Global ‘stilling’: Is climate change slowing down the wind?

Read the full story at e360.

As carbon dioxide levels rise and the Earth’s poles warm, researchers are predicting a decline in the planet’s wind speeds. This ‘stilling’ could impact wind energy production and plant growth and might even affect the Gulf Stream, which drives much of the world’s climate.

Combatting forever chemicals in our drinking water

Listen to the podcast at 1A.

At least one water system in every state across the U.S. contains forever chemicals known as PFAS, according to the Environmental Working Group. PFAS are widely-used chemicals present in everything from cosmetics to fast food wrappers. They also don’t break down in the environment.

Because they stick around for so long, low levels of PFAS can be found almost everywhere – in water, soil, wildlife – and in us. In fact, the CDC found that these chemicals are in nearly everyone’s blood. PFAS exposure has been linked to a host of health issues including cancer and birth defects.

new advisory from the EPA effectively eliminates any safe level of PFAS found in water. But how do you get rid of them? And what do you need to know to keep yourself safe?

Guests

Carol Kwiatkowski: senior associate, Green Science Policy Institute; adjunct assistant professor, North Carolina State University

Sandy Wynn-Stelt: co-chair, Great Lakes PFAS Action Network

Kyle Burton: field operations director at the Bureau of Drinking Water and Groundwater, Wisconsin Department of Natural Resources

How Yili is targeting the ‘low-carbon consumption’ trend: From ‘no ink’ packaging to China’s first carbon neutral yogurt

Read the full story at Dairy Reporter.

Earlier this year, Chinese dairy giant Yili set out its ambition for a carbon neutral future. The company is leveraging innovation to build more sustainable production processes and products. Here’s how.

Hydropower’s future is clouded by droughts, floods and climate change – it’s also essential to the US electric grid

Lake Powell’s water level has been falling amid a two-decade drought. The white ‘bathtub ring’ on the canyon walls marks the decline. Justin Sullivan/Getty Images

by Caitlin Grady, Penn State and Lauren Dennis, Penn State

The water in Lake Powell, one of the nation’s largest reservoirs, has fallen so low amid the Western drought that federal officials are resorting to emergency measures to avoid shutting down hydroelectric power at the Glen Canyon Dam.

The Arizona dam, which provides electricity to seven states, isn’t the only U.S. hydropower plant in trouble.

The iconic Hoover Dam, also on the Colorado River, has reduced its water flow and power production. California shut down a hydropower plant at the Oroville Dam for five months because of low water levels in 2021, and officials have warned the same thing could happen in 2022.

In the Northeast, a different kind of climate change problem has affected hydropower dams – too much rainfall all at once.

The United States has over 2,100 operational hydroelectric dams, with locations in nearly every state. They play essential roles in their regional power grids. But most were built in the past century under a different climate than they face today.

As global temperatures rise and the climate continues to change, competition for water will increase, and the way hydropower supply is managed within regions and across the power grid in the U.S. will have to evolve. We study the nation’s hydropower production at a systems level as engineers. Here are three key things to understand about one of the nation’s oldest sources of renewable energy in a changing climate.

Hydropower can do things other power plants can’t

Hydropower contributes 6% to 7% of all power generation in the U.S., but it is a crucial resource for managing the U.S. electric grids.

Because it can quickly be turned on and off, hydroelectric power can help control minute-to-minute supply and demand changes. It can also help power grids quickly bounce back when blackouts occur. Hydropower makes up about 40% of U.S. electric grid facilities that can be started without an additional power supply during a blackout, in part because the fuel needed to generate power is simply the water held in the reservoir behind the turbine.

People look at a partially rusting turbine set up for display outside. It's about twice the height of the tallest person in the crowd.
Tourists look at an old turbine that was replaced at the Glen Canyon Dam. AP Photo/Felicia Fonseca

In addition, it can also serve as a giant battery for the grid. The U.S. has over 40 pumped hydropower plants, which pump water uphill into a reservoir and later send it through turbines to generate electricity as needed.

So, while hydroelectricity represents a small portion of generation, these dams are integral to keeping the U.S. power supply flowing.

