The environmental debate thread

[Chris C]

Someone needs to point out something in the actual Nature Study that supports the "unreliable model" claim. Someone also needs to point out which model and in which public archive I can check it. These broad generalizations like "models aren't getting it right" don't get us anywhere, and in actual science they try to improve them, not complain about and dismiss them. Someone should also include the error bars (hint, high end) of the uncertainty, and where uncertanties lie.

 

Anyone can run summer temperatures for the dates in the study, and tell me where the models aren't getting the summer-winter variation in the study (i.e. amplification of the surface in winter, amplification in the troposphere in summer with near-zero surface due to phase change). Use "all forcings," and play around with different seasons with altitude.

http://data.giss.nasa.gov/modelE/transient/climsim.html

 

Also, the logic of "do nothing, because models are underestimating observed trends" escapes me. Might as well have a picnic. Rahmstorf 2007 on models and observation would be a good look-at.

[swansont]

Swansont said :

 

"A valid conclusion might be "do not assume global cooling of more than 2 years from a single volcanic event." But I have not claimed that the cooling in question comes from a single event."

 

If you read my reference on volcanoes, you will realise that eruptions large enough to cause global cooling are relatively few and far between. It also states that the Pinatubo/Hudson event (2 eruptions) was the largest of the 20th Century, and had the biggest climatic effect. It caused 2 years cooling. Rather unlikely that eruptions could cause 30 years cooling, especially when the last 10 were in the 20th Century.

 

That claim is not supported by your link. There is nothing in there that suggests that several small volcanoes cannot affect climate. It's not this is a binary state of affecting or not affecting, it's a matter of degree — how much and what type of material, and how much of an effect it has.

 

Regarding Pinatubo, it says "The data collected after these eruptions show that mean world temperatures decreased by about 1 degree Centigrade over the subsequent two years."

 

1 ºC for two years. Tambora was cited as being 3 ºC in another link of yours. But the effect we are discussing is an order of magnitude smaller. So, again, why can't increased overall volcanic activity cause cooling?

 

 

"I asked you to address the sulfate graph"

 

Sorry. I do not know which graph you mean. Can you post it again?

 

 

 

http://www.igac.noaa.gov/newsletter/highlights/1998/pascnl.php

Also linked to in post #155, and prior to that.

[iNow]

So far, no-one has satisfactorily responded to my challenge about ice melt.

 

http://www.ohio.com/news/nation/12998787.html

 

Arctic ice is melting much more quickly than global climate models predicted.

Climate models will predict ice melt which directly results from climate. However, where your approach here fails is in the assumption that it is only climate which results in ice melt. We know that is not the case, nor has anyone in this thread stated that was the case.

 

 

 

 

Here is evidence in support of my position:

 

http://www.nature.com/nature/journal/v423/n6943/full/nature01704.html

 

A high-resolution mapping and sampling study of the Gakkel ridge was accomplished during an international ice-breaker expedition to the high Arctic and North Pole in summer 2001.

 

For this slowest-spreading endmember of the global mid-ocean-ridge system, predictions were that magmatism should progressively diminish as the spreading rate decreases along the ridge, and that hydrothermal activity should be rare. Instead, it was found that magmatic variations are irregular, and that hydrothermal activity is abundant.

 

A 300-kilometre-long central amagmatic zone, where mantle peridotites are emplaced directly in the ridge axis, lies between abundant, continuous volcanism in the west, and large, widely spaced volcanic centres in the east. These observations demonstrate that the extent of mantle melting is not a simple function of spreading rate: mantle temperatures at depth or mantle chemistry (or both) must vary significantly along-axis.

 

Highly punctuated volcanism in the absence of ridge offsets suggests that first-order ridge segmentation is controlled by mantle processes of melting and melt segregation. The strong focusing of magmatic activity coupled with faulting may account for the unexpectedly high levels of hydrothermal activity observed.

 

 

http://www.msnbc.msn.com/id/22246005/

 

...clues to a new natural contribution to the melt arose when scientists discovered a thin spot in the Earth’s crust under the northeast corner of the Greenland Ice Sheet where heat from Earth’s insides could seep through, scientists will report here this week at a meeting of the American Geophysical Union.

