When my wife and I bought our house, the yard was typical for our neighborhood: a mostly barren plain of lawn so sunbaked that you could bounce a tennis ball off it. So being eco-groovy types, we've tried to improve the place: we put in a rain barrel, built a natural drainage system, and added topsoil planting berms. But I'm most proud of the trees we've planted: a pair of akebono cherries in the parking strip and a white-star magnolia in the front yard; and in the backyard, a shore pine, a Chinese dogwood, a couple of vine maples, a Japanese maple, and a limelight cypress.
I recently began wondering how much carbon our new trees are soaking up. Since tree planting is the sine qua non of carbon offset programs, how much of my emissions are offset by my yard? Enough, perhaps, to justify moving from a dense, highly walkable neighborhood to a still-urban but less foot-friendly place? (My Walkscore dropped from 92 to 80.)
The answer, I'm afraid, is "no."
I estimate that in an average year my nine trees will soak up right around 100 pounds of carbon-dioxide combined. (Brief methodology note at the end of this post.) That's the emissions equivalent of burning five gallons of gasoline -- or actually just four gallons, if you consider the "lifecycle" emissions of gas. In other words, my tree planting allows me to burn about one-third of a tank of gas guilt-free each year.
That's certainly better than nothing. But then again, the average American is responsible for about 45,000 pounds of yearly CO2 emissions from energy use alone. Nine trees like mine offset about 0.2 percent of those emissions -- and much less when nonenergy sources are considered.
Even giving myself a big benefit of the doubt -- my electricity is carbon-free hydropower and I take other steps to reduce my climate footprint -- it's highly unlikely that my trees are offsetting more than half a percent of my annual emissions. Plus, half of those tree offsets belong to my wife. So that means at the very, very most I'm offsetting about one-quarter of one percent of my own emissions.
I could do more for the climate by simply avoiding a couple of trips in my car.
Admittedly, we could fit a few more trees into the yard, though things would start to get crowded. And, in fact, we do have a few trees besides those I mentioned -- an apple, a yew, and two thickets of arbor vitaes -- which are also adding their own biomass and carbon each year. I didn't count their carbon sequestration because I can't take credit for them. They'd be around whether or not I owned the property.
In any case, it's hard to see how small-scale tree planting can be a viable solution for carbon offsets. After all, not everyone has an empty yard, just waiting to be stocked with trees. The better choice for the climate might be to do without a private backyard in the first place.
What's worse is that the carbon stored in my trees is only temporary. Someday, they'll die and they'll be chipped, or maybe they'll decay, and most of the CO2 will be released back into the atmosphere. It's possible that a portion will remain trapped in the soil (my backyard soil is vastly richer than it was before), but most will be lost. So when I take the long view, I haven't even effectively offset my emissions, I've just delayed them. In the accounting of global warming, the delay won't help at all.
Now, in defense of trees, it's worth mentioning that they do have some other climate benefits. Properly placed trees can shade buildings in the summer, lessening the energy needed for cooling. In the winter, they can act as wind breaks and slow the heat escaping from buildings.
And I should say this too: I love trees. I love all kinds, and I love them for all different reasons. In our yard alone, some have springtime flowers that dispel the winter's angst, while others have autumn foliage so brilliant it's heartbreaking. Still others provide food and shelter for the juncos, chickadees, flickers, and finches that are now common visitors to our property. They help screen our yard from the neighbors and the street, and they give our outdoor space more depth and appeal. In time, they'll help buffer city noises, shade our exposed lot, and soak up water in places that are inclined to be soggy. But the one thing they don't do, I'm sorry to report, is offset my carbon emissions.
A note about methodology. Calculating carbon storage in trees is notoriously tricky for many reasons. For this post, I tried to make a decent estimate -- about 100 pounds of CO2 per year -- but I'm not claiming great precision. I made some educated guesses about about my trees' growth rates, mature sizes, and lifespans, but I could be off by dozens of pounds of CO2 per year, and perhaps more. If others are interested in ballparking trees' carbon benefits, here's a metric tree carbon calculator based in Australia. I wasn't able to find any calculators from Canada or the U.S., but I may simply have overlooked them. Please share, if you know of others.