Climate change affects hydropower in different ways in different regions

Globally, drought has already decreased hydropower generation. How climate change affects hydropower in the U.S. going forward will depend in large part on each plants’ location.

In areas where melting snow affects the river flow, hydropower potential is expected to increase in winter, when more snow falls as rain, but then decrease in summer when less snowpack is left to become meltwater. This pattern is expected to occur in much of the western U.S., along with worsening multiyear droughts that could decrease some hydropower production, depending on the how much storage capacity the reservoir has.

The Northeast has a different challenge. There, extreme precipitation that can cause flooding is expected to increase. More rain can increase power generation potential, and there are discussions about retrofitting more existing dams to produce hydropower. But since many dams there are also used for flood control, the opportunity to produce extra energy from that increasing rainfall could be lost if water is released through an overflow channel.

In the southern U.S., decreasing precipitation and intensified drought are expected, which will likely result in decreased hydropower production.

Some grid operators face bigger challenges

The effect these changes have on the nation’s power grid will depend on how each part of the grid is managed.

Agencies known as balancing authorities manage their region’s electricity supply and demand in real time.

The largest balancing authority in terms of hydroelectric generation is the Bonneville Power Administration in the Northwest. It coordinates around 83,000 megawatt-hours of electricity annually across 59 dams, primarily in Washington, Oregon and Idaho. The Grand Coulee Dam complex alone can produce enough power for 1.8 million homes.

Much of this area shares a similar climate and will experience climate change in much the same way in the future. That means that a regional drought or snowless year could hit many of the Bonneville Power Administration’s hydropower producers at the same time. Researchers have found that this region’s climate impacts on hydropower present both a risk and opportunity for grid operators by increasing summer management challenges but also lowering winter electricity shortfalls.

Balancing authorities and the number of hydropower plants in each. Lauren Dennis, CC BY-ND

In the Midwest, it’s a different story. The Midcontinent Independent System Operator, or MISO, has 176 hydropower plants across an area 50% larger than that of Bonneville, from northern Minnesota to Louisiana.

Since its hydropower plants are more likely to experience different climates and regional effects at different times, MISO and similarly broad operators have the capability to balance out hydropower deficits in one area with generation in other areas.

Understanding these regional climate effects is increasingly essential for power supply planning and protecting grid security as balancing authorities work together to keep the lights on.

More change is coming

Climate change is not the only factor that will affect hydropower’s future. Competing demands already influence whether water is allocated for electricity generation or other uses such as irrigation and drinking.

Laws and water allocation also shift over time and change how water is managed through reservoirs, affecting hydroelectricity. The increase in renewable energy and the potential to use some dams and reservoirs for energy storage might also change the equation.

The importance of hydropower across the U.S. power grid means most dams are likely here to stay, but climate change will change how these plants are used and managed.

This article was updated May 18, 2022, to clarify that Bonneville Power Administration coordinates power from 59 dams.

Caitlin Grady, Assistant Professor of Civil and Environmental Engineering and Research Associate in the Rock Ethics Institute, Penn State and Lauren Dennis, Ph.D. Student in Civil Engineering and Climate Science, Penn State

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

Is it possible to heal the damage we have already done to the Earth?

The Earth viewed from the Apollo 8 lunar mission on Dec. 24, 1968. NASA

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.

by Scott Denning, Colorado State University


Is it possible to heal the damage we have already done to the Earth? – Anthony, age 13


Sometimes it may seem that humans have altered the Earth beyond repair. But our planet is an incredible system in which energy, water, carbon and so much else flows and nurtures life. It is about 4.5 billion years old and has been through enormous changes.

At some points in Earth’s history, fires burned over large areas. At others, much of it was covered with ice. There also have been mass extinctions that wiped out nearly every living thing on its surface.

Earth’s climate has varied from extremely warm periods with no polar ice caps to phases when much of the planet was frozen.

Our living planet is incredibly resilient and can heal itself over time. The problem is that its self-healing systems are very, very slow. The Earth will be fine, but humans’ problems are more immediate.

