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Planting 1.2T Trees Could Cancel Out a Decade of CO2 Emissions (yale.edu)
447 points by ToBeBannedSoon on April 21, 2019 | hide | past | favorite | 324 comments

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.

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.

> 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?

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.

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.

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.

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

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.

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

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

> 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"

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.

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.

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, 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.

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

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.

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

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.

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.

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.

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!

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.

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.

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

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

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

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?

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

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).

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.

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.

UK for me, never heard the term.

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.

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.

But, wait... some places are clearing forest for solar farms.

Georgetown https://www.washingtonpost.com/opinions/2019/04/01/georgetow...

Rhode Island https://www.providencejournal.com/news/20190414/proposed-ri-...

Prineville Oregon(I dont' know how many trees will be cleared for this, maybe it will be on existing farmland) https://www.oregonlive.com/silicon-forest/2018/07/massive_so...

This is total non-sense. There are so many deserted areas in the US and all over the planet -where radiance is actually a lot higher- where to install solar panels.

Transmission losses are not negligible, so power generation generally needs to be near people.

If the power could be used to create and concentrate ammonia, much of needed generation could be shifted to farms. Of course farms have other uses for sunlight, so wind is a better choice there.

Generating ammonia with wind power eliminates the problem of intermittent availability. You only produce ammonia when there is power for it.

Making your transmission line a lot longer doesn't scale your losses by that much surprisingly. The main transmission losses are at the conversion points and in the utility voltage cabling at the end, having long distance interconnects really only loses a percent or two over having short ones.

That's just a very naive simplification of a huge branch of electrical engineering.

To have low power losses in long distances, you use high voltage. The higher the voltage, the bigger (and more expensive) the "conversion points" need to be. Power losses will also be bigger.

To simplify greatly, having low-loss transmission lines costs more money, more equipment, more investment, more time. That's why it makes more sense to build the power source closer instead.

>That's just a very naive simplification of a huge branch of electrical engineering.

Anything I am going to squeeze into a comment on hacker news regarding the subject is likely to be. So are you against the concept of continent wide grids and transmitting power long distance from sparsely populated equatorial desert regions to the more populous temperate ones?

Your objection has merit, but this discussion seems to be focused on "what should we do going forward". While we currently suck at good & economical long distance transmission, this hardly seems to be based on physical limitations. Thus, if it is a worthy goal, we can & should guide our economies towards mastering that tech and driving prices down, kind of like we did with e.g. solar panels.

I'm especially eager to hear more about developments in / experiences with UHV DC lines, like in this ieee.org article + discussion: https://news.ycombinator.com/item?id=19295838

Regarding RI, your article is by no means the full picture nor clear support for your over-claim. 1) The biggest solar farm we're vying for here in RI is going to be in a disused industrial zone, not in a forest. 2) The article you linked is mostly about protecting forests proactively, not about a specific project and how it cleared the forests. 3) Speaking as one who drives the state constantly, there is actually very little utility scale solar. It's mostly turbines, there is solar here and there but it's usually adjacent to roads or structures or on rooftops, we have very few large solar farms due to our higher focus on wind and energy efficiency.

Overall, you're over-reaching with the RI claim that we're clearing forest for solar farms, as I've been local for decades and seen no evidence of that.

Most of the solar installations around Prineville are replacing sage scrub, not forest.

All things considered, clearing a forest to help wean us of natural gas and oil is probably a net positive.

nuclear power is significantly more (space-, energy-, ..) efficient and clean than solar farms https://www.forbes.com/sites/michaelshellenberger/2018/05/23...

Except for those two huge externalities that are never priced in and always overlooked by people who say nuclear is 'clean': the waste that will remain toxic for a very long time, and the risk of accidents (slim, but the consequences are really, really, really bad).

The waste that is very toxic is short-lived. The waste that is very long-lived isn't very toxic. That's how half-life works.

As for risk of accidents - nuclear is responsible for less deaths per MWh produced than coal, including all the accidents (Chernobyl and Fukushima too).

Coal powerplants also put more radioactive elements in the air than nuclear powerplants (including all accidents). And it's not "risk" in coal powerplants, it's their normal operation as designed.

Nuclear powerplants is the easiest way to replace baseload, and by insisting on not using it we increase the amount of radioactive elements in air, the deaths, and the CO2 emissions (because you can't replace most baseload with solar/wind - so if not nuclear it's coal/gas).

Here’s a source from Nasa: https://climate.nasa.gov/news/903/coal-and-gas-are-far-more-...

And a quote:

“Using historical electricity production data and mortality and emission factors from the peer-reviewed scientific literature, we found that despite the three major nuclear accidents the world has experienced, nuclear power prevented an average of over 1.8 million net deaths worldwide between 1971-2009 (see Fig. 1). This amounts to at least hundreds and more likely thousands of times more deaths than it caused. An average of 76,000 deaths per year were avoided annually between 2000-2009 (see Fig. 2), with a range of 19,000-300,000 per year.”

That's just comparing them with coal to sound great. The three major nuclear accidents do not represent the worst which nuclear plants are capable of. For example we have yet to see what can happen if a nuclear plant is sabotaged - that's not FUD its a real vulnerably of the technology and is a reason why they incur constant exceptional security as well as safety costs. They consume alot of water resource as well, for cooling.

Thankfully its an academic debate now anyway, because solar and wind prices are already much cheaper with no end to their continued improvement in sight.

