Although it is difficult to calculate exact numbers, several studies prove that earth is still absorbing more CO2 from the air then it produces naturally. This absorbing, also called CO2 sequestration, or carbon offset happens through many natural life systems including: plants, trees, soil, sea life, and even the interaction between rainwater and rocks. When we talk about clean air, we often think about the Amazon Rainforest. This rainforest is often called the Lungs of the Planet. Not only because of the oxygen its trees produce, but also for its CO2 sequestration. It’s estimated that the Amazon Rainforest still absorbs about 2.2 billion tons of CO2 a year, but since its size is decreasing, this amount is also decreasing. With seawater becoming more acid and forests being reduced, earth’s ability to absorb and store CO2 continues to decrease. This is extra worrying since the amount of CO2 in the air is already too high. So ideally we should help earth with absorbing more CO2.
Maybe because of our mental image of the Amazon Rainforest as the lungs of the planet most carbon offset programs are based on the carbon sequestration rate from reforestation. These programs aim to help earth in being able to absorb more CO2. According to Med Crave, Forestry Research and Engineering, the rate of carbon sequestration depends on plant growth characteristics of individual tree species, the density of the tree’s wood, and the conditions for growth where the tree is planted and plant stage, that is to say the greatest sequestration stage, is in the younger stages of tree growth, between 20 to 50 years. To calculate the CO2 offset of one hectare of reforestation, you will first have to estimate the number of trees on this hectare. Then combine this with the age of the trees and the CO2 adsorption capabilities of those trees. Not an easy task, but for those whom are interested:
Carbon offset or carbon sequestration programs are roughly based on the following calculations about an estimated CO2 sequestration rate for a given tree:
T (CO2)/T age = A rate
T(CO2) = estimated amount of CO2 sequestered in a given tree
/T age = divide by the age of the particular tree
A rate = annual sequestration rate.
To be able to calculate the amount of CO2 sequestered inside a given tree you first have to calculate it’s total (green) weight. For this I found the following example from the University of New Mexico:
Based on tree species in the Southeast United States, the algorithm to calculate the weight
of a tree is:
W = Above-ground weight of the tree in pounds
D = Diameter of the trunk in inches
H = Height of the tree in feet
For trees with D < 11 inches,
W = 0.25D2H
For trees with D >= 11 inches,
W = 0.15D2H
Depending on the species, the coefficient (e.g. 0.25) could change, and the variables D2 and H could be raised to exponents just above or below 1. However, these two equations could be seen as an “average” of all the species’ equations.
The root system weighs about 20% as much as the above-ground weight of the tree.
Therefore, to determine the total green weight of the tree, multiply the above-ground
weight of the tree by 120%.
Determine the dry weight of the tree
The dry weight of a tree is based on an extension publication from the University of Nebraska. This publication has a table with average weights for one cord of wood for different temperate tree species. Taking all species in the table into account, the average tree is 72.5% dry matter and 27.5% moisture.
Determine the weight of carbon in the tree
The average carbon content of a tree is generally 50% of the tree’s total volume. Therefore, in determining the weight of carbon in the tree, multiply the dry weight of the tree by 50%.
Determine the weight of carbon dioxide sequestered in the tree
The chemical composition of CO2 means that it is composed of one molecule of Carbon and 2 molecules of Oxygen. The atomic weight of Carbon is 12.001115. The atomic weight of Oxygen is 15.9994. Therefore the weight of CO2 in trees is determined by the ratio of CO2 is C+2*O=43.999915 to C is 43.999915/12.001115=3.6663 therefore, to determine the weight of carbon dioxide sequestered in the tree, multiply the weight of carbon in the tree by 3.6663.
To give an example:
A 10-year-old Calliandra tree would probably grow about 15 feet tall with a trunk about 8 inches in diameter. Therefore the CO2 offset of this one tree will be around:
W = 0.25D2H = 0.25*(82)*(15) = 0.25*64*15=240 lbs. green weight above ground.
240 lbs. * 120% = 288 lbs. green weight (roots included)
288 lbs. * 72.5% = 208.8 lbs. dry weight.