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wildleaf Posted 8:31 am
18 Sep 2007
It pushes people to actually except the stark truth. To be carbon neutral basically personal cars are not viable and never will be. Homes must be net zero, or negative CO2 if you own a bunch of products that involved energy intensive manufacturing, which is everything in our modern life.
We need people to give up their notion of what modern life looks like. I'm not advocating the stone age lifestyle. I'm talking about a renaisance where modern life is simpler by a thousand and smarter by a million.
The Black Car Project Killing cars before they kill us!
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wiscidea Posted 8:48 am
18 Sep 2007
Thank you for the post.
I was under the illusion that my own project, a 2-acre prairie remnant, was paying for itself just sequestering carbon. I was dismayed to learn that it was removing, at most, 4 tons of carbon from the atmosphere each year... net, even after burning the top off every few years.
My reaction, posted elsewhere on this website...
"Yahoo... all the effort, all the fuel burned, all the days in the hot sun rather than reading a book... hell, the water I pumped out of the ground to keep myself hydrated... is currently worth -- as judged by the free market -- about $16.40 per year."
But I added...
"Good thing that is not my primary motivation or I would not bother. I know preservation of biodiversity, setting an example for others, and the pure aesthetic value is worth more than that."
It is very important to point out -- AS OFTEN AS POSSIBLE -- that planting trees and other vegetation appropriate for a region is worth far more than what the market will ever assign to it. And there is more to preserving our natural environment than removing CO2 from the atmosphere.
I applaud your work and thank you for setting an example for others to follow. Even if your yard only stimulates a single child's interest in caring for the rest of the Earth, the effort you put into selecting and caring for the plants was worthwhile. And you never know... that apple tree might save a native pollinator's life and prevent an species from disappearing.
Another victim of Jean-Paul Marat's ghost and his virtual guillotine?
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Sam Wells Posted 9:06 am
18 Sep 2007
There seems to be some wild concept that if you plant a tree, it could absorb via photosynthesis all those guilty man-made CO2 emissions. Folks, it doesn't work that way. We could stop every car, industrial stack, and every combustion source in the world and you know what, those trees would do perfectly well - if not better.
Forgot to mention that stack and exhaust pipe emissions also contain ozone, sulfur acids, and other bad actors that TRY TO KILL TREES.
Face it, the whole thing is a sham. Enjoy your trees and take care of them as you can. Some bug, storm, fungus, or chainsaw is just dying to cut her down, so stand up for your rights, mon.
Onward through the fog
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naturescene Posted 9:30 am
18 Sep 2007
No one, except maybe a handful of people, argues that offsets are a silver bullet for global warming.
At this point, I don't understand attacking the merits of offsets. The voluntary carbon markets have hit the ground and taken off running, you're not going to stop it but you can provide information to make them better.
The only message I would take away from this piece is that buyers of carbon offsets should research what they are actually buying and decide if they think that's adequate to meet their desires for emissions reduction.
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naturescene Posted 9:35 am
18 Sep 2007
That is, stop calling them carbon offsets. Make them biodiversity credits, habitat credits, environmental credits, etc. Eco-conscious people should still want to pay for them (after all, the purchasers of offsets are already environmentally-minded).
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Sam Wells Posted 11:47 am
18 Sep 2007
Tell me one, just one excellent bio- or geo-engineering project that makes sense to offset man-made CO2 with something else. Gosh, on an annual basis (not forecasting for 30 year growth) I can't think of a single one. But you're smart, maybe you have some ideas.
DO YOU KNOW HOW STUPID IT IS DO OFFSET PRESENT DAY CO2 EMISSIONS WITH FUTURE REDUCTIONS THAT MAY OR MAY NOT EXIST, SUCH AS A TREE FARM?
I'm sure you do ... just checking.
sammie
Onward through the fog
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wayneluke Posted 12:01 pm
18 Sep 2007
Actually from what I have read on this site, most people aren't against the idea of carbon offsets. They are against their current implementation and the existing problem with no regulation.
For carbon offsets to work, we need more immediate solutions. Everyone pushes trees because they are cheap. They are pushing the message that everything can be offset with planting trees. Instead of planting trees, why not introduce neighborhood power generation? Wouldn't that have a more immediate effect and truly offset carbon usage? Look at Pacific Gas & Electric's program. They are selling trees that already exist and have offset their carbon to make people feel good about their electrical usage. However if they promoted tidal power generators along the breakwaters in numerous bays along California's coast or use the cash flow to provide needy families with solar panels on their homes, they would actually do more. Maybe they could figure out a way to generate wind power on the thousands of power transmission towers criss-crossing the state. New clean power generation without requiring more land would be nice.