> For example we have yet to see what can happen if a nuclear plant is sabotaged - that's not FUD

That's FUD. What are you proposing is going to happen that would be worse? You can't get a nuclear explosion; the fuel isn't weapons grade. You can get a meltdown and a hydrogen explosion, but that is what happened at Chernobyl. It leaves behind a hot mess and a large cleanup bill but hardly anybody dies. Especially if you're not an obtuse Soviet bureaucracy that dispatches ordinary firefighters to deal with it without adequate training or equipment.

> They consume alot of water resource as well, for cooling.

Water isn't "consumed", it starts off as H2O and ends up that way. It evaporates and then condenses again somewhere downwind.

The soviet response to Chernobyl was in many respects phenomenal. They mobilized hundreds of thousands of people to risk their lives to mitigate it.

One effort that stands out as "preventing something much worse" is that there was a risk of a potentially larger secondary explosion from steam buildup. They tunneled under the reactor and injected ~25 tons of liquid nitrogen a day (the tunnel started 6 days after the explosion, and was functional 8 days after the explosion). They had people risk/give their lives swimming in to close valves and pumping water out. Dates from here: http://www.chernobylgallery.com/chernobyl-disaster/timeline/

Also, you can absolutely get a nuclear explosion from a reactor, there is some suggestion that Chernobyl might have been a small one in fact (paper): https://www.tandfonline.com/doi/full/10.1080/00295450.2017.1...

There were personal heroics but the Soviet response was a catastrophe, it was Sweden that sounded the alarm and the Soviets allowed a May Day parade of children to march through the cloud in Kiev...

"For 36 hours after the explosion, people were given no reliable information about it and left virtually on their own. They never received instructions on how to protect themselves and their children. Radiation levels that according to Soviet laws were supposed to trigger an automatic public warning about the dangers of radiation exposure had already been recorded in the early hours of April 26—but were ignored by one official after another. Finally, people were asked to gather their belongings and wait on the street..." https://www.history.com/news/chernobyl-disaster-coverup


> One effort that stands out as "preventing something much worse" is that there was a risk of a potentially larger secondary explosion from steam buildup.

A larger conventional explosion would have been linearly worse, not worse rising to a separate category of problem.

> Also, you can absolutely get a nuclear explosion from a reactor, there is some suggestion that Chernobyl might have been a small one in fact (paper)

This is not what I'm referring to. It's one thing to have a "nuclear explosion" in the sense that the reaction generates enough heat to cause the rapid expansion of gasses which is technically an "explosion".

What I'm referring to is the sort of exponential chain reaction that happens in a nuclear weapon, resulting in something on that scale. You have to design for that on purpose to get it. The density and geometry has to be exactly right.

> you can absolutely get a nuclear explosion from a reactor, there is some suggestion that Chernobyl might have been a small one in fact (paper)

An explosion that's too weak to even blow apart its own assembly doesn't count.

"What are you proposing is going to happen that would be worse?"

No offense but if you can't see how Chernobyl or Fukushima could have turned out worse, or that unexpected accidents in other locations could happen and could be worse, you don't understand nuclear power. Its problematic because I expect you have read plenty on it in order to want to defend it in a topic about aforestation.

"Water isn't consumed"

Water resource is consumed, sure it rains again - often far away and into the sea. Fresh water resources are scarce and under pressure in many places, ancient aquifers are drying out, particularly in the US.

> No offense but if you can't see how Chernobyl or Fukushima could have turned out worse, or that unexpected accidents in other locations could happen and could be worse, you don't understand nuclear power.

I can't help but notice the lack of specific examples or explanations of any kind.

> Water resource is consumed, sure it rains again - often far away and into the sea. Fresh water resources are scarce and under pressure in many places, ancient aquifers are drying out, particularly in the US.

Ancient aquifers are drying out as a result of unsustainable resource management and climate change. Nuclear power helps with both of these, the first by providing power for desalination and the second by reducing carbon emissions. The amount of water it evaporates for cooling by comparison is a drop in the bucket. Also, the cooling can be done with seawater to begin with.

"I can't help but notice the lack of specific examples or explanations of any kind"

Because its so simple as saying, "the wind COULD have blown the fukushima fallout southwards over Tokyo instead of relatively promptly into the Pacific." A nuclear accident COULD deliver fallout to a highly populated area that cant be evacuated in time. A nuclear accident COULD generate much more fallout than Fukushima or Chernobyl. How can one understand the technology, and challenge the reality of such risks of nuclear power plants? Pretending that its been as bad as it might have been and as it could be - like a dangerous driver saying "its fine - I've only ever hit a tree!"

re: desalination - fine then, add the cost of desalinating salt water to replace the increasingly scarce resource that nuclear plants evaporate, to their already uncompetitive cost.

To add to your examples, there was the very real possibility with Fukushima that Tokyo would have had to be evacuated. This was seriously considered at the highest levels of the Japanese government (i.e. the PM and cabinet):

> The 400-page report, due to be released later this week, also describes a darkening mood at the prime minister’s residence as a series of hydrogen explosions rocked the plant on March 14 and 15. It says Mr. Kan and other officials began discussing a worst-case outcome if workers at the Fukushima Daiichi plant were evacuated. This would have allowed the plant to spiral out of control, releasing even larger amounts of radioactive material into the atmosphere that would in turn force the evacuation of other nearby nuclear plants, causing further meltdowns.

> The report quotes the chief cabinet secretary at the time, Yukio Edano, as having warned that such a “demonic chain reaction” of plant meltdowns could result in the evacuation of Tokyo, 150 miles to the south.

> “We would lose Fukushima Daini, then we would lose Tokai,” Mr. Edano is quoted as saying, naming two other nuclear plants. “If that happened, it was only logical to conclude that we would also lose Tokyo itself.”


