Australia. With fewer than 700 active researchers nationwide (including PhD students), this translates to 37 tonnes per astronomer per year.




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As a point of reference, the average Australian adult was responsible for 26 tonnes of emissions in 2019, total. That means the job of being an astronomer is 40% more carbon-intensive than the average Australian’s job and home life combined.

While we often defer to governments for climate policy, our global carbon footprint can be dramatically reduced if every industry promotes strategies to reduce their own footprint. For individual industries to make progress, they must first recognise just how much they contribute to the climate emergency.

Where do all the emissions come from?

We found 60% of astronomy’s carbon footprint comes from supercomputing. Astronomers rely on supercomputers to not only process the many terabytes of data they collect from observatories everyday, but also test their theories of how the Universe formed with simulations.

Antennas and a satellite dish in the foreground, with others in the background, in the WA desert.
Antennas of CSIRO’s ASKAP telescope at the Murchison Radio-astronomy Observatory in Western Australia.
CSIRO Science Image

Frequent flying has historically been par for the course for astronomers too, be it for conference attendance or on-site observatory visits all around the world. Prior to COVID-19, six tonnes of annual emissions from flights were attributed to the average astronomer.

An estimated five tonnes of additional emissions per astronomer are produced in powering observatories every year. Astronomical facilities tend to be remote, to escape the bright lights and radio signals from populous areas.

Some, like the Parkes radio telescope and the Anglo-Australian Telescope near Coonabarabran, are connected to the electricity grid, which is predominately powered by fossil fuels.

Others, like the Murchison Radio-astronomy Observatory in Western Australia, need to be powered by generators on site. Solar panels currently provide around 15% of the energy needs at the Murchison Radio-astronomy Observatory, but diesel is still used for the bulk of the energy demands.

Finally, the powering of office spaces accounts for three tonnes of emissions per person per year. This contribution is relatively small, but still non-negligible.

They’re doing it better in Germany

Australia has an embarrassing record of per-capita emissions. At almost four times the global average, Australia ranks in the top three OECD countries for the highest per-capita emissions. The problem at large is Australia’s archaic reliance on fossil fuels.

A study at the Max Planck Institute for Astronomy in Germany found the emissions of the average astronomer there to be less than half that in Australia.

The difference lies in the amount of renewable energy available in Germany versus Australia. The carbon emissions produced for each kilowatt-hour of electricity consumed at the German institute is less than a third pulled from the grid in Australia, on average.

The challenge astronomers in Australia face in reducing their carbon footprint is the same challenge all Australian residents face. For the country to claim any semblance of environmental sustainability, a swift and decisive transition to renewable energy is needed.

Taking emissions reduction into our own hands

A lack of coordinated action at a national level means organisations, individuals, and professions need to take emissions reduction into their own hands.

For astronomers, private arrangements for supercomputing centres, observatories, and universities to purchase dedicated wind and/or solar energy must be a top priority. Astronomers do not control the organisations that make these decisions, but we are not powerless to effect influence.




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The good news is this is already happening. A recent deal made by Swinburne University to procure 100% renewable energy means the OzSTAR supercomputer is now a “green machine”.

CSIRO expects the increasing fraction of on-site renewables at the Murchison Radio-astronomy Observatory has the potential to save 2,000 tonnes of emissions per year from diesel combustion. And most major universities in Australia have released plans to become carbon-neutral this decade.

As COVID-19 halted travel worldwide, meetings have transitioned to virtual platforms. Virtual conferences have a relatively minute carbon footprint, are cheaper, and have the potential to be more inclusive for those who lack the means to travel. Despite its challenges, COVID-19 has taught us we can dramatically reduce our flying. We must commit this lesson to memory.




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And it’s encouraging to see the global community banding together. Last year, 11,000 scientists from 153 countries signed a scientific paper, warning of a global climate emergency.

