Global warming is likely (and mostly) anthropogenic
In this debate, I am for the resolution. The BOP will be even since this is a contested issue--BOP shall not be negotiated.
The debate structure is first round acceptance, second round arguments (no rebuttals), third round rebuttals/defense, fourth round rebuttals/defense.
My opponent is familiar with the wording, and definitions are not needed.
I would like to thank DanT for accepting this debate. To not confuse other members, I would like to clarify that I am devils advocating.
I will be presenting similar ideas and data points as presented in the Rational Wiki article, but will expand on their current content .
1. The Earth's atmosphere keeps the planet much warmer than it would be without an atmosphere. Unless my opponent disagrees, I will proceed to the next point.
2. The main gases which contribute to this are carbon dioxide, methane and water vapor. Collectively these are called greenhouse gases. Unless my opponent disagrees, I will proceed.
3. The ability of these gases to act as greenhouse gases can be shown in a laboratory. Although my opponent likely agrees, I would like to expand on this somewhat. CO2 is a greenhouse gas and causes some warming. My opponent will likely argue, if he disagrees with this point, that the CO2 effect is minimal or the climate system deals with this through negative climate feedbacks. However, the empirical and peer-reviewed literature obliterates these claims. Recent studies have ranked CO2 the largest factor in the modern warming by far (figure right), and that the feedbacks amplify this initial greenhouse warming substantially (left) .
The National Research Council has come to similar conclusions noting, “A strong, credible body of scientific evidence shows that climate change is occurring, is caused largely by human activities, and poses significant risks for a broad range of human and natural systems”. Former research by Mike Lockwood, who used to be a skeptic and favor a celestial origin of climate change, has published studies noting that the main forcing in climate is human emissions—namely, CO2—humans cause at least 75% of the modern warm period . These laboratory measurement’s seem to be at work in our atmosphere.
4. The quantity of these greenhouse gases in the atmosphere has increased sharply since the Industrial Revolution, and their concentration continues to do so. My opponent likely agrees, again.
5. The concentration of these gases has increased as a consequence of human activity. Skeptic scientists also agree with this—all measurement’s here (well, nearly all) indicate that most of the CO2 increase is due to manmade sources.
6. The temperature of Earth's atmosphere has been increasing and continues to increase. The fact that we are in a warming phase is uncontroversial .
7. The increase in global temperature correlates with the increases of greenhouse gases. This is also a fact. Indeed, independent measurements have proven that long wave radiation is exiting at a slower pace indicating greenhouse gases, to some extent, have warmed the earth. Most likely very significantly . Nearly every estimate shows excellent correlation between the two (co2 vs temperature) . Other data using CO2 measurement’s from Mauna Loa vs global temperatures has found a remarkably close correlation between CO2 and Climate . Further analysis of paleoclimate noted CO2 has amplified past warmings .
That is it, for now.
As per the rules, I will wait until my next round to refute Pro’s arguments. Some of my arguments may overlap, but they were written before Pro posted his arguments.
1.) Correlation =/= Causation
Proponents of anthropogenic global warming often point to the correlation between CO2 and the rise in global temperatures. According to the Center for the Study of Carbon Dioxide and Global Change, in order to prove a causational relationship, one must prove that the supposed cause preceded the effect. The pseudoscientists who propose CO2 as a cause for global warming fail to address what came first; the rise in CO2 or the rise in temperatures. The Center for the Study of Carbon Dioxide and Global Change has suggested that the rise in temperature precedes the rise in CO2, and therefore the temperature is the cause of the rise in CO2.
2.) Ocean Temperatures and CO2
Studies have shown that a rise in ocean temperatures lead to a rise in CO2 in the atmosphere. Warmer waters release CO2 while colder waters absorb CO2. As global temperature rises, water temperatures increase, thereby releasing CO2 into the Earth’s atmosphere.
According to a study conducted by Lon Hocker; the atmosphere contains 720 billion tons of CO2, while the Earth’s Oceans contain 36 trillion tons. The study found that the oceans are responsible for 0.275 ppm of CO2 for every temperature increase of 1°C. Hocker concludes that the oceanic release of CO2 is responsible for the observed 0.22 ppm increase in CO2 per 1°C temperature increase.
