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

Mankind Is the Main Cause of Global Warming

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Post Voting Period
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Voting Style: Open Point System: Select Winner
Started: 3/22/2015 Category: Science
Updated: 3 years ago Status: Post Voting Period
Viewed: 3,151 times Debate No: 72122
Debate Rounds (4)
Comments (19)
Votes (3)




We've decided to redo this debate since Lannan was unable to finish it earlier.

Full Resolution

I will be arguing that mankind is the main cause of global warming. We will not be arguing if global warming exists or not, it will be assumed that it does; only if global warming has an anthropogenic cause.

BoP is shared.


Mankind: "The human race; human beings collectively without reference to sex; humankind."[1]

Main: "Chief in size, extent, or importance; principal; leading;"[2]

Cause: "A person or thing that acts, happens, or exists in such a way that some specific thing happens as a result; the producer of an effect."[3]

Global Warming: "Global warming is the rise in the average temperature of Earth's atmosphere and oceans since the late 19th century, and its projected continuation."[4]


1. The first round is for acceptance.
2. A forfeit or concession is not allowed.
3. No semantics or trolling.
4. All arguments must be visible inside this debate. Sources may be posted in an outside link.
5. Debate resolution, definitions, rules, and structure cannot be changed without asking in the comments before you post your round 1 argument. Debate resolution, definitions, rules, and structure cannot be changed in the middle of the debate.

Voters, in the case of the breaking of any of these rules by either debater, all seven points in voting should be given to the other person.

Debate Structure

Round 1: Acceptance
Round 2: Presenting all arguments (no rebuttals by con)
Round 3: Refutation of opponent's arguments (no new arguments)
Round 4: Defending your original arguments and conclusion (no new arguments)




I accept.
Debate Round No. 1


I would like to thank lannan13 for accepting this debate.

Human-Emitted Greenhouse Gases

It is known that CO2 levels are increasing. "In pre-industrial times over the last 10,000 years, CO2 was relatively stable at around 275 to 285 parts per million. Over the last 250 years, atmospheric CO2 levels have increased by about 100 parts per million." CO2 levels are increasing at a level not seen in at least 500,000 years, if not longer.[1]

Here is a graph showing CO2 concentrations over the last 10000 years:


This excess CO2 traps heat. Satellites measure less heat escaping out to space, at the particular wavelengths that CO2 absorbs heat, thus finding " experimental evidence for a significant increase in the Earth's greenhouse effect." In other words, the Earth is retaining more of the heat that it receives from the sun that it received from before. This excess heat manifests itself through global temperature increases.[4]

"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 moreheat returning at CO2 wavelengths, leadin 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 wa

CO2 correlates with temperature. Consider the Cenozoic era (the last 65 million years). Overall, solar activity increased 0.4% over this period. "Because Earth absorbs about 240 W/m^2 of solar energy, that brightness increase is a forcing of about 1 W/m^2. This small linear increase of forcing, by itself, would have caused a modest global warming through the Cenozoic Era." The CO2 levels caused a much higher forcing. In contrast, atmospheric CO2 during the Cenozoic changed from at least 1000 ppm in the early Cenozoic to as small as 170 ppm during recent ice ages. The resulting climate forcing, as can be computed accurately for this CO2 range using formulae in Table 1 of Hansen et al. (2000), exceeds 10 W/m^2. It is clear that CO2 was the dominant climate forcing in the Cenozoic."[7]

In fact, the temperature changes correspond to the CO2 changes. "...there is a close correlation between Antarctic temperature and atmospheric concentrations of CO2 (Barnola et al. 1987). The extension of the Vostok CO2 record shows that the main trends of CO2 are similar for each glacial cycle. Major transitions from the lowest to the highest values are associated with glacial-interglacial transitions. During these transitions, the atmospheric concentrations of CO2 rises from 180 to 280-300 ppmv (Petit et al. 1999). The extension of the Vostok CO2 record shows the present-day levels of CO2 are unprecedented during the past 420 kyr."[8]

This graph shows the CO2-temperature correlation over the last 700,000 years:

Indeed, it would be rather coincidental if the recent rise in global warming happened to start just around the time that humans started to emit large quantities of greenhouse gases. However, there is direct evidence as well, in addition to the already established correlation between temperature and CO2.

