When it comes to sucking up carbon, not all trees are equal

Hello, Earthlings! This is our weekly newsletter on all things environmental, where we highlight trends and solutions that are moving us to a more sustainable world. (Sign up here to get it in your inbox every Thursday.)

This week:

• When it comes to sucking up carbon, not all trees are equal
• The unstoppable David Attenborough
• How do you enforce carbon pricing beyond borders?

When it comes to sucking up carbon, not all trees are equal

This newsletter has often looked at the part trees can play as part of the climate change solution, with their ability to suck carbon out of the atmosphere and store it.

As with so much else, however, there is nuance — we need to be careful about assuming trees alone can save us. With wildfires and natural die-off, trees sometimes give off more carbon than they absorb.

And when it comes to sequestration, some trees and their ecosystems appear to be more effective than others over time.

With that in mind, it is notable to see a new tree-related carbon project finding favour with some high-profile corporations. Proctor and Gamble, Apple and Gucci have all announced projects to protect and restore the mangrove, a woody tree or shrub living in salty coastlines in the tropics and subtropics.

Mangroves (like the one being repopulated in the photo above) hold a particular allure as carbon sinks. "At a high level, [mangroves] are salty and wet, and that keeps the carbon from breaking down," Jen Howard, senior director of the blue carbon program for the American non-profit Conservation International, told GreenBiz. 

Conservation International says mangroves, which have been in decline in recent years, can sequester up to 10 times as much carbon compared to terrestrial forests.

Tania Clerac, dean of the school of environmental and natural resource sciences at Fleming College in Peterborough, Ont., said via email that mangroves and terrestrial systems "do store carbon in different ways, with trees storing carbon in their biomass, and mangroves sequestering it in their soil."

"The soil among mangroves has low biological activity and therefore that carbon is released slowly."

Clerac suggests mangroves shouldn't really be viewed as an either/or scenario when it comes to sequestration, or better or worse than others, but as one possibility. "Especially given that the solution of mangroves is not a possibility in Canada."

This country's managed forests have been a "significant carbon sink," says Natural Resources Canada on its website, given how the forests have steadily added carbon to that which was already stored.

But the NRCan site also notes that "in recent decades ... the situation has reversed in some years: Canada's forests have become carbon sources, releasing more carbon into the atmosphere than they are accumulating in any given year."

Several factors came into play, including an increase in the area consumed by wildfires annually, and dramatic shifts in yearly harvest rates, with increases in the 1990s and then sharp decreases with the global economic recession, NRCan said. 

Environmental activists have long called for protection of old-growth forests in particular, noting their carbon storage abilities, along with their ecosystems and the rich biodiversity found within them.

But what about on an individual level? Could a home- or landowner make a difference by planting some more trees?

"In terms of non-forest conditions such as a yard that is currently mown lawn or low-density garden plants, including more trees will help improve carbon sequestration," Clerac said. And some trees could be more effective than others.

"As far as planting individual species on a carbon-per-centimetre-diameter basis, the best are deciduous species, often called hardwoods, particularly those that are long-lived, such as sugar maple, oak, black walnut and hickory," said Clerac.

Some softwoods, such as red pine and white pine, are also good at storing carbon. Next come softer deciduous trees like birch, red or silver maple and poplar. Conifers like cedar or larch sequester less carbon. 

But again, there is nuance to this.

"This does not account for the rate of growth, so although some [trees] may grow more slowly and in the short term store less carbon, in the long term they are longer-lived and will store more carbon," Clerac said.

She has an additional suggestion for increasing the carbon storage abilities of trees: doing what you can to fight invasive species, such as the emerald ash borer, which has killed ash trees throughout eastern North America.

"This beetle did not have a fantastic ability to spread on its own, yet it did," Clerac said, with people moving infested wood around, which led to "a lot of tree mortality and carbon release." 

"When someone reports an invasive species and follows rules around moving wood products, the health of our trees and forests benefits, and so does their ability to sequester carbon."

— Janet Davison

Reader feedback

Mary Staszuk said the recent article on reducing beef consumption is "very interesting but it is not quite so simple. What is not mentioned is the fact that in order to produce milk, cows must have a calf every year. Something has to happen to those calves. Most of the males and some females will end up as beef. If cow herds are reduced because of reductions in beef consumption, it will impact many dairy products such as cheese, butter, cream and milk. Those products will be in shorter supply and many jobs lost in their production."

R.P. says, "I just read your article…. I guess you resort to provocative issues to spur people to read. Thankfully the article is quite balanced — even mentioning matters not accounted for. This subject is so complex! Not everyone can tolerate a vegan diet, which needs supplementation for key factors like vitamin B12. Others cannot adjust to certain plant protein sources such as soy. Complicating all this are food allergies!

"Food intake is very personal depending on one's genetics, as well as eating history and health history. The more you can attract and encourage readers to avoid toxins (artificial sweeteners, foods heavily treated with pesticides, etc.) and shift to healthy foods (more vegetables, some fruits), the better it will be for all. Keep up the good, sensible, balanced work!"

Write us at [email protected].

Old issues of What on Earth? are right here.

