Honest Question About Anthropomorphic Global Warming

[Carrikature]

I'll look into some of this at bit more.
Don't take the next paragraph as a dismissal of what you've already provided.

Based on a quick search I've learned that glaciers have been losing mass since about 1850. All things being equal it appears as if the trend of losing mass had been ongoing for 100 years before the 'latter half of the 20th century'. Given that, what is the justification for the increase of CO2 in the last 50 years being considered causation instead of correlation? It appears to me that with absolutely no C02 increase that the glaciers may have continued to lose mass right up until the current day. Couldn't I just as easily claim that my advancing age causes glaciers to melt?

Thanks in Advance

"Since 1850" means the end of the Industrial Revolution. The trend you refer to is itself a result of human action. Any increase in the last 50 years is more of the same. The change has been one of scale, not source.

[TheLurch]

"Since 1850" means the end of the Industrial Revolution. The trend you refer to is itself a result of human action. Any increase in the last 50 years is more of the same. The change has been one of scale, not source.

Someone's actually attempted to figure out what the temperature is based on the state of glaciers over the last few hundred years.
http://science.sciencemag.org/content/308/5722/675

I've screenshotted the key figure, which shows the temperature change over time:
Screen Shot 2016-05-17 at 9.17.43 AM.jpg

Now, two things should be clear: glaciers are a lousy thermometer (look at those error bars!), and things seem to be melting in a rather unprecedented manner.

I'm actually somewhat surprised by this, given that the Little Ice Age is a well-described event, and led to a lot of glacier advance. Part of the retreat in the late 1800s was probably driven by the end of the LIA. but this would suggest those changes were both part of the normal "noise" of the system.

[Carrikature]

Those are some serious error bars.

[Meh Gerbil]

I'm still thinking about the topic of this thread.
I learned some stuff and it help clarify some thoughts.

[shunyadragon]

I'm still thinking about the topic of this thread.
I learned some stuff and it help clarify some thoughts.

Any more thoughts or questions?

[Sea of red]

Meh Gerbil

What in particular are you struggling with? My background in this as physics/astronomy major gives me a little bit of insight into this topic, and so I might be able to answer some of your questions - providing you are serious.

[Meh Gerbil]

Meh Gerbil
What in particular are you struggling with? My background in this as physics/astronomy major gives me a little bit of insight into this topic, and so I might be able to answer some of your questions - providing you are serious.

I think the thread has illustrated that the glaciers have been melting for quite some time.
I initially thought the claim that the earth wasn't warming had some merit but the trend has been observed long enough as to be pretty solid, IMHO.
I know that was a silly position but I don't dig into this material very deep.

So we know the earth is warming and has been warming for quite some time.
So we know the amount of 'greenhouse gasses' has gone up and I see no reason to doubt those observations.

The gap for me would be proving a couple of things:
1: That CO2 as contributed by man has caused things to warm faster - this means showing that some other accelerant isn't in play.
2: That CO2 is taking us to a place we weren't going to be at in a few years anyways.

The reason that is important is because of public policy.
I'd ask: Why spend billions to slow our march to a warming temperature point that we'll reach anyways?
If we had carbon emissions when a glacier still covered Michigan would cutting that emission still have the state under a glacier?
No it wouldn't - an extreme example but you get the point.

So has the connection between C02 produced by man and an increase in temperatures been established, in your honest opinion?

[Sea of red]

I think the thread has illustrated that the glaciers have been melting for quite some time.
I initially thought the claim that the earth wasn't warming had some merit but the trend has been observed long enough as to be pretty solid, IMHO.
I know that was a silly position but I don't dig into this material very deep.

So we know the earth is warming and has been warming for quite some time.
So we know the amount of 'greenhouse gasses' has gone up and I see no reason to doubt those observations.

The gap for me would be proving a couple of things:
1: That CO2 as contributed by man has caused things to warm faster - this means showing that some other accelerant isn't in play.
2: That CO2 is taking us to a place we weren't going to be at in a few years anyways.

The reason that is important is because of public policy.
I'd ask: Why spend billions to slow our march to a warming temperature point that we'll reach anyways?
If we had carbon emissions when a glacier still covered Michigan would cutting that emission still have the state under a glacier?
No it wouldn't - an extreme example but you get the point.

So has the connection between C02 produced by man and an increase in temperatures been established, in your honest opinion?

The connection is so well established that only a few working scientists are skeptical - whom you can count on one hand.

We observe several things that we shouldn't see if the forces behind the warming were natural variations. One of the major (though not exclusive) drivers of the climate is the Sun, and many theorize that solar cycles might be the cause to the warming. To make it simple: 1)we need a solar cycle consistent with the rising temperatures, and 2) and equal warming throughout the layers of the Earths atmosphere.

Well, what we actual see is a strong diverging of sun-spots from increasing temperatures after the 1950's - after which most of the warming is anthropogenic.



The cooling of the stratosphere is something the contrarians in climate change discussions can never really fully explain. The issue? The stratosphere is cooling rather than warming, which is not what one would expect if solar related forcings were to blame for the observed warming in the troposphere and cooling in the stratosphere. It's also the case, that the leveling off of the warming in the troposphere as the tropopause begins is within predictive theory; this would require a very technical explanation for most of you but the research is out there, and the models are within observed readings.