> Because its so simple as saying, "the wind COULD have blown the fukushima fallout southwards over Tokyo instead of relatively promptly into the Pacific." A nuclear accident COULD deliver fallout to a highly populated area that cant be evacuated in time.

So the thing that actually happened with Chernobyl then, not something significantly worse than that.

> re: desalination - fine then, add the cost of desalinating salt water to replace the increasingly scarce resource that nuclear plants evaporate, to their already uncompetitive cost.

Evaporating the water is how you desalinate it. It starts as seawater, it evaporates, you recondense it as fresh water. The equipment needed to do that costs less than the value of the water; the major expense is generating the heat which you're already doing for power generation. So I guess we could subtract the net profits from producing that valuable side product from the cost of the power generation, sure.

Do we then get to add the costs of climate change to the cost of burning coal, or are we only attempting accurate accounting for nuclear and not anything else?

Actually - most desalination is done by reverse osmosis - which is much more efficient than evaporation.

> Water resource is consumed, sure it rains again...

And sometimes ocean water is rained back on land. Hurray, water cycle!

Normal operation of coal powerplants is more dangerous than the worst accidents we had with nuclear powerplants.

Modern nuclear powerplants are much safer than these that had accidents.

Yes you have to include the possibility of new accidents - being sabotaged or not. But that possibility needs to be weighed with the probability of it. And it's very low.

Meanwhile we completely ignore the 100% sure deaths and radiation caused by coal powerplants. Because we're used to it.

BTW sabotaging hydro powerplants can kill hundreds of thousands of people at once. And it's much easier than sabotaging a nuclear powerplant. Get one diver with a swimsuit and give him some TNT.

Somehow I haven't seen this used as a counterargument to renewable energy :)

For all the stretched comparisons about how safe nuclear can be, the technology is a liability which requires great care and expense to keep secure and safe.

Its promotion was competing with and obstructing the promotion of renewables for over a decade past, but its moot now that in the past couple of years the price performance of renewables has become unassailable. There's no point promoting nuclear anymore and arguing about how safe nuclear has been or could be - its more expensive already than wind and solar, materially, environmentally, security-wise and economically. Wind and solar are still on a rapid improvement curve. Nuclear powered heat plants are not futuristic generation options, they're relics from the nuclear arms race.

Yes you have to include the possibility of new accidents - being sabotaged or not. But that possibility needs to be weighed with the probability of it. And it's very low.

This is not a case of of risk but uncertainty - very different strategies apply here.

Thankfully its an academic debate now anyway, because solar and wind prices are already much cheaper with no end to their continued improvement in sight.

Has large scale energy storage been solved? I know there are a number of ways to do grid-scale storage, but are any of them scalable enough to power the entire country from solar and wind? Especially if another "storm of the century" (which seem to be happening more frequently now) reduces solar/wind output from a significant portion of the country so you need to draw deep into storage reserves.

> Has large scale energy storage been solved?

There are numerous technologies which can currently provide large scale energy storage at cost which is currently competitive in many situations and due to drop rapidly once they are actually required and built in quantity. To mention a few: flow batteries, hydrogen production and generation, carbon neutral biomass fuel, heat storage and conversion batteries including molten salt, enhancement of existing hydro schemes, online EV fleet, active geothermal... besides you know if pushed, even the occasional emergency fossil fuel burn if unprepared. Nuclear plants are not known for their uptime during storms either.

Current prices are detailed here, been dropping every year : https://www.lazard.com/perspective/levelized-cost-of-energy-...

>As for risk of accidents - nuclear is responsible for less deaths per MWh produced than coal, including all the accidents (Chernobyl and Fukushima too).

Do you have a source on this?

Search past HN posts or look it up on Wikipedia, it's been discussed many times.

Even if it's true, it's like using "there are more deaths by vending machine per year by shark" to justify everyone swimming with sharks. Not saying that nuclear is inherently unsafe, but if 100% of our power came from nuclear, then so would 100% of the deaths per MWh.

Bad analogy, it would be somewhat valid if I compared the TOTAL number of deaths between activities done by vastly different amount of people.

But I compared PER MWh PRODUCED, so it's nothing like with vending machines vs sharks.

> if 100% of our power came from nuclear, then so would 100% of the deaths per MWh.

If 100% of our MWh came from nuclear, and nuclear has less deaths per MWh - then some deaths would be avoided that now aren't.

How is that not important?

Honestly, your analogy was so bad it seems like intentional manipulation.

Installing solar panels kills more people than nuclear ever has by orders of magnitude.

We have the tech to deal with nuclear waste, we’ve just never spent the money to productionalize it. Look into “sub-critical nuclear reactors”, which “burn” nuclear waste for even more electricity!

> Installing solar panels kills more people than nuclear ever has by orders of magnitude.

Wait, what? Really?

“With solar, people fall off roofs installing panels — the health and safety standards are not the same.”


Haha, didn't know that one.

If you reprocess waste for potentially usable fuel, the amount of stuff that needs to be discarded is quite small. Like, we could probably put everything we've ever accumulated in the US in fly ash pond of an average coal plant, easily. Obviously that is a bad idea but just to give you an idea of the size of what's needed.

Also yes, I'm sure waste disposal is factored into nuclear plants. It's usually coal plants that get the free pass to spew radiation into the air, resulting in tens of thousands of deaths annually.

