I wanted to pull out one thought from my longer video and presentation on global warming.
As a reminder, I adhere to what I call the weak anthropogenic theory of global warming — that the Earth’s sensitivity to CO2, net of all feedback effects, is 1C per doubling of CO2 concentrations or less, and that while man may therefore be contributing to global warming with his CO2 (not to mention his land use and other practices) the net effect falls far short of catastrophic.
While in the media, alarmists want to imply that the their conclusions about climate sensitivity are based on a century of observation, but this is not entirely true. Certainly we have over a century of temperature measurements, but only a small part of this history is consistent with the strong anthropogenic theory. In fact, I observed in my video is that the entire IPCC case for a high climate sensitivity to CO2 is based on just 20 years of history, from about 1978 to 1998.
Here are the global temperatures in the Hadley CRUT3 data base, which is the primary data from which the IPCC worked (hat tip Junk Science Global Warming at a Glance) click to enlarge
Everything depends on how one counts it, but during the period of man-made CO2 creation, there are really just two warming periods, if we consider the time from 1910 to 1930 just a return to the mean.
- 1930-1952, where temperatures spiked about a half a degree and ended 0.2-0.3 higher than the past trend
- 1978-1998, where temperatures rose about a half a degree, and have remained at that level since
Given that man-made CO2 output did not really begin in earnest until after 1950 (see the blue curve of atmospheric CO2 levels on the chart), even few alarmists will attribute the runup in temperatures from 1930-1952 (a period of time including the 1930’s Dust Bowl) to anthropogenic CO2. This means that the only real upward change in temperatures that could potentially be blamed on man-made CO2 occurred from 1978-1998.
This is a very limited amount of time to make sweeping statements about climate change causation, particularly given the still infant-level knowledge of climate science. As a result, since 1970, skeptics and alarmists have roughly equal periods of time where they can make their point about temperature causation (e.g. 20 years of rising CO2 and flat temperatures vs. 20 years of rising CO2 and rising temperatures).
This means that in the last 40 years, both skeptics and alarmists must depend on other climate drivers to make their case (e.g. skeptics must point to other natural factors for the run-up in 1978-1998, while alarmists must find natural effects that offset or delayed warming in the decade either side of this period). To some extent, this situation slightly favors skeptics, as skeptics have always been open to natural effects driving climate while alarmists have consistently tried to downplay natural forcing changes.
I won’t repeat all the charts, but starting around chart 48 of this powerpoint deck (also in the video linked above) I present some alternate factors what may have contributed, along with greenhouse gases, to the 1978-1998 warming (including two of the strongest solar cycles of the century and a PDO warm period nearly exactly matching these two decades).
Postscript: Even if the entire 0.7C or so temperature increase in the whole of the 20th century is attributed to manmade CO2, this still implies a climate sensitivity FAR below what the IPCC and other alarmists use in their models. Given about 44% of a doubling since the industrial revolution began in CO2 concentrations, this would translate into a temperature sensitivity of 1.3C (not a linear extrapolation, the relationship is logarithmic).
This is why alarmists must argue that not only has all the warming we have seen been due to CO2 ( heroic assumption in and of itself) but that there are additional effects masking or hiding the true magnitude of past warming. Without these twin, largely unproven assumptions, current IPCC “consensus” numbers for climate sensitivity would be absurdly high. Again, I address this in more depth in my video.
There have been 3 periods of warming about 60 years apart. Ask Phil Jones of CRU infamy.
There have been 3 positive cycles of the El Nino/La Nina [PDO] 2 since good records have been available.
According to Phil Jones of CRU infamy they were 1860-1880, 1910-1940 and 1975-1998. The latest one was in no way special in length or slope [according to Dr Jones]
From 1940 to 1978 there is an overall downward trend in global temperature as measured by GISS.
During that time there were about 14 La Nina’s and 3 El Nino’s and the temperature went down. No surprise there ! I might add that there was world war II when industry was pumping out CO2 by the ton. [PDO was Negative]
From 1978 to 1998 there was a preponderance of El Nino’s over La Nina’s 11 to 2 and the temperature went up. [PDO was Positive and sunspots were maximum] No surprise there and no CO2 is required to explain it.
