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Earth Stopped Getting Greener 20 Years Ago (scientificamerican.com)
145 points by Podgajski on Oct 23, 2023 | hide | past | favorite | 105 comments



NASA Feb 2019

The world is literally a greener place than it was 20 years ago, and data from NASA satellites has revealed a counterintuitive source for much of this new foliage: China and India. A new study shows that the two emerging countries with the world’s biggest populations are leading the increase in greening on land. The effect stems mainly from ambitious tree planting programs in China and intensive agriculture in both countries.

https://www.nasa.gov/centers-and-facilities/ames/human-activ...


China literally paints their mountains green.

(Source: guy who lived in china for 12 years and did a travel documentary.then was forced out by government, now has contacts all around China)

https://youtu.be/Cvc7VymDa4c?si=xIcqLGiIC9gNTd7Y


I don't think NASA measures the leaf area by literally just looking at the color of the land it is surveying.


I mean they might literally do that with satellite imagery. How do you think they do it?


They use the difference between measured red and infrared light divided by the sum of measured red and infrared light https://en.wikipedia.org/wiki/Normalized_difference_vegetati...


I've read it and it states it is not an useful metric and, please correct me if I'm wrong, does not say anything about measuring fake plants. As far as I understood, it does use the reflectance in red and infra red to detect soil, water and vegetation, but it was not designed to detect fake green plastic from plants anyway.

I mean, who would think someone would use fake grass and fake plants and also use paint in mountains. It is so stupid that no one would even think in measuring it.


Plastic doesn't look like foliage under NIR.


Does tree planting make an area greener? How is greener measured? Planting trees just to cut them down for lumber doesn't seem very green in that typical sense. And treating agricultural areas as green doesn't seem accurate either. Agricultural plots decimate the local ecosystem. So maybe a picture of the rectangle from above is literally green, but is it really green in the sense of it promoting healthy ecosystems?


"Does tree planting make an area greener? "

In general, yes.

"Planting trees just to cut them down for lumber doesn't seem very green in that typical sense."

If it is done in a sustainable way, then also yes. Also chinas main motivation is actually to stop the desertification, so they want most the trees to stay.

"Agricultural plots decimate the local ecosystem"

Also depends. If you bring in irrigation, then you can have green, where there would be none before (but you can have all sorts of other trouble, if your water consumption is not sustainable).

So all in all, a true wilderness with old forest is surely way more beautiful and a way more valuable ecosystem, but even a forest plantation is way greener than a arid wasteland.


They mean greener quite literally. Satellite imagery is spectrally analyzed and more of the light reflected from the earth's surface is in a frequency range considered "green." It doesn't mean ecologically friendly. Replacing rainforest with oil palm monoculture is extremely destructive ecologically, but oil palms are just as green as any other tree.

Also, if they're analyzing water color as well, large-scale algal blooms can conceivably result in a greener surface, but they're a pretty bad thing because they suck up too much oxygen too quickly out of the water and kill everything else.


Planting trees and cutting them down is a very effective form of carbon capture (provided the felled trees aren’t burnt)

A tree’s dry weight is 50% carbon, captured from the atmosphere. Over a 100 year period, one tree absorbs a tonne of CO2


Who is correct?


Corollary: Is their correctness mutually exclusive?


Unfortunately this Nature article (https://www.nature.com/articles/s41893-019-0220-7 ) is behind a paywall, but the NASA summary implies they measured "leaf area".

The Science article (https://www.science.org/doi/10.1126/sciadv.aax1396 ) claims Leaf Area Index (same or different measure than the Nature study?) "exhibited a transition from increasing trends before the late 1990s to decreasing trends afterward".

So at first blush yes, but the details will doubtlessly prove otherwise.

If anyone has an institutional login and can post a pdf, please do.



Thank you.

So. Science Paper (SP) uses data from 2 spaceborne sensors, MODIS and AVHRR.