The banning of CFC's in the 1987 has lead to the recover to the ozone layer. Problem is, the recover is slowing down due to the radiative transferring increasing the amount of greenhouse gases (GHG) in the troposphere. And it's about the rate we would expect from human caused climate change.



http://www.wunderground.com/resource...to_cooling.asp

This is exactly what we should see if the warming is related to GHG's rather than solar cycles.

Lastly, lets talk about the connection between GHG's and the Earths history.

Glacial changes in the Earths history can be traced back via ice cores, and can be deduced from a number of factors. The Earths eccentricity is the first of these factors in changing on a time-scale of around 100,000 years. Eccentricity is simply the changing of the Earths orbit from being more like more elliptical, to being less elliptical with time. The second of these is changes in the axial tilt from 21.5 to 24.5 degrees. The third factor, is the Earths precession or wobble as it orbits the sun. This changes the North Star from being Polaris, to Vega.

These things put together are called the Milankovitch cycles.

This illustrates the Earths precession some fair justice:



It is these small changes that change the distribution of sunlight radiation on the Earth and radically alters the seasons, climate, and brings into and out of Ice-ages an Holocene.



We can also see looking back, that green house gases (GHC) both follow and drive climate. The reasoning is simple: as the climate warms, more GHG's are released into the atmosphere, further heating the earth, and this feed-back continues until the Earth reaches balance again. This is why the argument that GHG lag temperature is a non-sequitur; GHG's act as a feedback that amplifies temps.



So as you can see, the link between GHG's and climate is well established.

[Meh Gerbil]

Sea of Red,
Question: Would the GHGs which rise and fall with the ice ages (If I understood you correctly), even if man made, strike a balance and reduce on their own in time?

-Meh Gerbil

[Sea of red]

Sea of Red,
Question: Would the GHGs which rise and fall with the ice ages (If I understood you correctly), even if man made, strike a balance and reduce on their own in time?

-Meh Gerbil

Not exactly.

The Earth has points were it 'falls of the wagon' and you have runaway effects (feed-backs) until it reaches an energy balance again, due to the Earths albedo effect.

The albedo effect can be best illustrated with the graph below.



Compounding this effect is the melting of the ice sheets which exposes darker surface area, meaning less radiation is reflected back into space. Another issue is that the oceans hold CO2 in 'sinks' that are slow to start and slower to stop. This is sometime called the 'pipe line' of the climate. You also have Methane reserves deep inside the ocean vents that also contribute to the warming.

Would the Earth reach balance again? Eventually. After a lot damage to the ecosystem is done.

[Meh Gerbil]

Thanks for taking the time, Sea of Red, I'll have to think about this some more.
It's a lot of information.

[TheLurch]

Just to pick up a theme Sea of red hinted at: based on the Milankovitch cycles he mentioned, the Earth will have been cooling for the last 5,000 years or so, a trend that would have continued for a while into the future. So, any warming we are experiencing is taking us to someplace we wouldn't be going otherwise, as your question mentioned. And, if you use proxy readings of past temperatures, that's exactly what you see:

marcott1.jpg

(NB: the recent temperature rise in that graph comes from the instrumental record, and not the proxies, which do not have the resolution to pick up changes on time scales as short as a century.)

[Meh Gerbil]

Just to pick up a theme Sea of red hinted at: based on the Milankovitch cycles he mentioned, the Earth will have been cooling for the last 5,000 years or so, a trend that would have continued for a while into the future. So, any warming we are experiencing is taking us to someplace we wouldn't be going otherwise, as your question mentioned. And, if you use proxy readings of past temperatures, that's exactly what you see:

[ATTACH=CONFIG]15794[/ATTACH]

(NB: the recent temperature rise in that graph comes from the instrumental record, and not the proxies, which do not have the resolution to pick up changes on time scales as short as a century.)

Okay, now that throws me a little bit.
I thought we were within the window of a long term warming trend.
You seem to be claiming we should be in the window of a long term cooling trend.

Not trying to be difficult, I just missed a turn there somewhere.

[TheLurch]

Okay, now that throws me a little bit.
I thought we were within the window of a long term warming trend.
You seem to be claiming we should be in the window of a long term cooling trend.

Not trying to be difficult, I just missed a turn there somewhere.

No problem. We were not in any sort of warming trend until the recent greenhouse warming kicked in, at least as far as i know.

There have been some bits of warming recently that weren't greenhouse-based. The Little Ice Age ended with a bit of warming that wrapped up in the 1800s. There was also a bit of warming early last century that was partly greenhouse and partly solar activity. But there was no longer term trend that continued to this day.

If you want to explain how you came by the impression that we were in a warming trend, i'd be happy to figure out where that fits in with the larger picture.

[Meh Gerbil]

If you want to explain how you came by the impression that we were in a warming trend, i'd be happy to figure out where that fits in with the larger picture.

I think I crossed a couple of wires.

I thought we were in the part of the warming trend that started with the melt off of the glaciers that once covered Michigan.
I thought that although there had been some ups and downs that the overall trend for the past 10,000 years was warming.
Because of that I thought the glacier melt off for Mt. Kilimanjaro was just a part of that continuing trend and not part of a AGW trend observed since the 1850's.

That misunderstanding is why I thought the Mt. Kilimanjaro pictures from 1912 were significant.
If the glacier was retreating before AGW then current and future retreat would be hard to pin on AGW, or so the thinking goes.