Arctic ice melt could trigger uncontrollable climate change at global level

[qui_est_ce]

Over many decades and over centuries the average global temp has been going up and down, often due to solar radiation cycles. No one disputes that. Altho (not sure) I think some scientists attribute some of the cooling in the 70s to the aerosol effect – the pollutants like SO2, which have a cooling effect, that we emit when we emit GHGs. If anyone remembers the gross pollution in the 60s and early 70s (couldn’t even see your hand in front of your face in LA).

A couple of scientists not in the mainstream back then even thought we could perhaps trigger (after 100s or 1000s of years) an eventual ice age (due to knock-on effects in the climate & earth system).

The aerosol effect was not well understood back then. Now they understand it much better AND we’ve been able to reduce those aerosols, since they are also harmful pollutants.

Those aerosols have a residency in the atmosphere of a few weeks, while CO2 they say 100 years (but a portion can last up to 100,000 years), and CH4 (a potent GHG) some 10 years, so the bottom line is that most climate scientists back then still expected the warming to happen, which it eventually did.

As mentioned climate is a very long term thing, so we have to look over many decades, not just one or two. The longer the term we look at, the better we can understand what factors are driving the climate.

So think of it as natural fluctuations until the 80s – some ups some downs, much of it due to short term solar radiation cycles, some due to el ninos (sloshing in the system), etc. Then from the 80s, a divergence from the natural factors, and a warming despite natural cooling factors, tracking the increasing & accelerating GHG emissions (mainly CO2).

http://solar-center.stanford.edu/sun-on-earth/600px-Temp-sunspot-co2.svg.png

We need to go back centuries, because climate evolves over centuries. This graph
doesn’t go far enough back.

 

[LeafByNiggle]

We need to go back centuries, because climate evolves over centuries. This graph
doesn’t go far enough back.

Other graphs have been posted going back 1000s of years. Those graphs do not have any sudden rise in temperatures that is comparable to rate of warming evident in this graph.

 

[qui_est_ce]

Other graphs have been posted going back 1000s of years. Those graphs do not have any sudden rise in temperatures that is comparable to rate of warming evident in this graph.

Lynn’s graph shows a rise in temp of less the 1 degree C since 1860, when temperature recording began. Where did the data for these older graphs come from?

 

[LeafByNiggle]

Lynn’s graph shows a rise in temp of less the 1 degree C since 1860, when temperature recording began. Where did the data for these older graphs come from?

They come from several cross-checked reconstructions from proxies, like chemical analysis of ice deposits, tree rings etc. As I said multiple proxies have been extensively cross-checked for consistency. Google “temperature reconstructions” to learn more about them.

 

[vz71]

Lynn’s graph shows a rise in temp of less the 1 degree C since 1860, when temperature recording began. Where did the data for these older graphs come from?

They come from several cross-checked reconstructions from proxies, like chemical analysis of ice deposits, tree rings etc. As I said multiple proxies have been extensively cross-checked for consistency. Google “temperature reconstructions” to learn more about them.

They made them up.

 

[Ridgerunner]

Over many decades and over centuries the average global temp has been going up and down, often due to solar radiation cycles. No one disputes that. Altho (not sure) I think some scientists attribute some of the cooling in the 70s to the aerosol effect – the pollutants like SO2, which have a cooling effect, that we emit when we emit GHGs. If anyone remembers the gross pollution in the 60s and early 70s (couldn’t even see your hand in front of your face in LA).

A couple of scientists not in the mainstream back then even thought we could perhaps trigger (after 100s or 1000s of years) an eventual ice age (due to knock-on effects in the climate & earth system).

The aerosol effect was not well understood back then. Now they understand it much better AND we’ve been able to reduce those aerosols, since they are also harmful pollutants.

Those aerosols have a residency in the atmosphere of a few weeks, while CO2 they say 100 years (but a portion can last up to 100,000 years), and CH4 (a potent GHG) some 10 years, so the bottom line is that most climate scientists back then still expected the warming to happen, which it eventually did.

As mentioned climate is a very long term thing, so we have to look over many decades, not just one or two. The longer the term we look at, the better we can understand what factors are driving the climate.