From 1998 to present is where it really gets interesting.
In 1999 and 2000 and 2008 there were La Nina’s and between those dates there were El Nino’s and the temperature rose. The temperature resembles an inverted “U” with an up tick because of the El Nino in 2010.
The objection is made that ocean cycles cannot explain the approximately ½ ° C overall warming per century and that is true but it can make temperatures appear to be warmer or cooler by quite a bit.
In 1978 the alarmists became ….. alarmed because of the cooling since 1940. In 1998 the alarmists again became alarmed because of the natural warming since 1978.
The cause of the overall warming is a moot point of interest only to climatologists and not worthy of economy destroying taxes.
Since the warming began immediately after records were started at the end of the little ice age when CO2 production by humans was miniscule I doubt that it was the cause. In any case the warming is minimal and since we are at the top of the sine wave we will observe cooling for the next 20 to 30 years.
The overall pattern of warming is a ramp of approximately 1/2 ° C per century [of interest to climatologists only.] and a 60 year sine wave. This is caused by increased solar output at the end of the little ice age or [just barely] possibly CO2.
Here is a peer reviewed study which supports this view.
http://people.iarc.uaf.edu/~sakasofu/pdf/two_natural_components_recent_climate_change.pdf
When the sine wave was at the bottom the alarmists predicted another ice age and global cooling. When the sine wave was at it’s maximum in 1998 the alarmists passed the Kyoto accords. [They couldn’t do that today].
I don’t think that CO2 caused the 1/2 ° C per century warming because warming started long before CO2 output became significant but so what if it is? The amount of actual warming is far from catastrophic and we can conduct business as usual while transitioning to renewable fuels.
Woohoo, it’s the same shit, yet again. The same words, the same phrases, the same bullshit, the same tired old nonsense, and no doubt the same moronic failure to respond to criticism.
“While in the media, alarmists want to imply that the their conclusions about climate sensitivity are based on a century of observation, but this is not entirely true.”
Studies of climate sensitivity make use of data from timescales ranging from months to billions of years. Who exactly do you have in mind here?
“Certainly we have over a century of temperature measurements, but only a small part of this history is consistent with the strong anthropogenic theory”
We have hundreds of millions of years of temperature data, and every part of this history is consistent with CO2 being a greenhouse gas. Only a jabbering retard would think that temperature should follow CO2 concentration in a linear fashion.
“the entire IPCC case for a high climate sensitivity to CO2 is based on just 20 years of history, from about 1978 to 1998.”
Christ almighty, you don’t even understand that the IPCC doesn’t make a case for anything. Hundreds of independent papers in the scientific literature make the case, and they make it based on data over timescales from months to aeons.
“the only real upward change in temperatures that could potentially be blamed on man-made CO2 occurred from 1978-1998”
CO2 has always been a greenhouse gas. Not even for an instant has it not been. All of the rise in CO2 has affected the climate, not just one part of it. The bigger the increase, the greater the effect.
“…the still infant-level knowledge of climate science…” – you speak well for yourself.
“As a result, since 1970, skeptics and alarmists have roughly equal periods of time where they can make their point about temperature causation (e.g. 20 years of rising CO2 and flat temperatures vs. 20 years of rising CO2 and rising temperatures).”
You only need a tiny bit of intelligence to understand that there never has and never will be a linear relation between CO2 and temperature. You don’t have that tiny bit of intelligence.
“Even if the entire 0.7C or so temperature increase in the whole of the 20th century is attributed to manmade CO2, this still implies a climate sensitivity FAR below what the IPCC and other alarmists use in their models.”
No, it doesn’t. Climate sensitivities are outputs from models, not inputs, and observations and theory consistently point to the sensitivities that are reported by the IPCC.
“Given about 44% of a doubling since the industrial revolution began in CO2 concentrations, this would translate into a temperature sensitivity of 1.3C”
Only if you assume instantaneous response to forcings. Basic observations that can be made by six year olds show that this assumption is incorrect.
I wonder if you can muster up the intellect in your fog-filled chimp brain to respond to any of this. As you never have done before, it would certainly be surprising if you did.
