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

Mankind Is the Main Cause of Global Warming

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Voting Style: Open Point System: Select Winner
Started: 6/6/2015 Category: Science
Updated: 1 year ago Status: Post Voting Period
Viewed: 70,342 times Debate No: 75383
Debate Rounds (4)
Comments (163)
Votes (10)




You asked to accept this.

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 this debate
Debate Round No. 1


I would like to thank Kryptic for accepting this debate.

Correlation and Causation

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."[1]

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."[2]

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

Excess CO2 traps heat. Considering the recent global warming, 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."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 warming.'"[3][4][5]

Evidence of Mankind's Influence on the Recent Global Warming Trend

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.

Now, 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.[6]

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


Now, carbon has several isotopes, three of which are C12, C13, and C14. C14 is radioactive, and has a half life of around 5,730 years. The CO2 emissions that humans make come from fossil fuels. Thus, if humans were the cause of the excess CO2, we'd except the C14/C12 ratio to decline, because, while there is a relatively constant amount of C14 in the atmosphere due to continuous replenishment (when a neutron collides with a regular nitrogen atom, a C14 atom and a proton result), the amount of C14 in the Earth has steadily decreased because it is not replenished, and since fossil fuels come from the ground, almost pure C12 is being ejected into the atmosphere. Indeed, it is observed that the C14/C12 ratio has declined. And thus, if humans were the cause of the excess CO2, we'd except the C13/C12 ratio to decline, because plants find it easier to take in carbon dioxide with a C12 atom than one with a C13 atom, implying that plants have a lower C13/C12 ratio than the atmopshere and, since animals eat plants (either by directly eating then or eating something that eats plants), also implying that fossils also have a lower C13/C12 ratio than the atmopshere, implying that we'd see a decline in the C13/C12 ratio as well. Indeed it is also observed that the C13/C12 ratio has declined.[9][10][11]

This can be observed in the graph below (this is the C13/C12 ratio over the last 650 years; the C14/C12 ratio graph was too big to put in the debate):

The evidence that this excess CO2 is the cause of the recent global warming is voluminous. 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."[4][12][13]

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."[4][14]

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."[15]

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.[16]

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.[18]

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.


I will be debating against (Con) the idea that 'Mankind Is the Main Cause of Global Warming', I do not doubt that we are a huge factor in this, however I am arguing that we are not the leading cause of Global Warming, or known better recently as, Climate Change.
I would like to start talking about what Climate Change is.
- a change in global or regional climate patterns, in particular a change apparent from the mid to late 20th century onwards and attributed largely to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels.
This is the typical definition of Climate Change for the public, the use of fossil fuels and other carbon based structures that inevitably end up in the atmosphere, making a greenhouse effect and holding in more heat.

My argument is, ~ Humans and natural cycles is why we have Climate Change ~

Each year through our generation of electricity through coal [4], our consumption of petrol and oil and exhaust of our transportation [3], our destruction of natural filters such as plant life, phytoplankton [1] and bodies of water [2] have made our world a slightly different place that will radically change in the near future.
The science behind the principle of Climate Change is what we want to know.
How does Climate Change work?

If we look at the moon, the temperatures vary from -170C to 100C [5], however, on Earth we have a stronger gravity, this pulls our gaseous atmosphere closer to our planet through its mass. Gravity is a force and puts pressure on everything it can affect, as a result, everything becomes heavier; this means that the centrifugal force also applies more pressure due to the rotation of the axis [6]. Since our atmosphere is a lot closer and denser then the moons atmosphere, heat is locked in.
The question now is, how the atmosphere correlates to increased heat.
In order for our atmosphere to absorb radiation, it must have some electrically charged particles for passing electromagnetic waves to push around. Although most of the gasses in our atmosphere don't have a negative charge, instead, they have an equal distribution between both negative and positive charges. However, there is one good part about the placement of polarity, Water (H20), Ozone (O3) and Nitrous Oxide (N2O) which all have their negatively charged particles on one side allowing infrared radiation to absorb and reflect easily.[7]
Carbon Dioxide (C02) and Methane (CH4) move and shake continuously allowing the same result as the previous three elements. [8]
As a result, having these gasses enables more heat to be held together leading to hotter days.

I will not be going into Ozone Depletion however I will be going into how the real reason we have climate change is due to our oceans.

Opening statement.

The human use of elements that promote the greenhouse effect on the world has created a slight discourse in the typical cycles that would otherwise naturally occur. The waters are getting hotter, rising, and expelling carbon dioxide instead of holding it in, this has occurred in the past naturally without human intervention, the natural filters are being removed and as a result, more carbon dioxide is entering our atmosphere enabling Climate Change. This is the man made climate change that will affect the patterns of temperature cycles that have been happening for the last 4.5 billion years. Mankind is affecting the part of repair or restoration within natural filters. If we look at graphs that are 542 million years ago, we can see a general pattern, we are about to go into a cold spell soon too. The next ice age is on its way.
Currently I have no option to upload the graph so I will post it in the reference.