 

<...>

 

The newly discovered hotspot, an area where Earth’s crust is thinner, allowing hot magma from Earth's mantle to come closer to the surface, is just below the ice sheet and could have caused it to form, von Frese and his team suggest.

 

“Where the crust is thicker, things are cooler, and where it’s thinner, things are warmer,” von Frese explained. “And under a big place like Greenland or Antarctica, natural variations in the crust will make some parts of the ice sheet warmer than others.”

 

 

http://www.livescience.com/environment/070716_gw_notwrong.html

 

To be sure, there is a certain degree of uncertainty involved in modeling and predicting future changes in the climate, but “you don’t need to have a climate model to know that climate change is a problem,” Oreskes said.

 

Climate scientists have clearly met the burden of proof with the mounting evidence they’ve assembled and the strong predictive power of global warming theory, Oreskes said-- global warming is something to pay attention to.

 

Schmidt agrees. “All of these little things just reinforce the big picture,” he said.

 

 

 

 

 

 

 

Hence, the below is NOT a supported assertion nor conclusion:

 

This is clearly an example of these models failing.

 

This supports my assertion that we cannot trust computer climate models. They are unreliable and inaccurate.

 

 

 

And all of the rest of this is just strawman and misrepresentation/misinterpretation of the position of others:

 

I suspect that certain contributors to this thread have adopted computer models by a process analogous to the Act of Faith so important in religion. In religion, the follower hears what the teacher has to say, and adopts the teaching without evidence - takes it on faith. Here, we have people who adopt computer models purely on faith, because some climate guru says it is so.

 

I say that we should NEVER adopt anything purely because someone who is supposedly expert says it is so. We must remain sceptical, and accept only that for which there is good empirical evidence.

 

 

The above is a key example of why I have called you intellectually dishonest, and have decided to limit the amount of time I waste with you.

[SkepticLance]

To swansont

 

Re sulphate aerosols.

 

I took a look at your graph. It shows a small peak in aerosols around 1880, but minimal aerosol during most of the cooling period of 1880 to 1910, and a very large aerosol peak during the warming of 1910 to 1940. Sulphate aerosols are supposed to be a cooling influence. Your graph does not support your position, I am afraid.

 

Re volcanoes. You said :

 

"But the effect we are discussing is an order of magnitude smaller. "

 

If the volcanic effects you are discussing have been a major cooling influence, then we will see a major dip in the graph (1 to 3 C is massive!) of short duration. This is not what we see.

 

And as far as suggesting a large number of small eruptions - well, that seems unlikely. As I said before, every year sees a number of small eruptions world wide. This is the normal state.

 

The historic abnormal state is the odd massive eruption, which does not appear to have happened (except for Krakatoa, with a 12 month climate effect). If you are suggesting an abnormal number of intermediate size eruptions for that specific 30 year period, then you need to show evidence.

 

To iNow

 

It is a shame you finished your post with your last comment. I had thought you were returning to debating using science. Pity.

 

Your argument does not seem, however, to have much point. You quote a Nature article that deals with magma flows which seems to suggest geological contributions to ice melt.

 

This supports my view, frequently expressed, that there are unknown factors influencing climate, that have not yet been accounted for, and making models inaccurate. Magma flows make predictions inaccurate. What unknown will arise next to show even more inaccuracies in predictions?

 

And then you quote another opinion that, in fact, seems to agree with my point that global climate models are not accurate. Are you arguing with me or agreeing with me?

 

The statement that global warming is real and should be dealt with is not one that I have questioned.

[iNow]

Your argument does not seem, however, to have much point. You quote a Nature article that deals with magma flows which seems to suggest geological contributions to ice melt.

 

This supports my view, frequently expressed, that there are unknown factors influencing climate, that have not yet been accounted for, and making models inaccurate.

Magma flows (TTBOMK) don't impact climate, they impact ice melt, which was precisely my point.

 

You suggested that climate models did not fully account for the observed ice melt. I showed you why this is not an issue since climate models must only deal with ice melt resulting from climate changes. I reminded you that other factors impact ice melt besides just the climate.

 

I have shown that using the delta between observed ice melt and ice melt predicted from climate models alone is not grounds for a conclusion that the models are inaccurate nor untrustworthy, since non-climatary pressures also lead to ice melt.