One piece of evidence is a comparison of warming in the troposphere and stratosphere. Because the CO2 is in the upper troposphere, the troposphere temperature would increase, while the stratospheric temperature would decrease, because there would be less heat reaching the stratosphere. "Computer model estimates of the ‘human influence’ fingerprint are broadly similar to the observed pattern. In sharp contrast, model simulations of internal and total natural variability cannot produce the same sustained, large-scale warming of the troposphere and cooling of the stratosphere."[9][10]

This graph shows this:


Another piece of evidence is the frequency of cold days and nights. Because the sun only shines in the day time, is the sun was causing global warming, the days would warm faster than the nights, while if greenhouse gases were causing global warming, this wouldn't be observed. It is the latter's prediction that is observed. "What we observe is a decrease in cold nights greater than the decrease in cold days, and an increase in warm nights greater than the increase in warm days."[5][11]

This can be shown in the below graph:


Overall, the evidence shows that human-emitted greenhouse gases are the cause of global warming. CO2, in addition to other gases like methane and nitrous oxide are being emitted by humans in very large amounts, and this is manifesting itself in an increase in the average global temperature.

Climate Sensitivity and Feedbacks

Climate sensitivity is the amount the temperature would rise if the CO2 concentration were doubled. Obviously, if there's a large climate sensitivity, then increases in CO2 have large effect. It is known that the climate sensitivity is around 1 degree C. However, this can be amplified through feedbacks. Positive ones amplify the sensitivity, while negative ones diminish the sensitivity. The evidence overwhelmingly comes down on the former, that positive feedbacks are happening. Increases in CO2 cause temperature increases, which are amplified by water vapor and the effect on clouds.

"Since the radiative effects associated with the buildup of water vapor to near-saturation levels and the subsequent condensation into clouds are far stronger than the equilibrium level of radiative forcing by the non-condensing GHGs, this results in large local fluctuations in temperature about the global equilibrium value."[12]

This can be shown in the below graph:

Further, increases in CO2 affect the carbon cycle in this way:

Global warming can result in the death of vegetation (due to droughts) and the warming of the ocean. Both of these further reduce the maximum absorption of the Earths carbon cycle, thus resulting in even more CO2 being released into the atmosphere. And with this, CO2 increases even more. In other words, CO2-caused temperature increases are amplified by positive feedbacks and the mechanics of the carbon cycle.

So, the positive feedback amplifies the climate sensitivity. How much it is amplified can be determined through study. Using a Bayesian statistical approach, which is “the dominant [method] in the literature”, these findings support the notion of climate sensitivity as maximum 4 degrees C, a mean of 3 degrees C, and likely not lower than 3 degrees.[13]

The graph below gives a statistical analysis:


The mean is around 3 degrees C.

The CO2 that humans emit thus has an effect of 3 degrees C per doubling of CO2. This can be shown by the fact that CO2 concentrations have increased from around 275 ppm to around 400 ppm. This is an increase of around 40%. This should manifest itself with a temperature increase of a little less than 1.5 degrees C. Indeed, temperatures have increased around this amount over the last 150 years. The anthropogenic-forcing climate models thus match observations.[15]

In other words, in addition to the direct evidence of how the Earth is warming, the climate models based on a greenhouse gas cause to global warming explain almost perfectly the recent global warming. This is a lot of evidence for a human case to the recent global warming.


Greenhouse gases cause global warming because of their heat trapping abilities. Humans have been emitting vast amounts of greenhouse gases over the last 150 years, and this shows itself on the CO2 measurements. The atmospheric warming pattern and greater heating at night are evidence that the recent global warming is caused by those human emitted greenhouse gases. These increases are amplified through the water vapor and cloud positive feedbacks and the positive feedback that arises through the climate cycle. The climate sensitivity ends up being around 3 degrees C. Finally, the CO2-temperature record shows that the two correlate with remarkable correlation.