(note that there is a fair amount of low-level waste generated that tends to inflate the waste output figures... you need to do something with the wrenches and shoe covers and stuff that get some neutron activation, and there's a large volume of that stuff but it's nowhere near as dangerous as spent fuel.)

the mining is also a disaster for the affected region AFAIK

I’m pro nuclear power, but I also understand that politically and economically it’s a non starter. At this point in time it’s either solar (or wind) or natural gas. I’ll take the known local maximum over a global maximum that’s not feasible.

Does this figure factor in the $100 billion cost of the Fukushima disaster?

$100B is actually a very small percentage of world energy costs. Less than 0.1% of what we spend annually.

Studies on this are very valuable. The IPCC's AR5 advises this kind of action to be funded and analyzes different policy approaches to enable action.

There is no justification at skepticism and entertaining back-of-the-envelope gotchas about the climactic and environmental value of tree planting and enhanced forestry at this late stage. It needs to be supported !


" Reducing emissions from deforestation; reducing emissions from forest degradation; conservation of forest carbon stocks; sustainable management of forests; and enhancement of forest carbon stocks (REDD) consists of forest-related activities implemented voluntarily by developing countries that may, in isolation or jointly lead to significant climate change mitigation. REDD was introduced in the agenda of the UNFCCC in 2005, and has since evolved to an improved understanding of the potential positive and negative impacts, methodological issues, safeguards, and financial aspects associated with REDD implementation. " (page 865)

Not to be too snarky, but my first reaction to the headline was, “only 1.2 trillion? What are we waiting for!”

More seriously, though: the article claims there’s “ample acreage” for such an endeavor but I didn’t see where exactly they’re referring to. Are we supposed to imagine these are sprinkled here and there around the earth, and that there’s plenty of space just waiting for a tree to be planted, or is this something where we need to create or re-create vast forest lands for it to work?

The great plains have little vegetation on them, and take well to having trees planted on them. The trees in Kansas, for example, were planted by early settlers to break the wind, and have thrived.

(The historical reason trees were absent from the great plains was periodic fire.)

They were also once home to tallgrass prairie, now the most threatened biome on the planet.

That's only 160 trees for every man, woman, and child on Earth...

It doesn't seem like a particularly practical solution.

It seems incredibly practical to me. I've seen a quote for 40 dollars to plant a thousand trees. That's something like 50 billion to offset a decade of global warming? Doesn't sound so bad. Spread the cost out worldwide, 5 billion a year, split between a few big countries?


I don't think planting trees is the biggest issue. Access to water is. More practical solution would be to fill some desert with sea water and grow plankton, kelp etc.

Deforestation is one of the reasons some deserts have spread so rapidly. trees behave as a shield to that encroachment

I recently saw a video about doing this - apparently the desert is actually a really bad option if we want to combat climate change - the core problem is that the desert currently reflects a lot of light from the sun. If we cover it with forest or whatever, then suddenly we adjust the albedo of the earth and absorb more heat, negating some of the impact. Combined with the energy need to pump (and desalinate for trees - your suggestion of kelp would presumably help there) water, etc... make it not really work.

Source: https://www.youtube.com/watch?v=lfo8XHGFAIQ

I recommend watching the video - it explains it better and goes into detail - it cites its own sources.

I assume trees are good at trapping the energy from sunlight + combining it with c02 and water to produce carbon, oxygen and more water.

So planting trees in deserts with somewhat decent access to underground water tables should help cool the planet and create a great renewable resource right?

I don't think planting trees is considered to be the unquestionably most practical solution. But it's a simple solution that people can do on their own, and it has a lot of other side benefits like habitat, shade, & proven health benefits in humans.

That’s the price of the seeds though. The cost of finding the land, digging holes, planting seeds and watering them to sustainable growth would be much higher.

Honestly if HN knows any charities focused on tree planting, let me know. Happy to donate 1k-ish if it puts 10k trees to our family’s name.

Is that just for the seedlings and not the actual labor of planting them?

I've seen quotes for parts of developing countries where planting trees would cost $100 USD per thousands trees.

See FAQ point #11: https://trees.org/faqs/

> 40 dollars to plant a thousand trees

Presumably these would be some of the cheapest trees to plant. When that space is used up but the first few billion trees, where will the next billion go? How much will that cost?

trees are only a co2 buffer, they don't make it dissappear. and trees require water, and the burn up (which puts the c02 back also)

Even if we had to replant the trees every decade, that would only be 5 billion dollars a year, forever. Trivially affordable at "world power" scale.

Lack of water is a much more real blocker, with space not far behind.

The cost of global warming and the benefits we've reaped from its cause (cheap power) are both a significant fraction of world GDP. Planting 160 trees per person would be cheap, and even easily do-able by an individual in a few weekends (though it's obviously way more efficient to hire specialists to do it en mass).

The total suitable land area needed (more than the area of the USA, by my estimate) is much more likely to be the limiting factor than the per-person difficulty.

I dislike the US prison system but perhaps we could use prisoners to do it. They could plant hundreds If not thousands within a sentence and one day return to visit the forest they planted.

I like how we instinctively turn to slavery when there's a grand project that becomes vital.

Inmates already volunteer to do forestry work including firefighting. This has been going on for decades and isn't all that controversial. Expanding to planting trees shouldn't be too difficult.


All the grand projects of the past few centuries were based on it. Why change a winning strategy?

Well, we have better means for automation now. But I'm just fascinated how quickly that solution pops up in such discussions as soon as it's convenient.

I like how we instinctively characterize prisoners as slaves. Seems like it trivializes actual slavery, but I have been out of school for awhile, so the conventional wisdom is probably different now.

If you don't see labour camps as a form of modern slavery, then I'm genuinely asking you to provide the definition you've learned back at school.