 

Your response, whether intentionally or not, completely misrepresented my point, which I have now clarified again here above.

 

 

Further, nobody here has argued that the models are perfect. Nor has anyone here (meaning the skeptic side) challenged any specific models. Once you do, I'll begin to take you more seriously, but I will continue to dismiss your posts if all you do is continue making a bunch of blanket accusations against the entire process of modelling.

 

 

 

The statement that global warming is real and should be dealt with is not one that I have questioned.

 

Which is exactly why I keep asking you what you hope to achieve in this thread, and what is your intended goal. You keep responding that you're here for recreation, responding that people who hope to use such fora as these to educate people and get things done in the world are foolish. Your response to my question implies that you are just here to play at the expense of others, which IMO has many parallels to the behavior of a troll.

 

 

 

 

 

 

And then you quote another opinion that, in fact, seems to agree with my point that global climate models are not accurate. Are you arguing with me or agreeing with me?

To address this point, acknowledging a certain degree of uncertainty involved in modeling and predicting future changes is NOT the same as stating:

 

 

 

these models [are] failing.

 

<...>

we cannot trust computer climate models.

 

They are unreliable and inaccurate.

 

So stop equivocating...

[SkepticLance]

To iNow

 

Interesting reply. Still too personal, and too close to direct insults, which are considered unacceptable on these forum threads. Fortunately, I choose not to take offense.

 

On the magma. I do actually see your point. It is one way of looking at things. However, the computer models did make predictions about Arctic sea ice melt, and those predictions were not correct, which means my point remains valid.

 

You said :

 

"Your response to my question implies that you are just here to play at the expense of others"

 

All right. I do not take these forum discussions too seriously, for the simple reason that they do not matter in any significant way. However, since you think I am exploiting others, let me describe a little of my personal philosophy.

 

I am a sceptic. This means that I do not accept anything unless it is supported by good empirical evidence. Scepticism is absolutely vital in science. Without it, we end up with total bulldust. The history of science is riddled with examples where the accepted paradigm was later proven to be wrong. It is sceptics who question these paradigms, prove them wrong, and permit further scientific progress. Without scepticism, science would seize up, and get nowhere.

 

For example : For most of the 20th Century, medical science determined that ulcers and similar conditions were caused by acid damage to the lining of the stomach. Researchers came up with wonderful medications such as H2 blockers, which cut down on acid production, and relieved (to a degree) the symptoms. This symptomatic relief was considered to be 'proof' that their theory was correct.

 

Then some researchers noticed a bacterium associated with ulcers (Helicobacter pylori). They were brave enough to question the paradigm, and suggest that ulcers might be caused by bacteria. They treated ulcers with anti-biotics instead of H2 blockers, and healed them - something that conventional treatment could not do. They even went to the stage of inducing ulcers in themselves by eating cultures of Helicobacter pylori, and then healing themselves with anti-biotics. As close as you get in science to proof positive.

 

Yet it took over ten years after this 'proof' before the whole medical establishment accepted the new idea.

 

The point is that we must question scientific ideas continuously. Consensus is not a 'proof' of correctness. The medics had consensus on the cause of ulcers, and they were wrong. A good sceptic does not question good scientific data, but continuously questions interpretation.

 

That is what I do. If you wish, you can consider my postings here as a lesson to those who fail to question.

[swansont]

To swansont

 

Re sulphate aerosols.

 

I took a look at your graph. It shows a small peak in aerosols around 1880, but minimal aerosol during most of the cooling period of 1880 to 1910, and a very large aerosol peak during the warming of 1910 to 1940. Sulphate aerosols are supposed to be a cooling influence. Your graph does not support your position, I am afraid.

 

 

The mean sulfate level around 1880 is about 25. The mean suflate level by 1910 is about 75. By 1930 it's dropped to about 50.

 

 

Re volcanoes. You said :

 

"But the effect we are discussing is an order of magnitude smaller. "

 

If the volcanic effects you are discussing have been a major cooling influence, then we will see a major dip in the graph (1 to 3 C is massive!) of short duration. This is not what we see.

