I really wonder why, when talking about climate change, the reference to deforestation has been downplayed so much compared to a few years ago. Isn't that just as important as CO2 emissions?
Did some programming on the Kyoto accord. At the time, old forests were thought to be carbon neutral (e.g. in a steady state), while a growing forest clearly absorbs carbon, and we assumed cut trees were released carbon into the atmosphere.
I am curious about the last assumption: Wood products can hang around for quite a while, so while long-term decomposition may release their carbon into the atmosphere, in the short term we have some very old wood around. Hell, maybe we could grow trees and sink them into oxygen-deprived water where they never decay.
Ultimately investment in this area has been reduced as the truth could be very inconvenient for the economies that rely on tree farming or land created by deforestation. See the disgraceful yellow blob: https://en.wikipedia.org/wiki/Kyoto_Protocol
> I am curious about the last assumption: Wood products can hang around for quite a while, so while long-term decomposition may release their carbon into the atmosphere, in the short term we have some very old wood around.
I have a hard time thinking of significant amounts of wood that doesn't decompose, unless treated by humans. There are exceptions, including petrified wood or maybe wood in oxygen-deprived water (I don't know much about that) but I doubt it adds up to much. I know I've read studies about the carbon released by decaying organic matter in rivers and river deltas; it's a well-studied process as far as I know.
I'm following the CO₂ emissions discussion less closely than I should, but agricluture generally (broadly scoped, including forestry) is a major contributor. Soil has considerable carbon content, and that can be and is released through human activity and disruption.
Livestock account for 18% of CO₂ emissions, agricluture 8% (75% of that from production of ag chemicals -- pesticides and fertiliser).
US EPA gives 9% of total CO₂ emissions as from agriculture:
The problem with deforestation isn't just the CO2 emission, but, most importantly, the missed future CO2 absorption. At least, that what I was thinking about.
Grown forests are carbon stores, not carbon sinks: the carbon is locked into trees and released when the trees die (some of it might get sunk into the soil but IIRC it's a very small fraction). When the forest does not grow, its day-to-day carbon impact is pretty much neutral, growing trees are balanced by decaying dead trees.
There's limited "missed future CO2 absorption" to deforestation, but there's a huge "immediate" released of stored carbon.
> but there's a huge "immediate" released of stored carbon.
Surely that depends on where the tree goes. If it's burned, or left rotting, sure. If it's harvested for building materials, might it not even lead to increase storage of carbon overall.
> Soil has considerable carbon content, and that can be and is released through human activity and disruption.
None of your numbers suggest that carbon from soil is significant. The vast majority of carbon involved with agriculture comes burning fuel or from plants (such as when cows eat them and emit gas), and the carbon in plants comes from the air.
Quite honestly, I don't have the numbers I'd like on this. But you're talking about topsoil, which covers literally hundreds of millions of acres throughout the US, and probably on the order of billions of acres worldwide. And that for a depth of up to multiple meters. That's a vast, vast resource. And soil depletion is about exhausting that -- both returning the carbon content to the atmosphere and washing away topsoil.
OK, here's a Wikipedia stat:
Soil carbon is the generic name for carbon held within the soil, primarily in association with its organic content. Soil carbon is the largest terrestrial pool of carbon, containing 2,200 gigatonnes (Gt) of it.[1] Humans increasingly influence the size of this pool. Soil carbon plays a key role in the carbon cycle, and thus it is important in global climate models.
Citing: Batjes, N.H. (1996). "Total carbon and nitrogen in the soils of the world". Soil Science 47 (2): 151–163. doi:10.1111/j.1365-2389.1996.tb01386.x.
Continuing:
Although the figure is frequently being revised upwards with new discoveries, over 2,700 gigatonnes (Gt) of carbon is stored in soils worldwide, which is well above the combined total of atmosphere (780 Gt) or biomass (575 Gt), most of which is wood. Carbon is taken out of the atmosphere by plant photosynthesis; about 60 Gt annually is incorporated into various types of soil organic matter (SOM), including surface litter; about 60 Gt annually is respired or oxidized from soil.[2]
And I really don'tknow how that is influenced by human activity, climate change, changes in biocover, etc.
There's also loess, a high-carbon sediment covering 10% of the Earth's surface, to depths of tens of meters, over 100 meters in parts of China.
