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Pro vs. con view
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PRO

  • PRO

    In actuality, we observed .32 degrees of warming, almost...

    Global climate models are accurate enough to be relied upon

    Models can accurately reproduce past climate changes: Climate models have successfully simulated many aspects of the climate changes observed during the instrumental period. Most notably, models have reporduced the increase in surface air temperatures remarkably well (1-2). Scientists have also found a high degree of similarity between the simulated and observed evolution of global lower stratospheric temperatures during the past 25 years (3). Good agreement between model projections and observations has likewise been reported for decreases in Arctic Ocean ice cover. As one researcher concluded, “The simulated decreasing trend in average sea ice extent for 1970–1999 (–2.5% per decade) is very similar to observations" (4). In addition, model projections are consistent with observations of changes in ocean heat content since 1960 (5). Models have predicted changes in atmospheric temperatures nearly perfectly: In 1988, Dr. James Hansen predicted future atmospheric temperature changes using several different emissions scenarios. His second scenario most closely resembled the observed pattern of carbon dioxide emissions. Models which employed this scenario predicted that we should have seen .33 degrees Celsius of warming between 1988 and 2005. In actuality, we observed .32 degrees of warming, almost exactly what the models predicted (6). Climate models can accurately simulate important feedbacks: Climate models predict that atmospheric water vapor will increase as the surface warms. Observations have independently confirmed these predictions. Satellite measurements indicate that the total atmospheric water content, which is dominated by water vapor in the lower troposphere, has increased at a rate consistent with model predictions (7-8). Interestingly, upper tropospheric water vapor has also increased during the past two decades (9). Climate model simulations indicate that cloud cover changes will most likely amplify greenhouse gas warming. Observations have confirmed that these predictions are also correct. As Dr. Andrew Dessler noted, “The short-term cloud feedback has a magnitude of 0.54 ± 0.74 watts per square meter per kelvin, meaning that it is likely positive...Calculations of short-term cloud feedback in climate models yield a similar feedback” (10). In a few instances, models have been even more accurate than data: Observations themselves are not without error. In a few cases, model simulations have been even more accurate than data. For example, climate models in the 1990s could not reproduce the full extent of the Northern Hemispheric cooling in the 1950s as indicated by observational data. However, a careful analysis later revealed that the data had been distorted by a change in the way ocean temperatures were measured after World War II (11). In another example, satellite measurements in the early 2000s showed essentially no warming in the middle levels of the atmosphere. More direct measurements by balloons and radiosondes likewise showed no warming there. However, a "tropospheric hot spot" had been predicted by all models clear back to the 1970s. This alleged discrepancy was resolved to the satisfaction of most modelers in 2005, when several researchers documented errors in the sets of observations. For example, the observers had not taken proper account of how instruments in the weather balloons heated up when struck by sunlight. Once these errors were accounted for, it was evident that the middle levels of the atmosphere had indeed been warming up (12). Conclusion: As Dr. Michael Mann remarked, “Current climate models do a remarkably good job of reproducing key features of the actual climate...They also closely reproduce past climate changes. We therefore have good reason to take their predictions of possible future changes in climate seriously” (13). References: http://ipcc.ch... http://150.229.66.66/staff/jma/meehl_additivity.pdf http://atmosdyn.yonsei.ac.kr... http://www.cpom.org... http://www.sciencemag.org... http://pubs.giss.nasa.gov... http://geotest.tamu.edu... http://www.cgd.ucar.edu... http://www.dca.iag.usp.br... http://geotest.tamu.edu... http://www.atmos.colostate.edu... http://www.geo.utexas.edu... Mann, Michael E., and Lee R. Kump. Dire Predictions. New York: Pearson Education, 2008. Print.

  • PRO

    Dessler’s findings: My opponent claims that Dessler’s...

