How would planting 8 billion trees every year for 20 years affect Earth’s climate?


Planting 8 billion trees a year would replace about half of the 15 billion cut down annually.
Michael Tewelde/AFP via Getty Images

Karen D. Holl, University of California, Santa Cruz

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.


If we planted 8 billion trees a year for 20 years, what would happen on Earth? – Shivam K., age 14, Nawada, Bihar, India


Politicians, business leaders, YouTubers and celebrities are calling for the planting of millions, billions or even trillions of trees to slow climate change.

There are currently almost 8 billion people on Earth. If every single person planted a tree each year for the next 20 years, that would mean roughly 160 billion new trees.

Could massive tree planting actually slow climate change?

Trees and carbon

Carbon dioxide is the main gas that causes global warming. Through photosynthesis, trees and other plants transform carbon dioxide from the atmosphere into carbohydrates, which they use to make stems, leaves and roots.

The amount of carbon a tree can store varies a great deal. It depends on the tree species, where it is growing and how old it is.

Let’s say the average tree takes up 50 pounds of carbon dioxide a year. If a person planted a tree every year for 20 years – and each one survived, which is highly unlikely – those 20 trees would take up about 1,000 pounds, or half a ton, of carbon dioxide per year.

The average person in the United States produces a whopping 15.5 tons of carbon dioxide a year compared with 1.9 tons for an average person in India. This means that if each person in the U.S. planted one tree per year it would offset only about 3% of the carbon dioxide they produce each year, after all 20 trees had matured. But, it would offset 26% for somebody in India.

Planting trees is certainly part of the solution to climate change, but there are more important ones.

Aerial view of patchwork deforestation of rainforest.
Clearing the Amazon rainforest for livestock farms in Brazil in 2017.
Brazil Photos/LightRocket via Getty Images

Protecting the trees we have

There are about 3 trillion trees on Earth, which is only half as many as 12,000 years ago, at the start of human civilization.

People cut down an estimated 15 billion trees each year. A lot of those trees are in tropical forests, but deforestation is happening all over the planet.

Protecting existing forests makes sense. Not only do they absorb carbon dioxide in the trees and the soil, but they provide habitat for animals. Trees can provide firewood and fruit for people. In cities, they can offer shade and recreational spaces.

But trees should not be planted where they didn’t grow before, such as in native grasslands or savannas. These ecosystems provide important habitat for their own animals and plants – and already store carbon if they are left undisturbed.

Doing more

To slow climate change, people need to do much more than plant trees. Humans need to reduce their carbon dioxide and other greenhouse gas emissions quickly by transitioning to renewable energy sources, like solar and wind. People should also reduce the amount they drive and fly – and eat less meat, as meat has a much larger carbon footprint per calorie than grains and vegetables.

It is important that everybody – businesses, politicians, governments, adults and even kids – do what they can to reduce fossil fuel emissions. I know it can seem pretty overwhelming to think about what you as one person can do to help the planet. Fortunately, there are many options.

Volunteer with a local conservation organization, where you can help protect and restore local habitats. Discuss with your family new lifestyle choices, like biking, walking or taking public transit rather than driving.

Two Girl Scouts take a stand against deforestation.

And don’t be afraid to lead an effort to protect trees, locally or globally. Two 11-year-old Girl Scouts, concerned about the destruction of rainforests for palm oil plantations, led an effort to eliminate palm oil in Girl Scout cookies.

Sometimes change is slow, but together people can make it happen.


Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

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Karen D. Holl, Professor of Restoration Ecology, University of California, Santa Cruz

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

As the world battles to slash carbon emissions, Australia considers paying dirty coal stations to stay open longer


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Tim Nelson, Griffith University and Joel Gilmore, Griffith UniversityA long-anticipated plan to reform Australia’s electricity system was released on Thursday. One of the most controversial proposals by the Energy Security Board (ESB) concerns subsidies which critics say will encourage dirty coal plants to stay open longer.

The subsidies, under a so-called “capacity mechanism”, would aim to ensure reliable energy supplies as old coal plants retire.

Major coal generators say the proposal will achieve this aim. But renewables operators and others oppose the plan, saying it will pay coal plants for simply existing and delay the clean energy transition.

So where does the truth lie? Unless carefully designed, the proposal may enable coal generators to keep polluting when they might otherwise have closed. This is clearly at odds with the need to rapidly cut greenhouse gas emissions and stabilise Earth’s climate.

firefighter and bushfire engulfing house
Extending the life of coal plants is at odds with climate action efforts.
Dan Himbrechts/AAP

Paying coal stations to exist

The ESB provides advice to the nation’s energy ministers and comprises the heads of Australia’s major energy governing bodies.

Advice to the ministers on the electricity market redesign, released on Thursday, includes a recommendation for a mechanism formally known as the Physical Retailer Reliability Obligation (PRRO).