Sources in comments.


Contention 1: No Major/any CO2 Increase.

Many Global Warming advocates state that CO2 levels are skyrocketing, but that is incorrect. I give you the above graph measuring the past 600 million years of CO2 levels are we are actually at an all time low. Now the website I got this from no longer has this page up so I appologize. We can see from observance of this graph that we being at all time CO2 low levles that we are nowhere close to meeting the impact that my opponent brings up. We have been over 5,000 ppm of CO2 in our atmosphere and are now currently around apprx. 350 ppm CO2 levels.
Fig. 2. C13 fraction variations contained in seasonal versus, interannual versus decadal variability, compared to known geophysical sources.
The above graph shows that comparisions of C13 (Carbon isotope) and this shows that there is little to no trend pertrade in many of these as the average is zero while the trend for all of these are zero. (1) This is important as the Carbon isotope is important in measuring this so called "Global Warming."
This chart above shows the CO2 and Earth's temperatures for the past 600 million years. My opponent's claims are incorect as we have had aburd levels of CO2 and temperature on Earth and may I ask how did we survive that? (2)
Now I will move on to how Earth is actually cooling and how it's temperature is cooler than it has been.

Contention 2: Earth is cooling.
If we observe the above graph we can see that Earth has been a whole lot hotter than where we currently are to the point where the Earth's average temperature has been 7.5 degrees Celcuis hotter than it currently it is. You can also see that in the span of the past 10,000 years the temperature has leveld off, but you may ask yourself where does that place us in the lights of modern day?
I am going to site Dr. Done Easterbrook, who is a climate scientist. Back in 2000 he predicted that Earth was entering a cooling phase. He predicts that for the next 20 years Earth will cool by 3/10 degree each year and that we are going to enter another little Ice Age like we did from 1650 and 1790. (3) The funny thing is that many of my opponent's charts are actually from the incorrect IPPC.

How about the "Hockey Stick" graph that many Global Warming supporters , including my opponent, argue about? Well if we observe the fallowing chart taken from Northern Scandenavia we can see that the Global trend over the past 1,000 years that the Global Cooling trend slope is that of -0.31 Degrees Celcuis, give or take 0.03 degrees (for the error room). Professor Dr. Jan Esper has found that the Earth's temperature of Earth actually decreases 0.3 per millenia due to the Earth moving away from the sun. (4)
Here is another graph from 1920 to 2005 and we can see that the graph has a negative temperature slope, thus meaning that the Earth is under a period of cooling. (5)

You can see in terms of more Warming in the evidence in which Scientists use Ice Cores Earth has actually been Cooling the past Mellenium.

Finailly, lets bring up just how much these accused compounds exactly warm the Earth's atmosphere. CO2 for example has the global warming potential of 1. Here are the other numbers.
Carbon Dioxide -- 1
Methane -- 21
Nitrous Oxide -- 298-310
CFC's -- Various
Water Vapor -- 0.25
Now I just want you to keep this in mind for this next part here. We may observe that humans release approximately 35 gigatons of CO2 a year. [14] This is only 4.3% of the total amount of all Global Warming Gasses, however it is incrediably small when it comes to comparing the rest of the Global Warming gasses. If we observe the chart bellow we can see that Water Vapor is a large Contributor to Global Warming at 95% and CO2 comes in second. But here's the kicker. If we look at the Human contributed part that I'm about to post in the graph bellow we can see that it's very miniscule of 0.117% of all total Warming gasses. Now let's do some quick math here. CO2's increase was from what my opponent is claiming is from 295 ppm to 400ppm, a total of only 105 ppm. 1 Gigaton of CO2 is the equilivent of 2.13 ppm. [15] This means that increase of 105 ppm means a total of 49.29 gigatons. Since 1 gigaton of CO2 is the equivilance of .004% of the Greenhouse effect that means that 49.29 gigatons means an aditional .21% increase to Global Warming. This would account for a grand total of a 0.15 F increase in global temperature. This is a very measly amount and we can see that with my opponent's claims a simple 0.15 F increase isn't enough to melt glacers and have the effeccts that he is speaking of and it proves that this is NAUTRAL not man-made to fulfil his effects if they were real. Now remind yourself that this debate is about humans creating a LARGE amount of Global Warming, not a miniscule amount.