I do apologise for my incredibly short argument, it’s really late, and I did not have much time to work on this. I will finish my argument, address your rebuttals and complete round 2 and 3 off successfully in the next round. Thank you.


References: [1] [2] [3] [4] [5] [6] [7] [8] [9] [Graphs that were unable to upload]
Again, I apologise for any inconvenience. If you would like to render this arguement obsolete and start over, I would be more than happy to at a later date; this is a fun topic of discussion for me.
Debate Round No. 2


I would like to thank Kryptic for presenting his argument.

I agree with the alternate definition he provided. Looking back to the definition I cited in round 1, I defined global warming as "...the average temperature of Earth's atmosphere and oceans since the late 19th century, and its projected continuation." This means that any arguments regarding natural factors' effects on the climate before the late 19th century and long term climate projection of there being another ice age are irrelevant. I'm not contending that natural factors have no effect on the climate, or even that they are not usually the only cause of climate change. All I'm arguing is that the global warming since the late 19th century has been driven mostly by anthropogenic forcings.[1]

Since my opponent provided no other arguments, all I will do in this round is show how comparing natural factors and anthropogenic factors shows that humans are the main cause of global warming.

The most important of the natural climate forcings is the sun. It is the source of the Earth's energy. This energy comes from the radiation emitted as a result of fusion reactions at the core of the sun. This radiation is known as the Total Solar Irradiance (TSI). Any change in the TSI causes energy imbalances on the Earth. This energy imbalance can be calculated using the formula below:

Delta means change, so Delta(F) means the change in energy (i.e. energy imbalance) and Delta(TSI) means the change in solar irradiance. The 0.7 factor comes from the fact that the Earth reflects about 30% of the solar radiation it receives, and the 1/4 factor comes from spherical geometry.

Changes in temperature are proportional to the energy imbalance. This can be expressed in the formula below:

Lambda is the constant of proportionality, representing the climate sensitivity (discussed in my first argument) in this case.
The only thing that's left is to actually determine the values. First, the change in TSI (in this case, between 1900 and 1950). "Although Wang, Lean, and Sheeley's reconstructionputs the change in TSIsince 1900 at about 0.5 W-m-2, previous studies have shown a larger change, so we'll estimate the change in TSI at 0.5 to 2 W-m-2." This corresponds to an energy imbalance of around 0.1-0.35 W-m-2. Next, the lambda factor. I explained in the last article that the statistically most probable value for the climate sensitivity was around 3 degrees C. But, there was a lot of variation. "Studies have given a possible range of values of 2 to 4.5°C warming for a doubling of CO2, which corresponds to a range of 0.54 to 1.2°C/(W-m-2) for λ." This gives range of values from 0.05 to 0.4 degrees C, with a most probable value of 0.15 degrees C (corresponding to the statistically most likely climate sensitivity). In other words, solar activity from 1900 to 1950 raised the temperature of the Earth 0.15 degrees C.[2]

Looking at the effect of CO2 emissions over that same period, humans increased the concentration of CO2 in the atmosphere by about 20 parts per million, giving a range of values of 0.14-0.32 degrees C for the effect of that emission on the climate, with the most probable being 0.22 degrees C.[2]

This corresponds to CO2 amounting for 60% of the warming from 1900-1950. After that, it gets higher. CO2 emissions rise exponentally, and changes in the TSI start getting less positive, and eventually become negative after 1975. "Therefore, the solar forcing combined with theanthropogenicCO2forcing and other minor forcings (such as decreased volcanic activity) can account for the 0.4°C warming in the early 20th century, with the solar forcing accounting for about 40% of the total warming. Over the past century, this increase inTSIis responsible for about 15-20% of global warming. But sinceTSIhasn't increased in at least the past 32 years (and more like 60 years, based onreconstructions), the Sun is not directly responsible for the warming over that period." Solar activity cannot account for the warming after 1975, and even before that was a smaller factor than CO2.[2]

This can be shown in the image below:


CO2 correlates with CO2 more than solar activity, especially after 1975.

There are other natural forcings, ozone concentrations and volcanic activity being the other major ones. The ozone layer of the atmosphere blocks the sun's UV radiation from reaching the Earth. Lowering levels of ozone may cause warming then by allowing more solar radiation to reach the Earth. However, while ozone levels were decreasing before 1995, they are now increasing (regardless, the declining ozone levels were also caused by humans).