Nature Paper (NP) uses data from AVHRR alongside 3 other metrics: GLASS, GLOBMAP, and TCDR, all of which claim to be fusions of the same data from MODIS and AVHRR. (https://www.mdpi.com/2072-4292/8/3/263 ... https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/201... ... https://zenodo.org/records/4700264 )

NP supplementals show the data from AVHRR does trend upwards to the present data (agreeing with SP), but the other 3 metrics are trending flat (GLASS, TCDR) or downward (GLOBMAP).

I have neither the expertise nor inclination to delve further into the various methodologies of creating these various Leaf Area Indices.



Which will persuade people to believe in the correct narrative, and to disbelieve in the incorrect narrative?


What is the correct narrative? What is the incorrect narrative?


> data from NASA satellites has revealed a counterintuitive source for much of this new foliage: China and India.

The totally unnecessary framing with "counterintuitive" here reveals much about the epistemological crisis of the West. Poor, developing countries are only allowed to care about the environment insofar as it kneecaps their development and economic growth.


Is it an “epistemological crisis” to expect other human civilizations to act like we did?

The west didn’t have an eye towards environmental health while we rapidly industrialized, I don’t think it’s a negative to be surprised that these countries are seemingly doing better than we did on this one metric.

Personally my response upon reading that line was “kudos to them”


It's not an epistemological crisis, but it does expose a blind-spot in not understanding the principle of Uneven and Combined Development (https://en.wikipedia.org/wiki/Uneven_and_combined_developmen...). It assumes the conditions are the same in both cases, but they very much are not. I would not expect people to act the same way in the face of radically different developmental circumstances. And the circumstances of a country rapidly industrializing today are radically different than of those during the first period of rapid industrialization. The incentives/pressures, demographics, technology, geopolitical landscape, and resources available to newly industrializing countries are all completely different.


> Is it an “epistemological crisis” to expect other human civilizations to act like we did?

Yes, absolutely. Incuriosity and chauvinism towards non-Western civilizations, in the face of overwhelming evidence, is at the root of this crisis.


You may be reading a bit too much into this. It's counterintuitive specifically because the results are a byproduct of their economic growth, and not due to environmental policy.


You're proving my point by implying the two are mutually exclusive. China successfully regenerating forests and reversing desertification will certainly have (very long-term) economic benefit, but saying it is therefore "not environmental policy" is absurd.


They also have a lot of resources to fake the greenery as well.


You know what? You're entirely right.


> Declining plant growth is linked to decreasing air moisture tied to global warming

Atmospheric water vapor increases as the climate warms. https://climate.nasa.gov/explore/ask-nasa-climate/3143/steam...

Since the late 1800s, global average surface temperatures have increased by about 2 degrees Fahrenheit (1.1 degrees Celsius). Data from satellites, weather balloons, and ground measurements confirm the amount of atmospheric water vapor is increasing as the climate warms. (The United Nations’ Intergovernmental Panel on Climate Change Sixth Assessment Report states total atmospheric water vapor is increasing 1 to 2% per decade.) For every degree Celsius that Earth’s atmospheric temperature rises, the amount of water vapor in the atmosphere can increase by about 7%, according to the laws of thermodynamics.


> Vapor pressure deficit (VPD), which describes the difference between the water vapor pressure at saturation and the actual water vapor pressure for a given temperature, is an important driver of atmospheric water demand for plants (1). Rising air temperature increases saturated water vapor pressure at a rate of approximately 7%/K according to the Clauius-Clapeyron relationship, which will drive an increase in VPD if the actual atmospheric water vapor content does not increase by exactly the same amount as saturated vapor pressure (SVP).

https://www.science.org/doi/10.1126/sciadv.aax1396


This is a commonly overlooked factor in gardening and agriculture especially in beginners.


As a beginner gardener, I'm curious. How is this applied in practical terms? (eli5)


They're just saying that hotter air can hold more water, so if the temperature rises, you need to add water to the air, to keep a constant water vapor pressure, and presumably plants have a preferred vapor pressure more than a preferred humidity %, as the same humidity % at different temperatures has a different vapor pressure, is how I read it.