208.8 lbs. * 50% = 104.4 lbs. carbon
104.4 lbs * 3.6663 = 382.8 lbs. total CO2 sequestered
382.8 lbs / 10 years = 38.3 lbs. CO2 sequestered per year. 1 lbs is 0.0005 ton, so 38.3 equals 0.01915 ton of CO2 offset a year.
Carbon-offset schemes as offered by airlines and other big corporations are not universally supported and can be confusingly complex. As you could read earlier it is important to understand that there are many uncertainties involved in such offset schemes. On top of that, it is good to keep in mind that these carbon offset programs are based on the future offset of the carbon that you’re now producing. An example:
Say that you fly now from Amsterdam to New York on a direct flight. According to a carbon footprint calculator, a direct flight from Amsterdam to New York produces 0.81 tons of CO2 emission in Economic Class. Using our tree absorption calculation from the previous chapter, this means you will have to plant 0.81/ 0.01915 is 43 Calliandra trees to offset your carbon footprint, right? Well, more or less. Even if those trees are planted directly it will still take them at least a year to offset your carbon footprint. And this is only when all of those young trees survive. According to the carbon offset website, it will cost you only 6.45 US$ to have these 43 trees planted and looked after. According to the website from Teagasc, an Agriculture, and Food Development Autority, it will cost 3.80 US$ per tree if you plant and look after 500 trees for one year on one hectare. A more realistic price for planting 43 trees and looking for one year after those will then be 43 times 3.80 US$, which is around 163 US$. Would you like to pay 163 US$ extra for your flight between Amsterdam and New York?
Articles from The Conversation and BBC (both articles based on separate studies) agree that carbon offset programs based on reforestation are good, but they also warn that we shouldn’t be too positive about possible future results from reforestation. A common mistake from badly organized re-forestation projects is that they only plant trees and often quick-growing species of the same sort. They don’t look after those young trees and forget that growing mono-species makes these forests very sensitive to deceases. Again, it is better to cultivate a strong mix of different species rather than just one species. Keep in mind that the costs and effort needed to take care of new trees, future wildfires, and other (natural) disasters can heavily decrease the carbon offset value of reforestation. Another problem with CO2 offset schemes is that they aim merely to offset emissions rather than reduce them. For this reason, some people reject these schemes altogether as an option. Some even portray the notion of offsetting as a modern-day indulgence for climate sins. Part of these criticisms is valid. Purists miss however an important point: many activities that are vital to global development goals are unlikely ever to be emissions-free. Tourism is one such activity.
According to the study of Peeters CO2 offset schemes could also be used to support the economies of developing countries while allowing only limited flights. The alternative he proposes is a significant rise in carbon taxes on flight tickets. This raise should limit leisure travel, while the extra money from ‘necessary travel’ should go into funds that could raise trillions of USD to reduce climate change. Part of these tax revenues can be used to alleviate poverty in developing countries without having to fly there. Such funds could be purely subsistence subsidies, but also investments in creating an economy that is not based on high carbon emissions and has a long-term future.
Peeter’s idea is interesting, but it sounds a bit like the purpose of the World Bank. One of the problems of one gigantic fund is who decides when, where, and how to invest that money? Another problem is that it is more difficult with one source of money to spread this equally and fair within an economy. The following example shows a potential that comes with providing big loans. In October 2019 the Ecuadorian government was about to receive a loan of 4.2 billion US$ from the International Monetary Fund (IMF) to fight poverty and improve its economic situation. The IMF is partner of the World Bank and one of its goals is to reduce poverty around the world. Without going too much into details, this loan came with conditions. These conditions in combination with corruption within, and bad management from the Ecuadorian government resulted in very unpopular austerity measures. Cynical enough it were the poor indigenous farmers who were affected the most. With little to lose many indigenous took the streets and paralyzed the country for 11 days, until the government reversed part of the measures. These 11 days of protest might have cost the country 2.3 billion US$.
The tourist industry is very diverse, which makes it is more suitable to spread its spending within a local economy. Imagine a tourist who stays in a hotel, buys a local T-shirt as a souvenir, eats fish in a restaurant, drinks in a bar, and takes a taxi back to his hotel. This tourist doesn’t only spend money at these five locations, but indirectly also on the salary of the maids from the hotel, at the factory where the T-shirt is made, the market where the food from the restaurant came from, the fisher who caught the fish, etc. To fight poverty in a sustainable way it is important to stimulate a healthy economy little by little, not to just give or lend big sums of money.