It would mean electricity generators are paid not only for the actual electricity they produce, which is the case now, but also for having the capacity to scale up electricity generation when needed.

Electricity prices on the wholesale market – where electricity is bought and sold – vary depending on the time of day. Prices are typically much higher when consumer demand peaks, such as in the evenings when we turn on heaters or air-conditioners. This provides a strong financial incentive for generators to provide reliable electricity at these times.

As a result of these incentives, Australia’s electricity system has been very reliable to date.

But the ESB says as more renewables projects come online, this reliability is not assured – due to investor uncertainty around when coal plants will close and how governments will intervene in the market.




Read more:
IPCC report: how to make global emissions peak and fall – and what’s stopping us


Under the proposed change, electricity retailers – the companies everyday consumers buy energy from – must enter into contracts with individual electricity generators to make capacity available to the market.

Energy authorities would decide what proportion of a generator’s capacity could be relied upon at critical times. Retailers would then pay generators regardless of whether or not they produce electricity when needed.

Submissions to the ESB show widespread opposition to the proposed change: from clean energy investors, battery manufacturers, major energy users and consumer groups. The ESB acknowledges the proposal has few supporters.

In fact, coal generators are virtually the only groups backing the proposed change. They say it would keep the electricity system reliable, because the rapid expansion of rooftop solar has lowered wholesale prices to the point coal plants struggle to stay profitable.

The ESB says the subsidy would also go to other producers of dispatchable energy such as batteries and pumped hydro. It says such businesses require guaranteed revenue streams if they’re to invest in new infrastructure.

Man gives thumbs up in front of hydro project
Prime Minister Scott Morrison at the Snowy Hydro project. Such generators would also be eligible for the proposed subsidy.
Lukas Coch/AAP

A questionable plan

In our view, the arguments from coal generators and the ESB require greater scrutiny.

Firstly, the ESB’s suggestion that the existing market is not driving investment in new dispatchable generation is not supported by recent data. As the Australian Energy Market Operator recently noted, about 3.7 gigawatts of new gas, battery and hydro projects are set to enter the market in coming years. This is on top of 3.2 gigawatts of new wind and solar under construction. Together, this totals more than four times the operating capacity of AGL’s Liddell coal plant in New South Wales.

It’s also difficult to argue the system is made more reliable by paying dispatchable coal stations to stay around longer.

One in four Australian homes have rooftop solar panels, and installation continues to grow. This reduces demand for coal-fired power when the sun is shining.

The electricity market needs generators that can turn on and off quickly in response to this variable demand. Hydro, batteries and some gas plants can do this. Coal-fired power stations cannot – they are too slow and inflexible.

Coal stations are also becoming less reliable and prone to breakdowns as they age. Paying them to stay open can block investment in more flexible and reliable resources.

Critics of the proposed change argue coal generators can’t compete in a world of expanding rooftop solar, and when large corporate buyers are increasingly demanding zero-emissions electricity.

There is merit in these arguments. The recommended change may simply create a new revenue stream for coal plants enabling them to stay open when they might otherwise have exited the market.

Governments should also consider that up to A$5.5 billion in taxpayer assistance was allocated to coal-fired generators in 2012 to help them transition under the Gillard government’s (since repealed) climate policies. Asking consumers to again pay for coal stations to stay open doesn’t seem equitable.

Steam billows from coal plant
Coal plants have already received billions in subsidies.
Shutterstock

The ultimate test

The nation’s energy ministers have not yet decided on the reforms. As usual, the devil will be in the detail.

For any new scheme to improve electricity reliability, it should solely reward new flexible generation such as hydro, batteries, and 100% clean hydrogen or biofuel-ready gas turbines.

For example, reliability could be improved by establishing a physical “reserve market” of new, flexible generators which would operate alongside the existing market. This generation could be seamlessly introduced as existing generation fails and exits.

The ESB has recommended such a measure, and pivoting the capacity mechanism policy to reward only new generators could be beneficial.

The Grattan Institute
has also proposed a scheme to give businesses more certainty about when coal plant will close. Together, these options would address the ESB’s concerns.

This month’s troubling report by the Intergovernmental Panel on Climate Change was yet another reminder of the need to dramatically slash emissions from burning fossil fuels.

Energy regulators, politicians and the energy industry owe it to our children and future generations to embrace a zero-emissions energy system. The reform of Australia’s electricity market will ultimately be assessed against this overriding obligation.




Read more:
Climate change has already hit Australia. Unless we act now, a hotter, drier and more dangerous future awaits, IPCC warns


The Conversation


Tim Nelson, Associate Professor of Economics, Griffith University and Joel Gilmore, Associate Professor, Griffith University

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

From jet fuel to clothes, microbes can help us recycle carbon dioxide into everyday products


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Jamin Wood, The University of Queensland; Bernardino Virdis, The University of Queensland, and Shihu Hu, The University of QueenslandThe Intergovernmental Panel on Climate Change (IPCC) report released earlier this month sounded a “code red for humanity”. At such a crucial time, we should draw on all possible solutions to combating global warming.

