Guest essay by Tony Brown
Some readers might recall my recent article ‘The Long Slow Thaw?’
In this I reconstructed Central England temperature to 1538 from its current instrumental date of 1659.
I was surprised by two notable periods of warmth around 1630 and 1530. I am indebted amongst other material, to Phil Jones excellent book ‘Climate since 1500 AD’ plus such books as Le Roy Laduries’ Times of feast times of famine’ which confirm that these were indeed warm periods.
The graph below is from my article but to it has been added the official co2 levels. CET is seen by many scientists as a reasonable but by no means perfect proxy for Northern Hemisphere and Global temperatures.
Please note that the graphing package somewhat inflates the warmth in the decade around 1540, although my recent research- which will extend CET to 1498-demonstrates that the period 1500 to 1540 does indeed appear to be around as warm as the warm period in the recent CET period ending around the year 2000, characterised by the distinct hump.
Also from a graphing viewpoint it is debatable as to where the CO2 line should be placed. I chose to place it around the black trend line as the CO2 and temperature trend line probably needs to start together at the same place. This also provides clarity and context to the graphic although others might feel the CO2 line should be placed elsewhere.
However these are all nuances and the point I want to put over is that temperature is highly variable throughout the CET record -which is at variance to Dr Mann’s (global) work and the assertions of the Met office. This is despite a constant level of co2 until around 1900. The temperature decline since 2000 as the CO2 line rises ever further is especially intriguing.
Does it demonstrate that once you get to around the 300ppm level that the law of diminishing returns sets in as the logarithmic curve of CO2 versus temperatures takes effect? Does it illustrate nothing and the current downward CET slope is merely a blip that will increase sharply again as more CO2 is added?
The apparent effects of adding additional CO2 was clearly shown in an article by David Archibald several years ago,
http://wattsupwiththat.com/2010/03/08/the-logarithmic-effect-of-carbon-dioxide/
I merely present my research and findings for comment. An apparent decline perhaps as the logarithmic effect ceases to have any real world meaning? Or merely a hiatus in the ever upwards rise of temperatures since the start of the record in 1659 which may or may not be affected by CO2 and radiative physics?
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Re it’s vs. its: Just remember the phrase NEVER POSSESSIVE.
(I.e., it’s is always a contraction of it is.)
Robert L says: “Doug Jones , your post reminded me of this . http://www.history.com/this-day-in-history/gas-cloud-kills-cameroon-villagers”
Yes, we should remember the 1,700 people who died that day. We should also remember that although warmists claim volcanoes emit relatively little CO2, it was huge amounts of CO2 that killed the villagers. And that there are millions of subsea volcanoes…
In previous threads regarding CO2 emissions, the statement has been made that CO2 is rising exponentially. Note that since 1994, the increase is very close to linear.
“CET is seen by many scientists as a reasonable but by no means perfect proxy for Northern Hemisphere and Global temperatures.”
Any time we have a proxy but also have instrumental data it can be interesting to do the formal calibration.
1) You get an offset.
2) You get a bias.
3) You get an error.
That is: “How useful -is- it?”
Jimbo says:
May 8, 2013 at 5:25 pm
Why is ‘its’ and ‘it’s’ such a damned pain in my arse?
The easy way around the problem is to replace (in your mind) “it” with “he”. If it translates to
“his” then use “its”, if it becomes “he’s” (he is) use “it’s”. This should save your buttocks from the attention of the English master with his cane.
Tony, only a question. You say that many scientists see the CET series ‘as a reasonable but by no means perfect proxy for Northern Hemisphere and Global temperatures’, and no doubt there are some who do. But the Southern Hemisphere usually seems to be cooler than the North by a degree or two, and there are plausible arguments as to why that should be so.
Did you mean simply that the rise and fall as shown by CET is likely to be mirrored in the Southern Hemisphere as well — or at least that some scientists would think so?
Cheers,
Don
A link to the CO2 curve:
http://www.woodfortrees.org/plot/esrl-co2/plot/none
Note how linear the plot has been for the past 20 years.
And about solar cycles, PDOs, AMOs, El Nino, La Nina, Clouds, LIA recovering, Warm-First-Carbon-Later , etc etc
So Tony, how was the CO2 concentration measured from 1540 to 1900 to be that perfectly linear?
thanks
jorgekafkazar says:
May 8, 2013 at 6:20 pm
“Note how linear the plot has been for the past 20 years.”
Yep. That’s because the rate of change of CO2 is proportional to temperature anomaly (relative to a particular baseline). As temperatures leveled off in the past 20 years, so did the slope of the accumulated CO2.
Meanwhile, human inputs kept rising exponentially. When the temperatures start falling, as they already are, in tune with the natural ~60 year cycle, atmospheric measurements will assume an undeniable concavity, which will be in dramatic opposition to the convexity of human emissions. Then, maybe we can finally lay to rest the fiction that humans are having any significant effect on CO2 levels whatsoever.
climatereason says:
May 8, 2013 at 4:56 pm
>>>>>>>>>>>>>>>>>
Nick Stokes, that was a crushing response. Your silence speaks as loudly as Tony’s question to you.
Curious and curiouser the detachment from human CO2 emissions: http://c3headlines.typepad.com/.a/6a010536b58035970c0120a7c87805970b-pi
I say we do away with it’s and always use it is. Hmmmm, but do we always know what the meaning of is is.
