Hacker News Reader

Comment by Panino | Hacker News Reader

A good way to take part in increasing the number of trees, if you own your own home, is to improve the state of your shade trees. The trees absorb atmospheric carbon while also reducing home temperatures in summer, which in turn reduces the electricity people use for cooling. (And you save money!!) So a shade tree is a particularly effective way to reduce both atmospheric CO2 and electric bills. You might think of shade trees as cheap, biological solar panels.

Also, one can plant fruit trees in their yard. I put in 6 last fall and plan to put in another dozen in the next 2-3 weeks. Over the winter I added about 6 truck loads of wood chips to the yard to reduce water usage. (My general feeling at this point from working with the soil is that the wood chips reduce watering needs by at least 80% here. This is a form of xeriscaping, if you're interested.) With all this food growing in the coming years we'll be taking fewer trips to the grocery store while eating better. And probably giving away and trading a lot of food - we're already starting to trade for eggs from a friend, for example.

View on HN

I'm fortunate enough to have a pond and some marshy area bordering my house.

My neighbors sometimes wondered why I don't trim it up and make it look "nice" right up to the water like some folks do.

I like it wild, lots of trees and wildlife. I even let the wildness take a bit more of the yard than when i moved in. A few big trees quickly sprung up, no maintenance (compared to a yard) it looks great wild.

Perhaps if only out of laziness (yard work is kinda a pain). A few other neighbors who were maliciously caring for their lawn right up to the marsh (well the area you can do that to legally) have done the same as I have and we've got a much larger wild area now. It's full of blue jays, finches, cardinals, rabbits, owl visitors. We even get visited by some beautiful red foxes from time to time (i suspect quite often but they are very sneaky).

The kids mostly play in the front yard anyway where I actually bother to do more yard work to make it looks nice so a big lawn in the back makes no sense if nobody is really enjoying it.

The invertebrates that occupy that pond and its surrounds really appreciate that you're leaving it that condition.

The enormous snapping turtle that visits has chosen not to eat my children, I like that.

> A few other neighbors who were maliciously caring for their lawn

I think you meant meticulously, but it works either way. :)

It gets malicious real quick when they invoke the power of the HOA to force you to tame the wilderness in your back yard. :(

The next part is "have done the same as I have and we've got a much larger wild area now" so I suspect it was not "malicious"

> We even get visited by some beautiful red foxes from time to time

It's funny how urban adaptation affects perceptions of rarity. I live in fairly-central London and you can hardly set foot outside after dark without tripping over a red fox or three. Out in the countryside they're still pretty wary (with reason, since farmers will shoot them).

Are urban foxes a thing in the US too, or is this still a UK phenomenon?

Not so much, I think. In the upper Midwest, it’s mostly squirrels and rabbits.

We get squirrels too. (Squirrels are awesome.) Rabbits, never.

We have coyotes in many suburban areas.

Chicago at least has many _urban_ coyotes. I see them at least once a month walking my dog & I live in a pretty dense area.

Which neighborhood? I'm downtown and I only ever see rats. I've never seen a coyote anywhere in the metro area.

Hyde Park

There are some suburban ones but they tend to be pretty skittish - you generally see them through windows or cameras. I had one funny experience where they apparently moved stealthily enough that the motion activation mode on a security camera had them appear to teleport - it showed up for a few frames, appeared elsewhere in frame and then disappeared.

Really it is tameness that does it as they don't scatter before we even see them. The woods being quiet is because we scare the hell out of nearly everything, constantly walking on two legs like a bear ready to fight. Leave cameras behind and it gets noiser and more active.

I routinely come across coyotes in my neighborhood. Just this past week, I was out walking my dogs at 11AM and had one emerge from the bushes in the middle of a residential neighborhood. It was being harassed by a Blue Jay. It came within about 5 meters of my dogs and I, while we stood off the to the side to let it get past us and head towards the dry creek bed that they use to navigate the area. They're in our neighborhood for the rabbits.

