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Receding glacier causes Canadian river to vanish in four days

theguardian.com

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Re: Receding glacier causes Canadian river to vanish in four days

#61

Post by titojankowski »

thinkcontext wrote: post #55
titojankowski wrote: post #46

Earlier quoted context omitted.

Anyone working on new tech to plant trees more efficiently? Or engineering trees optimized for carbon sequestration?

Technology is not the biggest challenge to reforesting, people are. What good is planting millions of trees with robots if poor peasants graze their goats in the area that kill them all? To succeed you need to get them to buy into the outcome. China's efforts on the Loess Plateau has been held up as a success in reforestation which has also benefited the local agricultural economy. https://www.youtube.com/watch?v=sK8…

Thanks, I watched the whole video. A great success of natural capitalism. I wonder how drone surveys, satellite mapping, and synthetic biology could extend this 35 sq-km success to 3,500 sq-km and beyond, augmenting people's needs and efforts. As said in the video, let's "properly understand the miracles performed by trees" to make this more profitable and spread everywhere.

I also agree with the farmer who said "what about our children, they can't eat trees!!". There's an opportunity for climate change solutions need to be communicated at human timescales (days, months, years). Decades are too hard to imagine.

Thanks for the video!

Re: Receding glacier causes Canadian river to vanish in four days

#62

Post by komali2 »

DanBC wrote: post #58
komali2 wrote: post #57

Earlier quoted context omitted.

Shame, it was flagged and removed. It was a comment that was highly sarcastic and critical of climate change, but I'd say no more sarcastic than any other comment we might find on here. Perhaps we could have benefited from learning why people continue to falsely believe climate change isn't real.

"Booo it's the ghost of global warming! Always threatening, never happening." is a worthless pointless comment and there's not going to be any useful discussion coming from it. It's exactly the kind of comment that needs to be downvoted and flagged. Also, flagging doesn't really remove anything. You can change the "showdead" setting in your options to see all flagged comments.

Oh, I didn't know that, thank you.

Re: Receding glacier causes Canadian river to vanish in four days

#63

Post by titojankowski »

zokier wrote: post #60
titojankowski wrote: post #46

Earlier quoted context omitted.

Anyone working on new tech to plant trees more efficiently? Or engineering trees optimized for carbon sequestration?

For the latter, I think the research and other work for using Paulownia trees for carbon sequestration qualifies. I do seem to recall that there was some attempt to further cultivate it to be more suitable for that purpose.

Thanks! I hadnt heard of Paulownia before. 3-10x more sequestration than the average tree: http://paulowniabg.info/?page_id=56

One challenge with plant-based sequestration is that the carbon is released when the tree dies/decomposes. I wonder how planting more trees will balance out at the decade-century scale.

Re: Receding glacier causes Canadian river to vanish in four days

#64

Post by archgoon »

Almaviva wrote: post #30
acover wrote: post #28

Earlier quoted context omitted.

Here is the statistical analysis from the paper: The method of Roe et al. is summarized as follows. Let 1L be the change in glacier length over the past 130 years (∼1.9 km), and let σL be the standard deviation of glacier length due to stochastic fluctuations in mass balance, b, from natural, interannual climate variability. The signal-to-noise ratio is defined by sL =1L/σL . Likewise, sb =1b/σb . Ref. 12 demonstrate…

The 0.5% quote is fine. It's turning it into a 99.5% that is not fine. It's essentially like saying that a pair of dice that rolled a 12 has a 97% chance of being loaded, because there's only a 1 in 36 chance of rolling that high.

Let's think about this.

Let's assume that when a river gets redirected, a scientist goes and investigates it (which seems reasonable), and is asked what is the chance that it happened by natural causes, or is due to global warming. Based on the analysis that @acover shared with us, we can see that out of a thousand such dispatches, 995 will be due to global warming and 5 will be due to natural variability. So it seems correct for that scientist to conclude "It's 99.5% due to global warming.". In fact, saying that it's .5% due to natural variability is equivalent.

You are probably thinking of the jelly bean situation, where a test is performed to detect something within a sample population. The test has a failure rate, and the population has a base rate of occurrence.

In this case (thanks @acover), they are directly calculating the base rate.

Now, you could also ask "How many times in a year will a scientist be dispatched and be wrong", which is a again a different question (and is closer to the scenario you described).

