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An Overview of Modern Global Warming

Jack Hays

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This was presented by a regular contributor to Judith Curry's Climate, Etc. blog. It is refreshingly unpolemical.


Nature Unbound VIII – Modern global warming

Posted on February 26, 2018 | 12 comments
by Javier
Summary: Modern Global Warming has been taking place for the past 300 years. It is the last of several multi-century warming periods that have happened during the Neoglacial cooling of the past 3000 years. Analysis of Holocene climate cycles shows that the period 1600-2100 AD should be a period of warming. The evidence suggests that Modern Global Warming is within Holocene variability, but the cryosphere displays a non-cyclical retreat that appears to have undone thousands of years of Neoglacial ice advance. The last 70 out of 300 years of Modern Global Warming are characterized by human-caused, extremely unusual, rapidly increasing CO2 levels. In stark contrast with this rapidly accelerating anthropogenic forcing, global temperature and sea level appear to have continued their rising trend with no perceptible evidence of added acceleration. The evidence supports a higher sensitivity to CO2 in the cryosphere, suggesting a negative feedback by H2O, that prevents CO2 from having the same effect elsewhere.

Continue reading

Conclusions
1) Modern Global Warming is one of several multi-centennial warming periods that have taken place in the last 3000 years.
2) Holocene climate cycles project that the period 1600-2100 AD should be a period of warming.
3) A consilience of evidence supports that Modern Global Warming is within Holocene variability.
4) Modern Global Warming displays an unusual non-cyclical cryosphere retreat. The contraction appears to have undone most of the Neoglacial advance.
5) The last quarter (70 yr) of Modern Global Warming is characterized by extremely unusual and fast rising, very high CO2 levels, higher than at any time during the Late Pleistocene. This increase in CO2 is human caused.
6) The increase in temperatures over the past 120 years shows no perceptible acceleration, and contrasts with the accelerating CO2 forcing.
7) Sea level has been increasing for the past 200 years, and its modest acceleration for over a century shows no perceptible response for the last decades to strongly accelerating anthropogenic forcing.
8) The evidence supports a higher sensitivity to increased CO2 in the cryosphere, which is driving unusual melting and a small long-term sea level rise acceleration. The rest of the planet shows a lower sensitivity, indicating a negative feedback by H2O, that prevents CO2 from having the same effect elsewhere.
 
This was presented by a regular contributor to Judith Curry's Climate, Etc. blog. It is refreshingly unpolemical.


Nature Unbound VIII – Modern global warming

[FONT=&]Posted on February 26, 2018 | 12 comments[/FONT]
by Javier
Summary: Modern Global Warming has been taking place for the past 300 years. It is the last of several multi-century warming periods that have happened during the Neoglacial cooling of the past 3000 years. Analysis of Holocene climate cycles shows that the period 1600-2100 AD should be a period of warming. The evidence suggests that Modern Global Warming is within Holocene variability, but the cryosphere displays a non-cyclical retreat that appears to have undone thousands of years of Neoglacial ice advance. The last 70 out of 300 years of Modern Global Warming are characterized by human-caused, extremely unusual, rapidly increasing CO2 levels. In stark contrast with this rapidly accelerating anthropogenic forcing, global temperature and sea level appear to have continued their rising trend with no perceptible evidence of added acceleration. The evidence supports a higher sensitivity to CO2 in the cryosphere, suggesting a negative feedback by H2O, that prevents CO2 from having the same effect elsewhere.

Continue reading

Conclusions
1) Modern Global Warming is one of several multi-centennial warming periods that have taken place in the last 3000 years.
2) Holocene climate cycles project that the period 1600-2100 AD should be a period of warming.
3) A consilience of evidence supports that Modern Global Warming is within Holocene variability.
4) Modern Global Warming displays an unusual non-cyclical cryosphere retreat. The contraction appears to have undone most of the Neoglacial advance.
5) The last quarter (70 yr) of Modern Global Warming is characterized by extremely unusual and fast rising, very high CO2 levels, higher than at any time during the Late Pleistocene. This increase in CO2 is human caused.
6) The increase in temperatures over the past 120 years shows no perceptible acceleration, and contrasts with the accelerating CO2 forcing.
7) Sea level has been increasing for the past 200 years, and its modest acceleration for over a century shows no perceptible response for the last decades to strongly accelerating anthropogenic forcing.
8) The evidence supports a higher sensitivity to increased CO2 in the cryosphere, which is driving unusual melting and a small long-term sea level rise acceleration. The rest of the planet shows a lower sensitivity, indicating a negative feedback by H2O, that prevents CO2 from having the same effect elsewhere.

