Global Warming - Human caused or not?

[RickG]

Is there a legitimate hypothesis or theory that can show the current global warming trend (1880 to present) to be natural rather than anthropogenic?

 

[AV1611VET]

Is there a legitimate hypothesis or theory that can show the current global warming trend (1880 to present) to be natural rather than anthropogenic?

QV this doosey of a debate between Thaumaturgy and Glenn Morton: 1

 

[plindboe]

QV this doosey of a debate between Thaumaturgy and Glenn Morton: 1

Doosey? I thought it was an excellent debate. One I declare thaumaturgy the clear winner of. I recommend everyone to read it.

Peter

 

[Loudmouth]

Humans have increased the carbon dioxide level of the atmosphere by quite a bit. Prior the industrial revolution, the highest the atmospheric content got to was ~280 ppm. It is now ~390 ppm. This increase occurred in lock step with our consumption of fossil fuels. The link is undeniable. We have increased carbon dioxide levels well beyond what they would naturally be.

Let's even ignore the correlation between historic carbon dioxide levels and temperature proxies. Let's just look at the pure physics of it. If you increase the carbon dioxide levels in the atmosphere you trap more heat in the atmosphere. How much? That is what the current models are working on. However, more heat is being trapped. Our contribution to atmospheric carbon dioxide can also have other effects which amplify the effect. For example, for every little bit of heat trapped in the atmosphere more heat is transferred to ocean waters. The warmer the water the more carbon dioxide the water releases, amplifying the effects of the initial carbon dioxide addition. As the ocean waters warm, the land gets warmer too. This includes areas with permafrost. As permafrost thaws it rots. When it rots it releases massive amounts of methane. Methane is also a potent greenhouse gas, but it has a short residence time in the atmosphere because it is slowly oxidized. What is it oxidized to? Carbon dioxide.

 

[abysmul]

Going back tens of thousands, hundreds of thousands, millions, of years... has the Earth ever been warmer than it is now, or cooler?

 

[thaumaturgy]

Doosey? I thought it was an excellent debate. One I declare thaumaturgy the clear winner of. I recommend everyone to read it.

Peter

You are too kind.

It was a bruising debate and I don't think we ended it well. I wish it had gone a bit differently.

As to the OP: there are obviously hypotheses related to natural forcings, but from my understanding of the literature the various attribution studies keep coming back to Anthropogenic Forcings as dominant.

IPCC has an entire chapter dedicated to "Attribution Studies" (LINKY) But for my money the most interesting single graph that sums it all up is this one:

The best "explanation" of the data (using hindcast modelling, which is taking data from times and climate we have already experienced and running the models seems to show a much better fit when anthropogenic factors are added in.

The important key for all the skeptics to remember is: no scientist ignores outright the impact of natural forcings. It's a matter of how important, how much impact the various forcings have on explaining why the climate is doing what it is doing.

Think of it this way:

If you have a sudden increase in death in a given city you can look at the data and say "Well, there's always been a certain number of deaths that are attributable to, say, pedestrians being hit by cars, or natural causes like illness or heart attack, but in the past month we've seen a big increase in the rate of deaths"

If you look at the data you can still see the signal from "pedestrians being hit by cars" and "heart attacks" and other "standard" means that have always accounted for a given death rate. But if you look closely you might also see that there's a "gang war" going on in part of town that is racking up the body count.

So yes, some death is still occuring related to pedestrians crossing against the light which should be addressed or kept in mind, but the biggest increase lately is probably largely impacted by the gang war, so let's put some extra money and effort toward stopping this gang war.

 

[thaumaturgy]

Going back tens of thousands, hundreds of thousands, millions, of years... has the Earth ever been warmer than it is now, or cooler?

It has been both. And before humans we have an excellent way to assess how 'natural' forcings affect global climate. In fact one of the ways we have some assurity that our current release of huge amounts of greenhouse gases like CO2 (by our actions) will have a given effect on the temperature is because we know what natural CO2 changes have done in the past when humans weren't even around.

The earth's climate can be affected by a number of things. Not least of which is an animal who, in about the mid 19th century started putting enough CO2 into the atmosphere from burning of fossil fuels that it measurably changed the isotopic composition of the CO2 in the atmosphere in such a way as one would expect from the burning of fossil fuels on a massive scale.

This is just one bit of evidence. Couple these two together and you have a good case that the current reason the earth is warming may be largely due to human actions.

Here's my favorite syllogism for skeptics:

1. Gunshot wounds to the head often result in death.
2. Bob is dead.
3. Ergo Bob was shot in the head.

Does that make sense? Not really. Bob could have died from a heart attack or been hit by a car!

The same goes for the earth. There are natural forcings which can cause global warming. There are also anthropogenic forcings which can cause global warming. Just because there is global warming does not mean you automatically assume against all evidence that if it happened naturally in the past that it must be "natural" and not anthropogenic.

 

[Loudmouth]

Thaumaturgy,

I have often heard that historical increases in temperature preceded increases in atmospheric carbon dioxide (per ice cores). Is this a valid finding, and how does it affect our current understanding of anthropogenic warming?