Deforestation is a form of CO2 emission: a stable forest is roughly carbon-neutral (over long time scales obviously), a growing forest locks up carbon, a shrinking forest releases carbon.
From what I'm understanding this discovery doesn't help the current state of global warming:
> The study also finds that there are 46 percent fewer trees on Earth than there were before humans started the lengthy, but recently accelerating, process of deforestation.
“We can now say that there’s less trees than at any point in human civilization,”
> loss of 15.3 billion trees each year... 5 billion of those may grow back each year, so the net loss is more like 10 billion annually.
> does not in any way change our understanding of the current rates of deforestation... “It does not say there’s more forest. It just says there’s more trees in the forest,” says Lovejoy.
> deforestation is making global warming worse... if we were living on an Earth with close to 6 trillion trees, rather than 3 trillion, climate change would be less severe.
It makes no difference. The amount of carbon in the atmosphere has not changed. If anything, this might mean that trees are less effective at reducing carbon than we thought, because there are more trees than we thought there were.
Depends on if you look at the satellite troposphere data or the ground and sea thermometer data. The UAH/RSS satellite data say the troposphere hasn't warmed in ~19 years. The ground/sea based thermometers say we're all going to die in a fire (depending on which data revision you look at).
It's explained in the article. They have combined satellite imagery with observations from underneath the canopy, so they had both the area of forest and tree density in the particular forest.
> The scientists were able to reach these estimates by merging together two separate mechanisms for sampling trees — satellite observations and ground-based ecological work. The former gives an overall view of where forests do and don’t exist on the Earth’s surface. But the latter goes underneath the canopy to determine how many trees exist in a given area in a given type of forest. Thus, the study amplified satellite views with no less than 429,775 separate measurements of the density of trees at different locations around the globe.
"satellite observations and ground-based ecological work. The former gives an overall view of where forests do and don’t exist on the Earth’s surface. But the latter goes underneath the canopy to determine how many trees exist in a given area in a given type of forest."
It seems that satellites give a good measure of the acreage covered by forests but are not suitable for differentiating individual trees. To do that requires on the ground sampling and as more sampling is done it is being discovered that the actual number of trees differs substantially from previously established estimates.
Acreage doesn't tell you how much biomass there is. Imagine a 1m tall shrub with big leaves and not much underneath vs. a dense rainforest where the top canopy extends tens of metres up and there's massive undergrowth.
So I guess the answer it depends what you're trying to measure.
So basically we have no way of counting trees from pictures? I mean it shouldn't be that hard, right? You have green pixels and brown ones. We have software that can discern car license plates in urban environments where you have a gazillion of different colors in the picture.
I guess the need never arise for an automated tree counting algorithm.
General forest type can probably be determined quite well and I imagine that ecologists have been estimating tree mass of various types of forest for quite some time?
Recent developments with laser scanning using drones is likely to improve accuracy too.
The whole point of the article is that they've (hopefully) improved the accuracy by using recent developments and combining different types of counts, and that method dramatically increases the count.
From above, the green pixels will obscure the brown ones, so the best you could say is "there are 3 forests in this area". If you are under the canopy itself, you have much larger problems. The colours are very similar, so distinguishing between one tree trunk and another is not the same as distinguishing between a white licence plate and a blue car. The shapes are very similar, so distinguishing between one tree and another is not the same as distinguishing between a car and a house.
Some trees will be obscured by others so you will need a number of different cameras to create a 3D map. You would also need to measure the distance between the cameras to determine what area they cover.
A 10 minute analysis revealing a list of complexities as long as my arm is not a good start. It will probably be easier (let alone more accurate) to just count the trees.
Did you even ever set foot in a natural, dense, wild forest? This isn't like in a timber plantation or the park near your home, trees are fighting for light and overlap vertically, and satellite images happen to be two dimensional. Shouldn't be that hard to understand, right?
You can't read a license plate from a satellite image. Those high-res Google Maps images are from planes. The best satellite imagery is about 1 meter per pixel, and those probably don't cover all the forests in the world.
>So basically we have no way of counting trees from pictures? I mean it shouldn't be that hard, right?