Doesn't humidity already take this into account? It's measured in relative humidity which is the percent saturation of the air. So RH goes down as temperature goes up, unless there's more evaporation happening.


Apparently it doesn't. From what I read, relative humidity is maximum possible humidity divided by actual humidity (probably not the correct terms), whereas vapor pressure deficit is maximum possible minus actual. Fraction versus difference. So the same vapor pressure deficit could correspond to 80% relative humidity at one temperature, and 85% relative humidity at a higher temperature.


Depending on where you live and what plants you are growing and how picky they are, you may need to water less in hot weather (which is counterintuitive to most people). Unfortunately that can either be really good or really bad advice depending on your climate, the time of year, the type of plants you grow, etc so it's not a hard and fast rule, but especially if you have plants that struggle with molds, mildews, and/or fungi, keeping the top of the plant dry and letting the top part of the soil dry out regularly can be the difference between a healthy robust plant and a sickly one. The safest solution is an in-ground drip system, but that's also one of the hardest.

Honestly the best advice is to find a nice, elderly/retired person (usually women, but not always) who is into gardening in your area and have discussions with them. Bring pictures of your plants to the nursery and/or gardening store, or join a Facebook group or something and you can usually find people. Don't get discouraged if the first few people don't work out. Particularly if you are young, you'll get a lot better results if you are overly respectful and polite, at least until you get to know each other better. Give them the benefit of the doubt if they say something you find offensive and just observe/listen rather than lecture. Many older generations can be hesitant to engage with younger people because the social customs are just so different and it can make them uncomfortable. Ideally try to watch them do what they do (planting, pruning, tending, mulching, etc), because if you are on HN you may be more scientifically minded, but most of these people just do what they do and don't even think about it or even notice sometimes. It's very much an art to them. If you ask them things like "why do you mulch there and why do you use grass clipping" be prepared for them to have a terrible answer that doesn't make sense, but know that they are probably doing it because it works, but the reason why it works might be an exercise left for you to find out. A lot of them have generations worth of muscle memory and convention that is all good stuff, so don't discard it just because they can't explain why they do it.


Yes, the amount of vapor increases, which also contributes to global warming. But at the same time, the relative humidity might go down if the capacity of the air to hold water increases faster than the actual vapor amount. The consequence is: while there is more water in the air, there is less accessible for the plants.



But where does it get wetter? It's not helpful if the air over the oceans gets wetter while the air over dry regions gets dryer.


> But where does it get wetter? It's not helpful if the air over the oceans gets wetter while the air over dry regions gets dryer.

On average, global land areas have seen more precipitation since 1950. But even as much of the world has become wetter, some regions have become drier.

- https://www.nytimes.com/interactive/2021/08/24/climate/warme...


Absolutely or relatively? If the dry areas get 2 less inches of rain per year and the wet areas get 2 inches more, it's a much bigger impact on vegetation going from 12 to 10 inches of rain per year than going from 120 to 122 inches per year.


And considering how much vegetation was burned away this year in forest fires alone, I'm curious to see if there will be any regrowth.

"You have so much land, Canada, why is everyone huddled along the border?" Maybe one reason, not exactly an intentional one, is that it benefits us to have has much untouched, forested and wild lands as possible?

Maybe we should be building fewer roads that cut migratory paths and disrupt forested regions, fewer suburban communities, and manage forests and vegetation better in this crisis. Dunno, maybe living in urban neighbourhoods is better for us and the environment?


> You have so much land, Canada, why is everyone huddled along the border?

It's because of the Canadian Shield: https://en.wikipedia.org/wiki/Canadian_Shield

Basically, it's hard to farm because the topsoil is thin. (But I'm sure that if there's a will to live there, there's a way.)


