Reduce global warming, plant a tree

September 4, 2016
Allan Cooper

Allan Cooper


In urban “heat islands,” vast stretches of asphalt magnify and reflect sun, sending CO2 directly skyward and creating “dead zones” below. Adding street trees can actually lower summer temperatures through evaporative cooling. A tree forms an oasis of shade, provides wildlife habitat, and improves air quality. Forest soil acts as a sponge for water and deters runoff thereby recharging our aquifers.

But, sadly, on the West Coast last year, over 10 million acres of trees or 15,625 square miles were burned. In California nearly 58 million trees are near death due to drought conditions and another 888 million trees over an area of 41,000 square miles in California are drought stressed.

Stressed trees are a target for the dreaded bark beetle. All of this contributes to global warming because of the carbon produced from fires and dying trees.

Because of this, every effort should be made to preserve and add to our existing tree canopy.

Studies have identified several optimal tree species for carbon storage. When choosing trees to plant, consider:

  • Long-lived trees that can keep carbon stored for generations without releasing it in decomposition.
  • Fast growing trees that store the most carbon during their first decades, often a tree’s most productive period.
  • Large leaves and wide crowns enable maximum photosynthesis.
  • Native species will thrive in your soil and best support local wildlife.
  • Low-maintenance, disease-resistant species will do better without greenhouse-gas-producing fertilizers and equipment.

Among the trees listed on San Luis Obispo’s Street Tree Master List are reliable and versatile star-performers for carbon sequestration. They include the Tulip Tree (the top carbon storer), the Red Maple (can trap nearly 25,000 pounds of CO2 in a 55 year period), the Coast, Live, Valley, Cork and Holly Oaks (these have adapted to thrive in many climates, provide food and shelter to wildlife), the California Sycamore (very tolerant of pollution and root-cramping, resistant to cold and disease) and the Common Horse Chestnut (its domed top provides exceptional shade which offers passive cooling benefits). However, the City should consider other outstanding carbon storers not on this list such as the Red Mulberry (provides the added benefit of seasonal fruit for wildlife), the Red Pine (the most carbon-effective conifer), the Norfolk Island Pine, the Italian Stone Pine, and the Black Walnut.

Short of growth in perpetuity, reforestation with long-lived trees (i.e., greater than 100 years) will sequester carbon for a more graduated release, minimizing impact during the expected carbon crisis of the 21st century.

Bringing all of this closer to home, an example of what not to do, is the proposed removal of 48 old-growth trees at 71 Palomar to make way for a 33 unit apartment complex. Slated for removal – and among those that are remarkably long-lived – are two Norfolk Island Pines which can live on average to 150 years though there is mention of a 1,000 year old Norfolk Island Pine in Chile, 18 Eucalyptus Globulus where in temperate climates they can live 400-500 years, one Italian Stone pine where in Britain’s Kew Gardens there is a record of one that attained an age of 300 years, two Olive Trees, a tree that can live well over 500 years and still bear fruit and one Coast Live Oak, where in Temecula, Calif.  there is a specimen that is over 2,000 years old.

Many of these trees are also low-maintenance, disease-resistant species that will do better without greenhouse-gas-producing fertilizers and equipment. Norfolk Island pines are particularly tolerant of a variety of soils and windy conditions. The Italian Stone Pine is drought-tolerant, rarely bothered by deer and is not highly susceptible to many diseases. Stone pines thrive on the West Coast, especially in California where temperatures do not fluctuate severely. Tolerant of saltwater spray, this pine isn’t picky about where it lays down its roots and will grow in acidic and alkaline soils. This tree neither has pitch canker nor does it have root rot.

Then there are the species that will thrive in your soil and support local wildlife. Eucalyptus Globulos flowers are mainly pollinated by insects, but birds and small mammals may also act as pollinating agents. In fact, Eucalyptus is particularly valuable as bee pasture, because it blooms year-round. The hollows in older Eucalyptus trees also provide homes to animals and birds. Birders have identified over 40 species of birds in Sutro Forest. At Jepson Prairie Preserve, CA, Swainson’s hawk and yellow warblers, both of which are “Blue Listed” species of concern, nest in the trees.

Eucalyptus grove Laguna Lake area

Eucalyptus grove Laguna Lake area

At Pescadero Creek County Park, south of San Francisco along the coast of California, great blue herons and egrets use the trees to build their rookeries. As for European Olive Trees, fruit and seed eating birds, including finches, will steal fruit from these trees and even olives that aren’t yet ripe. The acorns of the Coast Live Oak feed everything from squirrels and deer to wild turkeys and black bears. More than 500 types of butterflies and moths are attracted to this host plant.

So the old adage “think globally and act locally” applies here. We urge you to consider the health of the entire planet while taking action in your own backyard.

We can start with the 71 Palomar project where the developer states: “The proposed project includes a conceptual landscape plan showing the removal of all of the existing vegetation with the exception of a 28-inch diameter eucalyptus tree at the southwest corner of the site and a 74-inch palm tree midway along the east property boundary.”

The trees proposed for removal sustain wildlife and are long-lived, disease-resistant, and healthy specimens. They add beauty to the north part of San Luis Obispo and are accessible for viewing and enjoyment by the public. But most importantly these trees are playing a vital role in carbon sequestration.

However, if you are not inclined to engage in the public arena, then please, depending on the size of your property, plant one or two trees in your own front or back yard, and preferably one of the tree types mentioned above.

Alan Cooper, a long-time San Luis Obispo resident, is the secretary of Save Our Downtown.


I did plant a tree. In my front yard. It is currently dying of thirst.


Not to worry, that new housing development nearby will fix everything.