About one-quarter of greenhouse gas emissions are associated with the manufacture of the products we use. While a small number of commercial uses for carbon dioxide exist — for instance in the beverage and chemical industries — the current demand isn’t enough to achieve meaningful carbon dioxide reduction.

As such, we need to find new ways to transform industrial manufacturing from being a carbon dioxide source to a carbon dioxide user.

The good news is that plastics, chemicals, cosmetics and many other products need a carbon source. If we could produce them using carbon dioxide instead of fossil hydrocarbons, we would be able to sequester billions of tonnes of greenhouse gases per year.

How, you may ask? Well, biology already has a solution.




Read more:
There aren’t enough trees in the world to offset society’s carbon emissions – and there never will be


Gas fermentation

You may have heard of microscopic organisms, or microbes — we use them to make beer, spirits and bread. But we can also use them to create biofuels such as ethanol.

They typically need sugar as an input, which competes with human food consumption. However, there are other microbes called “acetogens” which can use carbon dioxide as their input to make several chemicals including ethanol.

Acetogens are thought to be one of the first life-forms on Earth. The ancient Earth’s atmosphere was very different to the atmosphere today — there was no oxygen, yet plentiful carbon dioxide.

Acetogens were able to recycle this carbon using chemical energy sources, such as hydrogen, in a process called gas fermentation. Today, acetogens are found in many anaerobic environments, such as in animals’ guts.

Not being able to use oxygen makes acetogens less efficient at building biomass; they are slow growers. But interestingly, it makes them more efficient producers.

For example, a typical food crop’s energy efficiency (where sunlight is turned into a product) may be around 1%. On the other hand, if solar energy was used to provide renewable hydrogen for use in gas fermentation (via acetogens), this process would have an overall energy efficiency closer to 10-15%.

This means acetogens are potentially up to twice as efficient as most current industrial processes — which makes them a cheaper and more environmentally friendly option. That is, if we can bring the technology to scale.

About one-quarter of greenhouse gas emissions come from the manufacture of everyday products, while one-third come from electricity generation and another one-fifth come from transport.

Sustainable carbon recycling

Gas fermentation is scaling up in China, the United States and Europe. Industrial emissions of carbon monoxide and hydrogen are being recycled into ethanol to commercially produce aviation fuel from 2022, plastic bottles from 2024 and even polyester clothes.

In the future this could be expanded to produce chemicals needed to make rubber, plastics, paints and cosmetics, too.

But gas fermentation currently isn’t done commercially with carbon dioxide, despite this being a much larger emission source than carbon monoxide. In part this is because it poses an engineering and bioengineering challenge, but also because it’s expensive.

We recently published an economic assessment in Water Research to help chart a pathway towards widespread acetogen-carbon dioxide recycling.

We found economic barriers in producing some products, but not all. For instance, it is viable today to use carbon dioxide-acetogen fermentation to produce chemicals required to make perspex.

But unlike current commercial operations, this would be enabled by renewable hydrogen production. Increasing the availability of green hydrogen will greatly increase what we can do with gas fermentation.

Looking ahead

Australia has a competitive advantage and could be a leader in this technology. As host to the world’s largest green-hydrogen projects, we have the capacity to produce low-cost renewable hydrogen.

Underused renewable waste streams could also enable carbon recycling with acetogens. For instance, large amounts of biogas is produced at wastewater treatment plants and landfills. Currently it’s either burned as waste, or to generate heat and power.

Past research shows us biogas can be converted (or “reformed”) into renewable hydrogen and carbon in a carbon-neutral process.

And we found this carbon and hydrogen could then be used in gas fermentation to make carbon-neutral products. This would provide as much as 12 times more value than just burning biogas to generate heat and power.

The IPCC report shows carbon dioxide removal is required to limit global warming to less than 2℃.

Carbon capture and storage is on most governments’ agendas. But if we change our mindset from viewing carbon as a waste product, then we can change our economic incentive from carbon disposal to carbon reuse.

Carbon dioxide stored underground has no value. If we harness its full potential by using it to manufacture products, this could support myriad industries as they move to sustainable production.




Read more:
Our ability to manufacture minerals could transform the gem market, medical industries and even help suck carbon from the air


The Conversation


Jamin Wood, PhD Candidate at the Australian Centre for Water and Environmental Biotechnology (formerly Advanced Water Management Centre), The University of Queensland; Bernardino Virdis, Senior Researcher at the Australian Centre for Water and Environmental Biotechnology (formerly Advanced Water Management Centre), The University of Queensland, and Shihu Hu, Senior Research fellow at the Australian Centre for Water and Environmental Biotechnology (formerly Advanced Water Management Centre), The University of Queensland

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