Another recent study conducted by Dr. Jeffrey A. Glassman examined the CO2 -temperature relationship of the last 420 millennia. The study concluded atmospheric CO2 concentrations are an effect of changes in the earth’s temperature, not the cause. The study found that the atmospheric CO2 trends were caused by changes in ocean temperatures, and that, while a greenhouse gas, CO2 has “neither caused nor amplified global temperature increases”.
3.) Historical trends
Climate has been occurring all throughout Earth’s history; it has been occurring long before the evolution of man, and it will continue long after we are gone. The assumption that man is the reason for climate change is more of a religion than science; only instead of god punishing us, it is assumed that the earth is punishing us.
Because weather satellites only existed since the 1960’s and weather balloons only existed since the 1890’s, mapping historical data depends heavily on ice cores, and tree rings. Atmospheric temperature research began near the end of the little ice age; it is assumed that temperatures would increase after a mini ice age.
According to ice core research, most of the last 10,000 years were warmer than it is today. The current temperature is considered very low by comparison.
Most advocates of manmade global warming only look at the data dating back to the little ice age. This is because the global temperature has increased since the little ice age. If you want to see cooling or warming, it depends on where you start your timeline.
A study of Tree rings was conducted by the Department of Quaternary Paleogeography and Paleoecology at the University of Silesia and the Institute of Geography and Regional Development at the University of Wroclaw. The study mapped over 7,500 years of finish tree ring data, which coincides with the ice core samples.
Using the tree ring data, they were able to forecast future trends. They predicted that within the next 40 years there will be a cooling trend, followed by another warming period.
Just because the climate is changing, does not make it our fault. The climate has been changing since the earth’s conception.
4.) The real cause of global warming
The real cause of global warming is not man, but rather the sun. Increases and decrease in the frequency of sun spots have an impact on global temperatures and of course the climate. The frequency of volcanic activity also has an impact on the climate. Volcanoes shoot ash and CO2 into the air, blotting out the sun, thereby creating a cooling effect.
Global Warming is not man-made, it is a natural phenomenon. Climate change has been occurring throughout earth’s history.
1. Correlation and Causation
My opponent’s main argument is that correlation is not equal to causation, and I totally agree. However, some degree of correlation is needed to prove causation. The more robust the correlation, the more likely some causation exists. I have provided a large amount of data, simplified and shortened, which shows an excellent correlation between carbon dioxide and CO2 based on academic studies. Now, in science, many correlations have become nearly accepted facts. For example, enough data has been found showing that smoking causes cancer , based on correlations. Now, if we look at the raw data we could argue warming causes the CO2 increase (which is what my opponent argues later). And, looking at the raw data, cancer may cause smoking. The question is if these correlations hold up to scrutiny.
My opponent then cites co2science.org noting that CO2 lags temperature. Whether or not it is true, looking at these paleoclimatology correlations partially proves AGW. So, let’s assume CO2 actually does lag temperature. This does not disqualify CO2 as a driver, even a large driver, for climate change. Now, in the last 100,000 years the warming phases last around 5000 years (we are in one now—and have been for a few thousand years). The CO2 lag is only 800 years long. The lag ignores one important point: “[a]ll that the lag shows is that CO2 did not cause the first 800 years of warming, out of the 5000 year trend. The other 4200 years of warming could in fact have been caused by CO2, as far as we can tell from this ice core data.”
Even if we assume CO2 didn’t cause the rest of that warming, this still does not disqualify its ability to be an amplifier . For 600,000 years Co2 has not been at the levels it has been today . So, since the amount of CO2 is much larger now than it was throughout most interglacials, we can easily argue this current warm period has made this amplifier stronger than it has ever been. At least, for 600,000 years.