Even the statement "The evidence supports a higher sensitivity to increased CO2 in the cryosphere," must be taken with
a grain of salt, as the Southern cryosphere has seen minimal warming.
 
Even the statement "The evidence supports a higher sensitivity to increased CO2 in the cryosphere," must be taken with
a grain of salt, as the Southern cryosphere has seen minimal warming.

From the text:

. . . Antarctica is an exception to the global reduction of the cryosphere. The continent hasn’t warmed for the past 200 years (figure 110), and it is currently debated if Antarctic melting is contributing to sea level rise and by how much (Zwally et al., 2015). Antarctic lack of climatic response to MGW and CO2increase is not well understood, and it might have to do with the exceptional conditions of the continent that make it unique in many aspects. . . .
 
From the text:

. . . Antarctica is an exception to the global reduction of the cryosphere. The continent hasn’t warmed for the past 200 years (figure 110), and it is currently debated if Antarctic melting is contributing to sea level rise and by how much (Zwally et al., 2015). Antarctic lack of climatic response to MGW and CO2increase is not well understood, and it might have to do with the exceptional conditions of the continent that make it unique in many aspects. . . .

Fair enough, I was thinking of the cryosphere as both polar regions, as opposed to simply the arctic.
CO2 is the same in both places, so whatever is warming the arctic must only be partially related to added CO2.
 
Fair enough, I was thinking of the cryosphere as both polar regions, as opposed to simply the arctic.
CO2 is the same in both places, so whatever is warming the arctic must only be partially related to added CO2.

Judith Curry herself led off the comments.

curryja [FONT=&quot]| February 26, 2018 at 10:54 am | Reply[/FONT]
An alternative explanation/contribution for greater than normal melting of NH glaciers is soot
Feedbacks in the polar regions are somewhat counterintuitive, i spent the 90’s studying this. CO2 does have greater radiative impact at colder temperatures (with low water vapor). The water vapor feedback at these cold subzero temperatures is strongly positive, controlled by the temperature dependence of ice saturation (from Clausius Clapeyron). Cloud feedbacks are of opposite sign, with clouds in winter overall having a warming effect.
Some very interesting food for thought here.
 
Even the statement "The evidence supports a higher sensitivity to increased CO2 in the cryosphere," must be taken with
a grain of salt, as the Southern cryosphere has seen minimal warming.

Did you disregarded what follows?

The evidence supports a higher sensitivity to CO2 in the cryosphere, suggesting a negative feedback by H2O, that prevents CO2 from having the same effect elsewhere.​

There is far greater H2O in the mid and equatorial areas. This causes thicker clouds that shade the earth too. CO2 forcing has very little effect in the tropics due to humidity also. H2o and CO2 share a large part of their greenhouse spectra regions. This allows CO2 to have a greater change of forcing with changes of atmospheric content, as H2O is not already saturating parts of the spectra CO2 is active in.

That said, I agree CO2 still has little effect at the polar areas. It's already too far below freezing to matter much. Soot is the aggressive variable in the north ice melt, and we see almost no ice melting in the south... Very few nations close enough to where the polar cell sweeps aerosols up in the north, but lots of coal, oil, etc, being burned in the northern hemisphere near the polar cell.
 
This was presented by a regular contributor to Judith Curry's Climate, Etc. blog. It is refreshingly unpolemical.


Nature Unbound VIII – Modern global warming

Posted on February 26, 2018 | 12 comments
by Javier
Summary: Modern Global Warming has been taking place for the past 300 years. It is the last of several multi-century warming periods that have happened during the Neoglacial cooling of the past 3000 years. Analysis of Holocene climate cycles shows that the period 1600-2100 AD should be a period of warming. The evidence suggests that Modern Global Warming is within Holocene variability, but the cryosphere displays a non-cyclical retreat that appears to have undone thousands of years of Neoglacial ice advance. The last 70 out of 300 years of Modern Global Warming are characterized by human-caused, extremely unusual, rapidly increasing CO2 levels. In stark contrast with this rapidly accelerating anthropogenic forcing, global temperature and sea level appear to have continued their rising trend with no perceptible evidence of added acceleration. The evidence supports a higher sensitivity to CO2 in the cryosphere, suggesting a negative feedback by H2O, that prevents CO2 from having the same effect elsewhere.