Traditionally, prison labor is considered distinct from slavery for the same reason that prison is considered distinct from kidnapping and forced confinement: that it reflects just punishment for which someone is duly convicted. Whether that actually applies to most people in prison today is certainly up for debate, but to tell you'd mostly need to look at the judicial system (or society at large), not at the work camp.

One could plant that many pine saplings in a weekend with good hand tools. Mechanize it, spread the cost amongst many, I believe it wouldn’t cost, relative to what it offsetting, all that much. Land acquisition would probably be the larger obstacle.

I once worked for a short spell in a tree-planting squad in the highlands of Scotland. The seasoned planters were olympically fit and each planted around 100 saplings an hour across rough mountainside.

How hard is it to plant a tree? Especially if it's young and there is very clear guidance as to which native trees should be planted in which contexts you have available to you locally (account for full size growth and sunlight / water needs).

If over one year everyone planted 3 trees per week, and we employed a work force of people to cultivate them further, we would make a huge dent in our catastrophic risk exposure? Sure, it's seemingly impractical alongside the status quo of land distribution and use ( $$$ into develop all the land and farm humans for rent!!), but... more green will be good for the health of nearly all the living things on Earth, and at the very least give us more time to find even better solutions.

It’s cheap to plant baby trees, and baby trees are the ones that are about to go through their main carbon absorption cycle anyways.

It is not difficult but doing it without the right machinery requires back-breaking labor. It looks like this: https://www.youtube.com/watch?v=uUzeruQT8xE I did it one full weekend and I was totally exhausted. Of course, there exists machines to do that, but then you can't have every person in the world chipping in.

But planting is just the first step. If you own a growing forest it needs to be culled periodically, meaning that you cut down the worst performing 10-20% of all trees.

That video is what you consider back-breaking? I planted ten trees on my property with a mattock & shovel over the course of two weeks, removing maybe fifty gallons of clay for each hole, and while it was hard I wouldn't describe it as back-breaking. You'd also adapt to it as you got stronger...

With everybody trying to burn it, or steal it, or pour concrete over it, can be very hard.

Is an 80 years' work in any case.

For comparison, in Sweden, Finland etc there is 5-10000 trees per capita already. Adding a 1000 more per head would be easy in terms of space. So that would cover say 100M people.

But it might be part of a solution.

How many trees has been removed in total by deforestation? Planting trees is a good thing, but at the same time there is deforestation. The deforestation must also stop.

https://www.bbc.com/news/science-environment-34134366 Earth's trees number 'three trillion'

"Scientific research has shown that there were once six trillion trees on our planet, and now there are around three trillion left.[1] Human activity was the main driving force for this decrease and humans can, therefore, be the main driving force in increasing it again!" source: Trillion Trees Three major international conservation organizations – the Wildlife Conservation Society (WCS), the World Wide Fund for Nature - UK (WWF-UK) and BirdLife International (BLI)

We probably also need to remake the economic system what parameters it optimise's for, so that it does not focus on exponential economic output growth as that will drive exponential energy consumption. Reasoning, the planet is already literally on fire due to global warming, why put more fuel on the fire?

It doesn't look like they factored in the CO2 emissions from planting that many trees.

The actual presentation:


Under a business-as-usual climate scenario our model suggests that warming would drive the loss of ~55 gigatons of carbon from the upper soil horizons by 2050. This value is around 12–17 per cent of the expected anthropogenic emissions over this period.

You have wildly mistaken the plain meaning of that statement. They declare their model suggests global warming will drive the loss of carbon from soils - not Trees, or aforestation programs.

That’s a really good point also where water and irrigation is concerned hopefully that would be done in the most sustainable way possible. The idea of “offsets” unfortunately has been given a bad name politically due to unscrupulous actors. Really it could work if the public oversight was there in real time and all the facts on the table. Still, we are living in an age where efforts done “in everyone’s best interest” are a hard sell. We wouldn’t even be here if it weren’t easier to sell a pair of new shoes than clean air and water.

That’s a really good point also where water and irrigation is concerned hopefully that would be done in the most sustainable way possible.

I wonder how many of those 1.2T trees could be accomplished without starting huge new forests or in places that require irrigation.

There are cities in places with ample rain that already have 1,000's of vacant lots. Ten trees per vacant lot could start to make a big difference, if only regionally.

Maybe Americans should stop thinking of Arbor Day and the Arbor Day Foundation as quaint square leftovers from a past generation, and start thinking of them as a framework to save the planet.


I'd welcome two new trees in my front yard and two in the back, but my HOA won't allow it. I've already reached my maximum vegetation allowance.

Nor the emissions when those trees burn because they were planted in a place where waterbed can't support their density. This is happening in CA nearly every year.

The burning an decay of a planted tree would at worst be carbon neutral.

Right, but if the point of planting the trees is carbon amelioration, than carbon neutral would somewhat defeat the point.

I've seen this argument before, and I think the real place it falls down is that there just isn't that much space. For mature growth forest, you have something like 40-ish big hardwood trees per acre [1]. Those are, to my understanding, the only ones that are really relevant because they make up most of the biomass. Other types of trees are just a rounding error. `1.2e12 / 40 acres -> square miles` (frink) is 4.7e7 square miles. That is more than the whole land area of Earth [2]. There is certainly not enough land that would support mature forests available to plant so many trees, unless I have made a serious calculation error.

[1]: http://www.sbcounty.gov/calmast/sbc/html/healthy_forest.asp

[2]: https://hypertextbook.com/facts/2001/DanielChen.shtml

That only holds true if you assume that every tree ever planted burns down within ten years. Many, possibly even most, of them will be harvested for wood, becoming a permanent carbon sink, or will be left alone to grow to maturity.

