The Instigator
Con (against)
10 Points
The Contender
Pro (for)
0 Points

Global warming is likely anthropogenic

Do you like this debate?NoYes+3
Add this debate to Google Add this debate to Delicious Add this debate to FaceBook Add this debate to Digg  
Post Voting Period
The voting period for this debate has ended.
after 4 votes the winner is...
Voting Style: Open Point System: 7 Point
Started: 4/21/2013 Category: Science
Updated: 3 years ago Status: Post Voting Period
Viewed: 1,286 times Debate No: 32740
Debate Rounds (4)
Comments (1)
Votes (4)





1. Acceptance (ask any questions in the comments before accepting) (and CON's opening framework for debate)
2. Arguments (no rebuttals)
3. Rebuttals/defense
4. Rebuttals/defense


--> BOP even
--> No forfeits
--> If you wish to change the resolution, or any groundwork lied out in this first round, say so in the comments not after acceptance.


Global warming (or climate change): the overall warming trend since 1850
Anthropogenic: man-made by CO2 emissions
likely: over 60%

--> note in this debate neither side does not have to argue warming is entirely anthropogenic, or entirely natural, rather *mostly* natural or anthropogenic (mostly as in 51%)

good luck


I accept. Please present your arguments.
Debate Round No. 1


I thank my opponent for accepting.

1. A geological perspective

To understand the present, we must understand the past. If warming is not unprecedented, then there is no reason to believe in Anthropogenic warming (AGW).

All of the evidence regarding AGW is based on the short-erm 100 year period of warming from 1900 – 2000. Paleoclimatologists say that the 100 year interval is “too short to carry statistical significance regarding long-term climate change.”1

Geologists have a much longer perspective that greenhouse theorists often don’t account for. Climatologists have a very narrow view of climate within the past 100 years, but cannot fully comprehend the climate. When the past is accounted for, the proof is pretty conclusive: our current warming isn’t that scary, why worry about it? Now, to make this clear: I and geologists are not “deniers”. We accept the planet is warming, and that the climate has changed and will change again. We are skeptical of the man-made global warming conundrum. Here are the reconstructions of the past done by recent papers:1

We can see the modern warm period is cooler than all three warming periods in the past, including the roman and medieval warm periods when humanity flourished.

But what if we enter in CO2? Indeed, if CO2 correlates with these temperatures, I am wrong, and I lose. So lets extend the graph to 600 million years. What do we get? Nothing significant.2

Now, my opponent will inevitably have to argue co2 correlates with temperature in the last 100 years, even if it does not in the past, so therefore it must cause the warming today even if it never did in the past. I will refute in detail (if he does that) later. But I will use similar analysis here as I will in a future rebuttal:

(1) Correlation does not equal causation.

(2) Now, even if CO2 did correlate in the recent interglacial or in history (which it really didn’t), CO2 would have to precede the temperature increase.

(3) We need as much data as possible in order to weed out spurious correlations (which is why I am using geological proxies).

Now, in the past, is any of this true? No, it is not. There is little correlation between CO2 and temperature (and correlation =/= causation in the current century), and CO2 does not correlate with any temperature nor does it precede temperature. It actually lags temperature. CO2 in the last few hundred thousand years lags the temperature increase by 400 to 1000 years after the warming. When focusing on the modern interglacial, the finding is that “the start of the CO2 increase lagged the start of the temperature increase by 800 years.”3 Indeed, other analysis’s totally uncouple the two and find “after the termination of the last great ice age, the CO2 content of the air gradually rose by approximately 25 ppm in almost linear fashion between 8,200 and 1,200 years ago, also during a period of time that saw a slow but steady decline in mean global air temperature, which results are obviously just the opposite of what would be expected if changes in atmospheric CO2 drove climate change in the way claimed by the popular CO2-greenhouse effect theory.”4

Unless my opponent can prove CO2 can be, and has been, a major climate driver and not a secondary forcing agent I see no way he can win this debate.

Now, I hope not to confuse the readers or my opponent. CO2 is a greenhouse gas. CO2 can cause some warming, though its potential effects are overstated. Natural factors supersede Carbon Dioxide hands down. There is absolutely no proof outside of climate models that CO2 will cause catastrophic warming, and looking into the past merely demonstrates that point.

2. Plausible natural factors

The main driver of climate is the sun. Possibly the engine of our climate. To use an analogy similar to professor Tim Ball, the sun is like the engine of the car, and CO2 is like the screw on the wheel. And then there are two main contributing factors: i) Total solar irradiance (TSI) and ii) the magnetic flux.

The TSI is an obvious factor. The hotter the sun, the hotter the planets around it. Without the sun, we would be nothing. There is no need for explanation as to why it could be a cause in modern warming, but if it is.