So think of it as natural fluctuations until the 80s – some ups some downs, much of it due to short term solar radiation cycles, some due to el ninos (sloshing in the system), etc. Then from the 80s, a divergence from the natural factors, and a warming despite natural cooling factors, tracking the increasing & accelerating GHG emissions (mainly CO2).

http://solar-center.stanford.edu/sun-on-earth/600px-Temp-sunspot-co2.svg.png

The seeming significance of such things often depends on the scales one uses and the way one compares different trend lines on the same scale.

So, for example, worldwide average temperature is supposed to be about 14 degrees Celsius. The chart shows 8/10 of one degree change from the lowest point to the highest. That’s a difference of about 5.7%, some (or perhaps all) of which took place during a warmup from the Little Ice Age. On the graph, that 5.7% has a visual appearance of much more than a 5.7% change, and that’s because the “average” temperature is not used. Only change is compared to change.

But the difference in sunspot activity from the lowest to the present is about 300%, with an even higher peak in about 1960. The visual difference is very little on the graph because the segments are much larger than for the temperature graph.

The change in CO2 is about 24.5%. But that’s on a scale measuring a change that’s about .0075% of the atmospheric content. If the scale measured percentage of the whole rather than change in a very small number, the line would not seem to have moved at all.

Depending on how you design the chart, you could make an argument that sunspot activity is the real cause of global warming, using the very same numbers.

I’m not saying sunspots are the cause of warming, or even that there is warming going on, though one could argue that we’re still in a rewarming recovery from the Little Ice Age.

I’m just saying that the visual effect of graphs is greatly affected by the way one designs the graph; something that greatly diminishes their usefulness.

The

 

[LeafByNiggle]

The seeming significance of such things often depends on the scales one uses and the way one compares different trend lines on the same scale.

Not for someone who looks at graphs scientifically. You do not have to rely on the appearance of a graph or its rendering to know the significance of the data it represents. Either the graph is accurate or it is not.

So, for example, worldwide average temperature is supposed to be about 14 degrees Celsius. The chart shows 8/10 of one degree change from the lowest point to the highest. That’s a difference of about 5.7%

Ha! That’s a good one! The figure of 5.7% that you quote is absolutely meaningless. That is, it has no absolute meaning, because the “zero” point of temperature is arbitrary. It is easy to see how arbitrary your 5.7% figure is. Let’s just do the same calculation in Fahrenheit. A change of 0.8 degrees Celsius is the same as a change of 1.44 degrees Fahrenheit. And the worldwide average temperature would be 57.2 degrees Fahrenheit. Dividing 1.44 by 57.2 would say that the change represented on the graph is 2.52%. Not 5.7%. See what I mean? But instead of Fahrenheit, suppose we use Leaf degrees, which I just invented. They are Fahrenheit minus 50 degrees. That would mean that the global average temperature would be 57.2 - 50 = 7.2 degrees Leaf. 1.44 divided by 7.2 is 20%. So what is it? 20%? 2.52%? 5.7%? Whatever it is, it has no significance whatsoever. So your citing it to prove a point proves nothing.

But the difference in sunspot activity from the lowest to the present is about 300%, with an even higher peak in about 1960. The visual difference is very little on the graph because the segments are much larger than for the temperature graph.

No one familiar with graphs expects there to be a visual comparison between the span of the sunspot graph and the span of the temperature graph. They are just two separate graphs presented one over the other for correlation comparison. Also your citing of the 300% difference between sunspot minima and maxima proves nothing, other than that sunspots vary a lot. Without knowing how much they effect the total heat output of the sun, one cannot draw any conclusions about the expected effect on temperature. Now I have seen data elsewhere that shows that total heat output of the sun is affect by the number of sunspots (or at least correlated), but the effect is much smaller than the 300% span you see in the sunspot numbers themselves.

The change in CO2 is about 24.5%. But that’s on a scale measuring a change that’s about .0075% of the atmospheric content.