 

Those are the numbers from YOUR SOURCES for Pinatubo and Tambora. The effects we're looking at for 1880-1910 are an order of a magnitude smaller, so it requires volcanoes of much smaller effect to see that kind of cooling.

 

And as far as suggesting a large number of small eruptions - well, that seems unlikely. As I said before, every year sees a number of small eruptions world wide. This is the normal state.

 

Argument from incredulity.

 

 

The historic abnormal state is the odd massive eruption, which does not appear to have happened (except for Krakatoa, with a 12 month climate effect). If you are suggesting an abnormal number of intermediate size eruptions for that specific 30 year period, then you need to show evidence.

 

I've given a graph of sulphate measurements which, at least for the 19th century, should be due to natural sources.

[SkepticLance]

To swansont

 

I am sorry, but your sulphate aerosol graph does not support your case. High levels of sulphate are supposed to cause cooling. Low levels should, conversely, be associated with warming.

 

Your graph shows two medium peaks in 1880 and about 1885. The rest of the cooling period of 1880 to 1910 shows very low sulphate levels. Therefore the cooling of that period is not caused by sulphate aerosol, and your evidence of vulcanism (apart from 1880 and 1885) is not there.

 

Indeed, we see a large aerosol level from about 1905 to 1930. By your argument, this should cause cooling. Instead we see from 1910 to 1940 a warming of 0.4 C, which is massive bearing in mind that the CO2 increase was under 0.2 ppm per year.

 

I am sorry, Swansont, but it is not possible to conclude from the data presented that the 1880 to 1910 cooling had much, if anything to do with sulphate aerosols or vulcanism.

 

In fact, your graph even weakens the argument that the cooling of 1940 to 1950 was caused by aerosols, since it shows levels lower than around 1910, which was the beginning of a major warming.

[iNow]

On the magma. I do actually see your point. It is one way of looking at things. However, the computer models did make predictions about Arctic sea ice melt, and those predictions were not correct, which means my point remains valid.

I don't follow how you arrive at this conclusion.

 

You said the models cannot be trusted because they do not account for all ice melt.

 

I said the models account for ice melt resulting from climate, and since they are climate models, that's all they need to do. I showed how other factors result in ice melt, and that is why the climate model predictions of ice melt resulting from climate do not align fully with observed ice melt (which occurs due to a multitude of factors, not just climate).

 

You then state, "My point [that for this reason climate models cannot be trusted] remains valid."

 

 

Yeah... I need to stop replying to you again for a while.

[SkepticLance]

iNow

 

The whole point of computer models is to make predictions. If the predictions are wrong, then the models are not much use, no matter how you justify it. If the model makes unreliable or inaccurate predictions, then in effect the model is unreliable and inaccurate, since the predictions are the only thing that has practical benefit.

 

In fact, as a general rule in science, if a hypothesis does not lead to testable and correct predictions, then the hypothesis is wrong. The same applies to models.

 

You may recall that I have said all along that global climate models are unreliable and inaccurate for two reasons.

 

1. The unknowns that may affect results. In the case you outlined, the unknown was geological (magma). It could also be biological (phytoplankton effect) or astronomical (a change in sunspot activity, or an asteroid impact) or anthropogenic (some new pollution effect for example).

 

2. The built in assumptions. The example I gave was the assumption that global warming would not affect cloud formation in any way that might speed or slow the warming. The reference I posted showed how seriously the modellers themselves were taking this shortcoming.

 

Note that these two are NOT the normal error factor. The modellers will calculate probable errors in their models and write in limits. However, the errors from 1 and 2 above are not calculable in that way.

[Cap'n Refsmmat]

I am sorry, but your sulphate aerosol graph does not support your case. High levels of sulphate are supposed to cause cooling. Low levels should, conversely, be associated with warming.

Or maybe just less cooling?

[Chris C]

I'll just toss out my pet-peeve of this broad generalization of "models say" for a minute. A lot of models exist, some designed just to include hydrologic cycle changes with some forcing. Also models aren't just for the future, but whatever...

