Forests offset warming more than thought: study | Hacker News Reader

Forests offset warming more than thought: study

news.ucr.edu

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I think there are other benefits to having a lot of trees around you.

As a resident of the Houston area, I am abundantly familiar with the idea of an urban heat island. The difference between a hot day inside the 610 loop and one 50 miles north is quite significant.

I moved from what is effectively the middle of the world's largest parking lot to the middle of a forest and I feel like I've transported myself 1000 miles instead of 50.

I've also developed a strong sense that the forest seems to have some kind of influence over the weather patterns. Not a strong or active one, but it definitely seems like a thing when you're watching Doppler radar.

The science behind how forests impact weather is still developing, so I can’t make wild claims like I want to. Yet the evidence is extremely compelling. Trees seem to induce rain, reduce turbulence from winds, and as this article mentions, cool the air far more than we thought.

Trees seem to be—unsurprisingly—specialist organisms in the art of maximizing local hydrological features. They help create wetter environments so more trees can live there, and things can get a little more wet still, for more trees, then more water, and so on.

The research I’ve read is mostly along the lines of “we’ve observed these really interesting patterns and we suspect these are the underlying mechanisms”, but as I recall, proving the cause and effect of such large scale phenomenons isn’t trivial. I’m also not someone who researches this stuff, so my take on it is essentially irrelevant. The bottom line is: lots of evidence and research supports your observation, and it’s an extremely interesting field of research. I think it’s the key to making life better for a lot of life on the planet.

There's been a lot of study on this topic which is interesting! As you say, they collect moisture in a lot of ways. Part of this is done by the structure of the tree [1] (the surface area of the leaves is surprisingly large and catches a lot of moisture and other particulates in the air), rain drops hitting tree leaves cause droplets to break into a fog or mist, and some varieties of trees found in rainforests will also release various chemicals and compounds [2] that can encourage cloud formation and rainfall. It's fascinating stuff!

1. How Trees Bring Water: https://www.youtube.com/watch?v=oY8ds4BiG1A

2. Amazon Seeds Its Own Rain: https://www.science.org/content/article/amazon-seeds-its-own...

> reduce turbulence from winds

I'm convinced this is a very strong effect. The forest definitely protected my home from some nasty windstorms we've had. Out toward the lake where there is less coverage, essentially everyone was knocked off the grid for a whole day while I was unaffected - Despite having my power being delivered by similar overhead lines that follow a very narrow clearing through the middle of the forest. You'd think it would be a shooting gallery but it's the opposite thing. Isolated trees seem way more lethal to grid infrastructure.

I mean... this cannot be a surprise to anyone that a physical object affects wind?

It might be a surprise when looking at the stratification of the atmosphere, where winds can occur, the depth of the atmosphere, and how tiny trees are on that scale.

On one hand, the mechanism seems readily apparent. On the other, it's also astounding. It's not just that the trees create physical disruption with their own physical bodies, but also through how they modify the properties of the atmosphere above and around them. That's incredible. They transport immense amounts of water into the atmosphere.

Farmers in the Great Plains have been making wind shields for their lands with trees for a long time.

These shields are slightly different from what's happening on the weather-system scale. Those winds are low to the ground, and when you obstruct them, the wind is deflected upward and diffused by the trees absorbing some (a very tiny amount) of the wind's energy. So it's a highly local effect. Forests can also modulate properties of the atmosphere around them, which can do various things like alter cloud formation or even stimulate rain. Rain stimulation is still be studied as I recall, but it has huge implications if it's true.

When you've lived in the country most of your life, it's weird when you hear people discover basic things like windbreaks or the fact that tree shade is cooler than other shade. My great-grandparents would have said, "Well, duh."

Well, what we're talking about isn't micro, local-scale effects but more like climate and weather. I agree, those things are totally obvious, but it isn't always obvious what they mean at broader scales. Even some of the obvious local effects can totally transform once they culminate, leading to non-obvious results of very obvious local properties of trees.

I experience the opposite effect.

Where I live the forest effectively disappears every autumn, and then it gets really cold. Six months later the forest grows back and then it gets really hot. The ambient temperature is obviously intimately correlated with the presence or absence of the forest.

Amusing but obviously flawed - the science here is about the long time period correlations of mean forest coverage and mean regional tempretures (as you very likely are aware), not the short term seasonal cycle.

I chuckled .. others downvoted. Humour on HN is hard :/

This becomes even more apparent when you move to cities that are more integrated with local forests in part. You drive by the foresty adjacent area, not even in the forest, and the temperature drops dramatically, easily 5+ C. And as CO2 increases, so too is greenery. [1]

[1] - https://science.nasa.gov/earth/climate-change/co2-is-making-...

Not only forests but even just tree cover. I live in Berlin and there were a few days a few years ago over 40 degrees, and I remember the difference was stark going from my relatively tree-lined street to an area of the city with only concrete.

Houston eh!, well let me tell you that I use the GOES sattelites for local weather observation, and general real time views of varios conditions..... and Houston is the one city that stands right out, instantly visible and radiating in the infra red, never been there, but your spoke roads must be fucking HUGE, to be vissible from geosynchronous orbit, the whole thing working as a heat absorber/radiator. as a "controll" try as I might, Mexico city (others),remain invisible in the same images

> your spoke roads must be fucking HUGE

I don't know of any place on earth with more installed concrete or greater ability to deploy it.