For all reasons mentioned above I believe that’s better when travelers look for their own trustful carbon offset project and donate directly to them for ‘their travel sins’. Not only will you then be sure that your money arrives where you want it to be, but it will also make you more conscious about your carbon footprint.
• The Trillion Tree Campain
The Trillion Tree Campaign started out as the Billion Tree Campaign, but once they managed to plant over a billion trees they decided to continue. They changed their name into the Trillion Tree Campaign and now aim to plant over a trillion trees all over the world. If they succeed and maintain all of them alive, these trees will be able to absorb about 160 billion tons of CO2 from the air. This roughly equals 4 years of human contamination! A study from Science Magazin agrees that planting a trillion trees might even prevent climate change if they will all get the chance to grow.
• Spekboom reforestation
In South Africa, they hope to reduce climate change by replanting spekboom in the desert. In her 2014 thesis, Sara-Jane Paviour writes: “Because of spekboom’s remarkable growth rate, its rate of carbon capture can rival that of tropical forests”. The spekboom doesn’t need to be cultivated in a nursery before planting, which takes time and money. The result is that one ton of CO2 can be captured for less than a tenth of the cost of sinking the equivalent carbon by planting trees in temperate or tropical forests. To plant spekboom, all you need to do is to take a cutting from an older plant, place this where you’d like to plant it (sandy soil is best), and give it water.
A study in Research Gate suggests that one hectare of spekboom reforestation could absorb 15.4 tons of CO2 a year. This while typical sequestration rates for afforestation and reforestation, are: 0.8 to 2.4 ton of carbon per hectare per year in boreal forests, 0.7 to 7.5 ton in temperate regions, and 3.2 to 10 ton in the tropics according to the Food and Agriculture Organization from the United Nations.
Planting trees is a very popular way to ‘fight climate change’ but it often isn’t the most effective way. As mentioned earlier, the main problems are the time and energy needed for nursing the young trees before and after planting them. Another problem is that it is very difficult to re-create the same biodiversity as nature does. A new project led by Conservation International aims to restore nature on 70.000 acres of now pasture land in the Brazilian Amazon Rainforest. They plan to plant around 73 million trees in six years. Those trees will not be planted in a conventional way. Developed in Brazil only a few years ago, their new planting technique is called Muvuca. “In Portuguese, it means a lot of people in a very small place.” The Muvuca strategy requires that seeds from more than 200 native forest species are spread over every square meter of burnt and mismanaged land. The seeds are purchased from the Xingu Seed Network, which since 2007 has acted as a native seed supply for more than 30 organizations. This thanks to the help of more than 400 seed collectors–many of whom are indigenous women and local youths.
Of course, even in nitrogen- and phosphorus-rich soil, only some of these seeds will survive–but that bit of natural selection is key to the Muvuca magic. Several seeds germinate, compete between themselves for nutrients and sunlight, and then the strongest ultimately become big trees. According to a 2014 study by the Food and Agriculture Organization and Biodiversity International, more than 90% of native tree species planted with this strategy germinate, and they’re especially resilient, able to survive drought conditions for up to six months without irrigation. On top of these positive numbers for the environment, the Muvuca strategy provides new job opportunities for the local communities. Although the Muvuca reforestation method is very promising, any human-led reforestation still requires high maintenance to survive the first years. This is expensive and not always possible.
• Natural Regeneration
Luckily, recent studies now show that there’s an even better and cheaper solution. Some of those studies you can read for yourself in The UN Environment; Natural Climate Solutions; George Monbiot; Aljazeera and the Conservation.org. Natural regeneration is the method that helps nature run its course. It is a real, science-based strategy known as assisted natural regeneration. It is low-tech, high-yield, highly scalable, and up to 70 percent cheaper than planting new saplings! The premise of assisted natural regeneration is that the most economical way to restore and protect forests is to acknowledge nature’s resilience, remove barriers to natural regeneration and where necessary accelerate it. Given time, trees regrow and forests come back. Assisted natural regeneration simply supports and accelerates the process.