 

[thaumaturgy]

Thaumaturgy,

I have often heard that historical increases in temperature preceded increases in atmospheric carbon dioxide (per ice cores). Is this a valid finding, and how does it affect our current understanding of anthropogenic warming?

My understanding of this effect is (and it certainly stands to reason) that if you increase the global average temperature you will likely exsolve more gases from the oceans,including CO2.

So CO2 can lead as well as lag.

Any time you have a body of water and you heat it up it is reasonable to assume that more of the dissolved gases will come out.

The key factor here is that, CO2, regardless of its source is a known greenhouse gas. The nature of the O=C=O bonds means it absorbs nicely in the IR region. So it has the ability to be a greenhouse gas.

These are two kind of "unrelated" effects but in warming up a globe, say, by adding more greenhouse gas of whatever sort, perhaps, say, CO2, can lead to further exsolution of the gas from the ocean.

But let's say the globe is warming due to increased sun or Milankovich cycling, something unrelated to greenhouse gases, this too can result in release of CO2 dissolved in the oceans.

 

[RickG]

I have often heard that historical increases in temperature preceded increases in atmospheric carbon dioxide (per ice cores). Is this a valid finding, and how does it affect our current understanding of anthropogenic warming?

It's a completely valid finding and fully explainable with Milankovitch cycles, where warming was responsible for the release of more CO2, thus amplifying the effect. However today, the earth's eccentricity, obliquity and precession are not in a position to trigger either warming or cooling, thus, that can be ruled out as a natural cause. With the current warming trend, it is clear that CO2 is leading, not lagging.

 

[RickG]

Doosey? I thought it was an excellent debate. One I declare thaumaturgy the clear winner of. I recommend everyone to read it.

Peter

Wow! Yes, thaumaturgy was a clear winner after only reading the first page. It seems the only data the OP wanted to present was his own cherry picked data, ignoring the bulk of data that nullified his cherry picks. However, that debate begin in 2004, I wonder what his position is today; especially in light of the recently released "BEST" studies by some very well known GW skeptics that concluded that, "yup! the surface and sea temperature data is accurate and it is warming like they said".

 

[thaumaturgy]

Wow! Yes, thaumaturgy was a clear winner after only reading the first page. It seems the only data the OP wanted to present was his own cherry picked data, ignoring the bulk of data that nullified his cherry picks. However, that debate begin in 2004, I wonder what his position is today; especially in light of the recently released "BEST" studies by some very well known GW skeptics that concluded that, "yup! the surface and sea temperature data is accurate and it is warming like they said".

Mr. Morton is still an active skeptic, but his blog has not been updated for a while:

The Migrant Mind

Frankly I entered into the debate with Glenn because he was kind of a hero of mine for his stance on YEC. He's worked as a geologist and his story is legendary about how he moved away from YEC, even while still retaining his faith and his science.

However, after the bruising battle between us over global climate change I began to realize there were aspects about him that I didn't quite realize were there or like much.

It was actually quite sad. Glenn is a smart man, no doubt, but debating him on global climate change was a painful reminder that because you may agree with someone on one thing you can so strenuously disagree on another, and sometimes your heroes are not who you might wish they were.

 

[RickG]

Mr. Morton is still an active skeptic, but his blog has not been updated for a while:

The Migrant Mind

Frankly I entered into the debate with Glenn because he was kind of a hero of mine for his stance on YEC. He's worked as a geologist and his story is legendary about how he moved away from YEC, even while still retaining his faith and his science.

However, after the bruising battle between us over global climate change I began to realize there were aspects about him that I didn't quite realize were there or like much.

It was actually quite sad. Glenn is a smart man, no doubt, but debating him on global climate change was a painful reminder that because you may agree with someone on one thing you can so strenuously disagree on another, and sometimes your heroes are not who you might wish they were.

I recognized the name but didn't think it was "that" Glenn Morton. I think being honest enough to do what he did, he will eventually open up and look at all the evidence. Perhaps the lack of updating his blog is a sign that he is beginning to realize where his information comes from, i.e., media and "wanta be" climate science blogs, rather than the actual climate science literature.

I have yet to find a GW skeptic who is not politically conservative. It's really unfortunate that climate change has become politically polarized.

 

[RickG]

Above is a very revealing animated graphic (source: skepticalscience.com) that demonstrates how global warming skeptics manipulate (cherry pick) data to support their preconceived beliefs. Climate, as defined by the World Meteorological Association, is the average of weather over a period of 30 years or more. The reason for this that there are short term oscillations (ENSO & PDO for example) that affect long term weather a few months to a few years, but do not affect climate. These oscillations move heat around but do not add any to the earth's energy budget. Essentially, they are only noise in the system. That is why one must look at the long term data, not just a few data points to reveal the true trend of climate.

 

[plindboe]

It was a bruising debate and I don't think we ended it well. I wish it had gone a bit differently.

Indeed, but I was amazed at your patience at the end. Morton's demon was still hard at work and it wasn't a pretty sight. Sure, no side is ever perfect and there are always things that could have been improved, but I saw alot more introspection and honest debating from you than the other side.