Saw some urban foxes in Montreal - a tourist left a backpack with his dinner (rotisserie chicken) on the ground while the group went to take photos, upon their return they discovered that the foxes were already splitting the “catch”.

California has some raccoons and coyotes. Haven’t seen foxes in cities, but we do have them in the countryside.

I live in Minneapolis Minnesota. We have raccoons, opossums, squirrels, rabbits. That's all I have seen for small ground critters that aren't living in parks.

Skunks, there must be skunks. They are really thriving in (y)our neck of the woods due to milder winters.

I'm on the edge of the urban and rural suburban world so most wildlife is still a bit more wary, but yeah the urban foxes a few miles from me are far far less shy.

Reminda me of flying into Georgia as part of a trip leg. Much of the surrounding area looked like it was a suburban area overlaid on a forest or what modernn fantasy elves or something as houses were trqnsplanted to modern America - it was so filled with trees - given the heat and history it makes sense and was even oddly beautiful from the sky.

Really I think part of the cultural problem with home design environmentally - aside from the density issues is that so many don't even try to adapt to the environment and do daft things like trying to grow lush water thirsty grasses in the desert or cut away trees in areas that really need the drainage. They often do the equivalent of going around with a brazier of burning coals at 50F instead of putting on a jacket.

I think that's a side effect of the modern expectation that everyone move cross country on a dime if it makes sense economically. Kinda hard to figure out ecological best practices when families can barely stick around for a generation and people constantly move into areas they're just not familiar or comfortable with.

It takes a long time for best practices to become accepted and normal, and there just isn't the geneological inertia to develop that anymore

I think it predated that in that it occured with even slow "colonization" (regardless of it being occupied or not) but that is a good point. Expectations shape it first.

Cuts into my solar power generation through. So its a trade-off. Interestingly enough, from an energy production perspective the solar panels on the roof result in more reduction in CO2 than the trees do.

Can you prove that or back that up with some facts?

I suspect this is because you generate power all year round, while a shade tree doesn’t help heat your house in winter..

That’s pretty trivial to prove. Grid tied systems sell excess electricity back at bulk rates, at least in some states, which means that the solar panels are producing more electricity than the home needs for cooling. Thus such a house is actually spending negative carbon on cooling, since they’re providing green energy for their neighbors.

A shade tree can reduce your need for electricity, but it can’t turn you into a net producer.

Depending on the tree(s), it could be consuming CO2 24 hours a day, year round, solar is just part of the day and only reaches capacity for a brief moment. I don't know the numbers to show the difference. That is why I asked for some facts which the OP seems to know.

Trees consume CO2 because it's part of photosynthesis, so that's actually on the same schedule as a solar panel's electricity production. At night they're actually continuing to release some of that CO2.

A single average fully grown tree can sequester about 88lbs of CO2 per year according to the Center for Urban Forest Research, which is part of the US Forest Service. The average electricity service in the US produces about 1lb of CO2 per kWh, meaning that your solar panel needs to reduce your consumption by only 88 kWh per year below what your shaded house cost would be to be a net positive over a shade tree.

Don't quote me on this but from memory a tree is able to sequester a lot more in the first couple of years than as a fully grown tree. Intuitively that makes sense.

Yes, that is true. The carbon sequestration is greatest when the tree is turning CO2 into more tree (e.g. when it’s growing). This process largely stops as a tree hits maturity, and the CO2 is mostly returned when the tree burns or rots.

I’m making the explicit assumption that a shade tree will probably be fully grown.

Trees don't really continuously "consume" CO2 in this manner. The only CO2 removed by a tree is the carbon that ends up permanently Incorporated in the wood itself.

And if you burn that wood, it's all released back into the air. Even if it just dies and decays, some of it ends up being released.

Yea, so to sequester the carbon either build something out of it or dump it into the ocean. Maybe build a boat?