The last post is not my post.
It is the phony again !
Phony Netdr
Ad hominem attacks abuse and name calling are an admission of defeat and poor thinking skills !. Any fool can do them and most fools do.
The opponent has run out of reasons and resorted to the oldest and least effective form of attack. The “Your mother wears army boots” style of discourse isn’t suitable for this or any other site.
So thank you for once again publicly admitting defeat.!
You will notice that I never reply in kind. [I am a bigger person than that] I argue the facts which are enough to defeat alarmism easily.
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Second of all the only period of “anthropogenic global warming” is 1978 to 1998.
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During all past warming the warming has always preceded the CO2 or it is so far back in time that it is impossible to tell. There is no case in history when a change in CO2 caused warming.
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“I wonder if you can muster up the intellect in your fog-filled chimp brain to respond to any of this. As you never have done before, it would certainly be surprising if you did.”
Yes, it would be surprising if anyone responded. Most people have better things to do.
Pauld
I agree ignore the phony and he will go away.
It is no fun to spout hatred when no one responds.
Thank you, Warren. I enjoyed the presentation. I can report to you that every day people I know are jumping off the CAGW alarmism band wagon. This is thanks to the dissemination of information that exposes the flaws and weaknesses of the CAGW alarmist argument by persons such as yourself. Thank you and well done.
http://www.skepticalscience.com/global-warming-early-20th-century-advanced.htm
While natural forcings can account for much of the early 20th Century warming, humans played a role as well. Additionally, the early century warming wasn’t as large or rapid as the late century warming, to which these natural factors did not contribute in any significant amount.
But more importantly, we don’t assume that the current warming is caused by humans because it’s “unprecedented” or faster and larger than previous natural warming events. We know the current warming is anthropogenic because that’s what the physical evidence tells us.
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Net and I have talked about this before. I’ve always made the case that co2 is in balance with all the other forcings.
http://www.skepticalscience.com/global-warming-early-20th-century-advanced.htm
Although there was a significant increase in global temperature in the early 20th Century, the rate of warming from 1910 to 1940 was lower than the rate of warming from 1975 to 2005, at about 1.3 vs. 1.8°C per century, respectively. That being said, it’s worth taking a look at what caused the early century warming. Several different factors contributed.
http://www.skepticalscience.com/global-warming-1860-1880-and-1910-1940.htm
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The second site lists the warming per century rates of the different warming periods.
http://www.skepticalscience.com/global-warming-early-20th-century-advanced.htm
Carbon Dioxide
Although humans were not burning very large amounts of fossil fuels or emitting large amounts of carbon dioxide (CO2) in the early 20th Century, relative to the late century, CO2 emissions were non-negligible and did play a role in the early century warming.
From 1900 to 1940, atmospheric CO2 levels increased from approximately 295 to 310 parts per million by volume (ppmv). The equilibrium temperature change caused by this increase in CO2 is the climate sensitivity (λ) multiplied by the radiative forcing, which is approximately 5.35 times the natural log of the change in CO2 (Myhre 1998):
The best estimate for the climate sensitivity parameter is 0.8 (Wm-2K-1).
((((((((Thus at equilibrium, this CO2 change would be expected to cause a 0.22°C increase in the average global surface air temperature.))))))))
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So Warren Meyers has claimed that the scientists are overestimating climate sensitivity. It appears that the climate sensitivity is right on track for 1910 to 1940.
http://www.skepticalscience.com/global-warming-early-20th-century-advanced.htm
Meehl et al. (2004) plots the estimated anthropogenic contribution to temperature change in Figure 1 below. Most of the anthropogenic influence comes from CO2.
Figure 1: Climate model results from anthropogenic forcings compared to observations (black line). The red line is the average of the four-member ensemble. The pink shading is the model range. The blue line is the ensemble mean and the light blue shading is the ensemble range.
((((((As you can see, the best estimate of the anthropogenic contribution to the 1910-1940 warming is approximately 0.1 to 0.15°C.)))))))
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This would be from the thermal lag of the oceans.