We don't have that much untouched and naturally forested land any more. One of the major causes of the forest fires that we do have are that they spray any land that has a forest fire to prevent growth of low value species (like aspen that happen to be a fire break species) and then plant pine (which happens to be serotinous.)


This comment really irks me as someone who lives in a rural area.

The typical urbanite attitude seems to be that everything outside the city should be untouched, pristine wilderness which exists only for their occasional amusement when they feel like hiking, camping or bike riding.


I'd say Rural folk are fine in the grand scheme of damaging the environment thru land use. Tho it is terrible when people own incredibly large swaths of land and then proceed to fence it all off disrupting migration patterns.

The Suburbanites are the real problem. Urban Sprawl. And of course it isn't the people themselves who are at fault. They have no choice. It's the idiotic way we've developed around cars. This was only ever considered a good idea to begin with because the Auto/Oil industry pushed it thru propaganda and lobbying; and now it's sunken into people brains.


Suburbs became popular because cities became too expensive, cars were just the enabler. I’d rather have cars than horses and deal with mountains of horse crap and the diseases that come with them.


What an odd sentiment.

Surely more people die by vehicle traffic accident, cancer or respiratory issues than accidentally being infected by manure?


update: deleted


How about we make suburbs pay for the infrastructure they use? Most suburbs have urbans level of infrastructure with a tax base that is not enough to maintain it due to the lower density, and end up being paid for by city centers. Is that also fine?


Suburbia's ability to exist is currently funded by all of us. Small cities across the US are literally just sitting in a ponzy scheme of debt. The basics:

1. When you develop new stuff like a suburban neighborhood or one of those roads that has fast food restaurants and gas stations on it that are copy pasted all over our country, you get money from various different sources.

2. Federal > State > Local all fund this based on the idea that it's an overall good thing to develop stuff. So the Local cost is a small fraction of the total.

3. Cool. It's built now and once stuff is built then that's it right? No.

4. Maintenance. This doesn't rear its head until around 10-15 years later. Federal, and maybe State, have nothing to do with this cost. The Locals are responsible. OK! Well lets take all that month the new development made us and maintain it... But wait... the taxes don't even cover the costs. That McDonalds doesn't actually generate that much for the Local gov due to the ENORMOUS amount of space it takes up with a parking lot. Those Suburbia taxes won't even replace the roads.

5. Ponzy. Welp we gotta get money from somewhere.... So we build MORE Suburbia and MORE giant parking lot fast food restaurants, take that lump sum from Federal/State funds, use part of that to maintain our existing debt, and kick the can.

This is who pays for Suburbia. The only places that generate a net positive for a Local gov are city center-ish types. You know that nice little shopping area that has lots of different food/shop options that people flock to to walk around. That's probably net positive. That downtown Main St zone of a small city that's mostly dead now? Believe it or not even THAT is probably still net positive. The ugly road littered with nothing but shit food and gas stations? Paid for by the above. The asphalt hellscape with dots of corporate feed troughs (Applebees, Longhorn, Olive Garden, etc)? Paid for by the above unless they circle a shopping mall that covers them.

*The other guy seems to have deleted his post that this was responding to


If all of the urbanites changed their minds and moved to rural areas, there would be no more rural areas. The suburban sprawl would just end up creeping in and destroying the nature that exists there.

Feel as irked as you want about it, you're free to continue whatever lifestyle you please, but the ecological footprint of rural living is an order of magnitude higher than that of urban living. Rural living, outside those with careers in agriculture, is not scalable or sustainable.


I'm not saying that urbanites should move to rural areas, I'm saying they should stop trying to legislate against development and stop blocking job-creating projects in rural areas because they are worried it will disrupt a biking trail they visit once every few years.

> Rural living, outside those with careers in agriculture, is not scalable or sustainable.

I have no idea what you mean by this. Everyone outside of the city isn't a rancher or farmer. Ag is a huge industry with a lot of opportunity, but not the only game in town.

If you're talking about population density, we could easily double the number of people in my area with very little change in observable density. In the sq mile that I live there is only one other family.

