A century of reforestation helped keep the eastern US cool (2024) | Hacker News Reader

A century of reforestation helped keep the eastern US cool (2024)

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137 pointssoftwaredoug20 comments

Anecdata: I have a plot of land in the Santa Cruz Mountains and half of it has redwood coverage and the other half is sparsely covered by much smaller species. On hot days I can go to the redwood half and get an easy 10F temperature drop.

Shade is part of the equation and so is retaining water. Once I was introduced to the idea of check dams and their role in water conservation, I started noticing how the redwoods often build their own on hilly terrain.

The landscape in a forest can be quite complex and rich.

Can feel the same effect here in CA. I’ve heard that in areas with more humidity the effect is much weaker though, presumably because the air has higher heat capacity or something and so doesn’t cool as quickly in the shade.

I live in the Midwest US, plenty humid here in the summer but it’s consistently 5 degrees cooler in my wooded neighborhood than it is in the nearest town about 10 miles away. The effect is real.

Interesting. I asked a friend from Texas and he said he wasn't even aware that shade was cooler until he moved out. Need more data.

It’s not about shade alone. A cliff or single tree provides shade, but a forest provides evaporative cooling during the heat across a huge area alongside shade, it ends up a noticeably different climate.

There’s some other effects such as photosynthesis converting sunlight into chemical energy which in the short term is like reflecting that energy into the sky. At night plant metabolism warms the environment slightly and blocking the sky reduces radiative cooling to space, but that’s generally a good tradeoff for comfort.

Counterpoint: Shaded spots at work parking lots in Texas fill up the fastest. Conspicuously so. Also, use of windshield visors is much more prolific than in cooler climates.

I can't believe your Texan friend never noticed those phenomenon.

I don't respect your friend's observational skills. But to be pedantic, shades are cool because the sun does not heat up the air, but heats up the ground beneath you and it heats up the air. The water evaporated helps in cooling us down.

Might also have something to do with the ground and trees evaporating less water into the already humid air, reducing the cooling effect of evaporation.

I recall a factoid from growing up in southern New England: that Connecticut had more forestland in my youth than it had a hundred years earlier, because so much agricultural land had been abandoned to nature. Presumably farmers wanted soil without an annual stone harvest.

It was largely wool, as I understand it. Those rocky hills are terrible for row crops, but fine for pasture, so you stack up some rocks into fences and fill them with sheep.

Then people stop wearing wool, and here we are.

NE, winter. We still wearing wool, from Bean. My 2nd favorite fiber.

also why mutton went from being a very popular form of meat in the US (old sheep meant for wool who were no longer suited for it), to basically not existing as a major form of meat.

Reforestation is slowing to a crawl because land owners are realizing that you need expensive onerous permits to clear any serious (1 acre) amount of forested land so they maintain any cleared area whereas prior to the clean water act they let it grow and just cut it if they (or the next owner) had a reason to.

bit more north and east here in Nova Scotia, but this summer broke all records for heat and dryness, in the south facing slope in the back padock at my place the ground dryed so much that it started to open up cracks, months of no rain, forest fires, land use bans with 25k$ fines the plus sides are the most glorious fall display of the leaves turning coulors, ever, and many of the critters have had very high survival rates for there little ones

Apparently earthworms are a problem here. The saplings need the brush to protect them and the worms which are non native are mulching it. IIRC. If half of what I hear is happening in the Canadian forests or Amazon is true it’s sickening. Of course you have the naive and confused among us who debate or defend this abhorrent and unnecessary exploitation.

There used to be worms before the ice. They're just repopulating. By extension, none of the trees are native either. The natural state of the higher latitudes was mud and rock 10000 years ago.

North America did not have an extensive earthworm ecology like Eurasia even though they had some worms. They are an invasive animal[0] brought from Europe that creates problems for the many North American plants and ecosystems not adapted to the pervasive effects of such worms. The worms you find in soil are largely non-native.

[0] https://en.wikipedia.org/wiki/Invasive_earthworms_of_North_A...

That is the spiel from academics on the publish or perish treadmill. Fossil burrows of the same form as the European worms exist in North America. Worms were also maintained to the south of the ice cover so it is disingenuous to declare that all North American worms are nonnative.

> it is disingenuous to declare that all North American worms are nonnative.

Nobody made that claim. That's the strawman you chose to argue against instead.

Pressure to publish = dismiss any academic claim without evidence? No

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