Rather than sequestering all this carbon into wood and then trying to figure out what to do with the wood so that it doesn't decompose over time and release the CO2 back into the air, it'd make more sense to stop digging up lots of carbon from underground (where it's been stable for hundreds of millions of years in the form of coal and oil) and burning it to release the CO2 into the air.

We already have amazing reserves of CO2, and we're digging them up and releasing them by burning them! Trees are just a tiny band-aid on top of this massive harm we're self-inflicting.

Why can’t we do both ?

We can and should, but there's more impact to be had from ceasing to dig up the buried carbon and burning it. That's the equivalent of not punching holes in the hull, whereas planting trees is like bailing out the boat -- you'd rather it just didn't leak!

I can tell you how I reason to it.

According to many sources, but I will cite this one[1] a single tree converts about 50 lbs of CO2 in a year. There are three trees on my property, a city tree (planted by the city) and two Birch trees planed by the original developer. All are deciduous so lose leaves in the winter but we'll give them full credit anyway, so call it 150 lbs of CO2 a year.

My rooftop solar system nominally puts out 5.2 kW of power under full sunlight, although efficiencies cut that down to around 4.8 kW net into the grid. I have over 10 years of data from the system, drilled down though it averages out to about 4.5 "solar hours" per day with an average daily output of about 22 kWH per day or about 8 MWH per year.

The US Energy Information Association (EIA) tracks a number of statistics, but the one that is most relevant is the number of metric tons of CO2 per MWH per state. You can see California's number in this report : https://www.eia.gov/electricity/state/california/ is 474 lbs per MWH.

Using that number, my rooftop solar system "saves" (which is to say doesn't generate) about 3,792 lbs of CO2 a year. Which, is way more than the 150 lbs a year the trees are taking out of the air. This is why the 1.2T trees, or 160 per person, is such a large number. A family of four would need to plan 640 trees on their lot, which would remove 32,000 lbs of CO2, which is a lot. To match my solar panels I would need to plant an additional 76 trees.

What you can take away from that is that solar panels in places where you can't put trees are a solid alternative. And planting trees rather than letting unused land sit idle as a field of grass is also a good plan. As a home owner, solar, even in places where it won't generate all your energy needs, will help cut CO2 emissions.

[1] https://projects.ncsu.edu/project/treesofstrength/treefact.h...

Good reasoning! I agree with the basic premise - but I don't think you can ignore the CO2 cost to make a solar panel, vs to use one. A tree reduces CO2 as it's being 'built'. A solar panel requires many materials that are refined through various industrial processes - likely some of which produce CO2 - not withstanding the transportation CO2 cost. That all being said, I don't mean to disparage anyone who uses solar panels - and if you already have them (sunk cost) - less trees seems about right, to reduce carbon footprint.

The CO2 cost to make a panel has to be much less than the amount saved by using the panel for a shortish while, because making CO2 isn't free, and would figure into the price of the panel.

Depends on whether or not you believe NREL, to wit:

An average U.S. household uses 830 kilowatt-hours of electricity per month. On average,producing 1000 kWh of electricity with solar power reduces emissions by nearly 8 pounds ofsulfur dioxide, 5 pounds of nitrogen oxides, and more than 1,400 pounds of carbon dioxide.During its projected 28 years of clean energy production, a rooftop system with 2-year paybackand meeting half of a household’s electricity use would avoid conventional electrical plantemissions of more than half a ton of sulfur dioxide, one-third a ton of nitrogen oxides, and 100tons of carbon dioxide. PV is clearly a wise energy investment with great environmental benefits! -- https://www.nrel.gov/docs/fy99osti/24619.pdf

Valuable reasoned contribution. Bravo.

Of course, this reasoning is limited to carbon effects only. There are other important ecological concerns that trees might address that solar would not.