People have damaged the systems that sustain us in many ways. We have polluted air and water, strewn plastic and other trash on land and in oceans and rivers, and destroyed habitats for plants and animals.

But we know how to help natural processes clean up many of these messes. And there has been a lot of progress since people started waking up to these problems 50 years ago.

Graph showing economic trends since 1970 and decline in six major air pollutants.
Since 1970, the U.S. has greatly reduced air pollution even as its economy has grown dramatically. USEPA

There still are problems to solve. Some pollutants, like plastic, last for thousands of years, so it’s much better to stop releasing them than to try to collect them later. And extinction is permanent, so the only effective way to reduce it is to be more careful about protecting animals, plants and other species.

Reversing climate change

The most serious damage humans are doing to the Earth comes mainly from burning coal, oil and gas, which is dramatically warming its climate. Burning these carbon-based fuels is changing the fundamental chemistry and physics of the air and oceans.

Every lump of coal or gallon of gasoline that’s burned releases carbon dioxide into the atmosphere. There it heats the Earth’s surface, causing floods, fires and droughts. Some of this added carbon dioxide dissolves into the oceans and makes them more acidic, which threatens ocean food webs.

Climate change is a problem that will get worse until humans stop making it worse – and then it will take many centuries for the climate to return to what it was like before the Industrial Revolution, when human actions started altering it on a large scale.

The only way to avoid making things worse is to stop setting carbon on fire. That means societies need to work hard to build an energy system that can help everyone live well without the need to burn carbon.

The good news is that we know how to make energy without releasing carbon dioxide and other pollution. Electricity made from solar, wind and geothermal power is now the cheapest energy in history. Cleaning up the global electricity supply and then electrifying everything can very quickly stop carbon pollution from getting worse.

This will require electric cars and trains, electric heating and cooking, and electric factories. We’ll also need new kinds of transmission and storage systems to get all that clean electricity from where it’s made to where it’s used.

The rest of the carbon mess can be cleaned up through better farm and forest management that stores carbon in land and plants instead of releasing it into the atmosphere. This is also a problem that scientists know how to solve.

The Earth will certainly heal, but it may take a very long time. The best way to start is with everyone doing their part to avoid making the damage any worse.


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.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Scott Denning, Professor of Atmospheric Science, Colorado State University

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

Here’s how food waste can generate clean energy

In an effort to reduce the growing problem of food waste disposal, researchers are focusing on developing new green technologies that use food waste to generate clean energy. (Shutterstock)

by Salvador Escobedo Salas, Western University

Food waste is a growing problem in Canada and many other parts of the world — and it is only expected to get worse in the coming years. The world population is expected to grow to 9.7 billion by 2050, alongside global food demand.

Not only will this create large amounts of food and municipal organic waste, but there will also be increasing amounts of agricultural waste as the global demand of vegetables, fruits and grains increases. An estimated 60 per cent of food produced in Canada — over 35 million tonnes per year — ends up in landfills. However, Canadian cities have also run out of land to dispose this accumulating waste.

Food waste comes with its own set of issues, including greenhouse gas emissions, unpleasant odours, pests and toxic fluids that can infiltrate water sources. In addition, every year, municipal dumps take over more land, reaching the edges of communities, which can lead to health issues for those who are living nearby.

In an effort to reduce the growing problem of food waste disposal, researchers like myself are focusing on developing new technologies that use food waste to generate clean energy. My team and I are studying a process known as biomass gasification.

Biomass gasification

Biomass gasification uses heat, oxygen, steam, or a mixture of those, to convert biomass — food and agricultural waste or other biological materials — into a mixture of gases that can be used as fuel.

A diagram of the process of biomass gasification where food waste is mixed with heat, steam and oxygen to produce synthetic fuel or gasses called Syngas.
Biomass gasification uses heat, oxygen, steam, or a mixture of those, to convert biomass — food or agricultural waste, or other biological materials — into a mixture of fuel gases. (Salvador Escobedo Salas), Author provided

Biomass gasification works by feeding semi-dry food waste into a unit that looks a bit like a cooking pot, where it passes through a hot, bubbling substance that converts it to fuel gas. This process, known as fluidization is very efficient at converting food waste into high-valuable sources of energy-rich synthesis gas, a mixture of hydrogen, methane, carbon monoxide and carbon dioxide, also called syngas. Syngas can be used to generate heat and power. This process is sustainable because is considered to be carbon-neutral.