Humans could plant as many trees as possible in their lifetime and it would have no effect whatsoever on “global warming”. Besides, it isn’t “global warming” anymore…it is “climate change”.

Waste of time and ignorant article.


There are far too many people emotionally, politically and financially invested in climate change for them to ever admit the absurdity of it.


While it seems like there is a lot of asphalt around but it covers a very small percentage of the Earth’s surface. Compared to the total area of rocks and sand exposed on the surface it is minuscule. Your home is responsible for releasing at least half of your “carbon footprint”. Take shorter showers and give up the cloths drier and the giant screen TV. Get a small refrigerator. Don’t buy imported foods that are shipped from far away. Stop using the air conditioner and turn down the thermostat in winter.

Buy a small fuel efficient car and use it as little as possible; ride sharing is great. Stay off of jet airplanes; give up the foreign vacation travel. Buy fewer cloths because growing cotton or manufacturing nylon does great damage to the planet.

Planting a few trees will really do nothing except make you feel better. It won’t affect Global Climate Change. There are more trees in Europe than at any time in the last 300 years. It will take an economic and social revolution to reduce CO2 output enough to have a meaningful impact.


1) Let’s stop clear cutting forests to make room for more vineyards (or marijuana in the future) –all over the state.

2) Let’s stop State Parks from clear cutting Eucalyptus trees because they are non-native.

3) Let’s stop mass illegal immigration and resettlement of refugees into California. More people equals more carbon.

Nothing we do in California will stop global climate change. We can all help, but only if we are not adding millions of people here at the same time.

When will Californians speak up to global climate change and say “no” to millions of new people settling here.


The vineyards actually remove more CO2 than old oak trees. The total percentage of trees in California that are being cut by the State Parks is an extremely small and has zero impact on Global Warming. Sending immigrants away does nothing to reduce CO2. Their carbon footprint will be the same wherever they go and it is a small fraction of the carbon footprint of a wealthy American.


Stewart Resnick hates this article…


Quit building until we figure water sources, our smart government officials all want perfect landscaping.


Or, just quit inseminating. Nah, that’s our right as God’s favored species.


Kudos to Professor Cooper for this excellent Apologetica Arborealus, as a highly regarding teacher of architecture he knows full well the value of urban trees.

I have just two quibbles, and one does certainly not reflect on the Professor: first, the headline. It refers to a condition which even the advocates of anthropomorphic climate change don’t insist on now, after nearly two decades of lack of evidence that this is happening, and second, the Professor’s foray into climate science by referring to carbon dioxide as being a problem somehow to the planet. Serious climatologists attempt to cut through the non-scientific political noise and tell us that the percentage of CO² in our atmosphere is minor and changes (which have happened over the entire age of the atmosphere, before and after human influence) are also minor. CO² ain’t nothin’ to worry ’bout, folks.

The ignored elephant of greenhouse gases is water vapor, and nothing whatsoever can be done about that. That trees take in CO² is fine, they need it, but any amount they take is barely measurable and almost inconsequential.

I hope after a few more decades of non-warming, non-flooding, non-extinctions and non-starvation we can move on to real problems, like curing cancer.


Okay, folks. I don’t where from you’re getting your “facts”, but here

are a few “fairly reputable” sources I’ve used for this article:

According to Article 3.3 of the Kyoto Protocol, new tree planting

results in carbon fixation during tree growth, i.e. the creation of new

carbon sinks. At the United Nations Climate Change Conference in

Paris scientists and regulators placed increased emphasis on carbon

removal and sequestration by stripping CO2 or other greenhouse

gases from the air and stashing them in a variety of solid forms

including trees. There are two basic ways to capture carbon. “You can

put carbon in soil, and you can put carbon in long-lived perennial

plants, especially trees,” says Connor Stedman, an agricultural

consultant in the Hudson Valley with the firm AppleSeed

Permaculture. According to the Union of Concerned Scientists

“reforestation offers a great deal of promise for confronting climate

change” while benefits from mature trees should be maintained by

preventing deforestation.


While I love the use of the square, it does not belong on CO² but rather CO₂ (subscript that bad-boy!). I kept reading CO² as “see-oh-squared” – hehe.


How are you going to plant more trees in an environment where you can’t even water your lawn or flush your toilet every time you use it?


Good point – maybe stop popping out kids.


Plant a bee garden instead of a could use 1/5 the water a lawn does.

Trees send down roots to however deep the water table is..OLD TREES act as pumps bringing moisture up for younger trees.

Even raking /sweeping dead leaves back under the plants/trees will create some level of carbon-soil sequestration in dry times, more with moisture and rain. This covering also helps to retain soil moisture.

Where I live in the Berkeley/Oakland flats, the 11- 13 gallons of moisture captured per tall tree and shed into the water shed from hill top is enough for my trees. Now that 2.5 million trees are being cut down [where is the LUMBER going?], I wonder if that will hold true. I guess if I lose my fruit crops, and TTP passes, I can sue the county and board of regents for hurting my potential profits, but that won’t feed me, my bees or my neighbors.

Any positive action is better that speculating on whether or not it will make a difference.


Really wanna help the planet? Don’t reproduce. The day the human race is gone, Earth starts recovering immediately. Our absence is the planet’s only hope.


You first.


Already done my part – am an official member of VEHMT – the Voluntary Human Extinction Movement.


Correction – VHEMT – we’re not the greatest spellers.


Or shades my solar panels?


Just stopping procreating is not enough. For one thing the third world population is multiplying at a rate that would make a total cessation of births in the US meaningless. Active measures are necessary.


When you’re gone, there will be more air and water for the rest of us.


How effective is it if you plant a tree in back so it doesn’t block your view or your neighbor’s?