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This is smaller than the value we calculated above because the planet is not immediately in equilibrium. Much of the energy imbalance goes into the oceans, causing what’s known as the “ocean lag” due to the thermal inertia of the oceans. The same lag effect applies to natural forcings.
http://www.skepticalscience.com/global-warming-early-20th-century-advanced.htm
Conclusion
The “skeptic” logic behind this argument is usually that if the early 20th Century warming was as large as the late century warming, and was natural, then the current warming could be natural as well (note that we’ve discussed the mid-century cooling elsewhere).
Ultimately while natural forcings can account for much of the early 20th Century warming, humans played a role as well. Additionally, the early century warming wasn’t as large or rapid as the late century warming, to which these natural factors did not contribute in any significant amount.
But more importantly, we don’t assume that the current warming is caused by humans because it’s “unprecedented” or faster and larger than previous natural warming events. We know the current warming is anthropogenic because that’s what the physical evidence tells us.
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This is a very well put together explanation of the early climate in the beginning of the last century. There is more details to read through that I haven’t covered.
NetDr:
Second of all the only period of “anthropogenic global warming” is 1978 to 1998.
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2000 to 2009 was the warmest decade on the temperature history. I don’t believe the warming has stopped as some would like to think.
2005 and 2010 are tied for the hottest years on record. Oceans are gin
Oceans are gaining in heat content as measured by the argo buoys.
Made a keyboard fumble.
http://en.wikipedia.org/wiki/File:Radiative-forcings.svg
Radiative forcing from the many different components that balance to give us our climate. The Anthropogenic portion is positive even within the range of uncertainty.
Renewable guy seems to be arguing with himself. No serious skeptic doubts the basic equilibrium equation – the issue is the feedback. I have seen nothing in these comments that comes close to supporting the 4x or so feedback numbers of the alarmists.
In fact, the alarmist camp has done so badly that they’ve had to find another drum to beat – so they are claiming the excess CO2 is poisoning the oceans.
They’ll always have something to use as an excuse to hinder human progress.
I just finished reading the last thread where Renewable Guy was repeatedly trying to make the same invalid points, ignoring what other people were saying to him, until he was finally put in his place on Hansen’s “predictions”. I go into this new thread and lo and behold, here he is again. Sigh.
Renewable says: “Oceans are gaining in heat content as measured by the argo buoys.”
I would like to see your source for this. I am not sure of the exact date, but Argo data started sometime in the 2002 to 2004 range. The graph I have seen show that ocean heath content has been flat for the past 8 years or so.
Renewable say, “2000 to 2009 was the warmest decade on the temperature history. I don’t believe the warming has stopped as some would like to think. 2005 and 2010 are tied for the hottest years on record.”
Renewable: Go take a look at a temperature graph using any index you choose. As you look at it, ask yourself, how is it possible for the temperature trend since 2001 to be 0 or close to it and yet the decade of 2001 to 2010 is the warmest on record. If it is not immediately obvious as you gaze upon the graph, then think harder. It is important for you to understand this point, so don’t come back until you have completed this assignment.
Renewable: The problem with your skeptical science site is that is very slanted and does not tell the full story.
For example, consider the following response by Phil Jones, the director of the Climatic Research Unit (CRU) at the University of East Anglia (UEA). In case you don’t know, he is one of the major players on your side of the CAGW controversy.
This is from a BBC interview:
A – Do you agree that according to the global temperature record used by the IPCC, the rates of global warming from 1860-1880, 1910-1940 and 1975-1998 were identical?
An initial point to make is that in the responses to these questions I’ve assumed that when you talk about the global temperature record, you mean the record that combines the estimates from land regions with those from the marine regions of the world. CRU produces the land component, with the Met Office Hadley Centre producing the marine component.
Temperature data for the period 1860-1880 are more uncertain, because of sparser coverage, than for later periods in the 20th Century. The 1860-1880 period is also only 21 years in length. As for the two periods 1910-40 and 1975-1998 the warming rates are not statistically significantly different (see numbers below).
I have also included the trend over the period 1975 to 2009, which has a very similar trend to the period 1975-1998.
