Can 1 trillion trees capture enough carbon to save us?

Or should we focus efforts on carbon capture technology instead? 

By Grant Brown, Founder, Happy Eco News

A big announcement at COP26, one that has really seemed to capture the attention of the press and the imagination of people all over the world, is an agreement to protect millions of hectares of forests, a number equating to around 85% of the total. It is not a new concept, the idea that we could possibly save our climate by planting trees or protecting existing forests is tantalizing and has been around for decades. 

In 2015 Dr. Thomas Crowther was invited to help the UN with their billion tree program. His challenge? To identify exactly how many trees need to be planted to offset human-emitted carbon each year. 

The first order of business for Crowther was to understand how many trees were already on the planet; a census had never been done before. By leveraging satellite data and combining it with modern computing power, Dr. Crowther estimated the total number of trees currently on the planet as about 3 trillion. As a side note, Dr. Crowther is part of another project called Restor that is partnered with Google and attempts to document all of the reforestation projects currently in process. 

Dr. Thomas Crowther. Image: Daniel Auf der Mauer for Nature

Dr. Crowther determined that there are about 0.9 billion hectares of unused land where trees could grow. If this land were to regrow trees, it would be capable of naturally supporting 1 trillion trees in addition to the ones already in existence. 

Humans currently put out about 10 gigatonnes of carbon each year which in itself is not a huge number, all things considered. The problem is imbalance. Our forests have been under attack by human development for centuries. 3 trillion trees are about ½ of the amount we would have had before human industrial development began. Due to deforestation, we produce more carbon than can be reabsorbed, and have done so for decades. There is now a huge surplus of carbon in the atmosphere that drives current global warming. 

One trillion trees would potentially sequester ~200 gigatonnes of carbon, meaning they could sequester all our annual CO emissions plus about 30% of the excess already in the atmosphere. 

One trillion is a pretty easy number to remember. It’s comforting to quantify this problem but it’s not really quite that simple; most humans have a hard time fully understanding the difference between 1 million, 1 billion, and 1 trillion.

To put it in a perspective that we can all understand, it’s good to reference something we all know and deal with daily; time. The unit of one second would be appropriate for this example: One million seconds equates to about 12 days. One billion seconds is about 32 years, and one trillion seconds equals about 32,000 years. 

Let that sink in for a second. 

If we ramped up to the point where all of humanity was planting trees in a unified effort, it might take 10,000 years to plant the one trillion trees we need. In the meantime, due to the small size of seedlings not yet mature, only 1-2 GT of carbon would be sequestered per year. Not really the return on investment we need right now.

Does this mean planting trees as a lost cause? Certainly, I would never suggest that – we need trees for food, to support biodiversity, as building materials, and of course to produce oxygen. Natural old-growth forests are the most productive, so instead of massive monocrop type forests that are “easy” for humans to plant, we need to let them grow naturally (perhaps with some help from humans).

Planting trees takes significant effort. Image: Twenty20

As I have written in the past, nature has amazing resilience and the ability to recover and regenerate itself if it is just left alone. With a bit of help, it will quickly grow what is needed to heal the planet and put things back in balance. 

A natural forest doesn’t necessarily have to exclude food crops. They can often provide significant benefits to the people that live there. According to the UN, 1.6 billion people worldwide depend directly on forests for food, shelter, energy, medicines, and income. By including agroforestry in addition to wild plants, a forest can sequester carbon while at the same time providing for humans and other animals. Because a forest can provide significant economic benefits to the local economy, is an ideal way to get people behind the idea.

For example, coffee grown in a jungle with an intact tree canopy requires less human intervention in the form of water and fertilizer. The crop is protected by the canopy above, less water is required as it is naturally held in the soil of a forest better than a field, and the soil itself has more nutrients. These nutrients are constantly being replenished by falling leaves and the wild animals that live there. For these reasons, a food forest may often provide higher yields than crops grown on a traditional industrial farm – with far less cost and effort. 

But of course, the trees in a forest are far more than only a food source. We can also harvest the trees themselves (and do it sustainably), and build useful things from them. When a tree is harvested to be used in construction or manufacturing, the carbon is sequestered for as long as the building or item survives. Advances in wood construction techniques make building with this carbon-rich product more viable than ever. These days, even a skyscraper can be built from wood. When compared to concrete construction, wood buildings can not only be a way to sequester a lot of carbon, they can also be built to produce a negative carbon footprint. 

Take for example a 20 story civic center in Skelleftea, Sweden. The Sara Kulturhus is a public building and showcase for this new technology. Built to the highest standards, it contains 12,600 cubic meters of wood – all of it sequestering carbon for as long as the building remains intact. Of course, they didn’t stop there.

Sara Kulturhus, Skellefteå, Sweden. Image: Visitskelleftea.se

The building is equipped with solar panels, batteries, and a heat pump that works with electrical, water, and district heating. Every system in the building is powered by renewable energy and yet it is so efficient and generates so much energy, there is a surplus of electricity that is used in other parts of the city or stored in an on-site energy storage battery.

And while all of these are great ideas that are now being put into play, most of us are very aware that we don’t have 100 years to wait for the world’s forests to grow back on their own. We need to sequester carbon now and at scale, and this is where technological solutions (in addition to forests) begin to make a lot of sense. 

Carbon capture technology may become somewhat of a new gold rush. Scientists and entrepreneurs are currently working to find the best, most efficient, and cost-effective way to pull carbon out of the atmosphere and store it permanently. In Iceland, geothermal energy is used to power huge plants where they can pull carbon from the air and store it in volcanic stone. Some are focussed on ways to turn carbon back into coal and store it back in the ground, while others are looking at ways to turn atmospheric carbon into fuel that may be used to power aircraft and other types of transportation. 

Carbon sequestration technology is already here. Image: Climeworks.com

Some will be proven to be less than ideal and eventually will go by the wayside, others have not been discovered or thought of. But as demand increases and technologies develop, effectiveness will increase while costs decrease. Most would agree, unchecked industrialist mentality is largely responsible for getting us into the climate situation we are in now, however, nothing and nobody is more motivated than an entrepreneur that has a solid idea to make money. Ironically, greed is finally being used to make the planet better as opposed to worse. Carbon capture technology is here now and will soon be able to reduce global atmospheric carbon rapidly and effectively.

So it seems to me that we are not really at a crossroads of how we sequestration carbon. Instead, the question is not about choosing either a natural solution or a technological solution. It is not about low cost vs high cost. It would seem that we need all the solutions together all at once, and we needed to start yesterday. 

Yes, we also need to reduce the amount of carbon emitted as well, but that is already in play and is a topic for another day.

Thankfully it seems we have collectively seen the light. We are now focussing our collective energy on making the changes needed and I believe we will be successful. After all, we don’t really have any other choice. 

Grant Brown, Founder, Happy Eco News

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