2. Oceans cause the CO2 rise?
This is highly unlikely. Unless my opponent agrees this warming is unprecedented (which kind of concedes the debate for him…) it is hard to say oceans can cause record CO2 levels. There are two strong lines of evidence against this:
First, O2 is decreasing in the atmosphere. If the Ocean is emitting CO2, the amount of O2 would not decrease—but CO2 levels would still rise. Cars, however, use oxygen in their fuel systems and burn out Carbon Dioxide. The fact O2 is falling shows something that uses O2 is causing this decrease—which is most likely not a natural source. Second, the known fossil fuel burning easily fulfills the amount of CO2 increase. CO2 increases every year about 16 billion tonnes per year. Humans, on average, emit 30 billion tonnes of CO2. Half of our CO2 is soaked up by oceans (yes, they have stored CO2). So, unless nature through some other mechanism can soak up nearly all of our emissions, it is unlikely the ocean plays a larger role than man in the increase in CO2 .
Another line of evidence is the temperature itself. The temperature increase is erratic because natural factors (mainly, PDO and volcanoes) play short term roles in our climate. The CO2 increase is fairly linear, non-erratic, and consistent . If the Ocean emits CO2 due to temperature increases, we should see some large variation, then, if the ocean is the cause. Even if it is not as great as the temperature fluctuation. We have not seen this variation if we are to expect a natural cause emitting most of the modern CO2.
My opponent has provided insight opposing my amplifier argument under #1. A new paper by Shakun et al. 2012 has found CO2 often leads temperature, and ended the ice age (was a leading factor in its end), and amplified and sometimes controlled warming and cooling in our current interglacial . And the fact CO2 has warming properties as a greenhouse gas , saying it has no effect, or no amplification, is unbelievable.
3. Past climate
I agree that climate has changed, will change, and is changing. I will not, and can not, deny this. But saying climate has changed does not tell me why it has changed. One study pointed out, “Correlation of CO2 levels with estimates of palaeoclimate suggests that the atmospheric greenhouse effect has been a major factor in controlling global climate over the past 600 million years.” If anything, the paleoclimatology merely shows and proves that greenhouse gases control and amplify past warmings. And, I would like to note, the study cited has a longer time frame then any of my opponents graphs…
Further, the warming in my opponent’s graph, the medieval warm period, has been exaggerated and was a local phenomenon. The current warm period out paces the MWP and has increased to temperatures exceeding the warmth 1000 years ago .
The fact climate has changed does not tell me, or the voters, why it has changed. Only that is has done so. There is no reason to believe the drivers can change (it is arguable that the sun, PDO or AMO, and greenhouse gases) could have caused different warmings. There is a large amount of evidence that CO2 causes the current warming, and even played a significant role in the past.
4. The sun
My opponent provided no substance in his argument. He says sunspots influence warming—I agree. But the sun has not been proven to affect the current warm period. My opponent merely asserts that it does. Until he gives evidence for this point, it is not significant. All he shows is a graph of past climates, not solar irradiance, cosmic ray counts, etc. Solar irradiance reconstructions show the forcing of greenhouse gases is much stronger than the sun . The Stanford Solar Center has shown that the sun’s intensity has actually slightly lowered since the 60s, and the sunspots show little change. Whereas the temperature has increased .
My opponent has failed to demonstrate a link between solar activity and temperature for the modern era and has also failed to decouple CO2 and temperature. His lag theory has been refuted, and the fact that the CO2 increase is mostly anthropogenic is something skeptics even agree on. Past climate, too, seems to prove AGW and does not refute the presumption that humans cause the current warm period.
Pro claims, “The more robust the correlation, the more likely some causation exists.” This is blatantly false. The stronger the correlation the stronger the relationship, but it does not prove one thing caused the other. In order to prove causation, you need to prove that CO2 preceded the warming.
Pro also claims that CO2 in the atmosphere amplifies temperatures through the greenhouse effect. In actuality the cooling effect of CO2 is far greater than the heating effect. CO2 is commonly used as a refrigerant, due to its natural cooling properties. According to physicist Dr. Charles Anderson, “the cooling effect due to keeping incoming solar IR radiation away from the surface is about 100 times the re-heating effect proclaimed by greenhouse gas alarmists”. 
When you talk about greenhouse gasses, you need to remember that ozone or O3 is a greenhouse gas. The Ozone protects the earth from the sun, thereby cooling the earth.
A study conducted by NASA has found that CO2 and N2O block up to 95% of solar rays, thereby reducing the global temperature. 
My opponent had tried to make the claim that correlation between CO2 and Global temperatures is strong, when in reality the correlation is poor; it is just short of being fair. The coefficient of determination, R2, of CO2’s relation to USHCN2 surface temperature is only 0.44. 
