Climate Change

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Re: Climate Change

Postby DavidMaletsky » 19 Aug 2019, 19:40

Strategus wrote:You're the one doing the fistpounding. I am looking for the answers. But too much rhetoric comes from your side of the debate. "Overwhelming evidence".


To count as “looking for answers”, one has to actually look for answers, redundantly.

Another internal contradiction you’ve had in the past few minutes is that you demand I pull out samples from an enormous body of knowledge accessible to all... so I sigh and do just that... and then immediately nope, I immediately discount out of hand everything I just asked you to produce?

Sad.
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Re: Climate Change

Postby DavidMaletsky » 19 Aug 2019, 19:46

Oh, and as regards prevent versus prepare: preventative measures are useful in both cases. Even if you think we have crossed the tipping point, we have carbon capture and who knows what other future advances available to us; where’s the harm in buying ourselves some more time by reducing our collective footprint? It seems counterproductive to full steam ahead towards turning Earth into Venus, doesn’t it?
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Re: Climate Change

Postby Strategus » 19 Aug 2019, 19:58

DavidMaletsky wrote:Oh, and as regards prevent versus prepare: preventative measures are useful in both cases. Even if you think we have crossed the tipping point, we have carbon capture and who knows what other future advances available to us; where’s the harm in buying ourselves some more time by reducing our collective footprint? It seems counterproductive to full steam ahead towards turning Earth into Venus, doesn’t it?

That's a good point. Managing resources is good. I already said that. Except I don't believe we could turn the Earth into Venus. Too far from the Sun.
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Re: Climate Change

Postby DavidMaletsky » 19 Aug 2019, 20:03

https://www.sciencedirect.com/science/a ... via%3Dihub

Regarding Earth / Venus. Just in case there are others not ignoring the linked info.
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Re: Climate Change

Postby Strategus » 19 Aug 2019, 20:25

I clicked on that one. It says precisely SQRT(fuckall) as far as I can tell.
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Re: Climate Change

Postby DavidMaletsky » 19 Aug 2019, 20:40

It’s an abstract of copyrighted material; there’s a link on the page for renting or purchasing it. The gist is, Earth and Venus likely had similar histories early on, with Venus having both a similar atmosphere and oceans. What caused their paths to diverge was that Venus doesn’t generate a magnetic field in the same fashion Earth does, which caused atmospheric loss into space, eventually leading to a CO2 and nitrogen loaded atmosphere which generates its own magnetism and traps all the heat.

Point being, if Earth’s atmosphere were to be as loaded with CO2, it’s sufficiently similar in other regards that we can reasonably expect similar results regarding trapping of the sun’s rays generating a heat spiral.
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Re: Climate Change

Postby Strategus » 19 Aug 2019, 21:08

DavidMaletsky wrote:It’s an abstract of copyrighted material; there’s a link on the page for renting or purchasing it. The gist is, Earth and Venus likely had similar histories early on, with Venus having both a similar atmosphere and oceans. What caused their paths to diverge was that Venus doesn’t generate a magnetic field in the same fashion Earth does, which caused atmospheric loss into space, eventually leading to a CO2 and nitrogen loaded atmosphere which generates its own magnetism and traps all the heat.

Point being, if Earth’s atmosphere were to be as loaded with CO2, it’s sufficiently similar in other regards that we can reasonably expect similar results regarding trapping of the sun’s rays generating a heat spiral.

How loaded?
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Re: Climate Change

Postby DavidMaletsky » 19 Aug 2019, 21:12

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Re: Climate Change

Postby Strategus » 19 Aug 2019, 21:30

DavidMaletsky wrote:96.5% CO2, 3.5% Nitrogen.

https://en.m.wikipedia.org/wiki/Atmosphere_of_Venus

That's not gonna happen. Like, ever.
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Re: Climate Change

Postby WHSeward » 20 Aug 2019, 06:02

@strategus,

both Venus and Mars have atmospheres that are over 90% CO2. There is no geological or astronomical reason why the Earth couldn't too given our neighbors on both sides do. In fact, in all likelihood Earth's atmosphere once was over 90% CO2 too.

That is a good segue to the rest of my post I was planning on your OP - the statistical fallacy embedded in it.

The creator the graph in the OP wants the viewer to believe you can determine if a relationship, or in this case a non-relationship, is present just by looking at a plot of two data sets - CO2 and temperature. That is just not possible.

When you are modeling a multi-variable process, that is, the output of a process a function of not just of one thing but multiple things, you CANNOT estimate ANY of the variables ALONE. (This is called under-fitting your model and it results in "biased" and "inconsistent" estimators in statistics lingo.) You have to model them all at once. This is a fact drilled into undergrads in intro to stats classes.

Why? Consider this thought experiment. Imagine a spaceship where the temperature was in fact just a function of exactly two variables: CO2 which is warming, and alien laser zaps which are cooling. The mean aliens wished to hide this fact from the unwary observer, so they plotted CO2 against temperature for the ship but didn't mention laser zaps. The plot showed no relationship between CO2 and temperature, because whenever CO2 went up, the alien would secretly fire off a few zaps - sometime enough to cool the ship. In this way they kept their secret from the unwary observer that CO2 was warming.

In my 3 variable (CO2, zaps, temperature) example, it is pretty obvious, you have to look at ALL the variables to learn the effect of ANY of the variables.

So now think about the real Earth not my silly spaceship. MANY variables go into determining the temperature of earth including the atmosphere, biosphere, cyrosphere, geology and land-use, hydrosphere, as well as solar & orbital dynamics. There is NO WAY you can just look at 1 variable alone to figure out its relationship to temperature. If you do see a relationship in an underfit model, it means all the other variables are either stable, have a small effect, or are corelated with what you are looking at, but not seeing a relationship doesn't mean its not there if you are missing variables.

The reason Earth doesn't have an atmosphere of mostly CO2 like Venus and Mars is because of the second item on the list: Earth's biosphere. Earth had algae and bacteria (and much later plants) which introduced O2 liberation cycle and nitrogen-fixing, and this radically changed the planet's atmospheric chemistry. Kill off the biosphere and wait long enough and Earth's atmoshpere would look just like its neighbors.

Do not be fooled by climate change deniers that put together specious graphs and try to claim that CO2 doesn't warm the Earth. That CO2 is warming isn't even in question, we know it is a greenhouse gas. That is just physics. The reason modeling climate is so hard is because the amount of data that must be gathered is enourmous (e.g. what is the temperature of the atmosphere at every point on earth at multiple altitudes?), difficult to measure (e.g. what is the volume of biomass on Earth at this moment; what is the volume of ice?), and the factors are inter-related (e.g. how much do CO2 concentrations change primary productivity of biomass?)

So while some parts are of a climate model are relatively straight forward (like the evolution of the Earths' orbit around the sun) other parts are very difficult and can only be estimated indirectly. The incredible challenge of creating a whole Earth climate model doesn't mean we don't know anything about the climate at all. We know that
1) burning fosil fuels and destroying forests are adding big sources of warming to the planet
and
2) we are observing increasing temperatures at a non-geological rate.
It shouldn't be too hard to draw some conclusions from those two points without having a whole Earth climate model.

PS -
you asked about the red and blue lines on that paleoclimate chart. There is a legend on the left-hand side of the chart. The two lines are two different studies of O18 data which Scotese used to add more detail to his chart.
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