By Dr. John Happs
The 1997 climate treaty known as the Kyoto Protocol allows wealthy countries to count carbon storage in forests towards their targets for limiting greenhouse-gas emissions.
We often hear about various environmental groups that are intent on planting as many trees as possible, supposedly to offset anthropogenic carbon dioxide emissions. The Australian Government has described carbon offsetting as:
“An activity, process, organisation, event, building or precinct is carbon neutral when its net greenhouse gas emissions (emissions) are equal to zero. To become carbon neutral, entities must calculate their emissions, reduce these emissions as much as possible, and then purchase and cancel carbon offsets or carbon credits equivalent to the remaining emissions. This process results in emissions being offset and leads to net zero emissions or being carbon neutral.”
The Australian Government initially promised to work with the community to plant 20 million trees by 2020, to re-establish green corridors and urban forests.
Prime Minister Scott Morrison has now increased this commitment with the aim of planting 1 billion trees across Australia by 2030. Those trees will cover 400 thousand hectares of land.
There are many organisations available to assist in tree-planting ventures. Outland Resources Pty. Ltd. has tree-planting crews that meet various contracts with 250 million trees already planted Australia wide.
A range of tree-planting (paid work) positions are advertised in most states across Australia. These can be located at:
We are told that the Australian tree-planting scheme is designed to remove 18 million tons of carbon dioxide from the atmosphere over the next 10 years, enabling Australia to meet its Paris Agreement.
So the Australian tree-planting initiative will remove 1.8 million tons per annum. This might seem like a lot of carbon dioxide except that human respiration globally emits 2.25 billion tons of carbon dioxide per annum and termites produce far more carbon dioxide than the sum total of human activities.
There are many tree planting initiatives in Australia. In Western Australia, for instance, there is the self-funding, not for profit organisation Men of the Trees group with their website “Trillion Trees.”
A number of these initiatives make claims that appear both plausible and laudable. For instance, the Carbon Neutral Charitable Fund states:
“We plant trees for the planet” and presumably this well-intentioned group firmly believes that planting trees will reduce atmospheric carbon dioxide levels and save the planet. Exactly what the planet is being saved from isn’t made clear.
There is no doubt that many claims about the environmental benefits of trees are valid including their role in providing shade, habitat, shelter and food for a range of animals.
Trees are not only aesthetically pleasing, they can restore barren landscapes to provide more biodiversity, improve soil structure, increase surface water infiltration and combat soil erosion and salinity. Trees provide renewable resources such as timber, a range of foods, gums and resins. Rubber is a well-known resource.
Expanding forestry inevitably leads to more employment opportunities.
What’s not to like about tree-planting?
However, a number of claims made about the benefits of tree-planting are not supported by empirical evidence, including:
“Trees are the world’s single largest source of breathable oxygen.”
In fact terrestrial photosynthesis plays only a minor role in the production of atmospheric oxygen.
Oceans cover more than 70% of the planet and it is estimated that marine plants, including seaweed and the more than 7,000 species of algae, including cyanobacteria (blue-green algae) produce up to 80% of the oxygen that enters the atmosphere.
Of the remaining 20% of oxygen, a significant portion comes from the large areas of grasslands such as the Pampas in South America, the Steppes in Central Eurasia and the African Savannas, with only a relatively small portion coming from forested areas.
As Kasting and Siefert point out:
“Terrestrial photosynthesis has little effect on atmospheric O2 because it is nearly balanced by the reverse processes of respiration and decay.”
Another questionable claim made by some tree-planting groups is that:
“Maintaining our forests and restoring our natural landscape will make a real difference in reducing climate change.”
Whatever “reducing climate change” actually means.
Although many saplings will take up and use more carbon dioxide than the oxygen they liberate, most mature trees absorb no nett carbon dioxide over their lifetime. What they take up via their photosynthetic cells, they lose via their larger biomass of respiratory cells and, more importantly, by the decay of falling leaves, branches and eventually the tree trunk.
Dr. Harald Franzen explains:
“Trees only absorb large quantities of carbon during their growth, so once they are fully grown–in other words, when the reforestation is complete–they will not be able to serve as CO2 sinks.”
We are often told that the Amazon and other Rainforests, covering around 6% of the Earth’s surface, are the lungs of the planet. In fact tropical rainforests are large natural sources of carbon dioxide.
Monitoring of carbon dioxide from NASA’s Orbiting Carbon Dioxide Observatory-2 satellite shows how forested areas on Earth liberate copious quantities of carbon dioxide at night via respiration, organic matter decay and land clearing:
Note the relatively higher concentrations of carbon dioxide from the Amazon, African and Indonesian rainforests.