The Magnetic flux is a little more ambiguous. We know it correlates with temperature extremely well, but we don’t have a mechanism. We do not know what is special about this flux.

The magnetic flux and solar cycle length correlate like so:5

So, the question is why? Answer: it’s probably cosmic rays! This is the most likely explanation for the magnetic flux vs temperature link.

Clouds are a negative feedback. Cosmic rays have been demonstrated to cause more clouds. The fewer cosmic rays, the fewer clouds, and the more warming. Indeed, the scientific literature leads to the conclusion that “weak decreases in cosmic rays … show, as expected, a decreasing effect [of cloud cover].”6 During the solar cycle, there is a 3% decrease in clouds (which is why it is warmer when the sun is warmer). Svensmark noted how galactic cosmic rays explain this decrease in cloud cover (note no other theory does) and that cosmic rays can account for nearly all of the warming in the late 20th century.7

As for TSI, the IPCC and others assume in their models that the sun has not warmed significantly since 1950. However, empirical studies my Nicola Scafetta demonstrate “[w]hen taken into account the entire range of possible TSI satellite composite since 1980, the solar contribution to climate change ranges from a slight cooling to a significant warming, which can be as large as 65% of the total observed global warming.”8 Scafetta notes elsewhere, “the sun contributed as much as… 25–35% of the 1980–2000 global warming.”9


Using data from the geologic past it seems hard to accept that CO2 is the main driver of climate change. Instead, solar variations are a more likely cause.




4. Ibid

5. Eigil Friis-Christensen and K. Lassen. “Length of the Solar Cycle: An Indicator of Solar Activity Closely Associated with Climate.” Science, Volume 254, Number 5032, pp. 698-700, (1991).


7. Svensmark, H., and Friis-Christensen, E. Variation of cosmic ray flux and global cloud coverage: A missing link in solar climate relationships.” Journal of Atmos. Solar-Terr. Phys. 59, 1225– 1232 (1997).

8. Scafetta, N. “Empirical analysis of the solar contribution to global mean air surface temperature change.” Journal of Atmospheric and Solar-Terrestrial Physics, 71, 1916–1923 (2009).

9. Scafetta, N., and B. J. West. “Phenomenological solar contribution to the 1900-2000 global surface warming.” Geophysical Research Letters, (2006).



In its simplest form, the argument for anthropogenic climate change goes as follows.

1. The Earth's atmosphere keeps the planet much warmer than it would be without an atmosphere.1
2. The main gases which contribute to this are carbon dioxide, methane and water vapor. Collectively these are called greenhouse gases.2
3. The ability of these gases to act as greenhouse gases can be shown in a laboratory.3
4. The quantity of these greenhouse gases in the atmosphere has increased sharply since the Industrial Revolution, and their concentration continues to do so.4
5. The concentration of these gases has increased as a consequence of human activity.5
6. The temperature of Earth's atmosphere has been increasing and continues to increase.6
7. The increase in global temperature correlates with the increases of greenhouse gases.7, 8
8. The increase in temperature has been caused by the increase in greenhouse gases.9, 10, 11

Many different observations find a distinct human fingerprint on climate change:

1. Humans are currently emitting around 30 billion tonnes of CO2 into the atmosphere every year. Of course, it could be coincidence that CO2 levels are rising so sharply at the same time so let's look at more evidence that we're responsible for the rise in CO2 levels.12
2. When we measure the type of carbon accumulating in the atmosphere, we observe more of the type of carbon that comes from fossil fuels.13
3. This is corroborated by measurements of oxygen in the atmosphere. Oxygen levels are falling in line with the amount of carbon dioxide rising, just as you'd expect from fossil fuel burning which takes oxygen out of the air to create carbon dioxide.13
4. Further independent evidence that humans are raising CO2 levels comes from measurements of carbon found in coral records going back several centuries. These find a recent sharp rise in the type of carbon that comes from fossil fuels.14
5. So we know humans are raising CO2 levels. What's the effect? Satellites measure less heat escaping out to space, at the particular wavelengths that CO2 absorbs heat, thus finding "direct experimental evidence for a significant increase in the Earth's greenhouse effect"15, 16, 17
6. If less heat is escaping to space, where is it going? Back to the Earth's surface. Surface measurements confirm this, observing more downward infrared radiation A closer look at the downward radiation finds more heat returning at CO2 wavelengths, leading to the conclusion that "this experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming.18, 19, 20
7. If an increased greenhouse effect is causing global warming, we should see certain patterns in the warming. For example, the planet should warm faster at night than during the day. This is indeed being observed.21, 22
8. Another distinctive pattern of greenhouse warming is cooling in the upper atmosphere, otherwise known as the stratosphere. This is exactly what's happening.23
9. With the lower atmosphere (the troposphere) warming and the upper atmosphere (the stratosphere) cooling, another consequence is the boundary between the troposphere and stratosphere, otherwise known as the tropopause, should rise as a consequence of greenhouse warming. This has been observed.24
10. An even higher layer of the atmosphere, the ionosphere, is expected to cool and contract in response to greenhouse warming. This has been observed by satellites.25, 26

Overall, there is reason to believe that humans are the main cause of our recent global warming.