Re: Receding glacier causes Canadian river to vanish in four days

#65

Post by titojankowski »

ocschwar wrote: post #54
titojankowski wrote: post #47

Earlier quoted context omitted.

Yea totally! Does Hyperloop count as train tracks? I wonder what upcoming inventions in windmills look like...

Met a guy who was trying to sell a setup to plasma-fy the air along the edges of turbine wings to squeeze a bit more efficiency. There's room for improvement still.

Wow crazy, I don't understand plasma-fy tho...some device on the edge of the windmill blade would change the nature of the air to reduce friction?

Re: Receding glacier causes Canadian river to vanish in four days

#66

Post by discreteevent »

titojankowski wrote: post #63
zokier wrote: post #60

Earlier quoted context omitted.

For the latter, I think the research and other work for using Paulownia trees for carbon sequestration qualifies. I do seem to recall that there was some attempt to further cultivate it to be more suitable for that purpose.

Thanks! I hadnt heard of Paulownia before. 3-10x more sequestration than the average tree: http://paulowniabg.info/?page_id=56 One challenge with plant-based sequestration is that the carbon is released when the tree dies/decomposes. I wonder how planting more trees will balance out at the decade-century scale.

Cut them down when mature and use them as building material.

Re: Receding glacier causes Canadian river to vanish in four days

#67

Post by lostlogin »

douche wrote: post #3

This kind of thing has happened several times in China in recorded history with the Yellow River, to the point where sometimes the river has flowed into the ocean north of the Shandong peninsula and sometimes south of it. https://en.wikipedia.org/wiki/Yellow_River#History

The Amazon is another example of having flow reversal - presumably things got very damp as water levels sorted themselves out.

Re: Receding glacier causes Canadian river to vanish in four days

#68

Post by acover »

archgoon wrote: post #64
Almaviva wrote: post #30

Earlier quoted context omitted.

The 0.5% quote is fine. It's turning it into a 99.5% that is not fine. It's essentially like saying that a pair of dice that rolled a 12 has a 97% chance of being loaded, because there's only a 1 in 36 chance of rolling that high.

Let's think about this. Let's assume that when a river gets redirected, a scientist goes and investigates it (which seems reasonable), and is asked what is the chance that it happened by natural causes, or is due to global warming. Based on the analysis that @acover shared with us, we can see that out of a thousand such dispatches, 995 will be due to global warming and 5 will be due to natural variability. So it seem…

I am out of my depths but I do not think you are correct.

The paper appears to create a model for a single glacier's retreat. Selects the parameters of this model by analyzing all glaciers. Then determines the retreat of this glacier is unlikely under this model.

The issue is that there is a sampling bias. This glacier is not like most glaciers [I assume]. It was not randomly sampled from all glaciers. It was selected because of a river diversion due to glacial retreat.

What did they do to compensate for this sampling bias? I don't see it.

Re: Receding glacier causes Canadian river to vanish in four days

#69

Post by jimnotgym »

titojankowski wrote: post #35

Sweet, so what should we build to change this? Giant carbon-sucking machines, cube-sats pointed at glaciers? (planet labs is doing cool stuff in this space, including a project to count every tree on Earth every day). Solutions welcome!

Perhaps what we really need is political will. It has been much said in the UK that wind power has made various great strides forward, in terms of being able to operate in a greater range of wind speeds for example. This is in pursuit of EU green energy targets. With Brexit it sounds like the government are keen to resort to fossil fuels. Luddites

Re: Receding glacier causes Canadian river to vanish in four days

#70

Post by mnarayan01 »

acover wrote: post #53
Almaviva wrote: post #45

Earlier quoted context omitted.

"So it’s 99.5% that it occurred due to warming over the industrial era" There are at least a couple of statistical fallacies in this conclusion. And there isn't a lack of agreement about that. One problem with p-value tests is precisely that people misunderstand what the p-value means, which is where basic education comes in. It could save people from believing a lot of things they shouldn't. (Like many health and fi…

Do you agree to the statement "so it's 99.5% that we correctly reject the hypothesis it occurred without warming over the industrial era"?

I think you're mainly correct. The main issue is that there's an implied "given that the model from http://www.nature.com/ngeo/journal/v10/n2/full/ngeo2863.html is 'perfect' (at least for this case)". Since it seems unlikely that the model is perfect, the numbers they give are almost certainly inflated.
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