Bart- thanks for your insightful comments on several CO2 threads…
Here’s a recent paper published in Nature Climate Change which inadvertently reinforces your points:
http://hockeyschtick.blogspot.com/2013/04/new-paper-demonstrates-temperature.html
Nice work Tony
Hockey Schtick says:
May 8, 2013 at 6:45 pm
Nice. I’m no longer a lone voice wandering in the wilderness. Thanks.
I tried to post the following at your link but, for some reason, it does not accept an anonymous posting and I do not belong to any of the other profiles.
Tonyb,
“Thats why I made sure to insert the word ‘global.’”
Yes, but it only underlines the contradiction. Mann ‘s results are not at variance with yours. A global average, of anything, will almost always be less variable than a local. Five legged cats, redheads, whatever.
“Have you any comments as to the considerable variability of temperature over the last few hundred years at a constant level of co2, the recent decade long drop in temperatures we can observe , or indeed the centuries long uptick we can note,”
Yes. No-one said co2 is the only determinant of temperature, or that it caused past fluctuations.
But an increase does cause warming, and we’re digging up huge quantities of carbon and putting it in the atmosphere. That’s unprecedented.
I’ll ask the obvious question of a skeptic: In what way does this “[fly] n the face of radiative physics theory”? I assume you have some evidence that climate models with constant CO2 levels don’t show nearly this amount of variability at the local level?
Bart says:
May 8, 2013 at 7:05 pm
“…where k is a coupling constant…”
Please note that k is not necessarily constant. The values of k and Teq will be influenced by the CO2 content of currently upwelling waters, as well as other factors. They could easily vary in time, or even exhibit sudden shifts. However, they appear to have been fairly stable in the modern era since 1958, when reliable, direct measurements of CO2 began.
Nick Stokes says:
May 8, 2013 at 7:05 pm
“But an increase does cause warming…”
Not necessarily. Although a given quantity will heat the planet above what it would be without it, there is no guarantee that an incremental increase will necessarily result in an incremental increase in temperature.
“…and we’re digging up huge quantities of carbon and putting it in the atmosphere. That’s unprecedented.”
A lot of things we do today are unprecedented. It does not mean they are necessarily bad.
Bart says:
May 8, 2013 at 7:19 pm
“…there is no guarantee that an incremental increase will necessarily result in an incremental increase in temperature.”
Put another way, although the secant line necessarily has a positive slope, the tangent line can do whatever it likes, within only the constraint of integrating to a positive measure.
Bart says:
Sounds pretty convincing until you actually look at the data. An exponential looks locally linear…and indeed, you can fit a reasonable line over the past 20 years on this graph of cumulative emissions (which is expected to be proportional to atmospheric CO2 levels) too: http://cdiac.ornl.gov/trends/emis/graphics/cumulative_global_1751_2007.jpg
And, in fact, I think the most careful studies has shown that the fraction of CO2 rise in the atmosphere to CO2 emitted has remained stubbornly constant.
Well, we seem to be making progress with you. I believe you used to claim that CO2 levels will start to fall; now you are only claiming the concavity will change. Of course, I could never pin you down or actually get you to bet on future CO2 levels falling!
What I find amazing is the direct correlation between strong and weak solar cycles shown in this graph.
The Maunder Minimum lasted from 1645 to 1715 and there is a very steep drop in CET temperatures during that time. Conversely, when the strongest 63-year string of solar cycles in 11,400 years occurred between 1933-1996, there is definite spike in temperatures.
When the strong solar cycles ended in 1996, the global warming trend ended, too. We’re now into the 17th year of no statistically significant warming trend. The current solar cycle started in 2008 and is the weakest since 1906. Since the start if this weak cycle, 4 out of the last five Winters have been brutal in the Northern Hemisphere and this Winter doesn’t seem to want to end.
The next solar cycle, which starts around 2020, is predicted by some scientists to be the lowest since the Maunder Minimum, that ended in 1715. According to Penn & Livingston’s research, when the Sun’s Umbral Magnetic Field (UMF) falls below 1500 gauss, there will be insufficient magnetic force to hold sunspots together. The UMF is currently at around 2000 gauss and falling at a rate of around 50 gauss/year, so around 2023, it seems likely it’ll fall below this critical level, at the same time a weak solar cycle will just be starting.
It’s also interesting to note that around 2020, the AMO will enter its 30-year cooling cycle and the PDO already entered it’s 30-year cooling cycle in 2008. I also find it interesting that when the PDO entered it cooling cycle in 2008, the Arctic Ice extent on the Pacific side started setting records. It’s also interesting that when the AMO entered its 30-year warming cycle in 1996, that’s when the Arctic Ice started to decline. Accordingly, when the AMO starts it cooling cycle around 2020, it seems logical that the Atlantic side of the Arctic will also start gaining ice again.
The Antarctic is already setting record ice extents so when both poles are gaining ice, Earth’s albedo will increase, creating an additional cooling effect.
As a side note, there are usually about 3-4 major volcanic eruptions per century, so it’s highly probable a large eruption could take place around 2020 since we really haven’t had a big one this century…. and yeah, I know my laws of statistics, but hey, we’re “due” for one, OK?
A lot of potential cooling events will all be happening around 2020. It’ll be interesting to see if the mighty CO2 molecule is up to the task of overwhelming all these cooling effects… Given that there hasn’t been any warming into the 17th year, despite roughly 40% of all manmade CO2 emissions since 1750 have been emitted over the past 16 years and 4 months, it seems like CO2 is all tuckered out…
Is what we deal with today really a matter of climate in the end?
Think about it…………………
Minor comment: It is better to use a logarithmic scale for plotting CO2 when plotting against temperature since the response of temperature to CO2 is conjectured to be logarithmic.