Debate Round No. 2



1. Agreed

2. Agreed

3. Agreed

4. Agreed

5. Debatable. But I would also like to note only 50% of what we emit is actually gets into the atmosphere. Mother absorbs the other half [1], already decreasing any potential impact humans may have. Other calculations have noted the increase in CO2 could be “[at] most (1.71/1.98 = 86%) of the upward trend in carbon dioxide since CO2 monitoring began at Mauna Loa 50 years ago could indeed be explained as a result of the warming, rather than the other way around.”[2] But, I would agree humans do have a substantial effect on the amount of CO2, yes.

6. It has increased, but there is significant evidence that global warming stopped in the late 90s. One study found, “statistically significant cooling for the past 12 to 13 years, with it not being possible to reject a flat (0 slope) for 16 years.”[3]

7. Short term correlation of a few decades does not substantiate the claim about the causation of CO2 in the atmosphere. For CO2 to be a proven cause, or a dominant cause, it must correlate with temperature well throughout history. Scientists have determined a few facts:[4]

· CO2 does not correlate with temperature in the last 500 years

· CO2 does not correlate with temperature in the last million years

· In the past 10,000 years CO2 does not correlate with temperature

· In the last 100 years there is a weak correlation with temperature

If CO2 actually was a main driver, it would correlate with temperature in the past – why would it magically become a factor now? Ken Gregory writes, “Temperatures have been variable over time, and do not correlate to CO2 concentration. When CO2 concentrations were 10 times higher than they are now we were in a major ice age.”[5] Essentially, my opponent asks us to accept a 100 year correlation over a 500 million year correlation where CO2 is proven NOT to be a large factor in warming. Further, there are many trends within the 100 years (1950 – 1970, and 1997 – now) where there is no correlation. Actually, approximately 36 years with poor correlation. Studies have been done and find CO2 only has an r = .44 (44%) correlation with temperature. The sun actually scored better, with a 57% correlation, and the PDO with an 83% correlation [6].

I would again like to note correlation does not equal causation. Not like the sun or oceanic cycles where there is a clear causation factor, the effect of carbon dioxide is more unknown. The direct effect of carbon dioxide is much too low to cause a significant amount of the global warming, and the logarithmic effect of CO2 further lowers the chances for the effect to be large. The debate then becomes a debate about feedbacks (how climate reacts to CO2). Studies of paleoclimate are the best for analyzing earths true sensitivity and feedback mechanisms. They generally show CO2 is not a strong factor in climate [7].

8. It is highly unlikely for this to be true. Other than footnotes, my opponent really does not elaborate. Unless he does, I am not obligated to attack his sources, only what he says.

Second List

Although cited in his sources, the WHOLE list is taken from his reference 26. He takes it word by word and adds the exact sources from the website and cites them as his own. Although citing the source in the bibliography, he never gives it direct credit, making that plagiarism.

1. Agree. And I agree with the second statement it is just a coincidence.

2. I do not deny humans have had a large effect on the increase in CO2, or even a majority (the 89% estimate was a higher end estimate). So I really don’t have a beef with this.

3. Ok…

4. k

5. AHAH! Jackpot. The study my opponent cited has been highly criticized, has been forced to undergo massive corrections, and still has flawed methodology. Unlike measuring temperature (where stats mean a lot), the study claimed it found statistically significant differences. The difference, climactically, is extremely small although statistically significant. And looking at the results shows there was really little change in outgoing radiation in the period studied [8]. Other studies actually show outgoing radiations may have increased, meaning the greenhouse effect has gotten weaker since the 1970s [9]. How could this be? Answer: “[a]n analysis of NASA satellite data shows that water vapor, the most important greenhouse gas, has declined in the upper atmosphere causing a cooling effect that is 16 times greater than the warming effect from man-made greenhouse gas emissions during the period 1990 to 2001.”[10] The fact CO2 has little effect to begin with and the greenhouse effect is shrinking merely shows natural factors have accounted for most of the warming in the 20th century.

6. My source 10 is one of the most comprehensive studies which obliterates my opponents study.

7. Actually, this is fully explained by the urban heat island effect (UHI) which is stronger at night. When measuring the data from rural sites vs urban sites, only the urban sites tainted by urbanization show faster warming, whilst the rural sites which are untainted show little change in night temperatures [11].