As astronomers, we have now identified the significant size of our footprint, and where it comes from. Positive change is possible; the challenge simply needs to be tackled head-on.The Conversation

Adam Stevens, Research Fellow in Astrophysics, University of Western Australia and Sabine Bellstedt, Research Associate in Astronomy, University of Western Australia

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

Dishing the dirt: Australia’s move to store carbon in soil is a problem for tackling climate change



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Robert Edwin White, University of Melbourne and Brian Davidson, University of Melbourne

To slow climate change, humanity has two main options: reduce greenhouse gas emissions directly or find ways to remove them from the atmosphere. On the latter, storing carbon in soil – or carbon farming – is often touted as a promising way to offset emissions from other sources such as energy generation, industry and transport.

The Morrison government’s Technology Investment Roadmap, now open for public comment, identifies soil carbon as a potential way to reduce emissions from agriculture and to offset other emissions.

In particular, it points to so-called “biochar” – plant material transformed into carbon-rich charcoal then applied to soil.

But the government’s plan contains misconceptions about both biochar, and the general effectiveness of soil carbon as an emissions reduction strategy.

Emissions rising from a coal plant.
Soil carbon storage is touted as a way to offset emissions from industry and elsewhere.
Shutterstock

What is biochar?

Through photosynthesis, plants turn carbon dioxide (CO₂) into organic material known as biomass. When that biomass decomposes in soil, CO₂ is produced and mostly ends up in the atmosphere.

This is a natural process. But if we can intervene by using technology to keep carbon in the soil rather than in the atmosphere, in theory that will help mitigate climate change. That’s where biochar comes in.

Making biochar involves heating waste organic materials in a reduced-oxygen environment to create a charcoal-like product – a process called “pyrolysis”. The carbon from the biomass is stored in the charcoal, which is very stable and does not decompose for decades.

Plant materials are the predominant material or “feedstock” used to make biochar, but livestock manure can also be used. The biochar is applied to the soil, purportedly to boost soil fertility and productivity. This has been tested on grassland, cropping soils and in vineyards.

A handful of biochar.
Biochar is produced by burning organic material in a low oxygen environment.
Shutterstock

But there’s a catch

So far, so good. But there are a few downsides to consider.

First, the pyrolysis process produces combustible gases and uses energy – to the extent that when all energy inputs and outputs are considered in a life cycle analysis, the net energy balance can be negative. In other words, the process can create more greenhouse gas emissions than it saves. The balance depends on many factors including the type and condition of the feedstock and the rate and temperature of pyrolysis.

Second, while biochar may improve the soil carbon status at a new site, the sites from which the carbon residues are removed, such as farmers’ fields or harvested forests, will be depleted of soil carbon and associated nutrients. Hence there may be no overall gain in soil fertility.




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Third, the government roadmap claims increasing soil carbon can reduce emissions from livestock farming while increasing productivity. Theoretically, increased soil carbon should lead to better pasture growth. But the most efficient way for farmers to take advantage of the growth, and increase productivity, is to keep more livestock per hectare.

Livestock such as cows and sheep produce methane – a much more potent greenhouse gas than carbon dioxide. Our analysis suggests the methane produced by the extra stock would exceed the offsetting effect of storing more soil carbon. This would lead to a net increase, not decrease, in greenhouse gas

Beef cattle grazing in a field
Farmers would have to increase stock numbers to benefit from pasture growth.
Dan Peled/AAP

A policy failure

The government plan refers to the potential to build on the success of the Emissions Reduction Fund. Among other measures, the fund pays landholders to increase the amount of carbon stored in soil through carbon credits issued through the Carbon Farming Initiative.

However since 2014, the Emissions Reduction Fund has not significantly reduced Australia’s greenhouse gas emissions – and agriculture’s contribution has been smaller still.




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So far, the agriculture sector has been contracted to provide about 9.5% of the overall abatement, or about 18.3 million tonnes. To date, it’s supplied only 1.54 million tonnes – 8.4% of the sector’s commitment.