That in turn only works if you assume that wood never rots, burns, etc. I don't have any solid information on the annual growth in processed wood in existence, but I suspect that, to the extent it is increasing, this will gradually taper off as population growth slows. Now if you're saying we could bury the wood somewhere where it won't rot, well enough. That does seem feasible. But normally when I read stuff like this, people think just planting and leaving the trees will be sufficient. And it won't.

At any rate, if that's what the research is getting at, they probably need to title it differently, or explain early on that merely planting the trees is a necessary but not sufficient condition to achieve the wins they envision.

And burning trees is better than letting them rot, which releases methane.

Which Carbon though. Trading CO2 for CH4, for example, would not serve us well.

nor the small emission from natural decay of dead wood

That said it could also:

- absorb some heat

- create new wind / rain cycles

- provides a lot of material (construction/furniture) to replace cement and plastics

- kill millions of people of exhaustion from planting that many trees

Planting is something we know really well how to automate, though. Planting is the most tractable problem in this (hypothetical) solution.

Also, more rain means more clouds, and this is something the current climate models can't really model accurately, believe it or not. There's not even "consensus" on whether clouds are beneficial or detrimental.

I can certainly understands we have modeling limits

If each person on the planet would plant 150 trees this year, we would be finished.

For some reason I pictured people moving fully grown trees .. planting 150 seeds is not a lot indeed.

> the emissions when those trees burn

We'd probably have to sequester them somewhere anaerobic. Bottom of a deep-sea trench or underground. Which also reduces the net carbon footprint of the activity.

The best way for sequestering wood is turning it into biochar. You even get some energy out of it.

Doesn’t that release the captured carbon?

Not all of it, that's the point. Some pure carbon (charcoal) is left that makes good soil amendment. That carbon doesn't make it back to the atmosphere unless somehow burned.

But the comment said we could get energy out. Wouldn't we burn it to get energy?

The creation of charcoal itself generates heat which can be used.

The wood has lots of hydrogen in it that is burned off, leaving most of the carbon.

Why not do something more useful and sequester the trees in buildings? Timber-framed houses for everyone!

I wonder if the eventual fate of most lumber is to be burned, on the scale of tens of decades (as buildings deteriorate, are remodeled and older bits thrown out). In which case you're just postponing the need to sequester anyway.

I think you have to consider what you're comparing against. Are we comparing to just not cutting trees down? Trees fall and decompose, while wood buildings can last for centuries. Admittedly building 300-year houses seems like a pretty different idea of construction than what we're doing now. So it comes down to how long you expect the building to last, but it's important to remember the carbon in trees will eventually be released into the atmosphere in any case.

But! It's also important to consider what timber houses would replace - concrete. Concrete is not very climate friendly. Throwing that into the equation, I'd be surprised if wood construction wasn't better for the environment than what we're doing now.

It doesn't need to be sequestered eternally, it just needs to be captured and sequestered at a faster rate than it's being produced (from fossil fuels and decay/burning of wood).

Where I live (Kitchener-Waterloo), there are a lot of old factories with heavy timber frames and solid hardwood floors. These factories have since been converted into nice condos and commercial properties, with all of that wood preserved intact. The old timber beams and hardwood floors are actually very nice now.

Or use the wood in construction.

This makes me wonder - could trees be modified genetically to handle more CO2 in order to make this number lower? Could we, instead of trees, have huge walls made of plants that would consume our CO2?

I believe the Californian Redwoods are very good at this but one of their main disadvantages is they take forever to grow in their native climate.

Ironically, they grow much faster on the other side of the world (New Zealand) due to its wetter climate but the wood is not as hard due to this so they aren't useful in construction. Basically the ultimate carbon sync and useless for humans.

https://en.m.wikipedia.org/wiki/Redwoods_Forest,_Whakareware... neat! When I was young I used to wonder what redwoods would be like introduced outside their native range. Now, 15 years later, I know!

Would be trivial to put a hothouse over it for the first years to mimick the humid forest environment. Could act also as water collectors and a sort of fire barriers for stopping flying embers also. Metallic mesh dissipates hot.

Just use a bunch of these: https://en.m.wikipedia.org/wiki/Azolla_event

It worked 49 million years ago.

An incredibly short sighted solution to an incredibly complex problem.

Trees have been around for a very, very long time; much longer than we have. Complex evolutionary forces have shaped trees and forests into their current robust configurations.

Trees are intimately connected with their ecosystems, and interact with their surroundings in both known and unknown ways. For example, it has been discovered recently that trees communicate with one another through chemical, hormonal and slow-pulsing electrical signals, including through the air, using pheromones and other scent signals [1][2]

Mother nature is complex. We do not have enough understanding of her complexity, and neither enough computational power to reliably model and subsequently change diverse ecosystems.

[1] https://www.smithsonianmag.com/science-nature/the-whispering...

[2] https://www.amazon.com/dp/B01C9116AK

We have been genetically modifying plants to maximize CO2 utilization for millenia.

Plants try to minimize CO2 utilization becase it’s energy intensive. We could design something that stores more carbon, but with real tradeoffs as it would have less energy for other things.

You mean running a permanent experiment on the genetic diversity and interplay of forest species across the globe?

Luckily such recklessness is unnecessary.


This might be something you are referring to.

That's a lot of trees though and it cancels out only a decade.

EDIT: I just looked it up: there are roughly 4-10 trillion trees on earth right now.

And lots of land. Suppose you can plant them in say 4m rows with 4m separation, it would be approx 60K trees per 1km2 or 20million km2 in total. Twice of the size of the US?