Continue reading

Conclusions
1) Modern Global Warming is one of several multi-centennial warming periods that have taken place in the last 3000 years.
2) Holocene climate cycles project that the period 1600-2100 AD should be a period of warming.
3) A consilience of evidence supports that Modern Global Warming is within Holocene variability.
4) Modern Global Warming displays an unusual non-cyclical cryosphere retreat. The contraction appears to have undone most of the Neoglacial advance.
5) The last quarter (70 yr) of Modern Global Warming is characterized by extremely unusual and fast rising, very high CO2 levels, higher than at any time during the Late Pleistocene. This increase in CO2 is human caused.
6) The increase in temperatures over the past 120 years shows no perceptible acceleration, and contrasts with the accelerating CO2 forcing.
7) Sea level has been increasing for the past 200 years, and its modest acceleration for over a century shows no perceptible response for the last decades to strongly accelerating anthropogenic forcing.
8) The evidence supports a higher sensitivity to increased CO2 in the cryosphere, which is driving unusual melting and a small long-term sea level rise acceleration. The rest of the planet shows a lower sensitivity, indicating a negative feedback by H2O, that prevents CO2 from having the same effect elsewhere.

Who ya gonna believe?

Thousands of dedicated scientists or some dude named Javier on a denier blog?
 
Who ya gonna believe?

Thousands of dedicated scientists or some dude named Javier on a denier blog?

Many of them are referenced in the text.

It is a signal of unreasoning zealotry to call Judith Curry a denier.
 
Did you disregarded what follows?

The evidence supports a higher sensitivity to CO2 in the cryosphere, suggesting a negative feedback by H2O, that prevents CO2 from having the same effect elsewhere.​

There is far greater H2O in the mid and equatorial areas. This causes thicker clouds that shade the earth too. CO2 forcing has very little effect in the tropics due to humidity also. H2o and CO2 share a large part of their greenhouse spectra regions. This allows CO2 to have a greater change of forcing with changes of atmospheric content, as H2O is not already saturating parts of the spectra CO2 is active in.

That said, I agree CO2 still has little effect at the polar areas. It's already too far below freezing to matter much. Soot is the aggressive variable in the north ice melt, and we see almost no ice melting in the south... Very few nations close enough to where the polar cell sweeps aerosols up in the north, but lots of coal, oil, etc, being burned in the northern hemisphere near the polar cell.
Yes, sometimes I should read more than the highlights.
 
Hmm, it looks like Jack's trusted sources have been up to their graph-doctoring tricks again.

This is the graph quoted by Jack's source (Javier) and attributed to G.C. Hegerl et al. 2007. J. Clim. 20, 4, 650-666:

figure-103.png


Whereas this is that actual graph from that paper:

i1520-0442-20-4-650-f02.jpeg


Looks like the instrument record was a little too inconvenient to include. Never mind, Photoshop to the rescue! :lol:

Here's a link to the original paper:

Detection of Human Influence on a New, Validated 1500-Year Temperature Reconstruction
 
Hmm, it looks like Jack's trusted sources have been up to their graph-doctoring tricks again.

This is the graph quoted by Jack's source (Javier) and attributed to G.C. Hegerl et al. 2007. J. Clim. 20, 4, 650-666:

figure-103.png


Whereas this is that actual graph from that paper:

i1520-0442-20-4-650-f02.jpeg


Looks like the instrument record was a little too inconvenient to include. Never mind, Photoshop to the rescue! :lol:

Here's a link to the original paper:

Detection of Human Influence on a New, Validated 1500-Year Temperature Reconstruction

Surprising that got past Curry.
She’s usually so discerning and alert to dishonest arguments. [emoji849]
 
Hmm, it looks like Jack's trusted sources have been up to their graph-doctoring tricks again.

This is the graph quoted by Jack's source (Javier) and attributed to G.C. Hegerl et al. 2007. J. Clim. 20, 4, 650-666:

figure-103.png


Whereas this is that actual graph from that paper:

i1520-0442-20-4-650-f02.jpeg


Looks like the instrument record was a little too inconvenient to include. Never mind, Photoshop to the rescue! :lol:

Here's a link to the original paper:

Detection of Human Influence on a New, Validated 1500-Year Temperature Reconstruction
Perhaps you should have included the first sentence of the description attached to that graph.
Fig. 2. Proxy reconstruction of 30°–90°N mean annual decadally averaged temperatures over land back to a.d. 558.
It represents temperatures just over land, between 30°–90°N.
(I was wondering, because the "Instrumental" on the graph shows warming of 1.5°C,
and I think the decadally averages warming globally for the instrumental period is between .89 and .95°C.
It is likely just me, but I think the fact that their study excluded 3/4 of the planet,
should have been mentioned in the abstract.
 
Who ya gonna believe?

Thousands of dedicated scientists or some dude named Javier on a denier blog?

Since God gave us a brain we use it. Therefore, we question that which doesn't fit.
 
Surprising that got past Curry.
She’s usually so discerning and alert to dishonest arguments. [emoji849]

you won't know until you ask her.
 
Perhaps you should have included the first sentence of the description attached to that graph.