The initiative has largely failed because several factors have made it uneconomic for farmers to take part. They include:

  • overly complex regulations
  • requirements for expensive soil sampling and analysis
  • the low value of carbon credits (averaging $12 per tonne of CO₂-equivalent since the scheme began).
A farmer inspecting crops.
For many farmers, taking part in the Emissions Reduction Fund is uneconomic.
Shutterstock

A misguided strategy

We believe the government is misguided in considering soil carbon as an emissions reduction technology.

Certainly, increasing soil carbon at one location can boost soil fertility and potentially productivity, but these are largely private landholder benefits – paid for by taxpayers in the form of carbon credits.




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If emissions reduction is seen as a public benefit, then the payment to farmers becomes a subsidy. But it’s highly questionable whether the public benefit (in the form of reduced emissions) is worth the cost. The government has not yet done this analysis.

To be effective, future emissions technology in Australia should focus on improving energy efficiency in industry, the residential sector and transport, where big gains are to be made.The Conversation

Robert Edwin White, Professor Emeritus, University of Melbourne and Brian Davidson, Senior Lecturer, Department of Agriculture and Food Systems, University of Melbourne

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

Gabon’s large trees store huge amounts of carbon. What must be done to protect them



Ivanov Gleb/Shutterstock

John Poulsen, Duke University

Large trees are the living, breathing giants that tower over tropical forests, providing habitat and food for countless animals, insects and other plants. Could these giants also be the key to slowing climate change?

The Earth’s climate is changing rapidly due to the buildup of greenhouse gases, like carbon dioxide, in the atmosphere as a result of human activities. Trees absorb carbon from the air and store it in their trunks, branches, and roots. In general, the larger the tree, the more carbon it stores.

Globally, tropical forests remove a staggering 15% of carbon dioxide emissions that humans produce. Africa’s tropical forests – the second largest block of rainforest in the world – have a large role to play in slowing climate change.

But large trees are in trouble everywhere. I carried out research to examine the distribution, drivers and threats to large trees in Gabon. Gabon has 87% forest cover and is the second most forested country in the world.

By carrying out this project, I was able to identify areas with a wealth of large trees (and therefore key carbon stores and sinks), what needed to be done to better protect them and eventually recommend those areas as a priority for conservation.

National inventory

In 2012, the government of Gabon began a national inventory of its forests to measure the amount of carbon stored in its trees – one of the first nationwide efforts in the tropics.

An inventory of this scale isn’t easy, especially in a heavily forested country. Technicians from Gabon’s National Parks Agency travelled to every corner of the country, sometimes hiking more than two days crossing swamps and traversing rivers, to measure the diameter and height of trees in plots a bit larger in size than a soccer field.

Using Gabon’s new inventory of 104 plots, we calculated the amount of carbon in 67,466 trees, representing at least 578 different species. We did this by applying equations to the tree measurements.

The results indicated that the density of carbon stored in Gabon’s trees is among the highest in the world. On average, Gabon’s old growth forests harbour more carbon per area than old growth forests in Amazonia and Asia.

Most of this carbon is stored in the largest trees – those with diameters bigger than 70cm at 1.3 meters from the ground. Just the largest 5% of trees stored 50% of the forest carbon. In other words, 3,373 trees out of the 67,466 measured trees contained half of the carbon.

Drivers of forest carbon stocks

Next, we examined the drivers of carbon stocks. What determines whether an area of forest holds many large trees and lots of carbon? Do environmental conditions or human activities have the largest impact on forest carbon stocks?

Environmental factors – such as soil fertility and depth, temperature, precipitation, slope and elevation – often influence the amount of carbon in a forest. During photosynthesis, trees harness energy from the sun to convert water, carbon dioxide, and minerals into carbohydrates for growth. Therefore, forests with low levels of soil minerals or that receive little rainfall should store less carbon than areas with abundant minerals and water.

Human activities – like agriculture and logging – also influence carbon stocks. Cutting down trees for timber, to clear land for farming, or for construction reduces the amount of carbon stored in forests.