I guess some land may become available as permafrost melts?

Ah, so we've been trying to do good all this time with industrialisation!

That is a lot of trees, but a decade’s worth is a lot of emissions

Also when they are grown (30 years?) you could chop them, stack the wood or use it in some way that doesn't release the carbon and then grow another lot.

Indeed, we don't talk about the absolute numbers a lot but reportedly more than half of all CO2 emitted by human industrial activity has been released since 1988. So our current per-decade pace of emissions is truly colossal, historic, unprecedented, pick your term.

Y Combinator funded https://www.pachama.com/ in the batch of YC. They're building a marketplace of carbon credit to enable exactly this. They're hiring for engineering and operations in San Francisco right now https://angel.co/pachama/jobs

Thanks Gustaf! Yes, we will be hiring for many roles soon. Email us to jobs@pachama.com!

Just an aside, if you see campaigns such as "we have planted 2 trees for each widget you buy" you should understand that this is often in a forestry program where the new trees often get pruned or removed to make room. So a claim like "we planted 10k trees last year" doesnt mean much at all. the majority of trees planted in forestry do not survive. In terms of carbon a forestry program is neutral at best just replacing fallen trees and negative most of the time.

It's not the planting that counts, it's the leaving the trees alone.

> It's not the planting that counts, it's the leaving the trees alone.

And that's what's missing from the title (the "if we stop cutting down so many trees" part)

"Trees are supposed to slow global warming, but growing evidence suggests they might not always be climate saviours." https://www.nature.com/articles/d41586-019-00122-z https://news.ycombinator.com/item?id=19690382

I wonder if desert soil can be gradually converted to make the land fertile. That would definitely be helpful to convert a lot of land to plant trees which is currently of no particular use.

Any research or innovation on that front ?

The soil is generally fine, the limiting factor is water. In Central Oregon's "Lake County" near where I live, 10-20k years ago was dense forest and thousands of deep clear water lakes. It's all desert now except for the "Lost Forest" near Christmas Valley. A fascinating enclave of ancient trees that somehow survive in the middle of the desert due to what is suspected to be an unusually shallow ground water system.

I’ve heard that a critical mass of trees can effectively generate their own moisture and counter desertification. No idea how this works or if it is true, but I’d love to be corrected and/or learn more.

China tried it and it's not really working https://en.m.wikipedia.org/wiki/Three-North_Shelter_Forest_P....

Also looks like a similar project in Africa https://en.m.wikipedia.org/wiki/Great_Green_Wall

Water would be a problem, although that could theoretically be solved with solar powered desalination.

References: https://en.wikipedia.org/wiki/Desert_greening

That’s a really good point also where water and irrigation is concerned hopefully that would be done in the most sustainable way possible.

You need light, water, micro and macronutrients in right amounts.

Desert greening is essentially question of water availability and reversing soil erosion but you may also need the nutrients.

There have been many attempts in desert greening and oasification but they are expensive and have not been very successful in large scale. It's much easier to create a desert than do the opposite.

The Sahara desert is already being reclaimed at a remarkable rate by the people living at its edge, just to get more farmland for themselves. The more trees you have, the more precipition is collected.

Many places we think of as ancient deserts were climax forests in historical times, such as Petra. It became desert when too many trees were cut.

Ahem, how about the Sonoran?

Couldn't say.

You'll have to account for driving water to the desert. Desert soil is fine (for desert-aware trees), but trees like water, and large trees like lots of water. In my country, Australia-native Eucalyptus is doing well.


The Romans built aqueducts that spanned hundreds of miles and they did it thousands of years ago. Why do you assume that today water has to be 'driven' with trucks or something?

I'm sure we could build aqueducts.

Whatever you do, if the target is reducing CO2 emission, you'll have to account for the CO2 investment. All I am saying is it may be more cost-effective to leave the desert alone and put our Trillion trees where conditions are already great for large trees (Alaska, NZ), instead of pipe-dreaming about Roman aqueducts delivering water to a green Sahara or Gobi.

Planting floating seaweed forests seems like a more feasible thing to do at scale. It might even help with marine ecology.

I agree, in addition to planting trees.

Eg https://medium.com/invironment/an-army-of-ocean-farmers-on-t...

Also floating solar, with compressed-air energy storage in under-sea airbags (could work on hydro reservoirs too)

do both do everything we can

So humans are pumping, each year, 100 Billion trees worth of CO2

100 Billion trees.

Holy Crap.

So if every household in the UK planted a tree in their (often non existent) garden, that would be about 22 Million trees - or about 2 hours worth.

Holy fucking crap. that's a lot of CO2

If the US share is 10%, that amounts to planting 40,000 trees per square mile over 3 million square miles. That is a square grid of trees, every 26 feet in X and Y, over 80% of the US landmass. Say what?

One tree every 26 feet is barely anything. Every suburban yard could support that instead of grass, and more rural environments would simply have actual forests.

and just because the trees are in the ground everyone magically has enough water to care for them

> Trees are “our most powerful weapon in the fight against climate change”

No, our most powerful weapon against climate change is reducing human GHG emissions.

The should probably say 'most effective'. Yes not creating the problem in the first place would be the most powerful approach, but it's just not going to happen at least in the short to medium term. It would hit our standards of living (everybody's, including the poorest people on the planet) too much to be politically viable. The things we can do to reduce carbon emissions immediately are somewhat limited, but planting trees right now is comparatively easy.

You have to find a way to do that, though, in a way that doesn't result in a revolt.