Farms, cities and municipalities could implement this sustainable technology to cut utility expenses for heating or electricity. They could also significantly reduce dependency on landfills and lower the operating budget for solid waste management services which can reach near $380 million per year for a city the size of Toronto.

Replacing fossil fuels

The consumption of fossil fuels and their derivatives has created an environmental crisis, mainly due to greenhouse gas emissions in the atmosphere, which has led to climate change. As governments around the world implement climate policies that restrict greenhouse gas emissions or tax them, it is important to replace fossil fuels with alternative renewable sources of energy such as agricultural and food waste.

Although syngas can be used like a conventional natural gas, which is a methane-based fossil fuel, it is different from it because of its higher composition of carbon monoxide and hydrogen.

These gases can be further converted into high-value bio-based chemicals such as methanol and ammonia. Biomass gasification also generates biochar, which can be used to improve soil fertility.

The gasification process turns trash into gas in an economical and eco-friendly way.

While the production of syngas depends on the type of biomass and technology used. The Canadian Atikokan Generating Station, for instance, produced 205 megawatts of clean electricity. This is enough energy to power about 70, 000 residential and commercial buildings.

Global projects

Countries such as Finland, Brazil, Italy, Denmark and the United States are leading the way in developing sustainable and cost-efficient biomass gasification projects and using food waste to support their domestic production of heat, power and bio-based chemicals. Canada has a few companies supplying energy and bio-based chemicals from municipal waste. In this case, Canada produces 1.4 per cent of its electricity with Biomass.

A man shoveling coffee beans and keeping them to dry in a farm in Costa Rica.
Coffee cultivations in Costa Rica generate high amounts of waste that is being used to produce heat and power using biomass gasification. (Shutterstock)

Costa Rica is another example. As one of the top 20 coffee producers in the world, Costa Rica generates a significant amount of agricultural waste from coffee production and its disposal presents serious environmental problems. Its present solution is biomass gasification technologies to convert coffee pulp into heat and power.

Small and marginal communities could also take full advantage of biomass gasification technologies by reducing the amount of food waste that accumulates in landfills, producing their own energy and power and significantly lowering their utilities expenses.

A sustainable and circular economy

Biomass gasification is a sustainable and technological strategy that turns food waste to a value-added product. It is a step along the path to a circular economy culture of zero waste.

Policy leaders and governments need to support sustainable programs by providing financial aid, subsidies and tax incentives. These programs may also encourage individuals and companies to invest in biomass gasification technologies and develop them on a commercial scale.

Biomass gasification brings cities and municipalities one step closer to putting an end to concerns about food waste. It also helps meet energy demands and displace fossil fuel use and will help us transition towards a sustainable and circular economy.

Salvador Escobedo Salas, Research Associate | Faculty of Engineering | Chemical and Biochemical Engineering Department, Western University

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

Military action in radioactive Chernobyl could be dangerous for people and the environment

Much of the region around Chernobyl has been untouched by people since the nuclear disaster in 1986. Pavlo Gonchar/SOPA Images/LightRocket via Getty Images

by Timothy A. Mousseau, University of South Carolina

The site of the Chernobyl Nuclear Power Plant in northern Ukraine has been surrounded for more than three decades by a 1,000-square-mile (2,600-square-kilometer) exclusion zone that keeps people out. On April 26, 1986, Chernobyl’s reactor number four melted down as a result of human error, releasing vast quantities of radioactive particles and gases into the surrounding landscape – 400 times more radioactivity to the environment than the atomic bomb dropped on Hiroshima. Put in place to contain the radioactive contaminants, the exclusion zone also protects the region from human disturbance.