It can be shown both bottom-up and top-down, but I prefer the bottom-up: Photosynthesis is usually an order of magnitude more efficient than photovoltaics: https://en.wikipedia.org/wiki/Photosynthetic_efficiency

...an individual leaf might be peak out at 3% efficient, but it is operating just a portion of the year (maybe about a third to a half at full performance) and also much light gets reflected, absorbed by branches, or misses the leaves entirely.

Additionally, photovoltaics peak at 40% efficiency but get about 15-20% efficiency typically and can function the entire year (unless fully covered by snow). And they're displacing electricity produced primarily from fossil fuels which are burned at 30-40% efficiency.

Now from a top-down perspective: forests (in this case calculated by replacing cropland with forests) are estimated to sequester about 2 to 10 tons of CO2 per acre per year. https://fas.org/sgp/crs/misc/R40562.pdf

In principle, an acre of about 40% solar photovoltaic system with a 25% capacity factor could produce about 3.5GWh per year. But typically, about exactly one tenth that is done in practice: 0.35GWh/year/acre.

Since you'd be displacing electricity from the US grid, which is currently about 420 grams of CO2 per kWh (based on my calculations of the most recent eia.gov figures, but you can find similar figures by Googling), that's equivalent to 147 metric tons of CO2 per acre per year for typical photovoltaics (and over 1000 metric tons per acre per year in the idealized case).

This person's calculations reach similar conclusions: https://www.solarpowerrocks.com/environment/installing-solar...

So absolutely, it's better to use solar panels than trees, at least until the grid is fully or nearly-fully saturated by solar.

...BUT once we fully clean the grid, trees have some advantages: 1) they efficiently suck CO2 out of the air and store it, not just produce the energy. That means you can actually draw-down CO2, producing negative emissions. 2) They're scalable. A tree is like a solar farm, CO2 direct air absorption system, and a chemical factory but can be planted as just a seed. It may not be "efficient", but being self-replicating and scalable is pretty powerful.

Your first paragraph contradicts the rest, I assume by accident.

Ha, you're correct! And now I'm unable to edit.

Trees come with a whole bunch of other issues. I have something like 40 trees ranging up to 20m tall. Cleaning up the leaves and branches is a year-round job. Collecting and removing the waste involves time, money and CO2 producing trucks. If not removed promptly, waste left up on my flat roof causes water damage after rains. Heavy storms make me nervous because I've once seen a set of healthy branches large enough to kill me snap right off (this was some time after the storm).

Some of the trees also attract rats, which drives my dogs nuts at night and is then a source of anxiety given the high crime rate in our country. Trees along the perimeter of the property have damaged the boundary walls, and other trees have ruined sewerage lines. If you want to plant trees, make sure you understand the potential future costs associated with them.

In addition, while planting a tree costs only a few dollars, cutting down a 100 ft high tree in an urban space can easily set you back thousands of dollars.

I've had several trees fall this year, on or around my house. Wet year, and windy too. If they're near your house, you need to invest in making sure they're healthy trees! I'm thinking of planting new trees further back from the house, near the creek.

Why do you have a flat roof on a house that's surrounded by trees?

So does that mean cut down the forest and put up solar?

Maybe put up solar in places there already isn't forest.

So, uh, generate the power somewhere other than on shady roofs?

Seriously, I don't get the weird obsession with rooftop PV as if it's the only way to be green. PV is great, but, it doesn't work for every house. Personally, I have big oaks out front helping block passive solar windows in the summer, and the peak of my roof runs north-south so cell mounting would be tricky. That doesn't mean I can't get clean energy, it just means I buy it from a utility company, who are buying it from my neighbor's house where the orientation and canopy placement makes sense to do PV.

I’d love to see better off-the-shelf solar purgolas, gazebos and other shade generating buildings like that (partial shade greenhouses, maybe?).

The backside of solar panels are actually quite pretty, and provide shade + partial rain barriers.

This would open up more avenues to passive cooling and also reduce the lock-step replacement of the house’s roof with solar panel installation .

This is a fantastic idea which I also recently had. Doing prelim research into how to turn something like this into a side business.