When USHCN2 surface temperatures are plotted against solar activity, it shows a much greater relationship; while it is only a fair correlation, it has an R2 of 0.57.
The correlation between surface temperatures and the temperatures of the Atlantic and Pacific oceans are much stronger, with an R2 of 0.83. 
My opponent tries to refute this with the claim that CO2 levels are unprecedented. The current CO2 levels are 398.35 ppm.  2 million years ago CO2 levels was 300 ppm, 100 million years ago it was 1,200 ppm, and 540 million years ago it was as high as 7,000 PPM.  There is nothing unnatural about CO2 levels. CO2 levels have been pretty stable for the last 2 million years compared to earlier eras. 
Pro claims that humans are responsible for 16 billion tons of CO2 in the atmosphere and 14 billion tons of CO2 in the ocean. Once again, there are 720 billion tons of CO2 in the atmosphere, and there are 36 trillion tons of CO2 in the Ocean. Thus Humans would only be responsible for 2% of CO2 in the atmosphere, and 0.04% of CO2 in the ocean.
Pro tries to claim that because rises in CO2 preceded the end of the ice age, that CO2 caused the end of the ice age. First off, there has always been controversy over which came first during the ice age melt. The most comprehensive study to date came out in 2013. Using EPICA ice cores, they tracked CO2 records back 800,000 years. The study found that between 20,000 and 10,000 years ago, CO2 levels lagged global temperature by up to 1,400 years. 
My opponent has attacked my graphs claiming they were exaggerated without providing any evidence for exaggeration. Pro also claims that the medieval warming period was a local event. There has been evidence found in Antarctica, proving that the medieval warming period was global not local. 
Other than these points, Pro’s points are addressed in my other arguments, and Pro has ceded that climate change is a natural phenomenon.
My opponent tries to claim that solar activity as decreased since the 60’s. In actuality solar activity has remained relatively constant, while the intensity of solar radiation has increased by 0.05% per decade. In their report, NASA concluded that "This trend is important because, if sustained over many decades, it could cause significant climate change". 
Pro claims that the greenhouse gases that make up the atmosphere warms the earth, when in reality it protects the earth from the sun. 
All other points made by pro have been covered and/or made irrelevant by my above arguments.
The correlation between CO2 and temperature is too week to claim one causes the other; a wide variety of natural factors determines the level of CO2 in the atmosphere. A majority of the CO2 in the atmosphere is natural. CO2 causes more cooling than warming. The main cause of global temperatures is the sun, which has increased in intensity. CO2 lagged behind temperature when the ice age ended.
CON essentially says a robust correlation does not increase the chance for causation, only the relationship. However, for this correlation to be robust is has to precede the warming (or, in others, amplify them). In this debate I have not said CO2 is the only factor in climate change, rather it is the largest factor in modern climate change. In past cycles, CO2 has often played a secondary role, however amplifying warming significantly—and in other cycles it may have even been a predominant factor. My opponent ignores the study by Shakun, which found that CO2 preceded the warming at the end of the ice age. So, assuming CO2 still plays a secondary role, all Co2 needs to do is precede modern warming to show causation. Because if it is an amplifier, if it precedes now it likely plays a significant role. So, since CO2 has preceded modern temperature (and some older temperatures) .
My opponent’s second claim is from a source that denies the greenhouse effect—even Anthony Watts has responded to their literature and claims that they are misrepresenting science. The Press release by my opponent’s source assumes the atmosphere (upper and lower) work the same. Of course the upper atmosphere cools the planet by reflecting the sun’s rays, if it didn’t we would be dead . The upper atmosphere cooling actually proves man-made climate change. The upper atmosphere has cooled, as shown by satellites, and this has been predicted by models—and the cooling is because of the lower atmosphere greenhouse effect . We can also determine the power of CO2 from outgoing radiation measurements. A 2004 study has found that outgoing radiation has been decreasing due to the greenhouse effect . These studies have been cited throughout the debate. Skeptic Roy Spencer has even supported the CO2 greenhouse effect , though he thinks the effect is minimized via feedbacks (discussed R2).