We examined the amount of carbon in each tree plot in relation to the environmental factors and human activities associated with the plot. Surprisingly, we found that human activities, not environmental factors, overwhelmingly affect carbon stocks.

The impact of human activities on forest carbon was largely unexpected because of Gabon’s high forest cover (the second highest of any country) and low population density (9 people per square kilometer), 87% of which is located in urban areas. If human impacts are this strong in Gabon, what must their effects be in other tropical nations?

Although we don’t know for sure, we believe past and present swidden (slash-and-burn) agriculture is the principle cause for low carbon stocks in some areas. Forests close to villages had lower levels of carbon, probably because forest clearing for farming converts old growth forest to secondary forest.

Interestingly, forests in logging concessions held similar amounts of carbon as old growth forests. It is too early to conclude that timber harvest doesn’t reduce carbon levels by cutting large trees, but this finding gives hope that logging concessions can be managed sustainably to conserve carbon stocks.

Importantly, forests in national parks stored roughly 25% more carbon than forests outside of parks. Thus, protecting mostly undisturbed forests can effectively conserve carbon and biodiversity.

Saving Gabon’s giants

The critical role of humans in diminishing carbon stocks is both a blessing and a curse. One one hand, the future of forests are in our hands, giving us the power to choose our fate. On the other hand, we cannot ignore the responsibility to act collectively to secure these resources while considering the interests of the countries that host them.

Gabon is taking laudable actions to conserve its forests, including a protected area network of 13 parks. In addition, Gabon is reforming its logging sector and developing a nationwide land use plan. These actions are a great start, yet continued action is necessary to curb the effects of swidden agriculture and ensure that growing industrial agriculture does not reverse Gabon’s achievements.

Intact forests can pay returns. Norway recently committed to paying Gabon $150 million for stewardship of its forests. Conservation of forests requires sacrifice by the Gabonese people. Yet, this payment demonstrates that Gabon’s large trees are a national asset that can contribute to its development as well as an international resource requiring collective action to conserve.The Conversation

John Poulsen, Associate Professor of Tropical Ecology, Duke University

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

Planting non-native trees accelerates the release of carbon back into the atmosphere



native forest.

Lauren Waller and Warwick Allen, University of Canterbury

Large-scale reforestation projects such as New Zealand’s One Billion Trees programme are underway in many countries to help sequester carbon from the atmosphere.

But there is ongoing debate about whether to prioritise native or non-native plants to fight climate change. As our recent research shows, non-native plants often grow faster compared to native plants, but they also decompose faster and this helps to accelerate the release of 150% more carbon dioxide from the soil.

Our results highlight a challenging gap in our understanding of carbon cycling in newly planted or regenerating forests.

It is relatively easy to measure plant biomass (how quickly a plant grows) and to estimate how much carbon dioxide it has removed from the atmosphere. But measuring carbon release is more difficult because it involves complex interactions between the plant, plant-eating insects and soil microorganisms.

This lack of an integrated carbon cycling model that includes species interactions makes predictions for carbon budgeting exceedingly difficult.




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How non-native plants change the carbon cycle

There is uncertainty in our climate forecasting because we don’t fully understand how the factors that influence carbon cycling – the process in which carbon is both accumulated and lost by plants and soils – differ across ecosystems.

Carbon sequestration projects typically use fast-growing plant species that accumulate carbon in their tissues rapidly. Few projects focus on what goes on in the soil.

Non-native plants often accelerate carbon cycling. They usually have less dense tissues and can grow and incorporate carbon into their tissues faster than native plants. But they also decompose more readily, increasing carbon release back to the atmosphere.

Our research, recently published in the journal Science, shows that when non-native plants arrive in a new place, they establish new interactions with soil organisms. So far, research has mostly focused on how this resetting of interactions with soil microorganisms, herbivorous insects and other organisms helps exotic plants to invade a new place quickly, often overwhelming native species.