Shading your house will also cause the growth of moss and dump leaf litter everywhere, which will take off a significant chunk of your roof's lifespan (easily 5 years or more). So yeah you save $10/mo on your a/c bill and you spend that $20k to roof your house every 15 years instead of every 20 years. Let alone if you get a big storm and have some branches or a trunk come down and damage your house.

Regardless of the environmental angle, having trees near your house is not worth it financially.

While I agree with the sentiment of the GP, the reality is starkly different.

Most people I know go to great lengths to remove trees near their house. Some insurance companies lower premiums for it.

For any elevated property it adds a huge amount of value to kill a nice old established tree in the way of views.

That's awesome, this definitely helps. And if you don't own a house you can also take part on this by offsetting your emissions buying Forest Carbon Credits. At Pachama (YC W19) (Pachama.com) we're working to make it easier, cheaper and more reliable to certify and monitor carbon credits from Forest Projects, and then to make it easier for anyone to buy those credits. We're also hiring!

My favorite ground cover is clover. It’s tough, adds nitrogen (free fertilizer!), bees love it, and it stops the sun from drying your soil out.

Can you elaborate on "improve the state" of the shade trees? What does this entail?

Also do you recommend any resources for a beginner to get started on the fruit trees? Soil prep, watering schedule, etc.

Where do you live where shade trees are a thing?

Anywhere but super extreme latitudes? I'd never heard the concept spelled out like that, but I've seen / heard many instances. Basically any non-fruit tree which isn't kept at shrub / hedge size is at least in part intended for shade. Hell, it's also not uncommon for some fruit trees (I usually see walnuts and chestnuts as shade trees with the useful side-effect of nuts).

Here in North Florida, shade trees are very desirable when buying a home. Water and live oaks, magnolia and pines are very common here.

In Florida they are also very risky because they tend to destroy homes when they topple during a hurricane.

In my native Sweden (where it can be quite sunny in summer but not so much in winter) there is a concept of a "care tree", living up close to the manor of a yard of farm. [0] (link in Swedish, sorry, perhaps try Translate)

I am now living in Monrovia, Liberia, where you will often find large trees for shade, often mango, sometimes moringa or coconut. There's also a bougainvillea shading a bench in every village between Monrovia and Yekepa. :-)

Edit: I also want to mention the concept of agroforestry [1], a part of permaculture agricultural design principles, where trees (often fruit bearing) are used with lower vegetation, shrubbery and crops, creating a food forest. Incidentally, this is what farms often look like in West Africa, with coconut, banana, cocoa, papaya, cassava, etc growing intermingled on the farmland.

[0] https://sv.wikipedia.org/wiki/V%C3%A5rdtr%C3%A4d [1] https://en.wikipedia.org/wiki/Permaculture#Agroforestry

Where do you live where shade trees are not a thing? Genuinely curious. I've never known someone that didn't know what they were.

I live in Michigan and have four large trees surrounding the house, although we let their branches hang over the house, so 3 or so hours around noon, the house gets no shade.

There are essentially none where I live in SoCal (which actually bothers me a lot, because of how short-sighted it is but also because I grew up in the midwest and I genuinely miss having trees around). Most of the newer developments that I see and giant sections of LA and Orange county where I spend some time are little more than a sea of asphalt. There are trees in parks, of course, but they're more like decorations than something that serves a function.

UK for me, never heard the term.

The fact that you presume people outside the US know what and where "Michigan" is makes me think you don't know much about other countries at all.

Semi-arid region here, it can be 95 degrees out and you fry in the sun like an egg, but under a shady tree it can be comfy & breezy. Shade trees are extremely valuable here.

Although not everyone is onboard. To be sure, there are still drab boxy houses with nothing but lawn that run their sprinklers every morning and the A/C all day. Preferable to spending two hours a year raking up leaves in fall, I'm told.

Reply on news.ycombinator.com