    Global climate models are accurate enough to be relied upon

    My opponent's quotes: In the previous round, my opponent presented several quotes from experts who seemed to believe that models are not accurate enough to be relied upon. However, many of these quotes were taken from seriously flawed studies or biased sources. For instance, let’s consider his second quote which came from a scientific paper published by Douglass, Christy, Pearson, and Singer in late 2007. This paper purported to demonstrate that modeled and observed tropical temperature trends disagree to a statistically significant extent. However, other scientists have identified major flaws in this study. As Dr. Ben Santer and his colleagues stated, “The author’s conclusions were based on the application of a flawed statistical test and the use of older observational datasets.” (1) Once these errors were corrected, Dr. Santer found that model simulations matched the observations very closely. Let’s also examine my opponent’s third quote which came from an expert affiliated with the National Center for Policy Analysis. Interestingly, this conservative think tank has received thousands of dollars in funding from ExxonMobil and the Koch Industries. (2-3) As extensive research has shown, the conclusions of a scientific study usually support the interests of the study's financial sponsor. (4-5) Therefore, the quote my opponent provided should not be weighted heavily. Hansen’s projections: My opponent claims that I compared Hansen’s projections to only land temperature data. However, if my opponent had examined my sixth reference, he would realize that this is not the case. In reality, I compared the model projections to the GISS land-ocean temperature index, which includes data from all over the globe. My opponent also alleges that I compared the temperature data to model projections for Hansen’s “C” scenario. However, as I explained very clearly, I actually compared the data to the more realistic “B” scenario. Clearly, I was not "cherry-picking" data, as my opponent alleges. Dessler’s findings: My opponent claims that Dessler’s findings have been refuted by a study conducted by Roy Spencer. However, this is not the case. Spencer’s study was published nearly four years ago, while Dessler’s study was just released six months ago. Moreover, Spencer analyzed only five years of satellite data while Dessler considered an entire decade of observations. Spencer himself has even stated that,"The time scales addressed here are short and not necessarily indicative of climate time scales". Thus, we can be virtually certain that Dessler’s results are much more robust than Spencer’s. Dessler's conclusions are also supported by a variety of studies showing that Lindzen’s IRIS hypothesis is incorrect. (6-8) As Lin et al. stated, “The observations show that the clouds have much higher albedos and moderately larger longwave fluxes than those assumed by Lindzen et al. As a result, decreases in these clouds would cause a significant but weak positive feedback to the climate system, instead of providing a strong negative feedback.” (6) Upper Tropospheric warming: My opponent claims that the troposphere is not warming as rapidly as models predict. He cites two studies to back up this claim, both of which were published over four years ago. Obviously, new satellite and radiosonde datasets have been developed since the publication of these studies. These new datasets show enhanced tropospheric warming due to improvements in our ability to identify and adjust for biases introduced by changes over time in the instruments used to measure temperature. (1) As one study concluded, two newly adjusted radiosonde time series indicate that the upper troposphere is warming at a rate of .2–.3ºC per decade. This is almost exactly what the models have predicted. (9) Other independent observations also indicate that the upper troposphere is warming at a rate consistent with models. For example, one study used measurements of wind shear to estimate temperature trends. This study concluded as follows: “We derive estimates of temperature trends for the upper troposphere to the lower stratosphere since 1970. Over the period of observations, we find a maximum warming trend of 0.65º K per decade near the 200 hPa pressure level, below the tropical tropopause. Warming patterns are consistent with model predictions except for small discrepancies close to the tropopause. The agreement with models increases confidence in current model-based predictions of future climate change.” (10) In summary, the discrepancies that my opponent pointed out were most likely due to inaccuracies in the old observational datasets, not fundamental model errors. This is just another example demonstrating that models can actually be more accurate than data. Response to the Mount Pinatubo eruption: When Mount Pinatubo erupted in 1991, it provided a meaningful opportunity to evaluate how accurately models could predict the climate response to an increase in sulfate aerosols. The models accurately forecasted the subsequent global cooling of about 0.5°C soon after the eruption. Furthermore, the radiative, water vapor and dynamical feedbacks included in the models were verified. (11) Simulations of the planet’s energy imbalance: Global climate models have accurately simulated the planetary energy imbalance. As Dr. James Hansen concluded, “Our climate model...calculates that Earth is now absorbing 0.85 watts per square meter more energy from the Sun than it is emitting to space. This imbalance is confirmed by precise measurements of increasing ocean heat content over the past 10 years.” (12) Conclusion: As the Intergovernmental Panel on Climate Change concluded, “There is considerable confidence that climate models provide credible quantitative estimates of future climate change, particularly at continental scales and above. This confidence comes from the foundation of the models in accepted physical principles and from their ability to reproduce observed features of current climate and past climate changes. Over several decades of development, models have consistently provided a robust and unambiguous picture of significant climate warming in response to increasing greenhouse gases.” (13). References: http://www.realclimate.org... http://www.guardian.co.uk... http://www.greenpeace.org... http://www.bmj.com... http://onlinelibrary.wiley.com... http://journals.ametsoc.org... http://www.atmos-chem-phys-discuss.net... http://journals.ametsoc.org... http://journals.ametsoc.org... http://www.nature.com... http://pubs.giss.nasa.gov... http://pubs.giss.nasa.gov... http://ipcc.ch...

