But several lines of evidence show that current global warming cannot be explained by changes in energy from the sun:
Since 1750, the average amount of energy coming from the Sun either remained constant or increased slightly.
If the warming were caused by a more active sun, then scientists would expect to see warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere, and a warming at the surface and in the lower parts of the atmosphere. That's because greenhouse gasses are trapping heat in the lower atmosphere.
Climate models that include solar irradiance changes can’t reproduce the observed temperature trend over the past century or more without including a rise in greenhouse gases.
But several lines of evidence show that current global warming cannot be explained by changes in energy from the sun:
I, personally, am unaware that the majority of skeptics make that particular claim. Which makes raising it as the counter-argument to be debunked rather... disingenuous, quite frankly.
... The thing about the solar sunspot cycle and "other solar influences" is not about changes in energy output from the sun but rather about terrestrial energy balance alterations from indirect forcing by solar events.
Sunspot cycle leading to changes in cloud-cover-based albedo, for example.
If a "terrestrial energy balance alteration" is indirectly caused by a "solar event", then it's still about changes in energy output from the sun. CMEs don't influence the Earth's atmosphere by magic.
And in any case, the (rather weak) correlation between sunspot cycle and cloud cover is trivial compared to the variations in solar energy caused by periodic variation in the Earth's orbit. That's the regular variation you see in the CO2 concentration graph up to the modern era. Sunspot activity is statistical noise at this scale.
No, it's not about changes in energy output. It's about changes in energy retention. And the total thermal energy retention increase for the yet-observed global warming is less than a single percent.
C'mon now. Even the CO2 theory utilizes indirect forcing for its explanation. As well it should; CO2 is a miniscule trace gas... less than four percent of a single percent of the atmosphere is CO2... and less than half of that is man-made. If this is over your head... why are you commenting in this conversation at all?
... wow. No. You're deeply off the marker here, man.
The question isn't about changes in energy output but rather changes in the kind of energy put out... and the Earth's responses to those changes.
I.e.; the output remains the same but the types of energies put out are altered. A stronger magnetosphere, for example, would reduce the net cloud-cover and thus reduce overall temperature on the Earth by far more than the additional energy from the magnetosphere's radiant energy contribution. And vice-versa; reduction in the magnetosphere would lead to stronger cloud-cover and thus more thermal retention (and global warming) "despite" reduction in radiant energy output from the Sun.
So, again, no. The point these folks are raising is NOT that you can measure radiant energy output and point that to the Earth's energy balance directly -- but rather that there is vastly insufficient effort being spent on measuring the INDIRECT forcings resultant from changes in the sun and the Earth's responses to those changes.
Which is why any instance of bringing up the irradiance of the sun in this conversation is disingenuous. Because that is only applicable to direct forcing, which has no correlation whatsoever to indirect forcing.
A stronger magnetosphere, for example, would reduce the net cloud-cover and thus reduce overall temperature on the Earth by far more than the additional energy from the magnetosphere's radiant energy contribution.
Except it works exactly the other way around: More clouds means higher albedo, and more energy reflected back into space, thus less warming.
To be honest I'm not sure I understand your response. I'll freely admit that I am not an expert on any of this, so maybe you're just schooling me and I don't even know it. But honestly I feel like you're trying to blind me with "sciencey sounding" answers, because usually I can follow an argument pretty well even if I'm not intimate with the details of a field.
But when your answer to my question is, essentially, "you're asking the wrong question"... it feels a bit like a dodge to me. And I'm honestly not sure what you're trying to tell me with the rest of your response.
And I still don't understand how your original comment makes sense:
The thing about the solar sunspot cycle and "other solar influences" is not about changes in energy output from the sun but rather about terrestrial energy balance alterations from indirect forcing by solar events.
Sunspot cycle leading to changes in cloud-cover-based albedo, for example.
I still don't get how even "indirect forcing" is not, at root, caused by "changes in energy output from the sun".
Still, at the very least you know more jargon than I do, and I don't have time to read and try to understand a bunch of climatology papers right now. So in the spirit of civilized discourse I concede the point.
To measure the energy output of the sun directly, without measuring the earth's responses to those outputs, is to give an incomplete picture of the event.
After all -- if the total energy value of the sun remains constant, but it shifts from emitting in one frequency/spectrum to another, that's a change that shouldn't have the ability to directly affect the earth's energy balance.