 

Models don't predict anything, they do projections. If I run a model out to 2x CO2 I'm making a projection, assuming that 2x CO2 occurs and based on thermodynamic and geophysical fluid dynamic principles, the models are doing pretty good. If an asteroid hits the planet, I didn't predict this, nor do I need to. Models don't predict we're going to hit 2x CO2, or that an asteroid is/is not going to hit the planet or what have you, they make a projection saying "if we hit 2x CO2, and nothing unexpected occurs, this is what will happen." And the accuracy of models has shown to be within the range of "usefulness." If a volcanic eruption occurs, that aren't considered in the ensemble, this doesn't effect the usefulness (or lack of) of models. Given our understanding, we'd expect a cooling trend for a year or couple. Knowing what models do, and their limitations, is a good first step to deciding how useful they are. Knowing their history of success, or what would be wrong with them, is another step. If the arctic is melting faster tha nwe think, then it isn't the model that is wrong, it is the physical relationships or the presence of external inputs that we haven't considered, and when we learn about them, then we can make the models better.

 

This is not restricted to climate science

[JohnB]

Or maybe just less cooling?

Just my thought. I expect that if we were to plot the cooling effects by sulphate aerosols we would find the range "High Sulphate Aerosols-Low Suphate Aerosols" would align as "High Cooling Effect-Zero Effect".

 

PS. Thanks Swansont.

[swansont]

To swansont

 

I am sorry, but your sulphate aerosol graph does not support your case. High levels of sulphate are supposed to cause cooling. Low levels should, conversely, be associated with warming.

 

Your graph shows two medium peaks in 1880 and about 1885. The rest of the cooling period of 1880 to 1910 shows very low sulphate levels. Therefore the cooling of that period is not caused by sulphate aerosol, and your evidence of vulcanism (apart from 1880 and 1885) is not there.

 

Indeed, we see a large aerosol level from about 1905 to 1930. By your argument, this should cause cooling. Instead we see from 1910 to 1940 a warming of 0.4 C, which is massive bearing in mind that the CO2 increase was under 0.2 ppm per year.

 

How can 1910 show low sulfate levels and yet 1905 shows large levels? This is contradictory.

 

And the levels are clearly dropping before 1920.

 

In fact, your graph even weakens the argument that the cooling of 1940 to 1950 was caused by aerosols, since it shows levels lower than around 1910, which was the beginning of a major warming.

 

It weakens an argument I have not made?

 

All I've pointed out about that time period is that TSI is increasing then, and this questions the claim that solar could be responsible for 0.4 ºC of warming from 1910-1940.

[SkepticLance]

To Chris

 

Your description of models is probably close to the truth. I am not sure that the distinction between 'projections' and 'predictions' has much import apart from semantics, since predictions are also usually hedged with a few conditions also. However, lots of people, some here on this forum, some scientists, and plenty of media types, accept the models 'projections' as if they were gospel writ by God.

 

What I am trying to get through to people is that the models are not that good. Their projections or predictions have an error factor that is not just the calculated error that appears in scientific papers. Above and beyond that is the potential errors from unknown impacts (not necessarily asteroidal), and the errors that occur when people discover that the assumptions the models are based on are not strictly correct.

 

To swansont

 

You are clinging to evidence that has no substance. Take a look at your sulphate aerosol graph again. It does NOT show aerosols to be a cause of cooling during the 1880 to 1910 period.

[swansont]

I have to admit I was wrong on Mt. Pinatubo, which cooled the Earth for two years. Failure of memory. Deep sigh. Doesn't affect my argument. though.

 

It was more than three years before the aerosol level and temperature returned to normal, according to NASA data. And the model of the resulting temperature effect is also shown.

 

http://www.giss.nasa.gov/research/briefs/hansen_02/

http://www.sciencemag.org/cgi/content/full/296/5568/727/F2

http://earthobservatory.nasa.gov/Library/GlobalWarmingUpdate/global_warming_update4.html

[swansont]

To swansont

 

You are clinging to evidence that has no substance. Take a look at your sulphate aerosol graph again. It does NOT show aerosols to be a cause of cooling during the 1880 to 1910 period.

 

The mind boggles

[swansont]

Just for fun I superimposed the sulfate levels on the temperature graph (inverted because of the negative impact). Pretty good matchup of the big temperature drop around 1900-1910, and also how (presumably predominantly industrial) sulfates look to have had an impact after 1940, where the temperature dropped and then showed little increase.