So, in answer to the question, the warming rates for all 4 periods are similar and not statistically significantly different from each other.
http://news.bbc.co.uk/2/hi/science/nature/8511670.stm
@Renewable Guy:
Citing from your link:
http://www.skepticalscience.com/global-warming-early-20th-century-advanced.htm
“The ‘skeptic’ logic behind this argument is usually that if the early 20th Century warming was as large as the late century warming, and was natural, then the current warming could be natural as well (note that we’ve discussed the mid-century cooling elsewhere).
Ultimately while natural forcings can account for much of the early 20th Century warming, humans played a role as well. Additionally, the early century warming wasn’t as large or rapid as the late century warming, to which these natural factors did not contribute in any significant amount.”
The second paragraph presupposes that it has been unequivocally established that the warming in the early 20th Century happened because of the anthropogenic factor plus the natural factors cited in the link and nothing else. I fail to see how one can make such a statement given the current state of the our understanding of climate. The magnitude of factors such as cloud cover and aerosols are under debate, plausible ranges of values for climate sensitivity and a number of similar parameters are very wide, yet we are sure on exactly why the climate behaved the way it did some 70-100 years ago? Sorry, that’s just handwaving. Consequently, the skeptic’s argument in the first paragraph has not been countered.
Renewable:
Here is a nice graph showing the ARGO data since it became operational in 2003 through 2011. http://c3headlines.typepad.com/.a/6a010536b58035970c0154331e7d65970c-pi
It shows a extremely small, statistically-insignificant positive trend–for all practical purposes no warming in the 8 years that ARGO data has been available.
The graphic also show that the projected warming from Hansen’s model. For present purpose, ignore that for the time being. What Hansen’s model projects for ocean warming is somewhat controversial and I don’t want to get bogged down in that debate.
The point I want to make is that the ARGO data shows that global warming has for all practical purposes stopped for the period 2003 to 2011. This is admittedly a relatively short period. It will be interesting to see what happens over the next few years.
Booker says:
“The second paragraph presupposes that it has been unequivocally established that the warming in the early 20th Century happened because of the anthropogenic factor plus the natural factors cited in the link and nothing else. I fail to see how one can make such a statement given the current state of the our understanding of climate. The magnitude of factors such as cloud cover and aerosols are under debate, plausible ranges of values for climate sensitivity and a number of similar parameters are very wide, yet we are sure on exactly why the climate behaved the way it did some 70-100 years ago?”
Just to provide some support for this, here is what the IPCC AR4 says:
“Detection and attribution as well as modelling studies indicate more uncertainty regarding the causes of early 20th-century warming than the recent warming. A number of studies detect a significant natural contribution to early 20th-century warming (Tett et al., 2002; Stott et al., 2003b; Nozawa et al., 2005; Shiogama et al., 2006). Some studies find a greater role for solar forcing than other forcings before 1950 (Stott et al., 2003b), although one detection study finds a roughly equal role for solar and volcanic forcing (Shiogama et al., 2006), and others find that volcanic forcing (Hegerl et al., 2003, 2007) or a substantial contribution from natural internal variability (Tett et al., 2002; Hegerl et al., 2007) could be important. There could also be an early expression of greenhouse warming in the early 20th century (Tett et al., 2002; Hegerl et al., 2003, 2007).”
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-4-1-5.html
Pauld:
Renewable:
Here is a nice graph showing the ARGO data since it became operational in 2003 through 2011. http://c3headlines.typepad.com/.a/6a010536b58035970c0154331e7d65970c-pi
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The amount of energy it takes to heat water for a given temperature rise is much higher than the air. If you could calculate energy content, it would be substantial.
The earth’s energy content is increasing by 4 hiroshima bombs per second.
Booker:
The second paragraph presupposes that it has been unequivocally established that the warming in the early 20th Century happened because of the anthropogenic factor plus the natural factors cited in the link and nothing else. I fail to see how one can make such a statement given the current state of the our understanding of climate. The magnitude of factors such as cloud cover and aerosols are under debate, plausible ranges of values for climate sensitivity and a number of similar parameters are very wide, yet we are sure on exactly why the climate behaved the way it did some 70-100 years ago? Sorry, that’s just handwaving. Consequently, the skeptic’s argument in the first paragraph has not been countered.