Offsets or the ideas of offsets are nice. But promoting trees when their contribution is really not that great isn't. Planting a few million acres of rainforest in Brazil would definately help but its a lot more than trees that go into that equation.
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Sam Wells Posted 1:00 pm
18 Sep 2007
Onward through the fog
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Biodiversivist Posted 2:38 pm
18 Sep 2007
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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wayneluke Posted 3:37 pm
18 Sep 2007
http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2006/12/14/B ...
I would say the problem is that only 25 states have RES programs and some range as low as 5.5% (Texas). This would be from a lack of federal standards. However as more states mandate renewable purchases, the amount of coal will decrease. It isn't an overnight solution. Nothing would be.
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caniscandida Posted 3:49 pm
18 Sep 2007
<<
It is very important to point out -- AS OFTEN AS POSSIBLE -- that planting trees and other vegetation appropriate for a region is worth far more than what the market will ever assign to it. And there is more to preserving our natural environment than removing CO2 from the atmosphere.
>>
And I love NatureScene's suggestion about "biodiversity credits" and "habitat credits."
But I am puzzled, therefore, that we should judge Eric's tree-planting efforts to be well done on those terms. Are the trees that he chose to plant native to the Seattle region? He tells us that they have attracted birds, which is a very good thing. But will they attract native pollinators in the Spring?
I am only asking for information, and do not mean to imply any criticism. Quite the contrary: Eric did a praiseworthy thing by bringing down the curtain on the tennis-court lawn, and by planting trees.
Chickens are our cousins! So are fish! So are other sentient animals! Let us learn to be kind.
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spaceshaper Posted 9:40 pm
18 Sep 2007
The true meaning of life is to plant trees, under whose shade you do not expect to sit.
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farnishk Posted 11:58 pm
18 Sep 2007
In the first instance, dams kill rivers. A riperian landscape is rich in wildlife diversity, fertile soils and oxygenated water. When you take a river away from a landscape - leaving a tiny apparition of its former self - the land dries, and carbon dioxide is released from the soil. Carbon dioxide is also no longer absorbed by the rich flora that can no longer survive in a dry land. Furthermore, the fertile soils now have to be fertilised if they are to be farmed (note what happened to the Nile valley after the High Aswan Dam was installed). Artificial fertilisers take energy to make, or you can fertilise using belching methane machines (cattle) - your choice.
Secondly, the stagnant environment of the reservoir is a major source of methane (see this article for context). Where biological matter builds up methanogenic bacteria get to work and produce methane, so this alone could offset any energy saving benefits of hydroelectricity.
Hydro may appear to be a source of green energy, but it is just a way of producing large amounts of controllable power on the cheap.
Keith Farnish
www.theearthblog.org
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wiscidea Posted 1:02 am
19 Sep 2007
Damn degrades river and blocks salmon migration -- two strikes against the salmon.
Bears, raptors, and other predators can no longer hunt salmon, which they apparently drag or drop some distance from the river and consume only part of it.
Bear scat and scavenger scat no longer replenish nitrogen in soil.
Lack of nitrogen ptrevents healthy tree growth and forest regeneration.
Forest cover no longer protects stream from silt or maintains low water temperature for salmon.
The entire ecosystem collapses -- my extension of the horrible chain of events -- and no longer efficiently sequesters carbon.
Another victim of Jean-Paul Marat's ghost and his virtual guillotine?
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Eric de Place Posted 2:22 am
19 Sep 2007
My understanding is that the "ghgs from hydro" argument has been somewhat overblown. I'm not closely familiar with the literature, but I've been told by knowledgeable folks that the problem is much pronounced in tropical settings where there is much fluctuation in the water level (more biomass grows quickly and is subsequently innudated). I think it's a less serious problem in temperate zones. (Please correct me if I'm mistaken!)
In any event, my power, which is supplied by Seattle City Light, has been subjected to fairly rigorous audits and it is considered the only large U.S. utility with zero net emissions. Still debatable, I suppose, but I'll leave it for another time...