Peter

 

[thaumaturgy]

I recognized the name but didn't think it was "that" Glenn Morton. I think being honest enough to do what he did, he will eventually open up and look at all the evidence. Perhaps the lack of updating his blog is a sign that he is beginning to realize where his information comes from, i.e., media and "wanta be" climate science blogs, rather than the actual climate science literature.

I was wondering about the lack of updates for a while.

I have yet to find a GW skeptic who is not politically conservative. It's really unfortunate that climate change has become politically polarized.

It is a problem in the discussion. I wish it hadn't become a political football of sorts, but it was probably destined to be because the choices we're likely to have to make will require legislation and cost. And that's where our dedication to being proactive meets our fear of progressive actions.

It's understandable why some would fight this tooth and nail. But it's like fighting the bus that's barrelling down on you as you stand in the crosswalk.

 

[Greatcloud]

Global warming man made or natural ?
S Fred Singer

Hillsdale College - Imprimis Issue

 

[RickG]

Global warming man made or natural ?
S Fred Singer

Hillsdale College - Imprimis Issue

What has Fred Singer published in the climate science literature that backs his position that anthropogenic global warming isn't happening? Fred has stated in the link you provided, "there is no such consensus".

Maybe he's not familiar with:

Expert credibility in climate change (Anderegg 2010)
http://tigger.uic.edu/~pdoran/012009_Doran_final.pdf (Doran 2009)
The Scientific Consensus on Climate Change (Oreskes 2004)

 

[leftrightleftrightleft]

Is there a legitimate hypothesis or theory that can show the current global warming trend (1880 to present) to be natural rather than anthropogenic?

No. I have asked this question on this forum twice already and have never received an answer.

When I press for some hypothesis, anti-AGW advocates don't present one but rather begin pointing out the "flaws" in AGW and then proceed to post a multitude of graphs and links which are unscientific and show no basic understanding of the term "statistically significant".

Legitimate hypothesis: The atmosphere contains substances that act as "Greenhouse Gases" to "trap" outgoing longwave radiation and re-radiate it (at potentially different frequencies) back to the surface thereby keeping a greater amount of energy within the first several kilometers of the surface. Humans are injecting more of these substances into the atmosphere. Therefore, more heat gets trapped. Therefore the temperature goes up.

The logic is sound. The evidence supports it. There shouldn't be a debate.

I've always wondered what the reason is for people being so adamantly against it. Most science subjects don't become so emotional. Is it because of political or economic interests? Because it seems that there are plenty of economic benefits if the Earth were warmer anyway...

 

[RickG]

No. I have asked this question on this forum twice already and have never received an answer.

When I press for some hypothesis, anti-AGW advocates don't present one but rather begin pointing out the "flaws" in AGW and then proceed to post a multitude of graphs and links which are unscientific and show no basic understanding of the term "statistically significant".

Legitimate hypothesis: The atmosphere contains substances that act as "Greenhouse Gases" to "trap" outgoing longwave radiation and re-radiate it (at potentially different frequencies) back to the surface thereby keeping a greater amount of energy within the first several kilometers of the surface. Humans are injecting more of these substances into the atmosphere. Therefore, more heat gets trapped. Therefore the temperature goes up.

The logic is sound. The evidence supports it. There shouldn't be a debate.

I've always wondered what the reason is for people being so adamantly against it. Most science subjects don't become so emotional. Is it because of political or economic interests? Because it seems that there are plenty of economic benefits if the Earth were warmer anyway...

Exactly, there are no legitimate theories or even hypothesis that can explain the current warming trend without human influence. As you stated the skepticism and denial of global warming comes almost entirely from political associations and economic interests, rather than the actual science.

The three studies I linked to in my previous post above are an examination of the published climate science literature and the opinions of actual practicing climate scientists. For instance, the Anderegg 2010 study of the published literature shows 97% of all practicing climate scientists agree that global warming is occurring and it is anthropogenic. Most of that opposing 3% don't deny it, they mostly suggest that climate sensitivity in relation to CO2 is not as strong as the consensus says.

Conversely, look at the link given by Greatcloud to the Fred Singer article. True, Fred Singer was a legitimate atmospheric scientist. Nevertheless, he has never published anything in the scientific literature that demonstrates that GW is not happening or that int is not human caused. The reason for this is that there is no evidence to support his position. Anyone publishing such evidence overturning AGW would be shoe-in for a Nobel Prize. What the Singer article does give is unsupported criticisms.

Another of Singers argument is that climate change in the past has always been natural it is natural as well now. To do this he has to ignore 150 years of well understood greenhouse gas physics, in particular, that of carbon dioxide. One of his main confusions with CO2 is when he looks back at past glacials and interglacials, ignoring that CO2 is both a forcing and a feedback. The argument is that because warming lead CO2 rise in past interglacials, it cannot be the cause of the current warming. What he is missing is the cause of those glacials and interglacials, the Milankovitch Cycles. In such a case CO2 rise follows warming and becomes an amplifying feedback rather than a forcing.