  • PRO

    The easiest way to see increasing temperatures is through...

    Global Warming is Real.

    GLOBAL WARMING IS REAL Atmospheric carbon dioxide concentrations are higher today than at any time in at least the past 650,000 years. They are about 35% higher than before the industrial revolution, and this increase is caused by human activities, primarily the burning of fossil fuels. http://www.skeptic.com...; src="../../../photos/albums/1/4/3238/96287-3238-v3vsm-a.jpg" alt="http://www.skeptic.com...; /> http://www.skeptic.com...; src="../../../photos/albums/1/4/3238/96287-3238-38un8-a.jpg" alt="http://www.skeptic.com...; /> Earth has been in radiative imbalance since at least the 1970s, where less energy leaves the athmosphere than enters it. Most of this extra energy has been absorbed by the oceans. It is very likely that human activities substantially contributed to this increase in ocean heat content. The amount of heat stored in the oceans is one of the most important diagnostics for global warming, because about 90% of the additional heat is stored there. The atmosphere stores only about 2% because of its small heat capacity. The surface (including the continental ice masses) can only absorb heat slowly because it is a poor heat conductor. Thus, heat absorbed by the oceans accounts for almost all of the planet’s radiative imbalance. http://www.realclimate.org...; src="../../../photos/albums/1/4/3238/96287-3238-7g8k4-a.jpg" alt="http://www.realclimate.org...; /> Signs that the Earth is warming are recorded all over the globe. The easiest way to see increasing temperatures is through the thermometer records kept over the past century and a half. Around the world, the Earth's average temperature has risen more than 1 degree Fahrenheit (0.8 degrees Celsius) over the last century, and about twice that in parts of the Arctic. "The planet is red" in a global map of the change in average surface temperatures, noted Swiss climate scientist Thomas Stocker, co-chair of IPCC Working Group I responsible for this summary at a press conference. "The world is warming." http://data.giss.nasa.gov...; src="../../../photos/albums/1/4/3238/96287-3238-kw63s-a.jpg" alt="http://data.giss.nasa.gov...; /> The Earth's average surface temperature rose by 0.74±0.18 °C over the period 1906–2005. The rate of warming over the last half of that period was almost double that for the period as a whole (0.13±0.03 °C per decade, versus 0.07±0.02 °C per decade). The urban heat island effect is very small, estimated to account for less than 0.002 °C of warming per decade since 1900. Temperatures in the lower troposphere have increased between 0.13 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to satellite temperature measurements. Climate proxies show the temperature to have been relatively stable over the one or two thousand years before 1850, with regionally varying fluctuations such as the Medieval Warm Period and the Little Ice Age. The climate system can respond to changes in external forcings. External forcings can "push" the climate in the direction of warming or cooling. Examples of external forcings include changes in atmospheric composition (e.g., increased concentrations of greenhouse gases), solar luminosity, volcanic eruptions, and variations in Earth's orbit around the Sun. Orbital cycles vary slowly over tens of thousands of years and at present are in an overall cooling trend which would be expected to lead towards an ice age, but the 20th century instrumental temperature record shows a sudden rise in global temperatures. For a direct look at the atmosphere of the past, scientists drill cores through the Earth's polar ice sheets. Tiny bubbles trapped in the gas are actually pieces of the Earth's past atmosphere, frozen in time. That's how we know that the concentrations of greenhouse gases since the industrial revolution are higher than they've been for hundreds of thousands of years. But if Global Warming is real, then why it is cold in US now? First of all US is not whole Earth, second of all may be because it is winter in northern pole. December 2013 was an unusually warm month even though it was colder in the U.S. In past December, North America was colder than the average over the past decade. But Europe and Russia were much hotter than average. India was cooler than average. Australia was warmer than average. Global Temprature is the average temprature of globe, and sorry US is not globe (and who cares about US). http://www.youtube.com... [1] - http://on.natgeo.com/1bNQQJe [2] - http://bit.ly/1acL5Jh [3] - http://wapo.st/1idDRX8 [4] - http://bit.ly/1eiNzEA [5] - http://bit.ly/1bNR6rL [6] - http://bit.ly/19YXkZi [7] - http://1.usa.gov/1eEHLWB [8] - http://bit.ly/1cyoK8s [9] - http://bit.ly/1cyoLJA