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If the earth’s temperature is increasing, and it is, then negative feedbacks are constrained to be less than the positive feedbacks. Below is a link on cloud feedback.
http://www.skepticalscience.com/a-positive-outlook-for-clouds.html
Renewable says: “The amount of energy it takes to heat water for a given temperature rise is much higher than the air. If you could calculate energy content, it would be substantial.”
Take a look at the graph. The vertical axis shows “gigajoules per meter 2” Joules is a unit of “energy”
“If the earth’s temperature is increasing, and it is, then negative feedbacks are constrained to be less than the positive feedbacks.”
No temperature is a function of forcings and feedbacks.
Renewable Guy:
“If the earth’s temperature is increasing, and it is, then negative feedbacks are constrained to be less than the positive feedbacks.”
Let’s say the earth temperature is increasing. Are you saying that this proves that the combined magnitude of effects from cloud cover and aerosols is less than the magnitude of the warming induced by anthropogenic CO2?
PaulD:
So, in answer to the question, the warming rates for all 4 periods are similar and not statistically significantly different from each other.
http://news.bbc.co.uk/2/hi/science/nature/8511670.stm
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I’ve presented an analysis of the period. WIth more understanding, the statement may not be all that different from what I have presented. What differences would we be talking about? This is kind of a vague thing to talk about.
Booker:
Renewable Guy:
“If the earth’s temperature is increasing, and it is, then negative feedbacks are constrained to be less than the positive feedbacks.”
Let’s say the earth temperature is increasing. Are you saying that this proves that the combined magnitude of effects from cloud cover and aerosols is less than the magnitude of the warming induced by anthropogenic CO2?
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Cloud cover is showing to be a pos feedback with increasing temperature. Cloud cover decreases, allowing more sunlight to get through. The IRIS effect that Dr. Lindzen has talked about, is not bearing out.
Renewable: The problem with your skeptical science website is that it present the skeptical side in a very cusory and unsophisticated manner without any citations to the literature and then present the CAGW with journal citations, as if that settled the matter. Missing is any discussion of the skeptical response. The site implies that the skeptics have no response. This is false. The IPCC says there is a great deal of uncertainty in cloud feedbacks for a reason. The issue is far from settled.
Pauld:
“If the earth’s temperature is increasing, and it is, then negative feedbacks are constrained to be less than the positive feedbacks.”
No temperature is a function of forcings and feedbacks.
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I’ll let you back that one up.
Renewable Guy:
“Cloud cover is showing to be a pos feedback with increasing temperature.”
Wait, wait, wait. So, is cloud cover a net positive feedback or a net negative feedback? Can you answer this with certainty?
Pauld:
Renewable: The problem with your skeptical science website is that it present the skeptical side in a very cusory and unsophisticated manner without any citations to the literature and then present the CAGW with journal citations, as if that settled the matter. Missing is any discussion of the skeptical response. The site implies that the skeptics have no response. This is false. The IPCC says there is a great deal of uncertainty in cloud feedbacks for a reason. The issue is far from settled.
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I spent a great deal of time on reading cloud feedbacks. It is still uncertain but with preliminary observations showing some pos feedback. That is Dr Andrew Dessler’s paper. 20 years out we will be able to say with more certainty what it is. But even with observations, as temperature increases, cloud cover decreases.
“I’ve presented an analysis of the period. WIth more understanding, the statement may not be all that different from what I have presented. What differences would we be talking about? This is kind of a vague thing to talk about.”
Whether the periods are similar or not depends, in part, on how one defines the period. The trends are sensitive to the year one chooses as the starting and ending point. It also depends on which temperature index one uses. Finally, there is statistical uncertainty associated with any trend no matter what period or index one uses.
Jones states his conclusion precisely. There is no statistical difference between the trends in the periods he defines. He describes the temperature index he uses. I don’t understand why you think his analysis is vague.
“But even with observations, as temperature increases, cloud cover decreases.”
You obviously are not familiar with Dr. Spencer’s position regarding this very issue. It is not clear whether temperature increases cause decreased cloud cover or whether decreased cloud cover causes temperature increases.