2. Correlation strength
My opponents graphs rely upon data from Joseph D’Aleo. His study is also flawed in that it included data from pre-1970s. The IPCC and others have argued Co2 played a large role, but not a near-100% role, in that time period. It merely dilutes CO2’s near-100% role after that date. Further, it includes the cooling between 1950-60. This period still had a strong CO2 effect… why did it cool? Aerosols cooled the climate and temporarily override the greenhouse effect of the CO2 increase . Even if we add the beginning part, the middle cooling is responsible for the low correlation. This would be easily fixed if the cooling was accounted for by aerosols. And, if we add that in, it warms in that period. The PDO, too, has seen little change and has cooled since the 1980s 
I find a bigger problem: the study used local US data versus global CO2 data. The fact he didn’t use global data for both obfuscates the results and renders them useless. A study by Amman et al. 2003 finds when we compare the Keeling curve to GLOBAL temperature, we get an excellent correlation .
3. Ocean levels
To say that Co2 levels are not unprecedented is absolutely false. My opponent cites data from millions years ago. If temperature is causing the increase in CO2, and not vice versa, to obtain the CO2 level of 100 million years ago would have to mean unprecedented warming. This is in direct contradiction to my opponent’s later argument. If he says that we are 100 ppm above 2 million years ago, it means we have to be at the same temperature to meet that CO2 level (it was hotter then) if we say it is all natural. This forces him into contradiction. Human CO2 is identifiable to natural CO2. Studies have shown most of this CO2 is from fossil fuels .
To say humans are only a tiny fraction of the atmosphere is false. “Before the industrial revolution, the CO2 content in the air remained quite steady for thousands of years. Natural CO2 is not static, however. It is generated by natural processes, and absorbed by others. … But consider what happens when more CO2 is released from outside of the natural carbon cycle – by burning fossil fuels. Although our output of 29 gigatons of CO2 is tiny compared to the 750 gigatons moving through the carbon cycle each year, it adds up because the land and ocean cannot absorb all of the extra CO2. About 40% of this additional CO2 is absorbed. The rest remains in the atmosphere, and as a consequence, atmospheric CO2 is at its highest level in 15 to 20 million years”.
My opponent misrepresents his source on CO2 lag. It says “until now the most comprehensive records to date on a major change in Earth’s climate came from the EPICA Dome C ice core on the Antarctic Plateau”. In other words, the data my opponent cited is old school. The newer studies drastically reduce the lag to less 200 years and use less flawed ice core data . The reduced lag actually shows that CO2 could have been a driver in past climate .
4. Past Climate
I did present evidence—the fact I cited the whole paragraph I thought was noticeable. Although regionally the MWP was warmer, specifically in the Atlantic, global temperatures refute this conclusion and find that the MWP was cooler than today . A study by Kellerhals et al. finds that South American temperatures rose, but not to the levels of modern day warming . The MWP can be found in regions like my opponent pointed out, but the data shows that global temperatures were cooler in the MWP .
5. The sun
Closer examination of cons study yields this result, “Although the inferred increase of solar irradiance in 24 years, about 0.1 percent, is not enough to cause notable climate change, the trend would be important if maintained for a century or more”. It will be important in the future, but has not been important as of recently. The study my opponent cited refutes his sun-climate link for the 20th and 21st century.
His case, although he claims refutes mine, has been torn down with the facts. My opponent has been unable to de-link CO2 with past climate and modern climate, show natural cause, and his outright opposition to the greenhouse effect is unscientific. Even skeptic scientists agree that CO2 has some warming potential.
First off I did not ignore Pro’s study I rebutted it with a more recent study, which was much more extensive than the study provided by Pro. This false accusation is a weak attempt to deceive the voters.
Furthermore, while Pro has not claimed CO2 was the only cause of global warming, he did argue than man was the main cause of global warming due to their production of CO2.