 

Also, I overlayed the Solanki 2007 TSI graph. Notice how the only real significant correlation is around 1880, where temperature lags the solar decline by a few years. Then it's basically flat, while temperature continues to fall. The relatively large TSI rise that occurs later does not begin until 1930, lagging the temperature rise by 20 years, and so the temperature rise starting in 1910 cannot be caused by solar variation.

[iNow]

What I am trying to get through to people is that the models are not that good. Their projections or predictions have an error factor that is not just the calculated error that appears in scientific papers.

And as was asked on the second page of this very thread... Which models specifically? Sharing this openly will allow us to view your assertions in context and calculate for ourselves the error you've implied.

[SkepticLance]

To swansont

 

You are stretching......

 

First. Your references to Mt. Pinatubo. The world cooled for 2 years, and then was warming again. Warming began after less than 2 years according to your own reference. And this was for the largest volcanic event of the 20th Century.

 

Second : Your aerosols of 1880 to 1910. For most of that cooling period, aerosols were at a low level - way less than the average level for the 20th century. There were a couple of medium and quite unexceptional peaks around 1880, and then nothing till after 1905.

 

On the other hand, aerosol peaks were very high around 1910, which was when the second biggest warming event of the 20th Century began. The suggestion that cooling is caused by aerosols is counter-indicated by these figures.

 

It is interesting to see the very large peak around 1815, which probably relates to the eruption of Mt. Tambora, and which caused a major cooling lasting 12 months. This peak is larger by far than any until after 1990. It makes the peaks you refer to look tiny.

 

I do not dispute that sulphate aerosols are a cooling influence. Just that they had much influence 1880 to 1910. Your own figures deny that, and illustrate the much more powerful effect of some other factor.

[swansont]

First. Your references to Mt. Pinatubo. The world cooled for 2 years, and then was warming again. Warming began after less than 2 years according to your own reference. And this was for the largest volcanic event of the 20th Century.

 

It took 4 to return to "normal" levels.

 

before, you said

High levels of sulphate are supposed to cause cooling.

 

So using this definition, there were ~4 years of cooling, since the sulfate levels were high. Using another definition, it cooled for 2 years and warmed for 2, all the while being cooler than would have otherwise occurred. Doesn't really matter which one you use, but use it consistently.

 

Second : Your aerosols of 1880 to 1910. For most of that cooling period, aerosols were at a low level - way less than the average level for the 20th century. There were a couple of medium and quite unexceptional peaks around 1880, and then nothing till after 1905.

 

That's not a valid comparison unless you know how much cooling happened later in the 20th century! Even so, the change from 1880-1910 is larger (both in absolute and especially in relative terms) than the change from 1910 to present.

 

There is a very large change in the sulfate levels around 1900-1910, then they drop off. I don't see how you can look at the graph and deny that.

 

 

On the other hand, aerosol peaks were very high around 1910, which was when the second biggest warming event of the 20th Century began. The suggestion that cooling is caused by aerosols is counter-indicated by these figures.

 

And as you pointed out with Pinatubo, if you get cooling from elevated sulfate levels, you should get warming as they subside. Either it happens this way or it doesn't.

 

It is interesting to see the very large peak around 1815, which probably relates to the eruption of Mt. Tambora, and which caused a major cooling lasting 12 months. This peak is larger by far than any until after 1990. It makes the peaks you refer to look tiny.

 

Yes the peak is larger, but then so was the cooling. As your source pointed out, Tambora caused 3 ºC of cooling. How big does the peak need to be to cause, say, 10% of that amount of cooling?

[SkepticLance]

Swansont said

 

"It took 4 to return to "normal" levels."

 

There were two years of cooling. You are claiming that 30 years of cooling in 1880 to 1910 had the same cause. Pinatubo was the biggest volcanic event in 100 years, and caused only 2 years of cooling. Your claim that much lower levels of sulphate aerosol release can cause 30 years does not hold water.

 

You said

 

"There is a very large change in the sulfate levels around 1900-1910, then they drop off. I don't see how you can look at the graph and deny that."

 

There is a very important principle that goes : "Everything is relative."

So let me rephrase your statement.