Invasive non-native plants have already become a major problem worldwide, and are changing the composition and function of entire ecosystems. But it is less clear how the interactions of invasive non-native plants with other organisms affect carbon cycling.




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Planting non-native trees releases more carbon

We established 160 experimental plant communities, with different combinations of native and non-native plants. We collected and reared herbivorous insects and created identical mixtures which we added to half of the plots.

We also cultured soil microorganisms to create two different soils that we split across the plant communities. One soil contained microorganisms familiar to the plants and another was unfamiliar.

Herbivorous insects and soil microorganisms feed on live and decaying plant tissue. Their ability to grow depends on the nutritional quality of that food. We found that non-native plants provided a better food source for herbivores compared with native plants – and that resulted in more plant-eating insects in communities dominated by non-native plants.

Similarly, exotic plants also raised the abundance of soil microorganisms involved in the rapid decomposition of plant material. This synergy of multiple organisms and interactions (fast-growing plants with less dense tissues, high herbivore abundance, and increased decomposition by soil microorganisms) means that more of the plant carbon is released back into the atmosphere.

In a practical sense, these soil treatments (soils with microorganisms familiar vs. unfamiliar to the plants) mimic the difference between reforestation (replanting an area) and afforestation (planting trees to create a new forest).

Reforested areas are typically replanted with native species that occurred there before, whereas afforested areas are planted with new species. Our results suggest planting non-native trees into soils with microorganisms they have never encountered (in other words, afforestation with non-native plants) may lead to more rapid release of carbon and undermine the effort to mitigate climate change.The Conversation

Lauren Waller, Postdoctoral Fellow and Warwick Allen, Postdoctoral fellow, University of Canterbury

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

Australia’s hidden opportunity to cut carbon emissions, and make money in the process



A seagrass meadow. For the first time, researchers have counted the greenhouse gases stored by and emitted from such ecosystems.
NOAA/Heather Dine

Oscar Serrano, Edith Cowan University; Carlos Duarte, King Abdullah University of Science and Technology; Catherine Lovelock, The University of Queensland; Paul Lavery, Edith Cowan University, and Trisha B Atwood, Utah State University

It’s no secret that cutting down trees is a main driver of climate change. But a forgotten group of plants is critically important to fixing our climate — and they are being destroyed at an alarming rate.

Mangroves, tidal marshes and seagrasses along Australia’s coasts store huge amounts of greenhouse gases, known as blue carbon.

Our research, published in Nature Communications, shows that in Australia these ecosystems absorb 20 million tonnes of carbon dioxide each year. That’s about the same as 4 million cars.




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Worryingly, the research shows that between 2 million and 3 million tonnes of carbon dioxide is released each year by the same ecosystems, due to damage from human activity, severe weather and climate change.

This research represents the world’s most comprehensive audit of any nation’s blue carbon. Around 10% of such ecosystems are located in Australia — so preserving and restoring them could go a long way to meeting our Paris climate goals.

A pile of washed-up seaweed and beach erosion at Collaroy Beach on Sydney’s northern beaches. Storms can damage blue carbon ecosystems.
Megan Young/AAP

Super-charged carbon dioxide capture

Blue carbon ecosystems are vital in curbing greenhouse gas emissions. They account for 50% of carbon dioxide sequestered by oceans — despite covering just 0.2% of the world’s total ocean area — and absorb carbon dioxide up to 40 times faster than forests on land.

They do this by trapping particles from water and storing them in the soil. This means tidal marsh, mangrove and seagrass ecosystems bury organic carbon at an exceptionally high rate.

Globally, blue carbon ecosystems are being lost twice as fast as tropical rainforests despite covering a fraction of the area.

Since European settlement, about 25,000km² of tidal marsh and mangroves and 32,000km² of seagrass have been destroyed – up to half the original extent. Coastal development in Australia is causing further losses each year.