There's also a radio show and podcast! Caring about climate change often means feeling bad about your carbon footprint. But new research from Harvard quantifies how major oil companies used a page from the tobacco industry playbook and shifted responsibility away from themselves and onto consumers. This week, What on Earth host Laura Lynch hears from the research authors, Geoffrey Supran and Naomi Oreskes. What on Earth airs Sunday at 12:30 p.m., 1 p.m. in Newfoundland. Subscribe on your favourite podcast app or hear it on demand at CBC Listen.

***New newsletter alert! Our colleague Peter Armstrong has a newsletter called Mind Your Business, a weekly guide to understanding what's happening in the worlds of economics, business and finance. Subscribe to it here.

The Big Picture: The unstoppable David Attenborough

They used to call James Brown the hardest-working man in showbiz, but if the Godfather of Soul were alive today, he'd have strong competition from David Attenborough. The 95-year-old broadcaster does more than entertain, of course — he's the voice of countless nature documentaries and a renowned environmental activist. While he has done other documentary work as well, his stature is largely the result of the success of the BBC series Life on Earth (1979) and The Living Planet (1984), which were both epic in scope and showcased the latest innovations in film cameras. Since then, Attenborough has amassed a staggering body of work, including Planet Earth (2006), two Blue Planet docs and the eight-part Netflix series Our Planet (2019). Last year, he released the autobiographical David Attenborough: A Life on Our Planet. In January of this year, he narrated a BBC series called A Perfect Planet, followed up a few months later by Life in Colour, a Netflix show exploring the role of colour in the natural world that also sets a new bar for jaw-dropping footage. Attenborough is currently working on a new BBC series called The Green Planet, set to debut in 2022, all while advocating environmental causes. Truly, a force of nature.

Hot and bothered: Provocative ideas from around the web

• Airports are sprawling spaces. This is intentional, because planes need a wide berth. But some clean energy advocates say that some of those open spaces could be used for arrays of solar panels.

• The unpredictable journey of debris from a Chinese rocket recently was a reminder of the space junk that could fall to Earth. But a new study suggests that with higher carbon dioxide levels, which lowers the density of our upper atmosphere, it's possible more of that kind of junk could end up staying in space.

Fear of climate change rust belt has governments considering carbon border levy

If you thought Canada's carbon tax was controversial, just wait for the global equivalent being negotiated behind closed doors.

It's not a secret. In fact, the new charge got its own subheading in the recent federal budget. The plan is to "make sure that regulations on a price on carbon pollution apply fairly between trading partners," said the budget document. "This levels the playing field, ensures competitiveness and protects our shared environment."

The idea of a border charge is meant to address concerns that in countries with a price on carbon — like Canada — domestic players are at a disadvantage compared to imported goods from countries without those regulations. The fear is that it could entice companies that need aluminum, for example, to source it from the U.S. or somewhere else that doesn't have a carbon tax because it's cheaper than Canadian-made aluminum.

The "border adjustment" would be a levy to make sure imports are subject to something similar. 

Without a set of rules to equalize the economic cost of fighting climate change across national boundaries, countries like Canada and the U.S. or trade blocs like the European Union will be at a huge trade disadvantage to those like Russia or Brazil, where climate rules are light or non-existent.

As with Canada's domestic carbon tax, the battle over whether to impose a border charge will be political, said Gus Van Harten, a legal scholar at Osgoode Hall in Toronto and an early proponent of carbon equalization payments. 

But he said opponents will find it harder to convince voters that preventing carbon cheating by foreign producers is bad for Canadians and Canadian jobs when the alternative is to create a new Rust Belt of obsolete industries caused by climate change rules. 

"A [domestic] carbon tax is more easily misconstrued as picking from someone's pocket," he said.

According to University of Calgary economist Jennifer Winter, some industries "would be happy" about a border adjustment because it would protect them from foreign competition, including poorer countries that don't have stiff carbon rules.

It could also affect consumer prices. While things like cars made in Germany would be no more expensive, the new charge would raise the cost of goods imported from less regulated countries. Without a carefully agreed structure, such rules could be used for plain old protectionism, leading to tit-for-tat countermeasures and hurting world trade. 

Among the complications will be trying to put an equivalent carbon cost on different countries' climate change rules.

Canada has a national carbon tax, but the U.S. does not. Europe uses a system of trading carbon credits that has become increasingly expensive for its domestic producers. The cost of flexible regulations, which some say are a more effective tool, is difficult to quantify.

Trying to determine the carbon content of every imported part or ingredient will be difficult and could lead to mountains of documentation. That is why the first version of the levy will likely only apply to products like steel, aluminum and cement, where the carbon content is relatively easy to determine. But there are further difficulties.  

For example, how would you credit China's large investment in electric transport? How would you offer credits for the cost of U.S. President Joe Biden's plan to invest in a green economic transformation?

Even if there are no further delays and Europe unveils its carbon adjustment proposal in July, that is expected to be just the first step, leading to a long period of internal and international negotiation. Canada is already in international talks with what the budget calls "like-minded partners," and plans to start consultation with provinces and territories this summer.

But according to Angelo Katsoras, a geopolitical analyst and author of a recent National Bank of Canada report, a carbon border tax is inevitable.

"For Europe, it's a matter of economic survival," Katsoras said, and that applies to other countries like Canada and the U.S. now tightening greenhouse gas rules.

"I think it has become politically unsustainable to continue to put in stringent targets without a carbon border tax."

— Don Pittis

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Editor: Andre Mayer | Logo design: Sködt McNalty