Apart from a handful of industrial areas, most of the exclusion zone is completely isolated from human activity and appears almost normal. In some areas, where radiation levels have dropped over time, plants and animals have returned in significant numbers.

fox against grassy background
A fox near the Chernobyl Nuclear Power Plant. T. A. Mousseau, 2019, CC BY-ND

Some scientists have suggested the zone has become an Eden for wildlife, while others are skeptical of that possibility. Looks can be deceiving, at least in areas of high radioactivity, where bird, mammal and insect population sizes and diversity are significantly lower than in the “clean” parts of the exclusion zone.

I’ve spent more than 20 years working in Ukraine, as well as in Belarus and Fukushima, Japan, largely focused on the effects of radiation. I have been asked many times over the past days why Russian forces entered northern Ukraine via this atomic wasteland, and what the environmental consequences of military activity in the zone might be.

As of the beginning of March 2022, Russian forces controlled the Chernobyl facility.

Why invade via Chernobyl?

In hindsight, the strategic benefits of basing military operations in the Chernobyl exclusion zone seem obvious. It is a large, unpopulated area connected by a paved highway straight to the Ukrainian capital, with few obstacles or human developments along the way. The Chernobyl zone abuts Belarus and is thus immune from attack from Ukrainian forces from the north. The reactor site’s industrial area is, in effect, a large parking lot suitable for staging an invading army’s thousands of vehicles.

The power plant site also houses the main electrical grid switching network for the entire region. It’s possible to turn the lights off in Kyiv from here, even though the power plant itself has not generated any electricity since 2000, when the last of Chernobyl’s four reactors was shut down. Such control over the power supply likely has strategic importance, although Kyiv’s electrical needs could probably also be supplied via other nodes on the Ukrainian national power grid.

The reactor site likely offers considerable protection from aerial attack, given the improbability that Ukrainian or other forces would risk combat on a site containing more than 5.3 million pounds (2.4 million kilograms) of radioactive spent nuclear fuel. This is the highly radioactive material produced by a nuclear reactor during normal operations. A direct hit on the power plant’s spent fuel pools or dry cask storage facilities could release substantially more radioactive material into the environment than the original meltdown and explosions in 1986 and thus cause an environmental disaster of global proportions.

grassy foreground with industrial buildings in the distance
View of the power plant site from a distance, with the containment shield structure in place over the destroyed reactor. T.A. Mousseau, CC BY-ND

Environmental risks on the ground in Chernobyl

The Chernobyl exclusion zone is among the most radioactively contaminated regions on the planet. Thousands of acres surrounding the reactor site have ambient radiation dose rates exceeding typical background levels by thousands of times. In parts of the so-called Red Forest near the power plant it’s possible to receive a dangerous radiation dose in just a few days of exposure.

Radiation monitoring stations across the Chernobyl zone recorded the first obvious environmental impact of the invasion. Sensors put in place by the Ukrainian Chernobyl EcoCenter in case of accidents or forest fires showed dramatic jumps in radiation levels along major roads and next to the reactor facilities starting after 9 p.m on Feb. 24, 2022. That’s when Russian invaders reached the area from neighboring Belarus.

Because the rise in radiation levels was most obvious in the immediate vicinity of the reactor buildings, there was concern that the containment structures had been damaged, although Russian authorities have denied this possibility. The sensor network abruptly stopped reporting early on Feb. 25 and did not restart until March 1, 2022, so the full magnitude of disturbance to the region from the troop movements is unclear.

If, in fact, it was dust stirred up by vehicles and not damage to any containment facilities that caused the rise in radiation readings, and assuming the increase lasted for just a few hours, it’s not likely to be of long-term concern, as the dust will settle again once troops move through.

But the Russian soldiers, as well as the Ukrainian power plant workers who have been held hostage, undoubtedly inhaled some of the blowing dust. Researchers know the dirt in the Chernobyl exclusion zone can contain radionuclides including cesium-137, strontium-90, several isotopes of plutonium and uranium, and americium-241. Even at very low levels, they’re all toxic, carcinogenic or both if inhaled.

aerial view of fire burning on wooded landscape
Forest fires, like this one in 2020 in the Chernobyl exclusion zone, can release radioactive particles that had been trapped in the burning materials. Volodymyr Shuvayev/AFP via Getty Images

Possible impacts further afield

Perhaps the greater environmental threat to the region stems from the potential release to the atmosphere of radionuclides stored in soil and plants should a forest fire ignite.