When these ecosystems are damaged — through storms, heatwaves, dredging or other human development — the carbon stored in biomass and soils can make its way back into the environment as carbon dioxide, contributing to climate change.

In Western Australia in the summer of 2010-11, about 1,000km² of seagrass meadows at Shark Bay were lost due to a marine heatwave. Similarly, two cyclones and several other impacts devastated a 400km stretch of mangroves in the Gulf of Carpentaria in recent years.

The beach and Cape Kimberley hinterland at the mouth of the Daintree River in Queensland.
Brian Cassey/AAP

Such losses likely increase carbon dioxide emissions from land-use change in Australia by 12–21% per year.

Aside from the emissions reduction benefits, conserving and restoring blue carbon ecosystems would also increase the resilience of coasts to rising sea level and storm surge associated with climate change, and preserve habitats and nurseries for marine life.

How we measured blue carbon – and why

The project was part of a collaboration with CSIRO and included 44 researchers from 33 research institutions around the world.

To accurately quantify Australia’s blue carbon stocks, we divided Australia into five different climate zones. Variations in temperature, rainfall, tides, sediments and nutrients mean plant productivity and biomass varies across regions. So ecosystems in a tropical climate such as North Queensland store carbon dioxide at a different rate to those in temperate climates such as southeastern Australia.




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We estimated carbon dioxide stored in the vegetation above ground and soils below for each climate area. We measured the size and distribution of vegetation and took soil core samples to create the most accurate measurements possible.

Blue carbon must be assessed on a national scale before policies to preserve them can be developed. These policies might involve replanting seagrass meadows, reintroducing tidal flow to restore mangroves or preventing potential losses caused by coastal development.

Seagrass at Queensland’s Gladstone Harbour.
James Cook University

There’s a dollar to be made

Based on a carbon price of A$14 per tonne – the most recent price under the federal government’s Emissions Reduction Fund – blue carbon projects could be worth tens of millions of dollars per year in carbon credits. Our comprehensive measurements provide greater certainty of expected returns for financiers looking at investing in such projects.

Restoring just 10% of blue carbon ecosystems lost in Australia since European settlement could generate more than US$11 million per year in carbon credits. Conserving such ecosystems under threat could be worth between US$22 million and US$31 million per year.




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Blue carbon projects cannot currently be counted towards Australia’s Paris targets, but federal environment authorities are developing a methodology for their inclusion. The reintroduction of tidal flow to restore mangrove and tidal marsh ecosystems has been identified as the most promising potential activity.

Other activities being explored include planning for sea level rise to allow mangrove and tidal marsh to migrate inland, and avoiding the clearing of seagrass and mangroves.

There are still questions to be answered about exactly how blue carbon can be used to mitigate climate change. But our research shows the massive potential in Australia, and allows other countries to use the work for their own blue carbon assessments.The Conversation

Oscar Serrano, ARC DECRA Fellow, Edith Cowan University; Carlos Duarte, Adjunct professor, King Abdullah University of Science and Technology; Catherine Lovelock, Professor of Biology, The University of Queensland; Paul Lavery, Professor of Marine Ecology, Edith Cowan University, and Trisha B Atwood, Assistant Professor of aquatic ecology, Utah State University

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

What if we measured the thing that matters most: “carbon productivity”


Carbon productivity is the measure that matters, but we are hung up on the productivity of our workers.
pixabay/pexels

David Peetz, Griffith University

Ask any economist a question, and you will usually get the answer: “productivity”.

The winner of the 2008 Nobel Prize in Economics, Paul Krugman, set the standard in 1994:

Productivity isn’t everything, but, in the long run, it is almost everything. A country’s ability to improve its standard of living over time depends almost entirely on its ability to raise its output per worker.

The new head of Australia’s treasury, Steven Kennedy, said much the same thing this week:

The most important long-term contribution to wage growth is labour productivity.

For my money, they could say the same about “carbon productivity”, a idea that is going to matter to us more.

Labour productivity is notoriously hard to measure; measuring changes in it is harder still.