Putz et al. add:
“Tropical forest deforestation has been identified as a major source of CO2 emissions, though biomass loss due to fragmentation-the creation of additional forest edges-has been largely overlooked as an additional CO2 source.”
A number of tree-planting websites have claimed that carbon dioxide is a major greenhouse gas that traps heat and is leading to (imaginary) global warming. They ignore the fact that atmospheric carbon dioxide levels have never driven global temperature at any time over the last 500 million years.
A number of tree-planting websites have also claimed that carbon dioxide from industrial activity is raising the carbon dioxide content of the atmosphere, leading to more extreme weather. They ignore the fact that even the political/ideological Intergovernmental Panel on Climate Change (IPCC) has reported there is no evidence of increased extreme weather. (See Chapter 2 of the AR5 Report).
Patrick Moore, co-founder of Greenpeace observes:
“At 400 parts per million, all our food crops, forests, and natural ecosystems are still on a starvation diet for carbon dioxide. The optimum level of carbon dioxide for plant growth, given enough water and nutrients, is about 1,500 parts per million, nearly four times higher than today.”
Carbon dioxide is a colourless, odourless, non-toxic source of plant food and anyone who is serious about re-vegetating the Earth would see the need for much more atmospheric carbon dioxide. In other words, the planet needs more carbon dioxide – not less.
Possibly not aware of these facts, tree-planters might think they are “coming to the rescue of planet Earth.” They rightly point out that trees will take carbon dioxide from the atmosphere and release oxygen into the atmosphere. They also rightly explain that trees convert carbon dioxide and other chemicals into tree tissues such as cellulose (40% – 50%), hemicellulose (15% – 25%) and lignin (15% – 30%).
Well-intentioned tree-planters firmly believe that the carbon dioxide removed from the atmosphere has been taken care of but they ignore the fact that leaves and branches are constantly falling off trees. When this happens they decompose and carbon dioxide is released into the atmosphere. Similarly, when trees die, the stored wood decays with micro-organisms, fungi and termites breaking down the wood, releasing carbon dioxide back into the atmosphere.
Dr. Emma Sayer from the UK’s Centre for Ecology and Hydrology points out that any increase in litter-fall from trees stimulates soil micro-organisms leading to a release of stored soil carbon. Her research shows that:
“Extra litter-fall triggers an effect called ‘priming’ where fresh carbon from plant litter provides much-needed energy to micro-organisms, which then stimulates the decomposition of carbon stored in the soil.”
Another problem for climate alarmists and those protectors of wetlands is the fact that tropical forested wetlands are a significant source of atmospheric methane. Pangala et al. point out that methane, a far more potent greenhouse gas than carbon dioxide, is emitted from tree stems as well as peat surfaces yet these sources are ignored in any so-called carbon accounting.
Additionally, autotrophic respiration for growth and the maintenance of stems, roots and leaves will result in further release of carbon dioxide. Trees increase their respiration rate when producing flowers or leaves, fighting a pathogen or creating chemical defences. These responses by trees lead to more carbon dioxide being released.
Dr. Markus Eichhorn from the University of Nottingham adds:
“Many deciduous trees in Europe rot in the middle of their trunk – you may see some old British oaks like this. It’s usually not harmful to the tree, but it does mean that they give off carbon dioxide. When the tree is dying the same will happen.”
When a forest reaches maturity it attains a steady state and is carbon (dioxide) neutral, thus old growth, mature forests do nothing more for carbon dioxide sequestration and those who oppose the removal of old growth forest are doing nothing to reduce carbon dioxide emissions.
Dr. John Caspersen from Princeton University summed up the situation:
“Trees only absorb large quantities of carbon during their growth, so once they are fully grown–in other words, when the reforestation is complete–they will not be able to serve as CO2 sinks. It’s important to realize that when the forests have recovered, we have only gotten back to ground zero in terms of the carbon balance in the atmosphere.”
It’s worth noting that mature trees in both tropical rainforests and coniferous forests across Alaska, Canada and the northern US states give off more carbon dioxide than they take in.
A further problem that tree planters are probably unaware of arises during the planting of trees and this has been described by Dr. Riccardo Valentini from the University of Tuscia in Italy. He points out that planting trees to take up carbon dioxide from the atmosphere actually releases a surge of carbon dioxide when the soil cover is broken. Valentini reports that:
“The problem is soils. Forest soils and the organic matter buried in them typically contain three to four times as much carbon as the vegetation above.”