Such fires have recently increased in frequency, size and intensity, likely because of climate change, and these fires have released radioactive materials back into the air and and dispersed them far and wide. Radioactive fallout from forest fires may well represent the greatest threat from the Chernobyl site to human populations downwind of the region as well as the wildlife within the exclusion zone.

Currently the zone is home to massive amounts of dead trees and debris that could act as fuel for a fire. Even in the absence of combat, military activity – like thousands of troops transiting, eating, smoking and building campfires to stay warm – increases the risk of forest fires.

bird held in hands with tumor visible through feathers
A bird from Chernobyl with a tumor on its head. T. A. Mousseau, 2009, CC BY-ND

It’s hard to predict the effects of radioactive fallout on people, but the consequences to flora and fauna have been well documented. Chronic exposure to even relatively low levels of radionuclides has been linked to a wide variety of health consequences in wildlife, including genetic mutations, tumors, eye cataracts, sterility and neurological impairment, along with reductions in population sizes and biodiversity in areas of high contamination.

There is no “safe” level when it comes to ionizing radiation. The hazards to life are in direct proportion to the level of exposure. Should the ongoing conflict escalate and damage the radiation confinement facilities at Chernobyl, or at any of the 15 nuclear reactors at four other sites across Ukraine, the magnitude of harm to the environment would be catastrophic.

Timothy A. Mousseau, Professor of Biological Sciences, University of South Carolina

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

Americans largely favor U.S. taking steps to become carbon neutral by 2050

Read the full story from Pew.

Amid growing global energy demand and rising carbon dioxide emissions, majorities of Americans say the United States should prioritize the development of renewable energy sources, such as wind and solar, and take steps toward the country becoming carbon neutral by the year 2050.

Still, Americans stop short of backing a complete break with fossil fuels and many foresee unexpected problems in a major transition to renewable energy. Economic concerns are also front of mind for many when asked to think about what a transition away from fossil fuels could mean for their own lives.

Panasonic to use Redwood’s recycled materials in battery cell production at Tesla gigafactory

Read the full story at TechCrunch.

Panasonic battery cells made at the Gigafactory it operates with Tesla will use more recycled materials by the end of 2022 as part of an expanded partnership with startup Redwood Materials.

Forests can’t handle all the net-zero emissions plans – companies and countries expect nature to offset too much carbon

Companies’ net-zero pledges count on vast expanses of forest to hold carbon so they can continue emitting. AFP via Getty Images

by Doreen Stabinsky, College of the Atlantic and Kate Dooley, The University of Melbourne

Net-zero emissions pledges to protect the climate are coming fast and furious from companies, cities and countries. But declaring a net-zero target doesn’t mean they plan to stop their greenhouse gas emissions entirely – far from it. Most of these pledges rely heavily on planting trees or protecting forests or farmland to absorb some of their emissions.

That raises two questions: Can nature handle the expectations? And, more importantly, should it even be expected to?

We have been involved in international climate negotiations and land and forest climate research for years. Research and pledges from companies so far suggest that the answer to these questions is no.

What is net-zero?

Net-zero is the point at which all the carbon dioxide still emitted by human activities, such as running fossil fuel power plants or driving gas-powered vehicles, is balanced by the removal of carbon dioxide from the atmosphere. Since the world does not yet have technologies capable of removing carbon dioxide from air at any climate-relevant scale, that means relying on nature for carbon dioxide removal.

According to the Intergovernmental Panel on Climate Change, global carbon dioxide emissions will need to reach net-zero by at least midcentury for the world to have even a small chance of limiting warming to 1.5 degrees Celsius (2.7 F), an aim of the Paris climate agreement to avoid the worst impacts of climate change.

The devil of net-zero, of course, lies in its apparent simplicity.

Nature’s potential and its limits

Climate change is driven largely by cumulative emissions – carbon dioxide that accumulates in the atmosphere and stays there for hundreds to thousands of years, trapping heat near Earth’s surface.