Combine remote work with low property taxes and lower real estate values, living in a rural area is increasingly attractive and makes a hell of a lot of sense to those interested in that lifestyle.


Rural living has a huge carbon footprint compared to city living for many people. This is a real issue. Not that it can't be solved, but it is something that should be taken seriously.


As far as I can tell, unless an energy source as convenient, cheap, and portable as fossil fuels is discovered, the additional carbon footprint of moving more mass further distances (rural living) is unavoidable.


> Rural living has a huge carbon footprint compared to city living for many people.

Ugh...

I want to assume the best about comments like this, but what is the point of citing this metric without context? It just feels like the only point is shaming and virtue signaling.


It’s not a new or controversial statement. Not only personal transports, but every transport of any type of goods are shorter and more efficient. As a corollary to that less land is used for roads (per capita). Less land is used for dwellings when apartments are stacked on top of each other. This also make heating and cooling more efficient.


All true, but cities are also far warmer, noisier, light polluting, cause more acute poising of their local environment, cost more to live in, and usually have higher crime rates. As for cost of support… that’s iffy. Many cities don’t allow 18 wheelers, so they have to use local distributors and put everything on box trucks. Each time this happens, more lumpers are involved, more vehicles are involved, costs get driven higher, and the distribution centers eat up land. Just saying.


All of the things you mentioned are less per capita in the city than in the country side. Agrarian living gives the impression of less environmental impact because the impact is more spread out. Outside the cities those lumper trucks are each replaced with many dozens of SUVs or pickup trucks when every family does the distribution themselves from the supermarkets. Just saying.

And the reason it is more expensive to live in a city is because more people find it more attractive to live there. That, and that fuel is subsidised and agrarian roads are disproportionally paid by taxpayers.



Because nothing happened since 1894?


My post was in response to this:

> > Rural living, outside those with careers in agriculture, is not scalable or sustainable.

> I have no idea what you mean by this.

It was an attempt to explain how rural living is not scalable or sustainable. Maybe you do understand how unsustainable carbon emissions are, especially in terms of the rural versus urban footprint. I don't know.


Rural industries that supply the urban areas, agriculture especially, tend to be incredibly carbon intensive.

But he asks why rural living? I have to question that too. The thing I love most about rural living is everything is right there. I can literally watch my food being grown, my electricity being produced (wind turbines), etc. just by looking out the window. I only need a vehicle like once a month. My feet get me to anything else I would need on a day-to-day basis.

Meanwhile, all I ever hear from city dwellers is how their whole world is coming to and end because they don't have the best transit known to man. And, based on my time living in a city, I get it. You can't hardly live a day without needing access to some kind of vehicle in the city. There is nothing in your backyard except more people. Granted, some cities have better planning – putting jobs, and services, etc. in your backyard – but, especially in North America, that is rare.

As such, it is counterintuitive to hear that rural living is the more carbon emitting option.


> I only need a vehicle like once a month. My feet get me to anything else I would need on a day to day basis.

I don't have anything beyond anecdata here, but this is wildly out of sync with my perception of how most people who live in rural areas live. That is, what you're describing, I think, goes beyond what most people consider "rural". Yes, it's possible to live a relatively low-carbon rural existence if you're in a nearly entirely self-sustaining compound, but lots of (most?) people who aren't "urbanites" don't do that - they instead, routinely, drive vast distances on a near-daily basis to go to the store, secure healthcare, visit friends, head to the bar, go hiking/hunting/fishing, just for fun, etc.


> to go to the store

Practically speaking, you will have go to the store at some point, but near-daily seems unusual. What could you possibly need that frequently that you wouldn't stock up on?

> visit friends

Traditionally, your neighbours become your 'regular' friends. You likely visit other friends from time to time, but when they are at a distance it isn't going to be a daily thing. It is actually quite challenging to stay in close contact with friends when they are not immediately nearby. In fact, there was an article posted here recently about exactly that.

