Climate change is a big issue that overwhelms most of us. We are all part of the problem, but what can we do to be part of the solution? There’s no question that as individuals and as a society, we need to reduce carbon dioxide (CO2) gas emissions primarily by reducing the amount of fossil fuels we burn. To do that, we need to drive less and switch to fuel-efficient vehicles, use solar power in place of electricity made by burning fossil fuels, make buildings more energy efficient, stop deforestation, use less water, and so on.
There’s one additional thing we CAN do — we can plant trees.
Have you ever heard forests described as the “lungs of the earth?” Trees — and plants, including marine plants, — create the oxygen we breathe from sunlight, water, and CO2. Through the process of photosynthesis, water and CO2 become the tree, which includes —the wood, the leaves, and the roots. The process is referred to as “sequestering” CO2. As long as the CO2 remains bound up in the tree, it stays out of the atmosphere. Once the tree is cut down, it decays, and in the process, releases CO2 back into the atmosphere. So the more actively trees growing on earth, the more CO2 is removed from the atmosphere.
In fact, a single tree can absorb up to 48 pounds of CO2 per year, and sequester a ton of CO2 by the time the tree reaches its 40th birthday.
What trees should you plant? The best trees for sequestering CO2 are big trees with big, green leaves. In rainier climates, that describes most of the trees. In San Diego County, trees native and those best adapted to our area tend to have smallish or narrow leaves. Still, planting any kind of tree helps.
Deciduous trees (those that lose their leaves in winter) planted on the south and west sides of your home shade your house to cool it in summer so you use less air conditioning. In winter, after the leaves fall, sunlight penetrating through the branches warms the house, thus reduces your need to run the heater. Not using your heater or air conditioner saves money, conserves energy, and reduces the CO2 emissions from creating that energy.
Shade over concrete surfaces keeps the concrete cool, while planting a tree or large shrub to shade an air conditioner helps the unit run up to 10 percent more efficiently, which reduces its energy use.
In urban communities, properties might be too small for big trees, but several smaller trees can add up to the carbon sequestration job that a big tree would do. Choose a tree that is drought tolerant too. Consider planting Mexican redbud (Cercis mexicana), crape myrtle (Lagerstroemeria), pineapple guava (Acca sellowiana), fig trees, bay laurel (Laurus nobilis), or citrus trees (not so drought tolerant, but they fruit).
Find places in your neighborhood for bigger trees like our native live oak (Quercus agrifolia), Chinese pistache (Pistacia sinensis), tipu (Tipuana tipu), jacaranda (Jacaranda mimosifolia), or kurrajong (Brachychiton populneus). In addition to sequestering carbon, these trees reduce the heat-island effect to cool the entire community. In a park, trees create welcoming shady spaces, and can do so on a hot summer day, too.
If you live in a rural area with lots of room, please feel free to plant lots of trees. In rural areas, trees offer the same advantages as in urban areas, plus they serve as windbreaks, slow runoff, and erosion to protect the soil, serve as habitat for wild animals and insects, and offer many other ecosystem services. If space is not a problem, plant native live oak along with other natives such as sycamore (Platanus racemosa), Engelmann oak (Quercus engelmannii), and valley oak (Quercus lobata). Add large native shrubs such as toyon (Heteromeles arbutifolia), lemonade berry (Rhus integrifolia), and ‘Ray Hartman’ California lilac (Ceanothus ‘Ray Hartman’).
So this year, please, plant and care for at least two trees. Make it one of your New Year’s resolutions – two trees to cool the planet!