Nature has received a great deal of attention for its ability to remove carbon dioxide from the atmosphere and store it in the biosphere, such as in soils, grasslands, trees and mangroves, via photosynthesis. It is also a source of carbon dioxide emissions through deforestation, land and ecosystem degradation and agricultural practices. However, the right kinds of changes to land management practices can reduce emissions and improve carbon storage.

Net-zero proposals count on finding ways for these systems to take up more carbon than they already absorb.

Researchers estimate that nature might annually be able to remove 5 gigatons of carbon dioxide from the air and avoid another 5 gigatons through stopping emissions from deforestation, agriculture and other sources.

This 10-gigaton figure has regularly been cited as “one-third of the global effort needed to stop climate change,” but that’s misleading. Avoided emissions and removals are not additive.

A new forests and land-use declaration announced at the UN climate conference in November also highlights the ongoing challenges in bringing deforestation emissions to zero, including illegal logging and protecting the rights of Indigenous peoples.

Stored carbon doesn’t stay there forever

Reaching the point at which nature can remove 5 gigatons of carbon dioxide each year would take time. And there’s another problem: High levels of removal might last for only a decade or so.

When growing trees and restoring ecosystems, the storage potential develops to a peak over decades. While this continues, it reduces over time as ecosystems become saturated, meaning large-scale carbon dioxide removal by natural ecosystems is a one-off opportunity to restore lost carbon stocks.

Carbon stored in the terrestrial biosphere – in forests and other ecosystems – doesn’t stay there forever, either. Trees and plants die, sometimes as a result of climate-related wildfires, droughts and warming, and fields are tilled and release carbon.

When taking these factors into consideration – the delay while nature-based removals scale up, saturation and the one-off and reversible nature of enhanced terrestrial carbon storage – another team of researchers found that restoration of forest and agricultural ecosystems could be expected to remove only about 3.7 gigatons of carbon dioxide annually.

Over the century, ecosystem restoration might reduce global average temperature by approximately 0.12 C (0.2 F). But the scale of removals the world can expect from ecosystem restoration will not happen in time to reduce the warming that is expected within the next two decades.

Nature in net-zero pledges

Unfortunately there is not a great deal of useful information contained in net-zero pledges about the relative contributions of planned emissions reductions versus dependence on removals. There are, however, some indications of the magnitude of removals that major actors expect to have available for their use.

ActionAid reviewed the oil major Shell’s net-zero strategy and found that it includes offsetting 120 million tons of carbon dioxide per year through planting forests, estimated to require around 29.5 million acres (12 million hectares) of land. That’s roughly 45,000 square miles.

Oxfam reviewed the net-zero pledges for Shell and three other oil and gas producers – BP, TotalEnergies and ENI – and concluded that “their plans alone could require an area of land twice the size of the U.K. If the oil and gas sector as a whole adopted similar net zero targets, it could end up requiring land that is nearly half the size of the United States, or one-third of the world’s farmland.”

These numbers provide insight into how these companies, and perhaps many others, view net-zero.

Research indicates that net-zero strategies that rely on temporary removals to balance permanent emissions will fail. The temporary storage of nature-based removals, limited land availability and the time they take to scale up mean that, while they are a critical part of stabilizing the earth system, they cannot compensate for continued fossil fuel emissions.

This means that getting to net-zero will require rapid and dramatic reductions in emissions. Nature will be called upon to balance out what is left, mostly emissions from agriculture and land, but nature cannot balance out ongoing fossil emissions.

To actually reach net-zero will require reducing emissions close to zero.

COP26: the world’s biggest climate talks

This story is part of The Conversation’s coverage of COP26, the Glasgow climate conference, by experts from around the world.
Amid a rising tide of climate news and stories, The Conversation is here to clear the air and make sure you get information you can trust. Read more of our U.S. and global coverage.

Doreen Stabinsky, Professor of Global Environmental Politics, College of the Atlantic and Kate Dooley, Research Fellow, Climate & Energy College, The University of Melbourne

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