It's a difficult endeavor. It involves greatly reducing human population, and both quick (war, massive deaths) and slow (fewer births than deaths) come each with their own set of issues.

My gut reaction to suggestions like this one is that it seems so hard to do stuff that is as geographically distributed as this. I mean, to plant a billion trees we need to find suitable locations that have an enormous area (twice the US per some comment here). The odds, I'm guessing, are that this will be spread among many/all the continents over multiple countries, involving so many local stakeholders and potential nimby/yimby-disputes.

In my mind a solution needs to be implementable in a meaningful way by single actors. I'm not sure about the state of the art of direct air carbon capture, but for me it seems like a much easier solution. "Just" push X billion/trillion USD into an enormous plant somewhere in a dessert with access to solar/nuclear power and suck it up.

Maybe negative emission solutions will turn out to be not feasible anyways, and the best we can do is to focus our efforts on reaching close to zero new emissions.

The problem with a push-button solution like you describe is that anyone trying it would be fighting an exponential growth curve. Economic growth remains closely correlated with increased demand for energy. Any solution that doesn't address the consumption side of the equation will run into a brick wall sooner or later.

At the current rate of growth, we're not that far from directly producing more heat than the earth can radiate into space.

At this scale I think is where you must use distributed actors, which in turn implies you should be using economics. Name a price for each tree, establish quality control (inspection, approved list of species, etc) and let the billions of people on the planet figure the rest out.

While I certainly wish your view becomes the reality, in my mind, this problem is far too large for any single actor to ameliorate. I also worry that we are holding out for the best solution while ignoring decent solutions that could reduce the issue (perfect is the enemy of the good).

If there are seven times more trees than previously thought, as per the article, and 1.2 trillion would have this effect, then what effect does that have on climate models which counted sequestration by trees?

Likewise, is the water needed for 1.2 trillion trees calculated?

After reading a ton about genetics I wonder if it’s possible to modify one of our existing tree species to make them a better store of carbon without destroying wildlife habitats.

Entertain my thoughts: Suppose you could have a tree X. It grows fast, is very water efficient and better at trapping sunlight and C02 than existing specifies. It’s wood grows straight and makes a great building material. We could plant billions of it in semi-deserts and it would terraform the land into a livable habitat.

Basically the promise is rather than planting trillions of trees, can we plant billions of 1000x efficient trees in places where current trees don’t exist.

Until those trees die, then its all back again. Trees are just a buffer, and how much co2 would be produced mobilizing the planet to plant 1.2 trillion trees?

Not necessarily. As other posters in this discussion point out, you can for instance create biochar from trees, which can be permanently planted in the ground, thus finally returning in the place of origin the carbon we earlier dug out in the form of oil and natural gas.

but biochar requieres high temperatures, which usually produces co2... The problem with all this CO2 Storage is that we have a perfect storage for co2: Oil. Since we burn this storage, we release more and more of that CO2 without anyway to put it back to storage. The tree idea can maybe slow down the climate change, but it is in no way a solution, merely a short stopgap.

Biochar can be produced (and is) by burning off the hydrogen. This is done by restricting oxygen availability, which the hydrogen preferentially bonds with. When the hydrogen is used up, you are left with charcoal, which powdered and mixed into the soil improves it wonderfully.

Look up "terra nigra", invented in the Amazon basin.

Or they seed out (or are replaced by humans). A forest can hold carbon for as long as it is allowed to propagate. There is no permanent carbon sink, see peat bog fires.

There used to be this series about "guerilla gardening" where people would throw all kinds of seeds in an urban area and weeks later it would be over-run with beautiful flowers. You could do the same thing to plant trees with a drone and even water them. Throw in some IOT sensors and incentives, and you've got yourself a crap coin for tree drones that might actually help the environment.



anyone got any other suggestions for organizations to donate to to get trees planted fast ? Because I love trees regardless of whether they going to help save our home planet

Here is one I like: https://www.projectgreenhands.org

they have Guinness record for most tree saplings planted in a day, over 28M planted so far.

where are the best places on the planet to plant trees ? From the point of view of stabilizing soil, controlling local climate and politically.

One analysis I read some time back claimed that Trees are net positive when they are closer to equator, IIRC 30deg each way. fortunately for this topic, the areas close to equator are also significantly poorer countries thereby maximizing the roi of a fixed dollar expense.

Overall I believe that if a functioning carbon credit marketplace is established we can fund the whole green movement with a fraction of world GDP and might even end up creating a whole bunch of jobs doing it.

Trees For the Future

This is a great illustration of how there is no hope of sequestration as a solution. We're unlikely to plant even just a billion trees.

Why do you suppose that is the case? Is the cost per tree too great? Are you pessimistic about lowering that cost via automation? I read recently about drones that can drop large numbers of pods containing fertilizer and seeds over a huge area in little time; it doesn’t seem infeasible to iterate on a concept like that and drive down the costs considerably.

Article says "The United Nations’ Trillion Tree Campaign has planted nearly 15 billion trees across the globe in recent years."

this comment is a great example of baseless couch-general type of pessimism

Uh “Each year Americans plant at least 1.6 billion trees or about 6 trees for each one we use.”

- according to 5 sec of googling

We're on the way to drive billions of dollars for forest restoration via carbon credits. With economic incentives that work it absolutely possible.

I'm the founder of Pachama (YC W19) where we're working to help make this market efficient and accountable.

So we need the same effort only 1200 times over, which means something like 5 times for each country on earth including the very tiny ones.

Still, every little helps.

Any solution would need multiple avenues. Abandoning each avenue because it isn't a total solution by itself guarantees defeat.

Well, not with that attitude.

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