    • https://www.debate.org/debates/Global-Warming-is-Real./1/
    • score
      BM25 score: 19.17
      climate: 7.03
      premises: 5.78 (idf 4.80, tfNorm 1.21)
      sourceText: 1.25 (boost 0.20, idf 2.98, tfNorm 2.09)
      change: 1.69
      premises: 1.32 (idf 2.58, tfNorm 0.51)
      sourceText: 0.38 (boost 0.20, idf 0.93, tfNorm 2.03)
      real: 10.45
      conclusion: 7.94 (boost 1.50, idf 4.74, tfNorm 1.12)
      premises: 2.17 (idf 2.61, tfNorm 0.83)
      sourceText: 0.33 (boost 0.20, idf 0.92, tfNorm 1.81)
  • PRO

    It occurs

    Man made climate change is a myth

    It occurs

    • https://debatewise.org/debates/1757-man-made-climate-change-is-a-myth/
    • score
      BM25 score: 19.09
      climate: 10.47
      conclusion: 9.20 (boost 1.50, idf 6.06, tfNorm 1.01)
      sourceText: 1.28 (boost 0.20, idf 2.98, tfNorm 2.14)
      change: 8.35
      conclusion: 7.96 (boost 1.50, idf 5.24, tfNorm 1.01)
      sourceText: 0.39 (boost 0.20, idf 0.93, tfNorm 2.11)
  • PRO

    Artificial consensus

    Man made climate change is a myth

    Artificial consensus

    • https://debatewise.org/debates/1757-man-made-climate-change-is-a-myth/
    • score
      BM25 score: 19.09
      climate: 10.47
      conclusion: 9.20 (boost 1.50, idf 6.06, tfNorm 1.01)
      sourceText: 1.28 (boost 0.20, idf 2.98, tfNorm 2.14)
      change: 8.35
      conclusion: 7.96 (boost 1.50, idf 5.24, tfNorm 1.01)
      sourceText: 0.39 (boost 0.20, idf 0.93, tfNorm 2.11)
  • PRO

    They can mitigate, but developed countries have the...

    Developed Countries have a moral obligation to mitigate the effects of climate change