On a related point, damns definitely degrade river systems -- no doubt about it. While City Light's power doesn't come from dams that block migrating fish, much hydro power does. And I'm not saying that hydro is environmentally benign, just that it's climate-friendly.
Finally, to caniscandida's point, about half of my trees and other plantings are native to western Washington. I live in an urban area where the terrestial ecosystem conversion is somewhere near 100%. So my backyard efforts aren't aimed to restore the native coastal forests and bog-meadows -- what I'm doing is just not comparable to wiscidea's laudable prairie restoration -- but simply to support some of the native critters, even while I make it a great place to hang out. It's been pretty successful for birds. Some of favorite, though rare, visitors include downy woodpeckers, golden-crowned sparrows, and even a sharp-shinned hawk. But I don't know enough about pollinators to have even the foggiest idea about whether my yard can be successful on those terms.
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Earth Shaman Posted 5:53 am
19 Sep 2007
Earth Shaman
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Pangolin Posted 6:40 pm
19 Sep 2007
Let's just take this at face value and not try to find a source. Assuming that your house has 2 occupants the CO2 needing to be sequestered for those two amounts to 90 thousand pounds yearly. Of that 1/3 (.2727 actually) of the weight is carbon.
Doing some math 90,000x.2727 = 24,545 lbs of carbon that would have to be returned to the ground in mineral form each year in order for your household to claim carbon neutrality. Adding a bit (6%) for ash that would amount to some 13 tons of charcoal that you would have to bury on your lot each and every year.
Think of it as 3,000 ten lb bags of charcoal to bury just to break even on your households current emissions. That's only 70 lbs a day, about a 30 gallon trashcan full, 365 days a year. Making your own charcoal you only need to cook, in a retort, 280 lbs of dry wood (varies greatly) daily to get that weight of charcoal.
Using oak cordwood at about 3500 lbs to the cord....365/(3500/280)= 29.2 cords of wood converted to charcoal yearly to offset the emissions of two US residents. That's just about 2 1/2 cords of wood per month. (local value $500)
That is why carbon offsets are a stupid idea. They can do nothing in the face of continued emissions. We could quibble about my math but even the thought of burning 140 lbs. of dry plant matter daily just to bury and level your carbon emissions is insane.
We have to stop burning fossil fuels. There is NO ALTERNATIVE.
http://bioenergy.ornl.gov/papers/misc/energy_conv.html
Put the Carbon Back
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farnishk Posted 11:14 pm
19 Sep 2007
On the other hand, you are saying that the carbon dioxide in trees is not really in the trees, it is in your maple syrup, or something. Well, I don't know where you learnt your biology, but I don't remember the bit where all the carbon is immediately released back into the air.
Or maybe you are just a mad troll who has wasted my time. No matter, you still need to be told off.
Keith Farnish
www.theearthblog.org
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Adam Stein Posted 2:16 am
20 Sep 2007
Interesting discussion. A few comments:
Since tree planting is the sine qua non of carbon offset programs...
This isn't true in theory or in practice. Tree-planting projects are a very small percentage of offsetting projects worldwide. They're just what most people seem to have heard of.
That is why carbon offsets are a stupid idea. They can do nothing in the face of continued emissions. We could quibble about my math but even the thought of burning 140 lbs. of dry plant matter daily just to bury and level your carbon emissions is insane. We have to stop burning fossil fuels. There is NO ALTERNATIVE.
This is confused, to say the least. Carbon offsets are a funding mechanism for whatever means of carbon reductions you prefer, including alternatives to fossil fuel use. Far from being a "stupid idea", they are an enabling mechanism for the types of changes you would like to see take place -- changes that won't otherwise occur.
www.terrapass.com/blog
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Eric de Place Posted 2:52 am
20 Sep 2007
You write, "Tree-planting projects are a very small percentage of offsetting projects worldwide." Fair enough. I overstated the centrality of tree planting to offset projects.
Pangolin,
I have no idea what your point is. If you read my post, you would know that I think tree planting, especially on a small scale, is useless for offsetting emissions. And that finding ways to avoid emissions in the first place (i.e. less driving) is key.
Earth Shaman,
Dude, you are blowing my mind.
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