It’s relatively easy to measure in the jobs we are doing less of these days, such as making washing machines; harder to measure in the jobs we are doing more of, such as caring for people.

And it’s less important than you might think. People aren’t a particularly finite resource. Allowable carbon emissions are.

Carbon is the input that matters

Economist Paul Krugman. ‘In the long run productivity is almost everything.’
CHRISTOPHER BARTH/EPA

The Intergovernmental Panel on Climate Change says net carbon emissions will have to be reduced to zero.

That means we’ve a carbon budget, a limited amount of greenhouse gas we can emit from here on. It would make sense to use it wisely.

What I am proposing is a target for “carbon productivity”, the amount of production we achieve from each remaining unit of emissions – as a means of helping us cut overall carbon emissions.

It’s easy to calculate: gross domestic product divided by net emissions. We already measure GDP, and we already measure emissions in tonnes, albeit unevenly.

We are going to need huge increases in carbon productivity, much more so as a result of cutting emissions than increasing production.

Things that are good for labour productivity might well be bad for carbon productivity. For example, replacing a sweeper with an air blower is good on the first count, bad on the second.

Measuring carbon productivity…

If introduced at a national level, a target, or at least a widely published measure, could start to focus government minds on what’s important and what’s not, and assist in allocating resources. Solar farms would become more likely to gain support than coal-fired power plants.

Regulatory resources might be redirected in surprising ways. While a small number of large emitters constitutes an easy target for policymakers, if those large emitters are efficient, the government might find it has to move its focus to the larger number of small inefficient emitters.

It could also help us think about how we resolve the conflict between the perceived need for economic growth and the need to substantially cut emissions. Both would be important, the measures that achieved both would be the most important.

Accounting debates about whether to carry carry forward international credits would be rendered meaningless.




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Giving national attention to measuring carbon productivity would put more pressure on more firms to measure all of their emissions. Many already measure their “scope 1” direct emissions. A smaller number measure “scope 2” emissions (from things such as electricity used by the firm).

A much smaller number measure “scope 3” emissions (from sources they do not own, such as air travel, waste and water). They’re the hardest to measure.

…might just produce results

For some, sustainable economic growth is a contradiction in terms.

They argue that economic growth is incompatible with ecological survival.

But the population appears to want both, and the political and social consequences of failing to achieve both could be devastating for democratic society and the planet. It has already been established that rising unemployment reduces support for action on climate change.




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Targeting or measuring carbon productivity by itself won’t achieve those goals.

For that, we would need some form of carbon pricing and a government committed to the uptake of low-emission technologies.

But if we are to have a shot at achieving both, we’ll need to know where we are going.The Conversation

David Peetz, Professor of Employment Relations, Centre for Work, Organisation and Wellbeing, Griffith University

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

Climate explained: what each of us can do to reduce our carbon footprint



Eating less meat is one change many of us can make to reduce our contribution to climate change.
from http://www.shutterstock.com, CC BY-ND

Nick Golledge, Victoria University of Wellington


CC BY-ND

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

If you have a question you’d like an expert to answer, please send it to climate.change@stuff.co.nz

As an individual, what is the single, most important thing I can do in the face of climate change?

The most important individual climate action will depend on each person’s particular circumstances, but each of us can make some changes to reduce our own carbon footprint and to support others to do the same.

Generally, there are four lifestyle choices that can make a major difference: eat less or no meat, forego air travel, go electric or ditch your car, and have fewer children.

In New Zealand, half of our greenhouse gas emissions come from agriculture. This is more than all transport, power generation and manufacturing industries combined. Clearly the single biggest change an individual can make is therefore to reduce meat and dairy consumption. A shift from animal to plant-sourced protein would give us a 37% better chance of keeping temperature rise under 2℃ and an almost 50% better chance of staying below 1.5℃ – the targets of the Paris agreement.

Best of all, this can be done right now, at whatever level you can manage, and there are many people taking this step.