The 0.0075% figure is another misleading figure. You cite it to lead people into thinking that such a small concentration of CO2 could not possibly affect the heat-trapping effectiveness of the atmosphere. But if one takes into account the difference in infrared opacity between CO2 and N2 and O2 (the bulk of the rest of the atmosphere), we see that the CO2 is hugely more significant than the more transparent components of the atmosphere. This can be illustrated with an analogy. Consider an Olympic size swimming pool filled with clear water. The total content is 88,000 gallons. And you would have no trouble seeing the bottom of the pool clearly. Now take 0.0075% of that content (6.6 gallons) of black India ink and poor it into the pool. Can you imagine how 6.6 gallons of very opaque black ink would make it significantly harder to see to the bottom of the pool? And now consider increasing that by 24.5%. It is not hard to understand how the amount of light getting through the pool would also be decreased by 24.5%.

If the scale measured percentage of the whole rather than change in a very small number, the line would not seem to have moved at all.

But the change as a fraction of the total atmospheric content is a totally irrelevant measurement, so it does not matter if that irrelevant parameter seemed not to have moved at all. Go back to the swimming pool analogy. The increase in India ink would be a minuscule change in the total volume of the pool, but so what?

Depending on how you design the chart, you could make an argument that sunspot activity is the real cause of global warming, using the very same numbers.

You would not be able to convince anyone who knows how to read and understand charts.

I’m not saying sunspots are the cause of warming, or even that there is warming going on, though one could argue that we’re still in a rewarming recovery from the Little Ice Age.

You could try to make that argument, but it would not explain why the rate of warming is increasing. If the warming shown in the graph was just the tail end of Little Ice Age recovery, you would expect it to be leveling off a little bit. Instead, the warming in the last 50 years is greater than the warming in the previous 50 years. That sounds like we are heading toward something rather than just getting out of something.

 

[Ridgerunner]

Not for someone who looks at graphs scientifically. You do not have to rely on the appearance of a graph or its rendering to know the significance of the data it represents. Either the graph is accurate or it is not.

Ha! That’s a good one! The figure of 5.7% that you quote is absolutely meaningless. That is, it has no absolute meaning, because the “zero” point of temperature is arbitrary. It is easy to see how arbitrary your 5.7% figure is. Let’s just do the same calculation in Fahrenheit. A change of 0.8 degrees Celsius is the same as a change of 1.44 degrees Fahrenheit. And the worldwide average temperature would be 57.2 degrees Fahrenheit. Dividing 1.44 by 57.2 would say that the change represented on the graph is 2.52%. Not 5.7%. See what I mean? But instead of Fahrenheit, suppose we use Leaf degrees, which I just invented. They are Fahrenheit minus 50 degrees. That would mean that the global average temperature would be 57.2 - 50 = 7.2 degrees Leaf. 1.44 divided by 7.2 is 20%. So what is it? 20%? 2.52%? 5.7%? Whatever it is, it has no significance whatsoever. So your citing it to prove a point proves nothing.

No one familiar with graphs expects there to be a visual comparison between the span of the sunspot graph and the span of the temperature graph. They are just two separate graphs presented one over the other for correlation comparison. Also your citing of the 300% difference between sunspot minima and maxima proves nothing, other than that sunspots vary a lot. Without knowing how much they effect the total heat output of the sun, one cannot draw any conclusions about the expected effect on temperature. Now I have seen data elsewhere that shows that total heat output of the sun is affect by the number of sunspots (or at least correlated), but the effect is much smaller than the 300% span you see in the sunspot numbers themselves.

The 0.0075% figure is another misleading figure. You cite it to lead people into thinking that such a small concentration of CO2 could not possibly affect the heat-trapping effectiveness of the atmosphere. But if one takes into account the difference in infrared opacity between CO2 and N2 and O2 (the bulk of the rest of the atmosphere), we see that the CO2 is hugely more significant than the more transparent components of the atmosphere. This can be illustrated with an analogy. Consider an Olympic size swimming pool filled with clear water. The total content is 88,000 gallons. And you would have no trouble seeing the bottom of the pool clearly. Now take 0.0075% of that content (6.6 gallons) of black India ink and poor it into the pool. Can you imagine how 6.6 gallons of very opaque black ink would make it significantly harder to see to the bottom of the pool? And now consider increasing that by 24.5%. It is not hard to understand how the amount of light getting through the pool would also be decreased by 24.5%.