Pro tries to claim that temperatures now lag behind CO2. In actuality CO2 still lags behind temperatures. The only difference is that instead of lagging by hundreds of years it now lags by only 11 to 12 months. (1)
I have not now, nor have I ever denied the existence of the greenhouse effect. I do however disagree to the extent in which man has contributed to the greenhouse effect. As Pro’s chart shows, the greenhouse effect converts solar activity to heat in the lower atmosphere, but in the upper atmosphere it prevents solar activity from reaching the lower atmosphere. If the cooling effect in the upper atmosphere is 100 times greater than the heating effect in the lower atmosphere, than the cooling effect of the upper atmosphere cancels out the heating effect of the lower atmosphere. You cannot look at one without the other.
Pro’s rebuttal is based on the assumption that temperature now lags CO2; which it clearly does not. The role CO2 plays in global temperatures, if any, is too insignificant to be of any concern. (1)
According to geological records, sunspot cycle length plays a much larger role than CO2. It is far more likely that the sun is the real cause of Global Warming. (2)
My opponent cited a graph with a J-peg link, so I have no info to verify his study. Pro claims that the graph shows a stronger correlation using global temperatures, yet fails to provide any statistical information regarding the claim. By looking at the graph, I cannot see a strong correlation, as many times the temperature dips as CO2 rises, and the data points in the trends don’t seem to correlate with one another.
A bigger issue is that looking at past data, the correlation between CO2 and global temperatures tends to be very week. When CO2 was 7000 ppm the global temp was only 22 ºC, which was the same global temperature as when it was 1200 ppm. (3)
Pro claims that if CO2 levels were the same as millions of years ago, than there would be unprecedented warming; this is a false assumption. I did not say that temperature always correlates with CO2; only that recent correlation can be explained by oceanic temperature fluctuations. There are a number of other causes for CO2 levels, throughout history. This only shows that CO2 levels were much higher in the past, and it was not the end of the world.
That 2% figure came from the data pro provided. Pro tries to claim that a correlation between the industrial revolution and the rise in CO2 proves man caused the rise; once again correlation does not equal causation. According to studies, man is only responsible for 3.225% of CO2, which is close to the 2% figure received from Pro’s data. Water vapor also accounts for 95% of all greenhouse gases. (4)
Pro misrepresented my source. My source said, “the most comprehensive records to date on a major change in Earth’s climate came from the EPICA Dome C ice core on the Antarctic Plateau.” Pro skipped to the end of the article, clearly without reading its contents. At the end of the article it says that “Parrenin’s team addresses these concerns with a new method that establishes the different ages of the gas and ice.... The researchers then compared results from multiple locations to reduce the margin of error.” Thus the raw data showed a gap of up to 1,400 years. After correcting for the margin of error their published results “show CO2 lagged temperature by less than 200 years”. The study still found that CO2 lagged temperature; by correcting for the margin of error they reduced the gap. (5)
Pro attempts to refute my source, by citing Wikipedia; wiki is not the most reliable of sources. Even if the medieval warming period was on average cooler than today, it does not negate from the fact that the earth was much warmer in earth’s history previous to the medieval warm period. The medieval warm period occurred before the little ice age, and we have been warming since the end of the little ice age. Simply because it is hotter in point B than in point C does not mean man caused it to be hotter, especially when point A was hotter than point B and point C. Most of the history of Earth’s temperature was remained unchallenged because pro decided to fixate on the medieval warming period.
5. The sun
Pro is once again cherry picking quotes from my source, in order to misrepresent my sources.
Pro tried to quote my NASA source, in attempt to prove that the increase in sun activity was insignificant. But he quoted them out of context. The current heating trend was caused by the sun, but for it to pose any real threat it would have to continue for a century or more.
If pro read on he would have seen that my source also says; “TSI interaction with the Earth's atmosphere, oceans and landmasses is the biggest factor determining our climate. To put it into perspective, decreases in TSI of 0.2 percent occur during the weeklong passage of large sunspot groups across our side of the sun. These changes are relatively insignificant compared to the sun's total output of energy, yet equivalent to all the energy that mankind uses in a year. According to Willson, small variations, like the one found in this study, if sustained over many decades, could have significant climate effects.” (6)
CO2 has a week correlation to the changes in temperature. In recent years the correlation has gotten stronger, but the correlation lags behind the temperature fluctuations. The cooling effects of greenhouse gases are 100 times greater than their heating effects. Most greenhouse gases are natural, with only a tiny fraction being man made. The sun is primarily responsible for climate change.
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