And the volcanic activity forcing has actually had a cooling effect on the climate. "Foster and Rahmstorf (2011) used a multiple linear regression approach to filter out the effects of volcanic andsolar activity, and the El NiñoSouthern Oscillation(ENSO). They found that volcanic activity, as measured by aerosol optical thickness data (AOD) has only caused between 0.02 and 0.04°C per decade warming from 1979 through 2010 (Table 1, Figure 2), or about 0.06 to 0.12°C warming of the surface and lowertroposphere, repsectively, since 1979 (out of approximately 0.5°C observed surface warming)."[4]

In total, all the forcings, both natural and anthropogenic, can be shown below:


Greenhouse gases are far more important than solar activity (note that sulfate levels mostly correlate with volcanic activity).


I don't have anything more to say, since this is all my opponent talks about. Anthropogenic forcings were more important for global warming than natural forcings.




To be honest, I thought it would be a fun thing to debate someone on something controversial and funny. but I just can't bring my self to debate something that is intellectually dishonest and simply false. I withdraw my argument and forfeit.

Thanks for the debate so far, I would of totally kept the debate going if it was something I could persist with and have a drive of showing that I was in fact correct. but there is simply no evidence suggesting anything other than man has caused an over abundance of natural gases that has resulted in a process we call climate change.

if I continued this debate and got people on my side, I could not forgive my self for 'uneducating' people :P. it would be a disgrace to my growth in science and what I stand for.

I will happily continue on another topic on a different debate though. it was good debating you, also, even if I was to make another come back, you have covered everything. the only thing to possibly do is suggest it does not exist.

have a good day.
Debate Round No. 3


Well, then, I thank my opponent for presenting the arguments he did.

I invite anyone who wants to challenge my arguments to debate me.
Debate Round No. 4
163 comments have been posted on this debate. Showing 1 through 10 records.
Posted by Nivek 6 months ago
DBhundia. I disagree.

I've been in your position before. Endless amount of socializing, endless amount of going outside and experiencing life. Up to a certain point, you adapt to a set of stimulus and the feel of comfort sets in. You feel useless and you began comparing how social dramas are so petty it's ridiculous you even have them in the first place. DDO is a way to take refuge from the pettiness of life and it works really really well, especially if you know where to read.
Posted by Max.Wallace 6 months ago
In 2 years there has never been a debate worthy of recognition, except this one according to the establishment.
Posted by tbone8 6 months ago
A question for all the global warming alarmist/activists. Your cheerleader, the POTUS just recently took not one, but two airforce one jets down to South America on his last trip. Why, you ask? So his wife and kids had their own plane to fly around and sight see during their spring break vacation. This man claims that global warming is a more pressing issue than terror threats yet note the waste of energy not to mention taxpayer funds. This act alone of, "do as I say, not as I do" should be enough to wake you people up to the hypocrisy of this nonsense. Bury your heads back in the sand and serve as useful idiots or wake up!
Posted by Max.Wallace 6 months ago
Who made you the owner of this debate? Just wondering, politely. Thank you for your considerstion, Owner of Debate.
Posted by Max.Wallace 6 months ago
An aspiring tyrant told me it is.
Posted by Subutai 7 months ago
Then what are you doing commenting on my debate?
Posted by DBhundia 7 months ago
Jesus some people need to spend less time on and more time outisde
Posted by Max.Wallace 7 months ago
A vegan said it's all because of the cowfarts. Glad I am not a color.
Posted by Kid10 7 months ago
If u rape a chicken does that mean u can lay eggs
Posted by Bumfight2003 7 months ago
As far as I know this planet doesn't require human to exist. On a ecosystem you can eliminate human and ecosystem will still be a system and will function well . Humans known existence is only less than 500,000 years ago or surely less than that . There where no humans during the ages of the dinosaurs and some existed more than 50 million years and others still existing without human contact. So if humanity come to an end simply because of the same reason dinosaurs no longer exists. We are simply here for a reason and that reason is what you should learn and find out yourself. I don't agree with global warming I agree more on humans need of warmer climate to function but the problem is this planet earth doesn't care about humans . Global warming equals Ice age if this planet decides plants and animals will have to adopt. We are just accelerating our extinction...
10 votes have been placed for this debate. Showing 1 through 10 records.
Vote Placed by 1Historygenius 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Nice work Subutai.
Vote Placed by SamStevens 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Pro placed a great amount of evidence and analysis on the table to support his contentions. Con forfeited. Therefore, Pro won.
Vote Placed by evanjfarrar 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Pro brought up mountains of evidence to support his claim, and is backed by scientific experimentation and rational thinking.
Vote Placed by joetheripper117 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Con was intellectually honest and surrendered his point.
Vote Placed by Midnight1131 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Kryptic forfeited the debate, conceding all arguments.
Vote Placed by greatkitteh 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Con graciusly allowed Pro to win.
Vote Placed by Death23 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: FF
Vote Placed by ImmortalVoddoler 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Con conceded, even though he was right.
Vote Placed by tejretics 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: Concession.
Vote Placed by 16kadams 1 year ago
Who won the debate:Vote Checkmark-
Reasons for voting decision: pretty sure con conceded