But the change as a fraction of the total atmospheric content is a totally irrelevant measurement, so it does not matter if that irrelevant parameter seemed not to have moved at all. Go back to the swimming pool analogy. The increase in India ink would be a minuscule change in the total volume of the pool, but so what?

You would not be able to convince anyone who knows how to read and understand charts.

You could try to make that argument, but it would not explain why the rate of warming is increasing. If the warming shown in the graph was just the tail end of Little Ice Age recovery, you would expect it to be leveling off a little bit. Instead, the warming in the last 50 years is greater than the warming in the previous 50 years. That sounds like we are heading toward something rather than just getting out of something.

Interesting response, but certainly an attempt at overkill. My only point was that the graphs that are sometimes produced to show massive temp changes and try to establish causation by parallels with atmospheric CO2 are not something upon which people should base their beliefs about MMGW, since the way you construct a graph can make something appear much more significant than it will if you construct it another way.

I remember in high school algebra drawing out a graph now and then, only to discover that the scale was such that it showed essentially no change or progression. It was only when I changed the scale that it did. Now, that’s really basic stuff, but if you don’t know it, it’s easy to be misled.

Graphs are a neat way of visualizing numbers, though. And that’s their intent. But that visualization can also make a person think a change is more dramatic (or less) than it really is.

 

[LeafByNiggle]

My only point was that the graphs that are sometimes produced to show massive temp changes and try to establish causation by parallels with atmospheric CO2 are not something upon which people should base their beliefs about MMGW.

That is true. Mere correlation does not prove causation. In the case of CO2 and the greenhouse effect, the causation was not proposed based on observation of this correlation. It was proposed by the work of Joseph Fourier in the 1820s, long before the modern rise in CO2 was measurable. Since then the mechanism has been studied in various contexts. The current observed correlation is only meant as a partial confirmation of the theory. It does not prove the theory on its own.

However, if the correlation had turned out to be negative, that would have been a significant blow to the theory, causing scientists to re-evaluate their understanding of what they thought was happening. All scientific theories are refutable, given the proper evidence.

 

[lynnvinc]

That is true. Mere correlation does not prove causation. In the case of CO2 and the greenhouse effect, the causation was not proposed based on observation of this correlation. It was proposed by the work of Joseph Fourier in the 1820s, long before the modern rise in CO2 was measurable. Since then the mechanism has been studied in various contexts. The current observed correlation is only meant as a partial confirmation of the theory. It does not prove the theory on its own.

However, if the correlation had turned out to be negative, that would have been a significant blow to the theory, causing scientists to re-evaluate their understanding of what they thought was happening. All scientific theories are refutable, given the proper evidence.

Also I had not meant that chart as the definitive proof of CC, only that there are many factors that impact climate (in this case global average temps), including solar radiation cycles (and others), so I guess I WAS trying to show that solar radiation increases can increase global average temps and those temps somewhat tracked the solar cycle up until the 80s.

But no one here HAS to believe that the sun has an impact on the climate

 

[Ender]

Not for someone who looks at graphs scientifically. You do not have to rely on the appearance of a graph or its rendering to know the significance of the data it represents. Either the graph is accurate or it is not.

Hold that thought…

The 0.0075% figure is another misleading figure. You cite it to lead people into thinking that such a small concentration of CO2 could not possibly affect the heat-trapping effectiveness of the atmosphere.

It is not misleading “*for someone who looks at *[data] *scientifically…Either the *[data] *is accurate or it is not.” *Your comment about his data is the same as his comment about the graph. They are misleading.

Ender

 

[qui_est_ce]

They made them up.

We can’t be certain what the actual temperature was before 1860. We can probably come up with a pretty good idea of what the temperature range might have been. For example the fossil record shows Greenland to have been considerably warmer from approximately 950 until 1250 than it is today. And it was a positive thing. Greenland’s climate during this time period was able to to sustain dairy farming and pastureland for goats and sheep. They even grew barley for beer making! When the temperature began cooling around 1250, all these farmsteads vanished.