You can see that in terms of Gasses contribution to the Green House Effect the major contributer is Water Vapor and it's at 95% to CO2's 3.6% and this is the overall contribution including man made and natural. When we look to the chart on the left we can see that Man-Made CO2 does have a higher contribution to the atmosphere than Water Vapor, but that's because we do not create much water vapor as humans. Even with this evidence we can see that CO2 does not have any effect what-so-ever compared to Water Vapor. (6) Where might those CFCs be on this graph you may ask. Why it's under the Misc. gases section.

Contention 3: Artic Ice.

Al Gore stated that the Artic Ice would be completely melted by 2014, but he is incorrect then and now.
Jan. 6, 2012: The Coast Guard Cutter Healy breaks ice around the Russian-flagged tanker Renda 250 miles south of Nome. The Healy is the Coast Guard’s only currently operating polar icebreaker. The vessels are transiting through ice up to five-feet thick in this area. The 370-foot tanker Renda will have to go through more than 300 miles of sea ice to get to Nome, a city of about 3,500 people on the western Alaska coastline that did not get its last pre-winter fuel delivery because of a massive storm. (7)
Let's go back to 2007-2008 and see if his claim was justified in the Artic Ice activity.
Hmmm... It seems that he is incorrect, but let's look further into the near past. How about 2012-2013? (8)
We all remember the Climate Scientists that got stuck in Arctic Ice Earlier last year correct? Then a Russian Ice Breaker tried to free them, but got stuck. Can you guess what they were studying? They had predicted that all the Arctic Ice had melted due to Global Warming and that Earth would get flooded massively. Boy were they wrong. (9)
Dr. Koonin, former head of the Department of Energy under President Obama, has stated that the Global Warming scare is not suttle. This is because that he has found 3 things wrong and highly incorrect about the scare.
1. Shrinking of Artic Sea ice doesn't acount for the gaining of the Antartic ice.
2. The warming of Earth's temps today is the same as it was 30 years ago.
3. The sea levels rose at the same height and rate in the 20th cenury. (11)
Contention 4: Sea Levels
Here is another corralation that must happen. If the Ice Caps are completely melted as many GW advocates claim then the sea level would have risen completely drowning tons of land.
The graph above is raw satellite image data of the sea level rise over an 8 year period showing that there is little to no change in the Sea Levels rising. (12) The sea level rises, on average, about 3 inches per century and it has been found to not even been rising at all.
This graph is the sea levels off the cost of French Guyana which is one of the areas which is predicted to be flooded due to Global Warming, but as you can see by the graph (which goes to 2008) the sea level is currently on a downward trend. (13) The source is the PDF within the link.

Contention 5: The Weather

Many Global Warming Advocates claim that Hurricanes are increasing due to Global Warming, but this claim is indeed false! The hurricanes since the year 1900 to 2008 have actually been decreasing. The slope of this downward slope is .0016. Though it is small the hurricanes are still in a downward trend.

As a matter of fact not only are Hurricanes on a downward trend, but they are at an all time low as in the year 2010, there was only 68 Hurricanes Globally, which is an all time low in the past 40 years.

How about Tornados you may ask?


In the graph above you can see that tornados are at an all time low in the past 60 years! (14) But what about Hurricanes?

Here is a graph showing the number of days between hurricanes and this shows that the number of days between hurricanes is greatest at 76 days between hurricanes.The slope of this line is zero showing no trend of a massive storm increase.

Debate Round No. 2


I would like to thank lannan13 for posting his arguments.