Renewable Guy:
“I spent a great deal of time on reading cloud feedbacks. It is still uncertain but with preliminary observations showing some pos feedback. That is Dr Andrew Dessler’s paper. 20 years out we will be able to say with more certainty what it is.”
So, this is uncertain (although, of course, scientists have some ideas and theories, Dessler – his, and other scientists – theirs). This is what I was saying. Ditto everything else.
Do you agree then with what I said earlier as regards your skeptical science link?
The second paragraph presupposes that it has been unequivocally established that the warming in the early 20th Century happened because of the anthropogenic factor plus the natural factors cited in the link and nothing else. I fail to see how one can make such a statement given the current state of our understanding of climate. The magnitude of factors such as cloud cover and aerosols are under debate, plausible ranges of values for climate sensitivity and a number of similar parameters are very wide, yet we are sure on exactly why the climate behaved the way it did some 70-100 years ago? Sorry, that’s just handwaving. Consequently, the skeptic’s argument in the first paragraph has not been countered.
I said, “No temperature is a function of forcings and feedbacks.
You said, “I’ll let you back that one up.”
My statement is self-evident. CO2 is a positive forcing. Solar radiation is a positive forcing. Some aerosals are positive forcings,some are negative forcings. Are you suggesting that temperature is not effected by any of these forcings?
Feedbacks are the climate system’s response to these forcings. Changes in water vapor, cloud coverage, precipitation are examples of feedbacks.
Temperatures are a function of forcings and feedbacks. With which part do you disagree?
Booker:
Renewable Guy:
“I spent a great deal of time on reading cloud feedbacks. It is still uncertain but with preliminary observations showing some pos feedback. That is Dr Andrew Dessler’s paper. 20 years out we will be able to say with more certainty what it is.”
So, this is uncertain (although, of course, scientists have some ideas and theories, Dessler – his, and other scientists – theirs). This is what I was saying. Ditto everything else.
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NOt so. Dessler data based observations of earth’s cloud cover showed pos feedback. There is a very good chance that the next 20 years will bear out his first 10.
http://www.sciencedaily.com/releases/2010/12/101209141231.htm
http://www.skepticalscience.com/global-warming-early-20th-century-advanced.htm
The equation which is a graphic won’t copy over. The first equation under carbon dioxide.
Forcing and feedback affect temperature. How can it not?
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Pauld:
((((((((I said, “No temperature is a function of forcings and feedbacks.))))))
You said, “I’ll let you back that one up.”
My statement is self-evident. CO2 is a positive forcing. Solar radiation is a positive forcing. Some aerosals are positive forcings,some are negative forcings. Are you suggesting that temperature is not effected by any of these forcings?
Feedbacks are the climate system’s response to these forcings. Changes in water vapor, cloud coverage, precipitation are examples of feedbacks.
((((((((Temperatures are a function of forcings and feedbacks.))))))) With which part do you disagree?
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I have your statements in parenthesis.
I’m either misundersatanding what you are saying or you are contradicting yourself.
Figure 5: Climate model results from all natural forcings compared to observations (black line).
http://www.skepticalscience.com/global-warming-early-20th-century-advanced.htm
Booker:
Natural forcings were looked at. How deep we want to go will take some time to look into the uncertainty of that time period.
The co2 only went from 295 to 310. Other factors if you read the whole article were looked at.
Pauld:
“But even with observations, as temperature increases, cloud cover decreases.”
You obviously are not familiar with Dr. Spencer’s position regarding this very issue. It is not clear whether temperature increases cause decreased cloud cover or whether decreased cloud cover causes temperature increases.
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I’ve read a little of Dr. Spencer’s writings. When it comes to Spencer’s writing I always have to check which hat he has on. Is it his denial hat or his scientist hat. The guy plays both sides of the fence.
http://www.skepticalscience.com/internal-variability.htm
Spencer’s Hypothesis
Dr. Roy Spencer has proposed a hypothesis whereby some unknown internal mechanism causes cloud cover to change, which in turn changes the reflectivity (albedo) of the planet, thus causing warming or cooling. Spencer also attributes most of the global warming over the past century to this “internal radiative forcing.” There are some significant flaws in this hypothesis. For one thing, it fails to explain many of the observed “fingerprints” of human-caused global warming, such as the cooling upper atmosphere (stratosphere and above) and the higher rate of warming at night than during the day.