What does it look like in practice? Examples include stopping fires from burning young trees that are naturally regrowing, dispersing seed mixes in degraded areas close to intact forests, and developing national policies that incentivize intensifying agriculture in some areas in order to let others naturally regenerate. Eco Lodges that buy large areas of damaged nature can also help with allowing this nature to recover and wildlife to return. Even the 10 hectares of abandoned farmland that the Izhcayluma Eco Lodge turned into a garden, has already seen an increase of returning wildlife including many different bird species, squirrels, snakes, rabbits, bats, and even deer.
If natural regeneration is such an obvious and effective tactic, why has it not caught on yet? First, it does not have the same PR appeal as a person lowering a young sapling into the ground. Second, until recently, assisted natural regeneration was not seen as a solution that could work on a large scale. But advances in our ability to model and predict natural processes and an unlikely and unexpected test case in Brazil showed otherwise. Brazil’s Atlantic Forest stretches across 34 million hectares (84 million acres) of the country’s coastal southeast. As large as it is, it is a fraction of what it used to be, having lost nearly three-quarters of its original extent to deforestation. Over the past two decades, rural populations thinned, with people in farming communities abandoning their land to move to cities to find work. Well-organized local groups then ensured enforcement of a Brazilian law aimed at curbing deforestation. What happened next was remarkable: Between 1996 and 2015, nearly three million hectares (7.4 million acres) of the area was found to have regenerated naturally without a single sapling being planted!
• The advantages of algae
From the first plants that started the carbon circle of life on earth, algae might now be able to prevent our climate to change too drastically. Trees and algae sequester carbon dioxide naturally. Trees “consume” it as part of their photosynthesis process by “absorbing” carbon into their trunks and roots and releasing oxygen back into the air. Algae’s replicates the same process but “absorbs” the carbon in the form of more algae. Algae can consume more CO2 than trees because they can cover more surface area, grow faster, and be easier controlled. Hypergiant Industries even claims that their bioreactors can be 400% more effective at capturing carbon from the air than trees taking up the same footprint! Bioreactors can contain large amounts of algae and optimize for its growth (and related carbon sequestration) cycle in a way that is easier than trees. The overgrowth of algae is dehydrated and ultimately used as fuel or biomass.
Algae or seaweed can also be used as food. Seaweed absorbs minerals from the sea, making it a concentrated source of trace elements needed for human nutrition. A typical serving of dried kombu seaweed contains significantly more calcium than a cup of milk, according to the European Food Information Council. Seaweed is rich in iron, magnesium, potassium, zinc, and vitamin K and contains useful amounts of vitamin E, riboflavin, thiamine, niacin, and folate. Additionally, seaweed is high in soluble fiber and naturally low-fat. All of these characteristics make it an ideal food source that even reduces more CO2 than it produces. And as if the benefits of algae mentioned before aren’t enough, the scientists from the Technical University of Munich (TUM) have now developed a process that, according to initial calculations, can facilitate economically removing CO2 from the atmosphere. During this process, algae convert CO2 from the atmosphere into algae oil. In a subsequent step, this oil is then used to produce valuable carbon fibers. These carbon fibers can be deployed to produce lightweight and high-strength materials. Carbon fibers from algae are no different from conventional fibers and can therefore be used in all existing construction processes. Thanks to their strength, they save on cement, and granite reinforced with carbon fiber can even be used to produce beams that have the same load-bearing capacity as steel but are as lightweight as aluminum. At the end of their life cycle, these carbon fibers can be stockpiled in empty coal seams, permanently removing the associated CO2 equivalents from the atmosphere back to where it came from. “When you make plastics from carbon dioxide, it is quickly returned to the atmosphere through waste incineration plants following a few years of use,” says Kuse. “With the final safe storage, we remove the carbon dioxide from the atmosphere for millennia.
An interesting and complete new type of Carbon Offset Scheme is centered around protecting whales!
No matter how good the carbon extraction options are, in the end, it is still better to prevent having to remove this carbon from the air in the first place.