No Major CO2 Increase

This is true. CO2 levels have been higher. But what were the climactic conditions during those periods? "The last time carbon dioxide levels were apparently as high as they are today - and were sustained at those levels - global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland." Clearly, the levels that CO2 is reaching are unsustainable.[1]

The reason the CO2 rise is considered high is because the CO2 level is the highest in around 50 million years. And it only took 150 years to get that way. So, while the CO2 level is not as high as it has been, the climate was much warmer then, and the CO2 rise is large in the large scale.

CO2/Temperature Correlation

CO2 does not correlate exactly with temperature. However, if we consider CO2 and the sun, the correlation is almost perfect. The sun has not caused the most recent spurt of global warming, so it must be concluded that the rising CO2 levels are causing global warming.[2][3]

The graph below shows the two forcings plotted against temperature:

Further, my opponent's correlation graph is inaccurate. It forgets the huge uncertainty early on.

This graph shows the uncertainty:

With this uncertainty, Robert Berner (the author of the study and graph), said himself, "Eexact values of CO2... should not be taken literally." That correlation graph should not be taken seriously. The better one is the first graph above, that shows that CO2 has a big effect on the climate. Berner also said in the same study, "...over the long term there is indeed a correlation between CO2 and paleotemperature..."[4][5]

The Earth's Current Climactic Trend

My opponent's studies are based on faulty data sets and misunderstandings about how the climate works. Different data sets show the Earth is warming, and the Earth's climactic indicators show that the Earth is still warming.

For one thing, my opponent's temperature graphs are based off of RSS data. UAH and HADCRUT4 data both show that the Earth has been continuing to warm throughout the last 15 years.[6][7]

For another, it was found that the heat content of the Earth is increasing. "This new research combines measurements of oceanheat, land and atmosphere warming and ice melting to find that our climate system continued to accumulate heat through to 2008... Since 1970, the Earth's heat content has been rising at a rate of 6 x 10^21 Joules per year." If you look back to my first round, you'll see my point that excess CO2 traps heat, and this is exactly what we're seeing[8][9]:

Further, if we focus on surface and lower troposphere temperatures (just where we'd expect there to be warming), we see that the warming trend continues. "Foster and Rahmstorf (2011) used multiple linear regression to filter out the effects of the El Niño Southern Oscillation (ENSO), and solar and volcanic activity (Figure 2), and found that the underlying global surface and lower atmospherewarming trends have remained very steady in recent years."[8][10]:

Fig 5

The hockey stick continues to stick because there's no evidence that there were any periods for at least the last 2500 years that indicate that the climate was warmer then than it is now. The hockey stick was been replicated numerous times. This graph still appears to be the real story when it comes to the recent climate[11]:

Interestingly, my opponent's "Greenland GISP2 Ice Core - Temperature last 10,000 years" graph cuts off at 1850.[12]

Water Vapor

My opponent is correct that water vapor is the most important greenhouse gas. However, water vapor only acts as an amplifier of other warming. Water vapor levels can't be raised. However, since CO2 levels can, the warming that follows is amplified by water vapor in the atmosphere. In other words, it's a positive feedback (see my first argument), not a cause of warming in and of itself.[13]

Arctic Ice Levels

The claim that the arctic sea ice would be completely gone was an apocalyptic one that did not turn out to be true. However, it is still known that the levels of sea ice are decreasing.

See the below graph:

"The blue line represents the trend calculated from January 1 1979 to the most recent date indicated on the figure. Monthly averaged ice volume for September 2014 was 6,970 km. This value is 40% lower than the mean over this period, 59% lower than the maximum in 1979, and 0.7 standard deviations above the 1979-2013 trend." The arctic sea ice levels are decreasing.[14]

As for the Antarctic sea ice claim, while the sea ice is gaining in extent, it is decreasing in mass. This is the result of a complex set of scenarios.[15]

This graph shows the loss in Antarctic ice mass:


The claim that the temperature are warming at the same rate doesn't change the fact that increasing CO2 levels are behind the warming. As for the claim that arctic sea ice levels are rising at the same level, this is blatantly false, as the graph below shows:

summer sea ice extent


Sea Levels

It is true that the sea ice melting portends rising sea levels. However, the sea level is actually increasing. Looking at the sea level for an eight year period hardly shows a long-term trend, especially when there's variation in the climate. The sea level rise in French Guiana would not have inundated the country. Further, there's also variation in the sea level rise in different places.

