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A global reforestation project is how we fix climate change

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Re: A global reforestation project is how we fix climate change

#141

Post by llebttam »

ulrikrasmussen wrote: post #29
Ndymium wrote: post #14

Earlier quoted context omitted.

But when the trees die, new trees will grow in the same area, sequestering more or less that CO2 that was emitted from the dying tree, no? Would this not turn the forests into a permanent CO2 sink, at least on a rough scale? Or do they sequester less than they emit?

I unfortunately can't find a reference, but I heard that it takes about 20 years for a newly planted tree to peak with regards to absorption of carbon, and after about 100 years it reaches equilibrium where the forest emits about the same amount of carbon to the atmosphere as it absorbs (through decaying matter, fallen trees, and whatnot). It of course depends on the type of tree.

I'm not an expert in this area, but from what I can tell:

Young rapidly growing forests sequester carbon more quickly than mature forests, but mature forests still sequester some carbon, possibly into the soil. (One source https://www.sciencedaily.com/releases/2008/09/080910133934.h... ) Separately, the regrown forest could be maintained in a state of peak carbon sequestration by doing selective logging from time to time, and as a bonus it would be profitable to do so.

Re: A global reforestation project is how we fix climate change

#142

Post by llebttam »

jdlyga wrote: post #59

You can't outrun a bad diet. Sure we can plant a ton of trees to recapture carbon, but we also need to cut down emissions.

I agree, but I still think of this as a useful part of a complete solution. It's something that buys us time to shift away from fossil fuels.

With current tech, we could drastically reduce emissions by moving to a mix of nuclear (the modern, safe kind) for baseload plus wind and solar for peak, but it's going to take few decades to build it all out, and during the intervening period we have a lot of excess CO2 we need to sequester.

Re: A global reforestation project is how we fix climate change

#143

Post by llebttam »

awb wrote: post #134

> Thus, to reforest 3 billion acres at current prices will cost the world an investment of $3 trillion/year for 20 years. That sounds like a lot, but the world GDP of 2017 was $80 trillion. Therefore, this plan would require an investment of a little less than 4% of world GDP every year for 20 years. $3T each year (4% of world GDP) for 20 years still sounds like a lot.

Yeah, it's definitely a lot.

I think the actual costs will be a lot lower as this will take many years of experimentation before scaling, and by then the cost of the solar panels (which I think is the vast majority of the cost) will likely have continued to ride its exponential downward cost curve. One source: https://earthtechling.com/solar-energy-costs-trends/

Re: A global reforestation project is how we fix climate change

#144

Post by hinkley »

pjkundert wrote: post #137
hinkley wrote: post #122

Earlier quoted context omitted.

Literally survivor bias. The old growth forests that survived loggers were the ones they couldn’t get to for a profit. Those will be in or near geographic barriers like swamps or rocky terrain.

Hmmm? I've rarely hiked in harvested and replanted forests; these are boring. I did most of my hiking in central/northern BC and Alberta, Canada. These are some of the largest tracts of old-growth timber in the world. The many old-growth forests I've hiked (sample: >1,000km, mostly dominated by conifers), with last burn times ranging from decades to centuries, have rarely boasted deep soil levels. This hypothesis is…

Oh, North Canada? That's some tricky terrain. Bedrock is very near the surface, and you're right, it's hard to build up. Short growing season, for one.

The article you link mentions softwood forests being problematic for carbon accumulation. Not hardwood forests. Old growth temperate hardwood forests are quite rare now, and some of the apex tree species in those forests have very serious pathogens keeping them from re-establishing, more's the pity.

Re: A global reforestation project is how we fix climate change

#145

Post by ahartman00 »

Merrill wrote: post #70

The core assumption is that 3 billion out of a total of 4.7 billion acres of desert currently existing can be reforested by planting trees and irrigating them for 20 years, after which they will continue growing without irrigation. Is this possible, except for marginal areas bordering the deserts? Aren't most desert areas desert because of very low precipitation? This may be practical for areas such as the example in…

>irrigating them for 20 years

And there is an assumption that there is enough freshwater to do this.

"A third of the world’s biggest groundwater systems are already in distress"

"Water scarcity already affects every continent. Water use has been growing globally at more than twice the rate of population increase in the last century, and an increasing number of regions are reaching the limit at which water services can be sustainably delivered, especially in arid regions"

https://www.unwater.org/water-facts/scarcity/

Re: A global reforestation project is how we fix climate change

#146

Post by llebttam »

ericmay wrote: post #103

How can I today, directly add to creating new trees either through helping to plant, or by donating money?

A friend of mine who's studied climate change in detail recommended the following company for voluntary carbon offsets:

https://carbonfund.org/product-category/plant-trees/

Re: A global reforestation project is how we fix climate change

#148

Post by revscat »

dang wrote: post #119
revscat wrote: post #44

Does that series cover eliminating Rupert Murdoch? I know that this is taboo to discuss, but it is becoming increasingly apparent that non-technical solutions to climate change will necessarily include the elimination of those who metaphorically are holding a gun to humanity's head.

You can't post like this on HN. Please don't do it again. We detached this subthread from https://news.ycombinator.com/item?id=22064871 and marked it off-topic. https://news.ycombinator.com/newsguidelines.html Edit: we've had to ask you about this before: https://news.ycombinator.com/item?id=19252288

I disagree with the position that even the discussion of the necessity for war, or any active engagements, in the pursuit of solutions to the existential threats posed by climate change are forever off limits. I understand their presence, but as the danger continues to increase, and the solutions so inadequate, directly addressing the root causes — specifically, the apparent necessity to go to physical war against those who seek to destroy humanity — should not be so taboo.

But it’s your site. I hope you and your colleagues reconsider this stance, however, at least in regards to this specific issue, especially given its unprecedented importance.

Re: A global reforestation project is how we fix climate change

#149

Post by llebttam »

Tade0 wrote: post #39

IIRC a single tree absorbs around 25kg of CO2 annually during its fastest growth stage. That's an equivalent of less than 200km in a compact car or 2kg of beef. I believe it makes more sense to pick the low hanging fruit which is making transportation more efficient and reducing the impact of food production.

The world has a lot of land, though. Before humans came along, there were roughly 6 trillion trees in the world. Now there are about 3 trillion, mainly due to forests being cut down for agriculture, wood, etc. Getting back the other 3 trillion trees would sequester an additional 75 gigatons of CO2 per year using your figure of 25kg/tree/year. Human activity emits 45gt/year according to his article.

Re: A global reforestation project is how we fix climate change

#150

Post by madhadron »

dghughes wrote: post #116
NeedMoreTea wrote: post #80

Far too little, far too late. It may have helped fix climate if we had stopped deforestation in 1992 after the first UN climate summit, used only sustainable wood from that moment on and cleared no mature forest for pasture or palm oil. Oh, and started migrating to zero carbon economies when it would have taken a percent or two reduction a year, rather than the throw ourselves off a reduction cliff required now. Than…

I'd assume growing trees would sequester far more carbon than mature trees? Grow, chop, grow perhaps?

Data shows the opposite. Mature trees are more efficient at sequestration.
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