In order for internal variability to account for the global warming over the past century (especially over the past 40 years), it requires that the large greenhouse gas radiative forcing can’t have much effect on global temperatures. For this to be true, climate sensitivity must be low. But as discussed in Swanson et al. (2009), if climate is more sensitive to internal variability than currently thought, this would also mean climate is more sensitive to external forcings, including CO2. This is a Catch-22 for Spencer’s hypothesis; it effectively requires that climate sensitivity is simultaneously both low and high.
Dr. Andrew Dessler published a study (Dessler 2010) which casts further doubt on Spencer’s hypothesis, as detailed in an email exchange between the two scientists. In short, Dessler argues that cloud cover change is a feedback to a radiative forcing, for example increasing greenhouse gases, while Spencer argues that clouds are changing due to some other, unknown cause, and acting as a forcing themselves. Unlike Spencer, Dessler explains the mechanism and supporting evidence behind his cloud feedback research:
“My cloud feedback calculation is supported by a firm causal link: ENSO causes surface temperature variations which causes cloud changes. This is supported by the iron triangle of observations, theory, and climate models.”
Booker:
Renewable Guy:
“Cloud cover is showing to be a pos feedback with increasing temperature.”
Wait, wait, wait. So, is cloud cover a net positive feedback or a net negative feedback? Can you answer this with certainty?
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http://www.climate4you.com/ClimateAndClouds.htm#Cloud cover effects on climate
There is a graph of cloud cover versus temperature in this link. Cloud cover decreases with temperature giving us a pos feedback. Decreasing cloud cover allows more sunlight to hit the earth.
Pauld:
Renewable: The problem with your skeptical science website is that it present the skeptical side in a very cusory and unsophisticated manner without any citations to the literature and then present the CAGW with journal citations, as if that settled the matter. Missing is any discussion of the skeptical response. The site implies that the skeptics have no response. This is false. The IPCC says there is a great deal of uncertainty in cloud feedbacks for a reason. The issue is far from settled.
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I have just been reading about cloud feedback new observations in just the last year or so. The IPCC would not of known about it then.
Pauld:
Renewable says: “The amount of energy it takes to heat water for a given temperature rise is much higher than the air. If you could calculate energy content, it would be substantial.”
Take a look at the graph. The vertical axis shows “gigajoules per meter 2″ Joules is a unit of “energy”
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You are right, that was my mistake. Just by eyeball there is a 20 to 1 ratio of ocean to land and atmosphere heating difference. Once the ocean is heated up, we are stuck with it for thousands of years.
http://www.skepticalscience.com/graphics.php?g=4
Booker:
Renewable Guy:
“If the earth’s temperature is increasing, and it is, then negative feedbacks are constrained to be less than the positive feedbacks.”
Let’s say the earth temperature is increasing. Are you saying that this proves that the combined magnitude of effects from cloud cover and aerosols is less than the magnitude of the warming induced by anthropogenic CO2?
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Pos forcing outweighs negative forcings.
1910 to 1940 solar slightly increased
co2 also increased
and the temperature increased.
This is just off the top of my head. There are other factors. If aeorosols became dominant say like during a volcano, then the temperature falls. Mt Pinatubo comes to mind.
Renewable: I just don’t find anything on skeptical science to be very convincing because it does not fully present both sides of the debate. It always ends with the CAGW rebuttal and never discusses the skeptic’s surrerebutal. It thereby creates the illusion that controversial topics have been satisfactorily resolved in favor of CAGW. That is why I don’t find its discussion of Spencer to be helpful. You need to read wider if you really want to understand the controversy.
Renewable: Did you actually read the article you cited, that is: http://www.climate4you.com/ClimateAndClouds.htm#Cloud
It makes many important points that support skeptics. I would have recommended the article, if you hadn’t already done so.