It represents temperatures just over land, between 30°–90°N.
(I was wondering, because the "Instrumental" on the graph shows warming of 1.5°C,
and I think the decadally averages warming globally for the instrumental period is between .89 and .95°C.
It is likely just me, but I think the fact that their study excluded 3/4 of the planet,
should have been mentioned in the abstract.

The source that Photoshopped the graph from that paper was Jack's, not mine.

Anyway, my comment doesn't concern the validity or otherwise of the paper; it concerns the dishonesty of Jack's source (Javier) whose argument relies on a doctored graph from said paper. The fact that Judith Curry publishes articles based on Photoshopped graphs rather undermines her credibility too, don't you think?
 
The source that Photoshopped the graph from that paper was Jack's, not mine.

Anyway, my comment doesn't concern the validity or otherwise of the paper; it concerns the dishonesty of Jack's source (Javier) whose argument relies on a doctored graph from said paper. The fact that Judith Curry publishes articles based on Photoshopped graphs rather undermines her credibility too, don't you think?
I am being critical of the published graph.
The study covers only a small fraction of the planet, yet that is not stated in the abstract.
I also did not see in the paper, them stating what their temporal resolution was,
At least Marcott stated the temporal resolution was an average of 120 years.
 
I am being critical of the published graph.
The study covers only a small fraction of the planet, yet that is not stated in the abstract.
I also did not see in the paper, them stating what their temporal resolution was,
At least Marcott stated the temporal resolution was an average of 120 years.

Well, I'm hardly about to defend the paper. It is Jack's source, Javier, who is (ab)using it to wrongly claim that recent warming is not unusual!
 
Well, I'm hardly about to defend the paper. It is Jack's source, Javier, who is (ab)using it to wrongly claim that recent warming is not unusual!
Actually you cited the original paper, Post #13
https://journals.ametsoc.org/doi/full/10.1175/JCLI4011.1
that is what I am critical of.
The Instrumental graph used only covered the land areas between 30 and 90 North, which just
on a sphere is only 25%, but dropping the ocean areas, likely makes the reference area only about half of that.
Neither the small latitude not the land only statement were found in the abstract.
 
Actually you cited the original paper, Post #13
https://journals.ametsoc.org/doi/full/10.1175/JCLI4011.1
that is what I am critical of.
The Instrumental graph used only covered the land areas between 30 and 90 North, which just
on a sphere is only 25%, but dropping the ocean areas, likely makes the reference area only about half of that.
Neither the small latitude not the land only statement were found in the abstract.

Oh, for heaven's sake! The paper was originally cited by the source that Jack links to in the opening post of this thread. Do you people ever actually read anything? It is Jack's source's argument that is based on this paper, not mine! You don't like the paper? Fine. Then your argument is with Jack, not me.
 
Oh, for heaven's sake! The paper was originally cited by the source that Jack links to in the opening post of this thread. Do you people ever actually read anything? It is Jack's source's argument that is based on this paper, not mine! You don't like the paper? Fine. Then your argument is with Jack, not me.
No, you cited a paper to support your position, I am saying your cited paper has issues with quality.
In the first place, it is not best practice to mix samples with such a wide range of sampling resolution,
the resulting graph means almost nothing.
The instrument record is likely at least 12 hour resolution, whereas the proxies have greater
than a century of average resolution, can you possible see how that might be an issue?
Secondly, the abstract of the paper fails to mention that the proxies used are from only a small fraction of the earth.
If this is what passes for Peer Review these days, then the peer review system is broken.
 
No, you cited a paper to support your position, I am saying your cited paper has issues with quality.
In the first place, it is not best practice to mix samples with such a wide range of sampling resolution,
the resulting graph means almost nothing.
The instrument record is likely at least 12 hour resolution, whereas the proxies have greater
than a century of average resolution, can you possible see how that might be an issue?
Secondly, the abstract of the paper fails to mention that the proxies used are from only a small fraction of the earth.
If this is what passes for Peer Review these days, then the peer review system is broken.

No, I did not cite this paper to support my position! How are you not understanding this? This one of the papers cited by Javier in support of the article that Jack quoted in the original post. I merely linked to it for convenience. You say the paper has issues with quality? Fine. In which case I presume you disagree with the premise of the article quoted by Jack, which is based on a doctored graph from that paper.
 
No, I did not cite this paper to support my position! How are you not understanding this? This one of the papers cited by Javier in support of the article that Jack quoted in the original post. I merely linked to it for convenience. You say the paper has issues with quality? Fine. In which case I presume you disagree with the premise of the article quoted by Jack, which is based on a doctored graph from that paper.

Gotta love how all the deniers rush to criticize a published paper that they have no expertise in, but are totally OK with Jacks dishonest blog spam.

Tells us a lot, actually.
 
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