> go hiking/hunting/fishing

Are those not the pastimes that rural backyards are best suited for? I know some who like to travel to other parts of the world to hunt/fish different species not found locally, but that's an infrequent vacation, not something done on the regular.

> this is wildly out of sync with my perception of how most people who live in rural areas live.

Is your perception based on living rurally? I get the impression from your comment that you see rural residents living exactly like city residents do, only differing by having to drive to the city each day. There may be someone who does that, but generally I find it is a different lifestyle.


My first-hand experience with rural living comes from time I spent with an ex's family, who lived in rural Montana, and also conversations with her about growing up there. They drove regularly for all the things I listed and more (I stupidly omitted a, maybe the, big one - driving to work every day). The distances they'd have to drive were enormous, too - the nearest Walmart was 90 miles away, and at least monthly they'd need to make the 200 mile drive to Billings (the nearest major city).

Anyway, anecdata aside: Google shows that the states with the highest per capita carbon emissions do tend to be states with lower urbanization rates. Montana, for instance, is the fifth least urbanized state and the sixth highest polluter per capita.

https://solarpower.guide/solar-energy-insights/states-ranked...

https://www.visualcapitalist.com/sp/mapping-us-urbanization-...


> Google shows that the states with the highest per capita carbon emissions do tend to be states with lower urbanization rates.

But that's due to industry, no? Agriculture and forestry alone count for ~20% of all carbon emissions. And getting those goods into the urban areas means shipping, which is another major contributor.

Even in more populace states, power generation typically happens in rural areas. Landfills are located in rural areas. Even large factories, even when they employ city-based workers, are quite often located in rural areas.

On balance, there isn't much that happens in large urban areas other than a whole lot of moving people around with machines (which seems completely ridiculous) and commercial business operations, which is not insignificant with respect to carbon emissions, but only about 6% of total emissions.

Basic household living probably isn't much different either way.


I wouldn't put too much stock into personal carbon footprint estimates.

It's just a way of re-framing the carbon problem away from those actually responsible for it and turn it into to a battle between folks arguing who is more virtuous.

--

Thought experiment:

What if we removed the "people" from the problem and just looked at the geographic area?

Does a rural 10 square mile produce as much GHG as an urban 10 square mile?

--

When you analyze it based on personal carbon footprint you are ignoring business and industry and focusing on residential.

This is by design, so those responsible aren't even included in the equation.


It's ok, the actual real reason urbanites live in the city is for the jobs, and for all the other people they know there, that are also there for jobs.

That said green belts are great for stopping urban sprawl. They don't extend indefinitely though and they certainly don't uproot existing small towns/villages.


I try to live in urban areas because walkability measurably improves my health in every metric.


To be honest I was mostly trying to reassure the reactionary urbanite-hater that we aren't trying to take their stuff.


Everyone is huddled against the US border because Canadian Shield causes huge problems for farming: https://en.wikipedia.org/wiki/Canadian_Shield


its not rocket science. its because north of the border is a frozen fuckin wasteland.


The title seems (unless the data since 2016 tells a different story) at odds with the 2016 Nature paper by Zhu et.al and others who conclude from satellite observations that "show a persistent and widespread increase of growing season integrated LAI (greening) over 25% to 50% of the global vegetated area, whereas less than 4% of the globe shows decreasing LAI (browning)".

They add "Factorial simulations with multiple global ecosystem models suggest that CO2 fertilization effects explain 70% of the observed greening trend, followed by nitrogen deposition (9%), climate change (8%) and land cover change (LCC) (4%). CO2 fertilization effects explain most of the greening trends in the tropics, whereas climate change resulted in greening of the high latitudes and the Tibetan Plateau.".\\

https://www.nature.com/articles/nclimate3004


Plant more trees! Don't underestimate the impact that planting even just one or two trees as an individual can have. It's also a lot of fun.