Are you a programmer? Have you never had to deal with someone who thinks they're smarter than they are and thinks they know everything get pushy about the simplicity of doing things that are not as simple as they assume? I have, and I can't say I'm a fan of those conversations or the people who initiate them. Your comment feels a lot like that.
I didn't attack or criticized anyone specifically so no, I don't think I'm smarter than everyone else or knowing everything. I'm just expressing a genuine question as to how we ended up with such a miscalculation and whether there is software that could help in that direction.
Perhaps you need to chill down a bit. This isn't Reddit. We're all here to learn something.
I admit it's rare, but sometimes, with a fresh perspective, and not falling into believing something is best just because it's the way it's always done, what programmers do actually is needlessly complicated and difficult. Examples are the entire J2EE ecosystem from 10 years ago, forcing concepts into baroque relational DB models that don't fit, or XML.
Scientists discover the world can support dramatically more humans that was thought after zillions of spermatozoans were found in each male human.
A 10 cm trunk diameter pine is not a tree, is a... (let's invent a new word for this) a 'treeddler', a baby. This is a classical case of apparent amount of population after dissapearing of the older trees. You can pack instead a lot of little trees in less space, but is not even remotely the same and only one or two will survive.
> A 10 cm trunk diameter pine is not a tree, is a... (let's invent a new word for this) a 'treeddler', a baby.
The claim is that the number of trees was dramatically underestimated in previous studies. Which definition of tree was used doesn't make a difference as long as the same definition was used in the previous studies. Unfortunatly this is not made explicit in the article, anyone knows?
Sapling is too generic to me. Two leaves in a 2 cm stick is a sapling but a juvenile 5 m high tree is also a sapling. Some trees grow really slow, some plants are not trees but have a 'similar' function in nature (bamboo for example) and a lot of trees begin as multitrunked shrubs. Is not trivial to count trees in a forest when several trunks share the same root system so we can expect a lot of troubles and variations. We should focus in measuring live biomass probably instead. To group different saplings of different species and try to cook a result from this is always a problem.
Maybe to make people understanding the consequences of deforestation we need to create a new system and talk instead of ecological categories like seed, seedling, 'treedler', tree and perhaps 'treelder', but I'm just having fun with the words.
Ash, for example, is equal to "a common tree" but people forget often that the morphospecies "a 500 years ash" is extinct in most forests (as all species that depend on it). This is like if we try to define and understand human societies just looking at "people from 20 years or less".
Perhaps "awakened to their sheer lack of perspective?" That a global total estimate could be off by 8x, should probably bring a few other global estimations into question, but probably won't. Epistemology is a lost art.
Maybe it's me being grumpy this morning, or I'm too used to thinking in log-scales, but 7.6x doesn't strike me as "dramatically" more. It's not even an order of magnitude more! Sounds within the bounds of estimation error, which is what the scientist do, because surely they're not going out there and counting trees one at a time.
What's "dramatically more" is all about context, it's not just about the relative change regarless of what's changed.
Wouldn't you consider a 7.6x change in your salary "dramatically more"?
>It's not even an order of magnitude more!
That's irrelevant. Even in software profiling, making something run "merely" 2x as fast can result in HUGE profits and savings (e.g. the movie studio that gets its rendering done in 3 months instead of 6).
This isn't astrophysics. Personally, I had hoped the climate models would be sensitive enough to depend on 7x changes in key carbon sinks. Maybe they measure carbon absorption per acre rather than per tree and this result doesn't matter?
Yes I know. But many forests are growing, not static, and in fact are a huge impact on the carbon cycle:
>In the past few decades, the world's forests have absorbed as much as 30% (2 petagrams of carbon per year; Pg C year−1) of annual global anthropogenic CO2 emissions1 — about the same amount as the oceans.
Furthermore, for reasons not yet understood, even static forests appear to be a continuing carbon sink over measured timescales.
> Much has been learned about the carbon cycle in forests, but there are still too many gaps in our knowledge. New observations have called long-accepted theories into question: the finding that unharvested forests, for example, are absorbing more carbon than they release2, accounting for half the sink, is contrary to the tenet of ecology, known as Odum's framework, that carbon flows in natural forests should be in equilibrium.
From what I've heard, it sounds like this is really "new method of counting trees produces much bigger results". The new estimate may be better, but it may not.