About the weather patterns. We live near a large area of natural dunes. In school we were taught that the natural dunes reflect sunlight, leading to rising air. Although I can't remember the exact meteorology (rising air generally leads to rain) they showed us the precipitation patterns and the surrounding areas get more rain and the dunes less. As a layman, I except forest vs. concrete will lead to similar situations. More rain near forests, less near concrete. Is that what you see on radar?

I now see that u/steve_adams posted pretty much the same point. I wonder how I was taught this 25 years ago in high school, with local graphs for evidence, and it still isn't scientific consensus. Super local weather models aren't a thing? (This is in jest, they obviously are a thing. Perhaps it's harder than I imagine.)

I misread this at first and understood it to say “growing trees is better for reducing global warming than performative hypothetical discussions thinking about the negative impacts of global warming”

> restoring forests to their preindustrial extent could lower global average temperatures by 0.34 degrees Celsius

Which would be an absolutely huge (and practically impossible) change in, say, Western Europe. Maybe 80–90% of all farmland would have to be reforested. It was difficult enough to get people to agree on the 20% goal of EU's Nature Restoration Regulation.

It depends what preindustrial means exactly. Most of the forests in Western Europe were cut well before that, I believe around 1800 is actually the trough. Your 80-90% figure is probably back to the original state, but I would guess it's antiquity or pre-antiquity levels.

Yeah, fair point.

Why stop at pre-industrial. We can go extra-natural. Naturally most forests were grazed at by large roaming herbivores.

Some interesting, recent discussion: "Interview at the Technical University of Munich: Not only are forests more complex than is commonly realized, they also do more." [1]

[1]: https://bioticregulation.substack.com/p/in-focus-green-ocean...

Actual title and subtitle:

Does planting trees really help cool the planet?

Forests offset warming more than thought, but not enough

By itself

A major volcanic eruption is the only significant event which would lead to a reduction.

Heat balance can also be achieved by investing $10b a year to mimic volcanic activity

Disclaimer : Will cause white sky and unknown health effects.

Don’t get me wrong : we may or may not have to do this one day but it can only be a temporary solution in a too late transition scenario. It’s not a solution on top of our current fossil based economy else that would just be a time bomb.

If we keep having exponential growth in solar for another 15 years, we will be in a fine position to transition. But better to start asap and prevent runaway feedback loops.

And by start, I mean do tests and research. That is currently banned.

Restoring forests is clearly valuable, especially in the tropics, but it's not a get-out-of-jail-free card for emissions. The fact that even replanting all lost trees would only offset about 0.34°C puts things in perspective.

What’s 0.34 Celsius in years? I think it’s at least a decade which isn’t that bad.

Trees baby, trees is the campaign slogan we'll never hear anywhere.

"Have trees, not babies nor pets to save the planet"

I had read this book many years ago.

thought it was good.

https://www.goodreads.com/en/book/show/1481687.The_Forest_an...

https://www.amazon.com/Forest-Sea-Economy-Nature-Ecology/dp/...

Is it possible to genetically engineer fast-growing but sterile trees that are 5x the height and width of mature hardwoods? Plant one in every sizeable park, greenbelt, and plaza. Would add some nice green variety to skylines and suburbs and make for comfortable shade for much of the surrounding area and trails. The only downside is liability and danger of falling limbs, especially during storms.

I know nothing about this but typically fast growing trees are less sturdy (they shed a lot of branches) and short-lived.

I doubt it.

Where would these enormous fast-growing trees get their hefty nutrient requirements from?

Specifically, the partial pressure of carbon dioxide.

https://en.wikipedia.org/wiki/Artificial_photosynthesis#Some...

"the efficiency of photosynthesis ... is usually below 1%, ... However, plants are efficient in using CO2 at atmospheric concentrations,"

This engineered tree would have to pump CO2 into itself.

Nutrients are largely material that plants draw from the earth, not atmospheric gasses.

I figured that's a detail, when the goal is to remove CO2 from the atmosphere.

Yeah, too bad we cut them.

This is a good example of a headline that is both accurate and dishonestly misleading.

Like if we discovered spitting at a housefire would slow it down more than expected, it's still not preventing it from burning to the ground. It's just going to allow some asshat to say "See? Let's defund the fire brigade."

It states that reforestation would result in a reduction in excess of 25% of all observed warming since preindustrial times. And there is every reason to believe there's even more feedback systems we are, as of yet, unaware of that could increase that further (though also potentially decrease it of course).

In any case it's certainly not spitting at a fire.

It's also not possible to tap into the full amount of reduction because of the land use

The figure they measured, in terms of global acreage, works out to an increase in forestry across 8% of the Earth's land area. That's completely viable, in fact some multiple of that is as well. The overwhelming majority of land on this planet is doing pretty much nothing owing to our habit of packing ourselves into tiny densely packed cities which are supported by a fairly small amount of agriculture - 39% of all land there to be exact. [1]

So this is completely viable, and then some! Even more so if one accounts for the fact that increases in CO2 are creating a substantially greener planet making this even easier.

[1] - https://data.worldbank.org/indicator/AG.LND.AGRI.ZS

I see where you’re coming from, and maybe you meant to be hyperbolic, but the impact of forests on quality of life for humans goes beyond cooling effects, which on their own are more significant than you’re giving credit. I think there’s more to gain here than you’d get in the house fire scenario.

I also don’t see anyone wanting to defund other efforts because trees make a difference. We may see local improvements, but I doubt we’d see global improvements such that anyone would think we’re home free. I could be wrong.

I see this as more of a quality of life improvement that could help make the inevitable bigger fight more bearable.

or does it mean we should stop Reforestation??? ^^

This seems like a good takeaway to me

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