Somehow people want to end everything even if they don't have a stake in the opposite. Where I live is a quite small nature park in a desert ; it rains here, it's green, it works. But when you say plant trees, they say it doesn't matter unless it's 1000s of km2. It's not. This is much smaller and it looks like a cartoon cloud above this place when it rains as everything around is completely dry. Not sure why people don't just try; they'll see it works, but he.


I am glad to hear that it rains and is green in that corner of the desert, my friend. That is a beautiful image indeed. I am really excited about the possibility of reforesting in deserts, although deserts are beautiful habitats in themselves so we should definitely keep deserts around too.

I think people just feel defeated as individuals because they read only doomer content on climate change and as a result they feel overwhelmed unless some larger entity takes on the fight on their behalf. They've come to underestimate the impact individuals can have in effecting great change. I'm optimistic that little by little things can improve and that people can enjoy having a fun time contributing to the fight in positive ways as individuals.


>They've come to underestimate the impact individuals can have in effecting great change.

The tiny thing the GP is talking about, a small park, is completely out of reach of individuals.

Small communities can have an impact. But the only thing individuals can do is to pick what initiatives they support and what they wont have any piece of.


The prime mover in any small community is an individual!


"Primer mover" isn't a concept that exists.

You can either help organize something or act alone. Those are completely different kinds of action. And acting alone won't achieve anything.


So how is that state of mind not going to end the world?


Refusing to acknowledge it hasn't work any well...

But do you have any evidence of the contrary? I'm eager to listen to it.


At the risk of sounding like a concern troll, I wish people were more thoughtful with tree planting campaigns. Rich ecosystems (peatlands, grasslands, savannas) have been damaged by attempts to introduce trees where they don't really belong. Surprisingly, this can cause a net decrease in carbon capture! And monoculture forests support relatively little biodiversity even though they look so green.

Sometimes planting more trees is the right answer, and we should absolutely do it. But often it feels like planting trees is a cheap way to score some green points without actually establishing healthy, sustainable ecosystems.


I read once about an idea of forcing every school in the US to have a small nature preserve - just some local trees and flowers and wild grasses. This would create habitats all across the nation which would serve to protect wild animals and give humans a chance, as they're growing, to develop a respect for nature.

Ever since then, I can't get the idea out of my head. It seems really nice. Excuse the pun, but this is one place where grassroots movements can have massively outsized effects.


That's a neat idea. It'd be cool if they also had a school garden as well, then everyone can learn to appreciate growing their own fruits and vegetables as well.

And I love your pun! :D


Statistically, this paper seems weak.

https://www.science.org/doi/10.1126/sciadv.aax1396


> Declining plant growth is linked to decreasing air moisture tied to global warming

I thought air moisture was increasing because of global warming, because evaporation from oceans increases and warmer air can hold more moisture. I'm confused.

Certainly, the trend here in the UK is that we're getting, and will continue to get, more rain because of that.


Warm water also increases evapotranspriration over land, which can dry out the land.



> The declines challenge an argument often presented by skeptics of mainstream climate science to downplay the consequences of global warming: the idea that plants will grow faster with larger amounts of carbon dioxide. The argument hinges on the idea that food supplies will increase.

> It’s largely a red herring, as climate scientists have patiently explained for years. Rising CO2 does benefit plants, at least up to a point, but it’s just one factor. Plants are also affected by many other symptoms of climate change, including rising temperatures, changing weather patterns, shifts in water availability and so on.


You're thinking in terms of sides rather than facts.

I think the question is the following: the NASA article seems to indicate that the Earth is getting greener. The headline in the posted article says no greening has occurred. Which is correct?


I linked a quote from the article without commentary. I am very intentionally not thinking at all.

Which NASA article are you referencing?


the one you were originally replying to :)


Got it (there's another linked further up the thread). Let's think!

The NASA article claims our planet became greener from 1982-2015.

The new study agrees the earth became significantly greener in the 80s and 90s, but the trend started reversing in the 2000s.

