Trees and our Atmosphere

The humble non assuming essential tree.  Where would we be without them!  Trees come in many different shapes and sizes.  They occupy nearly every biome on the planet, from excessively dry to excessively wet, and all of the thermal variances inbetween.  According the the 2022 study known as “The State of the World’s Trees” report by Botanic Gardens Conservation International (BGCI), they estimated that there are over 60,000 tree species worldwide.

Let’s see… Acer saccharum (Sugar Maple), Quercus alba (White Oak), Betula papyrifera (Paper Birch), Fagus sylvatica (European Beech), Picea abies (Norway Spruce), Pinus sylvestris (Scots Pine), Sequoia sempervirens (Coast Redwood), Eucalyptus globulus (Blue Gum), Magnolia grandiflora (Southern Magnolia), Ulmus americana (American Elm), Cedrus atlantica (Atlas Cedar), Salix babylonica (Weeping Willow), Juglans nigra (Black Walnut), Tilia cordata (Littleleaf Linden), Ginkgo biloba (Ginkgo).  That’s fifteen…

Trees are an essential part of our lives.  From toothpicks to telephone poles, trees provide essential materials for all sorts of things.  Yet, they are hardly recognized as an essential tool in the climate management toolbox.

Our ubiquitous tree, it turns out, is so much more that just a source for materials to build with.  The humble tree is an integrated part of the global climate management ecosystems responsible for managing greenhouse gases and providing the impetus for cloud formation, and much more.

Of course they are wonderful sources of relaxation and endless fun.  We just never think of them as the mighty steadfast warriors protecting us from an ever increasing number of toxins and continual fluctuations of temperature and moisture.

Our trees are working all day every day to process greenhouse gases and release microscopic compounds that work to seed clouds and produce rain.

Trees offer a multitude of environmental benefits.  Some benefits we are still discovering.

In addition to trees providing carbon sequestration, Oxygen production, and pollutant absorption; trees also support biodiversity, erosion control, water quality improvement, and temperature regulation by mitigating   the heat island effect through shading and transpiration.  In essence, trees are just really well designed to “keep in check” global damage caused by people and natural events.

Following the explosion at the Chernobyl Nuclear Power Plant, a large area, known as the Chernobyl Exclusion Zone (CEZ), was evacuated and restricted due to high levels of radiation. This zone covers roughly 2,600 square kilometers (1,000 square miles).  Scientists have discovered much of the agricultural and urban land within the Exclusion Zone has been overtaken by forests. The Red Forest, named for the pine trees that turned reddish-brown and died after absorbing high radiation levels immediately after the disaster, has seen new growth and is now the source of flourishing new tree growth.

Trees are simply remarkable!

Just looking at sequestration of CO2 (carbon Dioxide) a full-grown tree absorbs a surprisingly significant amount of this gaseous compound.

The chart shows a list of 20 different species and their yearly absorption of CO2.  Some trees absorb more than others.  The Redwood and Sequoia list higher because of their enormous size in comparison to the others in the chart.

Fun math: if we take the chart average of 20 kg CO2/yr/ tree and extrapolate that number to a single square mile of mature trees in a forest (approximately 200 trees per acre, 640 acres per square mile, 128,000 trees per square mile).  The amount of CO2 that is absorbed by one square mile of forested trees is 2,560,000 kg per year that is removed from the atmosphere.

Taking one step farther we can see the amazing ability of trees to remove CO2.  The average person regardless of country has a carbon footprint of 5,000 kg CO2 (a little math behind the scenes to get 5,000 kg as the average CO2 footprint of the average world citizen).  Disclaimer: might be a little less, but this is a good number to work an example with.

Using the 5,000 kg/yr carbon footprint and dividing it into the 2,460,000 kg/yr CO2 absorption rate of the forest.  The average 1 square mile of forest will absorb the full carbon footprint of 512 people.

Let’s extrapolate a little  more…

Using the U.S. Govt estimate of 1,254,000 square miles of forested land in the U.S. and multiplying the number of square miles by our carbon footprint group (512 people) we can derive that in the United States our tree cover can fully absorb the carbon footprint of every person in the country (331,000,000)  and have a 50% margin to absorb an additional carbon footprint of over 310,000,000 people!

Recently scientists announced they have determined that trees emit a chemical compound that has an effect on cloud formation.  This is in addition to the already known Volatile Organic Compounds (VOCs) of isoprene and monoterpenes.

This lesser known group of sesquiterpenes are a class of terpenes that consist of three isoprene units, which means they have 15 carbon atoms. They are part of a larger family of compounds known as terpenoids, which are naturally occurring organic chemicals based on combinations of the isoprene unit.

The sesquiterpenes have some interesting characteristics:

Structure: The basic molecular formula for sesquiterpenes is C_{15}H_{24}C15​H24​.

Sources: Sesquiterpenes are found in a variety of plants and some animals. They are especially prevalent in essential oils, such as those from cedarwood, ginger, myrrh, and ylang-ylang.

Diversity: Sesquiterpenes have a wide range of structures and functions. This diversity is due to the various ways the three isoprene units can be combined and modified.

Biological Activities: Many sesquiterpenes have significant biological activities. For example, they can act as anti-inflammatory, antimicrobial, or antifungal agents. Some sesquiterpenes also have a role in plant defense mechanisms against herbivores.

Aroma: Many sesquiterpenes contribute to the distinctive fragrances of plants and essential oils. They can smell spicy, earthy, woodsy, and sometimes citrus like.

Biosynthesis: In plants, sesquiterpenes are synthesized from the precursor farnesyl pyrophosphate (FPP), a compound formed from the joining of three isoprene units.

Industrial Use: Due to their varied properties, sesquiterpenes have applications in the perfume industry, food flavoring, and pharmaceuticals, among others.

Sesquiterpenes are a fascinating and diverse group of compounds with a wide range of applications and biological activities.

A research team headed by Lubna Dada who is a scientist performing research into how aerosols formed naturally can react with sunlight and Ozone to create secondary aerosols which can potentially  have an affect on the climate.

Due to their size, numbers, and reactivity, sesquiterpenes are more effective than previously thought at seeding clouds.  This ties trees into the process of seeding clouds as opposed to just seeding from airborne release of particulates.

While the research is not earth shattering, the implications are that scientists may have been undercounting the number of aerosols around the globe.  Trees may have been producing enormous quantities of aerosols and having a much greater affect on cloud formation than previously thought.

This new information has implications for radiative forcing.  The equations and assumptions will likely change and with it the assumptions and calculations for the cooling effect clouds have on the atmosphere and the ground.

Perhaps the most encouraging information in this piece is that the ability of trees to absorb CO2 is quite significant.  The fear mongers that are touting the extremely high concentrations of CO2 are causing climate change should tone it down a bit.

Using U.S. Gov’t data and a little simple math we can demonstrate that just looking at the ability of trees to absorb CO2 and the number of trees in the U.S. alone we have twice the capacity to absorb all the CO2 the U.S. generates.  If we were to add field crops, ground covers et al.  It’s easily demonstrable that CO2 is not a problem and it has little to no impact with climate change.

Do you want to add to the ability of the U.S. to absorb CO2?  plant a tree!, or a shrub, or a garden, or … well… just plant something!