 

"Relative to the degree of change in aerosol level over the entire graph, there is a very small, almost trivial, increase in sulphate levels around 1900 - 1910, then they drop off."

 

You are making very big claims for a very small change. As I said, you are stretching. The increase in aerosols around 1910 is massive compared to this trivial change. If your principle is correct, then there should be a massive cooling from 1910 on. Instead we get the second greatest warming in the last 100 years. As the great robot said : "This does not compute!"

 

"Yes the peak is larger, but then so was the cooling. As your source pointed out, Tambora caused 3 ºC of cooling. How big does the peak need to be to cause, say, 10% of that amount of cooling?"

 

The degree of cooling is not the point. It is the period of cooling that matters. Tambora caused a cooling of 12 months. You are claiming minimal increase in aerosols causing a cooling of 30 years, whereas much larger increases in aerosols are associated with the warming from 1910 on. Can you not see the problems here?

[swansont]

Swansont said

 

"It took 4 to return to "normal" levels."

 

There were two years of cooling. You are claiming that 30 years of cooling in 1880 to 1910 had the same cause. Pinatubo was the biggest volcanic event in 100 years, and caused only 2 years of cooling. Your claim that much lower levels of sulphate aerosol release can cause 30 years does not hold water.

 

No, I am not. It's clear when you paraphrase me that you have not understood my arguments at all. I have never claimed that any forcing is the sole cause of any temperature change — you're the one who keeps phrasing things that way.

 

My claim has been that your starting point of 1910 (for the 1910-1940 warming) comes at the end of some significant cooling from volcanic activity. You're the one who keeps bringing up the 30-year stretch; I have never claimed that the entire cooling of that time was due to volcanic activity!

 

To refresh your memory:

Let's take the temperature increase from ~1910-1940 at 0.4 ºC as correct. Now, the CO2 increase then was "trivial" but how much is that? Half of the recent increase? A third? Because that still gives an increase of ~0.15 - 0.2 ºC as being due to CO2 (0.15 - 0.2 ºC per decade, three decades, and take a third of that). And, as we've discussed before, ~1910 represents the end of some high volcano activity, which had caused significant cooling. So what does that contribute? 0.1 - 0.2 ºC? The combination of those two take up more than half of the observed increase.

 

See! I claimed that the decrease in volcanic activity caused 0.1 - 0.2 ºC of cooling and subsequent warming. The cooling from 1880-1910 was almost 0.4 ºC.

 

You said

 

"There is a very large change in the sulfate levels around 1900-1910, then they drop off. I don't see how you can look at the graph and deny that."

 

There is a very important principle that goes : "Everything is relative."

So let me rephrase your statement.

 

"Relative to the degree of change in aerosol level over the entire graph, there is a very small, almost trivial, increase in sulphate levels around 1900 - 1910, then they drop off."

 

No, as I stated before, the sulfate level rises from around 25 to around 75, with the bulk of that occurring between 1900 and 1910. Compare this to the mean level at around 1970, where the average is between 100 and 125 (looks to be ~110).

 

You have to quantify these things. The use of adjectives is a poor way to analyze things, especially when you do it incorrectly. An increase from 25 to 75 is certainly not small or trivial. It's comparable to the increase from 1940 to 1970.

 

 

You are making very big claims for a very small change. As I said, you are stretching. The increase in aerosols around 1910 is massive compared to this trivial change. If your principle is correct, then there should be a massive cooling from 1910 on. Instead we get the second greatest warming in the last 100 years. As the great robot said : "This does not compute!"

 

 

The increase in aerosols around 1900-1910 (and the subsequent decrease) is what I'm talking about! Why do you think there should be massive cooling after 1910, since that's around when the sulfate levels start falling? I'm certainly not making that claim.

 

 

"Yes the peak is larger, but then so was the cooling. As your source pointed out, Tambora caused 3 ºC of cooling. How big does the peak need to be to cause, say, 10% of that amount of cooling?"

 

The degree of cooling is not the point. It is the period of cooling that matters. Tambora caused a cooling of 12 months. You are claiming minimal increase in aerosols causing a cooling of 30 years, whereas much larger increases in aerosols are associated with the warming from 1910 on. Can you not see the problems here?