I think they do not necessarily contradict each another.


Nasa also says the world was greening 2000-2017

https://www.nasa.gov/centers-and-facilities/ames/human-activ...

5% increase in leaf area over the period (from CO2 and land-use changes) https://www.nature.com/articles/s41893-019-0220-7

The paper for this thread https://www.science.org/doi/10.1126/sciadv.aax1396 also addresses data generally ending in 2015, and says "all four LAI [Leaf Area Index] datasets exhibited a transition from increasing trends before the late 1990s to decreasing trends afterward (fig. S5)"

Those claims appear to be in direct contradiction, and I don't see any immediate way to reconcile them.


That would be the case if the NASA article was "The earth became greener from 1985-2000", but that's not the case. I think the quotes you cited earlier, which add up to "The baddies say this; here's a superficial response you can brush them off with", are indicative of the problem with politicised science. No one will admit that things might not be as they are constantly communicated to be, generally by communicators who are not scientists.

In this case: it's interesting that CO2 has a negative feedback loop where less CO2 means fewer plants, increasing CO2, and more CO2 means more plants, decreasing CO2; have climate models taken this into account (enough)?


The article you linked is based on the difference between 1985 and 2015, while the article OP links is based on shorter and more recent data spans. Sadly, NASA's link to the original article is now dead.

A large increase between 1985 and 2000, followed by a slow decrease between 2000 and now would perfectly fit both assertions.


oh... that's funny because i was going to share another link: https://climate.nasa.gov/news/2436/co2-is-making-earth-green...


> It’s largely a red herring, as climate scientists have patiently explained for years.

This sort of editorialization does not help the conversation.


"That’s not to say every last corner of Earth is losing its vegetation. Some recent studies have revealed that parts of the Arctic are “greening” as the chilly landscape warms. And there’s increasing plant growth still happening in other regions of the world, as well."

So, a sensationalist headline. The H20 on Earth doesn't change, it might shift to other areas, like has for billions of years. Climate change or not we've always had shifting biomes, which is why we've got deserts in areas now that were essentially jungles in the past.


Actually, it is quite alarming if the Arctic is turning green. That itself is sensationalist. One of the primary ways our planet cools itself is by reflecting heat back into space. A white arctic is very efficient at reflecting heat. Green is not so good at that.

In terms of shifting biomes -- there used to be alligators that lived in the arctic. We seem determined to make that possible again. Such a world would be drastically different than the one we live in now. Such possibilities are indeed alarming.


The title wasn't about the arctic. It literally says THE EARTH stopped getting greener. This is a lie.


> The H20 on Earth doesn't change

It actually does. That is the whole premise behind global warming. CO2 alone would not be able to warm up the planet more than 1C - and that is if we keep burning fuels at max rate with no reduction.

The idea is that the 1C warming will cause the hotter air to support more water vapor, and water vapor is a much more potent gas than CO2, so it will warm the Earth additionally 2-3 or even 4C if we don't stop the CO2 emissions. This is the positive feedback loop. There are other feedback loops - some are negative and work towards decreasing the impact, for example the greening of the planet: if plants have more CO2, they will grow faster, bigger and be more resilient to drought, so they will absorb more CO2 overall.

If the "idea" above wouldn't be true, there would be no global warming crisis.


[dead]


We've banned this account for repeatedly breaking the site guidelines and ignoring our request to stop. You can't post like this no matter how wrong someone else is or you feel they are.

If you don't want to be banned, you're welcome to email hn@ycombinator.com and give us reason to believe that you'll follow the rules in the future. They're here: https://news.ycombinator.com/newsguidelines.html.


There is no need for insults.

I will reply for other people reading this: the total water on Earth stays the same, but how much is in the air changes the global warming equation.

> the moisture is still there it's just evaporating faster

and staying longer in the atmosphere, also producing more precipitation.


Technically - but greening in the arctic is bad news for us https://www.nature.com/articles/nclimate1858/




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