When the global data is analyzed, a clear trend of sea level rise is seen. "To construct a global historical record of sea levels, tide gauge records are taken from locations away from plate boundaries and subject to little isostatic rebound. This has been done in A 20th century acceleration in global sea-level rise (Church 2006) which reconstructs global sea level rise from tide gauges across the globe."[18][19]:

What can be seen is that the sea levels are rising, and that the increase is accelerating. Relying on isolated events and short-term trends does not answer the question of whether sea levels are rising as a whole globally.

The Weather

The correlation between global warming and weather is much more complex than my opponent gives the anthropogenic global warming theory credit for. For one thing, storms rely on many more variables than just temperature, especially tornadoes. "Then there are problems unique to tornadoes. Beyond knowing that they require a certain type of wind shear, meteorologists just don’t know much about why some thunderstorms generate tornadoes and others don’t." If we don't understand why certain thunderstorms create tornadoes, then we are in no place to analyze the correlation between tornadoes and one variable. We simply just don't know enough yet here.[20]

Hurricanes can be better analyzed, because they are more dependent on ocean temperatures than tornadoes are on land temperatures. Higher temperatures won't necessarily lead to more hurricanes, but they will lead to stronger hurricanes. "The Power Dissipation Index is found to increase since the mid-1970s, due to both longer and more intense storms. Hurricane intensity is also highly correlated with sea surface temperature. This suggests that future warming will lead to an increase in the destructive potential of tropical hurricanes."[21][22]

The below graph shows this:

Hurricane Intensity (Power Dissipation Index) versus North Atlantic Sea Surface Temperature - Emmanuel 2005

The correlation is clear here. Further, it was found that while the number of lower-intensity hurricanes has stayed about the same, the number of higher-intensity hurricanes has increased for this very reason. The greater number of hurricanes seen would be small, considering most hurricanes are lower-intensity.[23]


Sources in comments.


My opponent has convinced me to his position, henceforth I can no longer argue my side.
Debate Round No. 3


16k, you, and I have now all changed to the pro-AGW side. Who would have thought that would ever happen? Are there even any prominent con-AGW debaters on this site any more? I guess that's a good thing.

Thanks for the debate though. The arguments I made helped me to decide on the issue once and for all.
Debate Round No. 4
19 comments have been posted on this debate. Showing 1 through 10 records.
Posted by Josh_debate 3 years ago
There is on evidence to man made global warming
Posted by Genghis_Khan 3 years ago
"Are there even any prominent con-AGW debaters on this site any more?"

RoyLatham and Donald.Keller

But yes, it's still pretty amazing that so many historically anti-AGW debaters have switched sides.
Posted by Subutai 3 years ago
Yes I did. I've spent so much time on the global warming issue that I've changed sides a few times, but I think this change is permanent.
Posted by bsh1 3 years ago
Sub, did you change your views since your debate with Tyler?
Posted by lannan13 3 years ago
Must just be my computer.
Posted by Subutai 3 years ago
Everything appears fine to me.
Posted by lannan13 3 years ago
A few of your graphs aren't popping up.
Posted by lannan13 3 years ago
Alright I think I'll do that when I post.
Posted by Subutai 3 years ago
I got the sourcing right this time.

Also, Lannan, if you need to, you can post your sources in the comments.
3 votes have been placed for this debate. Showing 1 through 3 records.
Vote Placed by The-Voice-of-Truth 3 years ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Con conceded Pro's points. Good debate; it was interesting.
Vote Placed by tejretics 3 years ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Graceful concession by Con. Pro's statistics were also more reliable as to the rates of CO2 as opposed to climatic conditions.
Vote Placed by Varrack 3 years ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Con conceded.