(emphasis added)

 

The mind boggles, again. The degree of cooling is not the point? It's exactly the point! If Tambora cause 3 ºC of cooling for sulfate levels that spiked to 275 (and were not sustained to that level), what level of cooling will you get for a sustained increase from 25 to 50? You seem to be claiming that it can't be as large as a few tenths of a degree, yet that's what the proportions are — it's one-tenth of the increase.

[SkepticLance]

Swansont

 

I have to conclude either

1. We are looking at different graphs, or

2. You haven't the faintest idea of how to read a graph.

 

I do not believe the latter, since you are clearly not stupid. However, some of the things you have said about the sulphate graph are just wrong.

 

The graph I am looking at says :

Around 1880, two peaks reaching a maximum of just under 150ng/g

About 1885 to about 1895, sulphate falling to about 30 ng/g

1895 to about 1905, sulphate rising to about 40 ng/g average

After 1905, rising to a maximum of about 240 ng/g, although with a medium term average of about 75.

The mean level appears to rise from 75 to about 100 by 1950

 

In other words, sulphate aerosol levels by 1910 are large and grow even larger. If they are cooling influences, then why does the temperature rise so dramatically 1910 to 1940?

 

You said :

 

"My claim has been that your starting point of 1910 (for the 1910-1940 warming) comes at the end of some significant cooling from volcanic activity."

 

The way I read the graph, is that the starting point of 1910 just after the beginning of some significant rise in sulphate aerosol. If sulphate comes from vulcanism, then there must have been a hell of a lot of it from 1910 onwards. And we know that was not true. If we read the sulphate graph from 1910 to 1930, in isolation, without knowing any of the other values, we would conclude that higher sulphate levels caused global warming.

 

Swansont

 

We might be looking at the same graph, but we sure are not seeing the same graph. What you claim is so tainted by your expectation, that you simply cannot see what is in front of you.

[swansont]

Swansont

 

I have to conclude either

1. We are looking at different graphs, or

2. You haven't the faintest idea of how to read a graph.

 

I do not believe the latter, since you are clearly not stupid. However, some of the things you have said about the sulphate graph are just wrong.

 

The graph I am looking at says :

Around 1880, two peaks reaching a maximum of just under 150ng/g

About 1885 to about 1895, sulphate falling to about 30 ng/g

1895 to about 1905, sulphate rising to about 40 ng/g average

After 1905, rising to a maximum of about 240 ng/g, although with a medium term average of about 75.

The mean level appears to rise from 75 to about 100 by 1950

 

I've said "mean sulfate level" about a half-dozen times, so I though it would be clear I'm not looking at the spikes, which are of relatively short duration.

 

 

But, if you want to look at the peaks, OK. Peak in 1883. What effect does that have on temperature?

 

Several medium peaks between 1900 and 1910. Large peak around 1903 and another in ~1910. What effect does that have on temperature?

 

 

In other words, sulphate aerosol levels by 1910 are large and grow even larger. If they are cooling influences, then why does the temperature rise so dramatically 1910 to 1940?

 

Sulfate levels are clearly dropping between 1910 and 1935. The claim that the levels grow after 1910 is clearly not true.

 

What is the mean sulfate level in 1935? (about 50 ng/g)

Is that bigger or smaller than in 1910? (smaller, by about 25 ng/g)

 

What effect will smaller sulfate levels have on temperature? (it will go up)

 

 

You said :

 

"My claim has been that your starting point of 1910 (for the 1910-1940 warming) comes at the end of some significant cooling from volcanic activity."

 

The way I read the graph, is that the starting point of 1910 just after the beginning of some significant rise in sulphate aerosol. If sulphate comes from vulcanism, then there must have been a hell of a lot of it from 1910 onwards. And we know that was not true. If we read the sulphate graph from 1910 to 1930, in isolation, without knowing any of the other values, we would conclude that higher sulphate levels caused global warming.

 

The level is going down in that time span, so I don't see what the problem is here.

 

Swansont

 

We might be looking at the same graph, but we sure are not seeing the same graph. What you claim is so tainted by your expectation, that you simply cannot see what is in front of you.

 

Yeah, me and those other silly scientists who actually do this for a living.

http://www.grida.no/climate/ipcc_tar/wg1/fig6-8.htm (graph d)