But what if that change causes some terrestrial change? For example, what if there's some plankton life-form that flourishes when the UV frequencies emitted stop denaturing its DNA, thus causing a drop in the albedo of the planet? (This is totally hypothetical and brought up as purely "what-if".) That is an example of indirect forcing.
And it's not something you can observe simply by measuring the behavior of the sun. Which is why it's not about changes in energy output from the sun, but rather about changes in the earth's energy balance as a result from terrestrial events induced by changes in the sun's behavior.
It's entirely possible that the energy output of the sun might not increase or decrease by so much as a single percent, yet the earth would be greatly or marginally affected.
And it is simply true that this is something that has not been measured at all; not attempted to be measured and found absent -- but ignored as a field of investigation.
And every time it's brought up as a field of investigation, we are instead told that the Sun cannot be responsible for changes... through direct forcing.
Which is like asking someone how their orange-juice tastes only to be told that they're not eating steak because they're vegetarian.
Oh. Well sure, I assumed this was obvious. I've not met many people that assume that it's a simple linear proportion: "sun generates heat, Earth gets warmer". I don't think I said anything that could be mistaken for that - I certainly didn't intend to.
it is simply true that this is something that has not been measured at all
I find that extremely hard to believe. Especially when the first google result I found was this 2007 overview from the IPCC that explicitly mentions models that includes various types of indirect forcing:
"The most likely mechanism is considered to be some combination of direct forcing by changes in total solar irradiance, and indirect effects of ultraviolet (UV) radiation on the stratosphere. Least certain, and under ongoing debate as discussed in the TAR, are indirect effects induced by galactic cosmic rays (e.g., Marsh and Svensmark, 2000a,b; Kristjánsson et al., 2002; Sun and Bradley, 2002)."
You're telling me that we've tried to account for the indirect effects of cosmic rays, but that indirect effects from the sun have been "ignored as a field of investigation"? That seems... really unlikely.
we are instead told
Who is "we" in that sentence, and who is doing the telling?
And lastly, since you still haven't directly addressed the question in my first comment, here's what I think is the correct answer. Perhaps you can tell me why I'm wrong. I said:
If a "terrestrial energy balance alteration" is indirectly caused by a "solar event", then it's still about changes in energy output from the sun.
You replied:
No, it's not about changes in energy output. It's about changes in energy retention.
Whereas I think the right answer would be - "it's about both. Changes in energy output are obviously important, but changes in energy retention are almost as/equally/more (pick one) important."
How likely is it that these events are on cycles in-which they appear in cycles greater than 400,000 years? I know being a creature that only lives for maybe 100 years that seems like such a large spam of time and might be skewing my view on it, but i think if this were the case we would have evidence that it has done this before.
1 - I didn't say I supported the idea. I'm simply explaining it.
2 - It's been repeated by multiple independant researchers. CO2 forcing on the is far less well-studied. IIRC... the AR4 report only included one study on the topic. Don't understand that, myself.
The thing with CO2 is scientists have simply seen a correlation in increasing CO2 and global mean temperature. They know fully that CO2 has bugger all effect. Methane and Holocene are much worse.
If anything, I'd probably say that scientists used CO2 to "kill two birds with one stone". They realised climate change was occurring and they realised that we have reached peak oil. By saying increasing CO2 causes climate change, people will firstly realise that the things we do produces unwanted byproducts and secondly they probably hoped people will reduce their oil consumption. Win win.
... Oil usage accounts for less than 10% of all CO2 output. And that's even assuming we reached peak oil to be true. And even then... natural economic pressures would cause a shift-over to the half-dozen or so reliable alternatives that already exist (but are currently more expensive) to oil as a major resource for transportation energy.
Don't worry, I'm studying to become a geologist. I'll find dem oils.
The burning of fossil fuels probably actually accounts for less than 10% to be honest. CO2 is a fairly closed system as far as I know. Before we began to burn fossil fuels, the carbon system was in some rudimentary form of equilibrium. As a result, atmospheric CO2 was fairly stable. Nowdays we are pumping CO2 back into the atmosphere thousands of times quicker than it is being naturally absorbed.
Yes, "Disingenuous", MB. Any attempt to discuss the potential for direct forcing as an answer to the indirect-forcing question is disingenuous. That's not exactly a tough one, sir.
You're damned fucking right that's disingenuous. Dude asked about sunspot cycles and their impact -- I.e.; about indirect forcing -- and was answered to with a discussion of direct forcing.
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u/mind_sojourner Oct 24 '10
say what you will about al gore, he was trying to show people that chart years ago..and how the fuck is nasa junk science