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Death by hockey sticks

dothemath.ucsd.edu

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Re: Death by hockey sticks

#101

Post by actionfromafar »

betwixthewires wrote: post #81
WoodenChair wrote: post #41

You can't make hockey sticks out of just a few data points, as this author does in several of the charts. For example, the deforestation chart is based on a few data points from a UN study (where Our World in Data that the author links to cites as its source). But tree coverage has actually increased over the past 30 years according to some studies by NASA and elsewhere. For example, one 2018 paper from Nature says:…

The author also mentions that their forest cover graph is "old growth", and even claims that this strengthens their point! So if I plant a tree today, or did so 30 years ago, this does not count against their deforestation graph, even though the tree exists, this somehow makes their plot more accurate.

Tree farms are not at all the same environment as old forest growth. I'm all for the critique of S-curves in other responses but this resembles dog-piling.

Or would you say an old meadow full of species of bird, foxes, rabbits and insects, is equivalent to a wheat field?

Planting trees is better than not planting trees, but it's not going to restore the ecosystem that came before it.

Re: Death by hockey sticks

#102

Post by sidewndr46 »

dane-pgp wrote: post #95
telotortium wrote: post #63

Oh God, it's the Exponential Economist Meets Finite Physicist[1] dude again. [1] http://physics.ucsd.edu/do-the-math/2012/04/economist-meets-...

Sadly he's still at it. To save people from subjecting themselves to all of his tortured logic, here's just a sample from the article you linked: > The upshot is that at a 2.3% growth rate (conveniently chosen to represent a 10× increase every century), we would reach boiling temperature in about 400 years. Basically his conclusion is that at some point in the next 400 years, the predominant economic system on Earth…

How is energy consumption per GDP measured? All the relevant currencies are inflationary in policy. 2020 proved you can grow the economy at any rate despite any circumstances so long as you are willing to accept out of control inflation.

Re: Death by hockey sticks

#103

Post by Trombone12 »

Archelaos wrote: post #71
sdenton4 wrote: post #44

Earlier quoted context omitted.

(It's a day ending in y, so here I go again...) It depends on the sign of the exponent. Negative exponential growth, as we see in wild animal populations, is not guaranteed to turn into an S-curve. As the passenger pigeon would attest, were any of them left. Meanwhile, to consider a positive exponent case, there's a real question of what will actually cause the bend in the curve of human population. Will it be gettin…

> It depends on the sign of the exponent. Negative exponential growth, as we see in wild animal populations, is not guaranteed to turn into an S-curve. As the passenger pigeon would attest, were any of them left. Sigmoid functions are defined over real input values (not integers). If you were to model the decline in (integer) numbers of passenger pigeons with reals, you would get a sigmoid function were the number at…

What are you trying to achieve by pointing out one of the ways to construct an incorrect model of the passenger pigeon population?

Re: Death by hockey sticks

#104

Post by Trombone12 »

mupra wrote: post #42
WoodenChair wrote: post #41

You can't make hockey sticks out of just a few data points, as this author does in several of the charts. For example, the deforestation chart is based on a few data points from a UN study (where Our World in Data that the author links to cites as its source). But tree coverage has actually increased over the past 30 years according to some studies by NASA and elsewhere. For example, one 2018 paper from Nature says:…

A hockey stick is the initial part of an S-curve. A point to consider is that all complex systems are functions of multiple variables and more often than not, non-linear. A complete view of the past and the present is not a guarantee of the future. At best, it can be a guide for having cautious behavior.

Don't forget the infinite families of higher order polynomials that can have arbitrary shapes beyond the point the observed data ends.

Re: Death by hockey sticks

#106

Post by wongarsu »

thrown_22 wrote: post #54
sdenton4 wrote: post #44

Earlier quoted context omitted.

(It's a day ending in y, so here I go again...) It depends on the sign of the exponent. Negative exponential growth, as we see in wild animal populations, is not guaranteed to turn into an S-curve. As the passenger pigeon would attest, were any of them left. Meanwhile, to consider a positive exponent case, there's a real question of what will actually cause the bend in the curve of human population. Will it be gettin…

Or will it be that people just don't find life worth living and stop having children? E.g. South Korea.

Nearly all developed countries have birth rates below the replacement level. The cluster of reasons for this effect is indeed almost certainly why population levels will level off

Re: Death by hockey sticks

#108

Post by jimbokun »

wildmanxx wrote: post #76
m_dupont wrote: post #62

Earlier quoted context omitted.

Yeah the worst thing is that with the extinction rate, he states that he implicitly sets the background extinction rate to 0 in the year 1000. This is going to bias his 3-point curve fitting even moreso. The background extinction rate in the absence of humans is probably much higher than 0. New species are also continuously emerging while others are going extinct, so that the total number remains steady.

You are kinda arguing against your point. Around the year 1000, it's a reasonable guess to assume that emergence of new species and species extinction were roughly in balance, so net extinction rate was indeed around 0. Today, it's well-established that this net extinction rate is as horrible as is described. A few new species emerging here and there are not enough to compensate for the mess that we are causing on th…

> Around the year 1000, it's a reasonable guess to assume that emergence of new species and species extinction were roughly in balance

Why?

Re: Death by hockey sticks

#109

Post by jimbokun »

mxkopy wrote: post #17
credit_guy wrote: post #4

Another way to look at it is that it's life by hockey sticks. Literally. We have 8 billion people alive today. Which is about 7.5 billion more than before the population hockey stick was a thing. Not only life, but the good life. 90% of people today live a much better life than lords and kings lived 500 years ago.

> 90% of people today live a much better life than lords and kings lived 500 years ago. I'm not sure this is true. For one, you can't really compare lives, and for two, happiness seems to be determined by social factors in ways that would make this untrue. Being able to play music whenever I want is a power that kings could only dream of, but if they had it they would get bored of it probably pretty quickly. If I cou…

Giving up a access to modern medicine would probably be the biggest downside.
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