We know from both written and fossil records that Newfoundland also was able to support vineyards, something that is not possible today due to the cold climate.

What the exact temperatures in these areas were, no one knows. We do know that the climate then was able to support much more farming and pasturing activity than it can today.

 

[LeafByNiggle]

Hold that thought…
It is not misleading “*for someone who looks at *[data] *scientifically…Either the *[data] *is accurate or it is not.” *Your comment about his data is the same as his comment about the graph. They are misleading.

Ender

It is misleading for those who do not understand. It is irrelevant for those who do.

 

[LeafByNiggle]

We can’t be certain what the actual temperature was before 1860. We can probably come up with a pretty good idea of what the temperature range might have been. For example the fossil record shows Greenland to have been considerably warmer from approximately 950 until 1250 than it is today. And it was a positive thing. Greenland’s climate during this time period was able to to sustain dairy farming and pastureland for goats and sheep. They even grew barley for beer making! When the temperature began cooling around 1250, all these farmsteads vanished.

We know from both written and fossil records that Newfoundland also was able to support vineyards, something that is not possible today due to the cold climate.

What the exact temperatures in these areas were, no one knows. We do know that the climate then was able to support much more farming and pasturing activity than it can today.

The question is about global climate change - not about the climate of Greenland.

 

[qui_est_ce]

The question is about global climate change - not about the climate of Greenland.

I believe I also mentioned North America in my post.

 

[tomarin]

We can’t be certain what the actual temperature was before 1860. We can probably come up with a pretty good idea of what the temperature range might have been. For example the fossil record shows Greenland to have been considerably warmer from approximately 950 until 1250 than it is today. And it was a positive thing. Greenland’s climate during this time period was able to to sustain dairy farming and pastureland for goats and sheep. They even grew barley for beer making! When the temperature began cooling around 1250, all these farmsteads vanished.

We know from both written and fossil records that Newfoundland also was able to support vineyards, something that is not possible today due to the cold climate.

What the exact temperatures in these areas were, no one knows. We do know that the climate then was able to support much more farming and pasturing activity than it can today.

So that’s why they named it Greenland! I’ve often wondered about that.

 

[Ender]

The question is about global climate change - not about the climate of Greenland.

It seems a bit counterintuitive to talk about a global climate on the one hand, and on the other to suggest that the climate in Greenland for 300 years was somehow anomalous to the rest of the world. Yours is an argument suggesting it is valid to discount inconvenient data.

Ender

 

[qui_est_ce]

So that’s why they named it Greenland! I’ve often wondered about that.

Yup. It’s something that’s fascinated me since high school.

 

[Ridgerunner]

Yup. It’s something that’s fascinated me since high school.

I realize it’s largely irrelevant to this topic, but among other interesting things about temperature changes is the effect it might have had on human history. It’s hard to imagine, for instance, a less welcoming environment than the Eurasian steppes. The way they are today, not many could live there unless heavily resourced.

There are those who claim that the destruction of the Roman Empire was linked to climate change, among other things. The steppes warmed considerably and over a few generations, allowing for a population explosion on the steppes. Then the climate took a change for the cooler, causing peoples to push into more moderate climates. The numbers were too much for western Europe to contain or absorb.

At least some think that. Not sure what it’s based on.

 

[LeafByNiggle]

It seems a bit counterintuitive to talk about a global climate on the one hand, and on the other to suggest that the climate in Greenland for 300 years was somehow anomalous to the rest of the world. Yours is an argument suggesting it is valid to discount inconvenient data.

Ender

Not at all. Whatever happened in Greenland 900 years ago happened gradually. What is happening now due to climate change is happening suddenly, and even Greenland is part of that trend. But even if it weren’t, it is not contradictory to have global warming and some anomalous localized cooling. In the case of Greenland, its temperature is greatly influenced by the North Atlantic Current, which, when it is flowing well, brings warm equatorial waters up north. If climate change weakens the NAC, Greenland might not get as much equatorial heat, which could make it anomalously cooler. Perhaps what happened in 950-1250 was a strengthening NAC.