One aspect that is often overlooked is that carnivorous pets (mainly dogs, cats) consume lots of meat, with all the associated impacts described above. A recent US study concluded that dog and cat ownership is responsible for nearly one third of the environmental impacts associated with animal production (land use, water, fossil fuels). So ideally, if you’re getting a new pet, go for something herbivorous.

Buy locally, eat seasonally

Buy local produce, whether it’s food grown locally or goods manufactured locally rather than imported from overseas. Goods that are transported around the world by sea account for 3.3% of global carbon dioxide emissions and 33% of all trade-related emissions from fossil fuel combustion, so reducing our dependence on imports makes a big difference to our overall carbon footprint.

Car use is a problem, because we all enjoy the personal mobility cars provide. But it comes with an excessively high carbon cost. Using public transport where possible is of course preferable, but for some the lack of personal freedom is a big disadvantage, as well as the sometimes less than perfect transit networks that exist in many parts of the country.

One alternative for many people looking to commute short distances might be an e-bike, but think of it as an alternative to your car rather than a replacement for your bike. For those looking to replace their car, buying a hybrid or full electric model would be the best thing from an emissions perspective, even if the production of the cars themselves isn’t entirely without environmental problems.

New Zealand’s network of electric vehicle (EV) chargers is growing rapidly, but generally speaking it is easiest to charge at home if you’re doing daily commutes. This becomes economical if you have an electricity supplier offering a special low rate for EV charging.

On the subject of electricity, an easy and quick way to reduce your carbon footprint is to switch to a supplier that generates electricity only from renewable sources. In New Zealand, we have an abundance of renewable options, from solar, wind and hydro.

Plant trees

Planting trees requires having some space, but if you have land available, planting trees is a great way to invest in longer-term carbon sequestration. There is a lot of variability between species, but as a rule of thumb, a tree that lives to 40 or 50 years will have taken up about a ton of carbon dioxide.




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Air travel is, for many of us, an essential part of our work. There is some progress in the field of aviation emissions reductions, but it is still a long way off. In the short term we have to find alternatives, whether that is in the form of teleconferencing or, if travel is essential, carbon offsetting schemes (although this is far from a perfect solution unfortunately).

Vote for climate-aware politicians and council representatives. These are the people who have the power to implement changes beyond the scope of individual actions. Make your voice heard through voting, and by contributing to discussion and consultation processes.

Community initiatives such as tree planting or shared gardens, or just maintaining wild spaces are ideal for carbon sequestration. This isn’t just because of the plants these spaces accommodate, but also because of the soil. Globally, soil holds two to three times more carbon than the atmosphere, but the ability of soil to retain this depends on it being managed well. Generally speaking, the longer and more densely planted an area of soil is, the better it will sequester carbon.

How to cope

One of the frustrations is the realisation that climate change is not something that can be left to politicians to deal with on our behalf. The urgency is simply too great. The responsibility has been implicitly devolved to the individual, without any prior consent.




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But individual actions are massively important in two ways. First, they have an immediate impact on our total carbon footprint, without any of the inertia of political machinations. Secondly, by adopting and advocating for low-carbon life choices, individuals are sending a clear message to political leaders that a growing proportion of the voting population will favour policies that are aligned with similar priorities.

It is of course hard to stand your ground and stick with new lifestyle choices when you feel surrounded by people who choose not to change, or worse, actively mock and criticise. This is normal human psychology. People subconsciously tend to feel attacked if they see someone else making a so-called ethical or moral choice, as if they themselves are being judged, or criticised.

In the context of climate change, the science is so overwhelmingly clear, and the current and future impacts so manifestly important, that not to acknowledge this in a meaningful manner either reflects a lack of understanding or awareness, or is simply selfish. Rather than taking issue with those members of society, a more positive approach that can help you cope with the feeling of marginalisation is to actively seek out like-minded people.The Conversation

Nick Golledge, Associate Professor of Glaciology, Victoria University of Wellington

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