“When ground is cleared for forest planting, rotting organic matter in the soil releases a surge of CO2 into the air.”
He also notes that the Kyoto Protocol takes none of this into account and says:
“Besides ignoring soils, it has no measures to stop deforestation. Instead, it seems to give countries a perverse incentive to chop down existing natural forests and replace them with plantations.”
“They will be able to claim carbon credits for the new planting, while in reality releasing huge amounts of CO2 into the air. There is nothing in the protocol to stop this.”
Proposals to plant more trees in our cities are always well received since most people appreciate the attractiveness of trees and see the benefits of having more shade and habitats for a variety of wildlife.
What is not generally understood is the fact that, on hot days, trees release volatile organic compounds (VOCS) including isoprene and mono-terpenes. When released in cities, these compounds can lead to the production of significant amounts of ozone.
Eucalypts release VOCS that are flammable and bushfires can travel rapidly as a result of the release of these compounds. Many homes have been destroyed in Australia because of their proximity to stands of burning eucalypts.
Another instance where so-called “carbon sequestration by trees” is countered was given by Colorado State Forester Mike Lester who testified before a state legislative committee, saying:
“When so many trees die and large wildfires follow, our forests quickly turn from a carbon sink into a carbon source.”
Greg Walcher is president of the Natural Resources Group and author of “Smoking Them Out: The Theft of the Environment and How to Take it Back.” He is a former secretary of the Colorado Department of Natural Resources and says:
“The more concerned people are about climate change, the more they should be interested in active management to restore forest health. Yet many of the groups pushing urgent climate policies are the same groups that continue to fight logging, tree thinning and other management necessary for healthy forests. The result is more of the same disasters we have seen unfolding for over 20 years: dead and dying forests, catastrophic wildfires, habitat devastation, loss of human property and lives, and destruction of wildlife.”
Foresters in Australia, such as Roger Underwood, would say “Amen” to that.
Everyone should applaud and support schemes to re-vegetate the planet, especially when they are established by “not for profit” groups. However, it should be pointed out that spending money on tree planting will be beneficial in so many ways but it will not reduce atmospheric carbon dioxide levels or save the planet from (imaginary) global warming.
Professor of atmospheric chemistry at Yale University Dr. Nadine Unger is author of: “To Save the Planet, Don’t Plant Trees.” For all the reasons already stated, she concludes:
“More funding for forestry might seem like a tempting easy win for the world leaders at the United Nations, but it’s a bad bet.”
A number of organisations that generate carbon dioxide emissions during their commercial operations offer their clients an option to purchase “carbon offsets” that commonly involves planting trees.
At least 11 airlines offer carbon (dioxide) offset programs since climate alarmists have convinced them that air travel generates large quantities of carbon dioxide that contributes to (imaginary) global warming.
Some airline chiefs have actually done their homework and have not bowed to pressure from climate alarmists and environmental activists. In 2008 Ryanair’s Michael O’Leary made clear his disbelief in the link between carbon dioxide and global temperature.
Passengers travelling on those airlines offering offset programs are given the option to pay an additional amount for carbon (dioxide) offsetting with the money going into a range of environmental schemes although Emirates doesn’t ask passengers to pay. Rather the airline generously pays for offsets.
Air New Zealand has a carbon (dioxide) offset scheme, providing passengers with a calculator so they can work out the cost of offsetting their flight. The airline supports a number of projects with the offset money collected, including a project at Mangara Station in Hawkes Bay where they have already planted 85,000 trees.
Overall, airlines are doing the planet a great service by pumping large amounts of invisible, non-toxic life-giving carbon dioxide into the atmosphere during every flight.
It is estimated that a mere 10% of travellers want to purchase offsets whilst flying. These are the people wanting to fly and are willing to pay for the planting of more trees, to help “Save the planet.”
Perhaps this should be called Gullible Travels.
Flying off-setters should be congratulated for their two-fold contribution to atmospheric life-giving carbon dioxide levels. After all, if we are serious about further greening the planet, reducing desert areas and increasing food crop yields, we need all the carbon dioxide we can get from aircraft and of course all those beautiful trees that will eventually return their stored carbon dioxide back to the atmosphere where it is badly needed.
Dr. John Happs M.Sc.1st Class; D.Phil. John has an academic background in the geosciences with special interests in climate, and paleoclimate. He has been a science educator at several universities in Australia and overseas and was President of the Western Australian Skeptics for 25 years.