8. There is no tropospheric warming, that is a lie and I don’t know how it still exists. The troposphere has actually not warmed significantly since 1970, which directly invalidates the whole AGW theory [12]. Another study concluded, “Model results and observed temperature trends are in disagreement in most of the tropical troposphere, being separated by more than twice the uncertainty of the model mean. In layers near 5 km, the modeled trend is 100 to 300% higher than observed, and, above 8 km, modeled and observed trends have opposite signs.”[13]

9. The tropopause warming is impossible because the troposphere has not warmed significantly. Any warming observed in that layer is, then, likely based on spurious data. Indeed, the literature does not say “that is what’s happening”, it says “no, no trends in either. Slight cooling trends sometimes.”[12]

10. The fact CO2 is one of the weakest greenhouse gasses leads me to believe these correlations are probably pretty weak in reality and exaggerated by alarmists. Further, many solar scientists have noted how we still don’t understand the solar-climate link (though we know it does exist) and it could possibly confuse the two in the data.




Occam7 forfeited this round.
Debate Round No. 3


"In Greenland, the three most recent historic warm peaks of the Bond cycle (Minoan, Roman, and Mediaeval Warm Periods) all attained or exceeded the magnitude of the late twentieth century warming."
--Bob Carter. "Climate, the counter consensus"

"In thus considering the seven greatest temperature transitions of the past half-million years - three glacial terminations and four glacial inceptions - we note that increases and decreases in atmospheric CO2 concentration not only did not precede the changes in air temperature, they followed them, and by hundreds to thousands of years! There were also long periods of time when atmospheric CO2 remained unchanged, while air temperature dropped, as well as times when the air's CO2 content dropped, while air temperature remained unchanged or actually rose. Hence, the climate history of the past half-million years provides absolutely no evidence to suggest that the ongoing rise in the air's CO2 concentration will lead to significant global warming. ... l negative feedbacks could easily thwart the impetus for warming provided by future increases in the air's CO2 content."
--C. D. Idso and K. E. Idso.

"From a scientific point-of-view the cosmic ray theory is in much better shape. ... Variations in the rate if warming during the past 100 years also match the variations in cosmic-ray intensity."
--Henrik Svensmark and Nigel Calder. "The Chilling Stars: a Cosmic View of Climate Change."


Occam7 forfeited this round.
Debate Round No. 4
1 comment has been posted on this debate.
Posted by RussellCook 3 years ago
1Historygenius referred me to your debate. Congrats on winning! Fun that you have Dr Soon as a photo icon, I got the guest comment of Dr Soon's at my GelbspanFiles blog yesterday ( ), reproduced at WUWT ( )
4 votes have been placed for this debate. Showing 1 through 4 records.
Vote Placed by Vulpes_Inculta 3 years ago
Agreed with before the debate:--Vote Checkmark0 points
Agreed with after the debate:--Vote Checkmark0 points
Who had better conduct:Vote Checkmark--1 point
Had better spelling and grammar:--Vote Checkmark1 point
Made more convincing arguments:--Vote Checkmark3 points
Used the most reliable sources:--Vote Checkmark2 points
Total points awarded:10 
Reasons for voting decision: FF
Vote Placed by jackintosh 3 years ago
Agreed with before the debate:--Vote Checkmark0 points
Agreed with after the debate:--Vote Checkmark0 points
Who had better conduct:Vote Checkmark--1 point
Had better spelling and grammar:--Vote Checkmark1 point
Made more convincing arguments:Vote Checkmark--3 points
Used the most reliable sources:--Vote Checkmark2 points
Total points awarded:40 
Reasons for voting decision: FF so conduct goes to Con, and the best arguments have to go to the person who gave some...Also con
Vote Placed by 1Devilsadvocate 3 years ago
Agreed with before the debate:--Vote Checkmark0 points
Agreed with after the debate:--Vote Checkmark0 points
Who had better conduct:Vote Checkmark--1 point
Had better spelling and grammar:--Vote Checkmark1 point
Made more convincing arguments:Vote Checkmark--3 points
Used the most reliable sources:--Vote Checkmark2 points
Total points awarded:40 
Reasons for voting decision: This looked like a good debate until Pro F.F.
Vote Placed by Ragnar 3 years ago
Agreed with before the debate:--Vote Checkmark0 points
Agreed with after the debate:--Vote Checkmark0 points
Who had better conduct:Vote Checkmark--1 point
Had better spelling and grammar:--Vote Checkmark1 point
Made more convincing arguments:--Vote Checkmark3 points
Used the most reliable sources:--Vote Checkmark2 points
Total points awarded:10 
Reasons for voting decision: ff.