    Thanks for debating. I will first refute my opponents arguments and strengthen our own. Their first contention was that other individuals and organizations can helo They stated how Gas comapnies will lose their industries. My response is 1. Are you going to let the climate go on how it is going and have a 1.9 trillion dollar cost of global warming in the next century. This completly outweighs their gas companies going out of buisness 2. the renewable industries created 35 M jobs in 2011- UN 3. If we cut funding into oil, then terrorists will lose money and stop killing innocent lives. I value lives greatly over money, Judge Their second contention was that developed countries shouldn't be the only ones mitigating. My response is 1. The topic doesn't limit developing countries, which i believe you are refering to. They can mitigate, but developed countries have the obligation as they created this mess. 2. Also, developed countries emmitted a lot of C02 into the atmosphere during their industrial revolution. Now the developing countries are going through their's and since the developed countries have emmitted so much, they have the moral obligation. Now they refuted my case They said to my terrorism subpoint that oil comapnies will lose their induestries and that green energy is not linked. My responses are 1. Are you going to let the climate go on how it is going and have a 1.9 trillion dollar cost of global warming in the next century. This completly outweighs their gas companies going out of buisness 2. the renewable industries created 35 M jobs in 2011- UN 3. If we cut funding into oil, then terrorists will lose money and stop killing innocent lives. I value lives greatly over money, Judge They said against my moral obligation impact that developing nations should do this too My response is 1. The topic doesn't limit developing countries, which i believe you are refering to. They can mitigate, but developed countries have the obligation as they created this mess. 2. Also, developed countries emmitted a lot of C02 into the atmosphere during their industrial revolution. Now the developing countries are going through their's and since the developed countries have emmitted so much, they have the moral obligation. They said that someone should not clean someone else's mess My response is 1. The topic doesn't limit developing countries, which i believe you are refering to. They can mitigate, but developed countries have the obligation as they created this mess. 2. Also, developed countries emmitted a lot of C02 into the atmosphere during their industrial revolution. Now the developing countries are going through their's and since the developed countries have emmitted so much, they have the moral obligation. 3. This has nothing to do with the contention at hand. They said to my moral obligation and mess argument that developed nations shouldn't clean up someone else's mess My response is 1. The topic doesn't limit developing countries, which i believe you are refering to. They can mitigate, but developed countries have the obligation as they created this mess. 2. Also, developed countries emmitted a lot of C02 into the atmosphere during their industrial revolution. Now the developing countries are going through their's and since the developed countries have emmitted so much, they have the moral obligation. Thus as you can see, we are saving many lives with vaccines, controlling the enviorment, and through terrorism. Thanks for debating, opponent and thanks for Judging this round, Judge/Judges

  • PRO

    Plus you have taken attitudes towards me that are not to...

    Global Climate Change is a problem and needs to be addressed.

    Ok first off you have proven in other debates that you don't read between the lines that well. Plus you have taken attitudes towards me that are not to kindly either. So don't patronize me. She cited the National Oceanic and Atmospheric Administration on the second or third line. Their research Plus you have taken attitudes towards me that are not to kindly either. So don't patronize me. She cited the National Oceanic and Atmospheric Administration on the second or third line. Their research is enclosed here http://www.esrl.noaa.gov... Rhett Butler the founder of mongbay is an environmental writer that is featured in several newspapers and is endorsed by several scientists. But here is the same research presented on a different site. http://earthobservatory.nasa.gov... All of the articles I have posted you can find any where else on the internet. You just need to look. Plus the internet is a bad place to look for good scientific journals. I am now going to list several books and journals that maybe you should read. Tim Flannery, Weather Maker G. Tyler Miller Jr., Sustaining the Earth Fritjof Capra-Systems Theories Fritjof Capra-Gaia Curtis Moore, Green Revolution in the making Jeremy Rifkin, The hydrogen economy There, start with that. Many of those points that I made are happening. We are experiencing warming and rapid change to our various ecosystems. Clear cutting eliminates wind breaks , destroys soil quality, and enables erosion. I don't see how just nitpicking my evidence helps your cause. A separate point aside. Avery and Singer fail to address several important factors Solar Dimming Carbon accumulation and acceleration I mean the point where they day the Atmosphere is "saturated with CO2" is wrong. There is still C02 being pumped into the air today, right now. Plus they were funded by Natural Gas.

  • PRO

    14 Jun 2005 - "City officials are not sitting idly by...

    The Chicago Climate Exchange is a success and model.

    Jason Margolis. "My Kind of Down Chicago Climate Exchange paves the way for U.S. emissions trading". 14 Jun 2005 - "City officials are not sitting idly by waiting to see if or when such things could happen. This spring, Oakland became the second U.S. municipality to join the Chicago Climate Exchange (CCX) -- North America's first and only voluntary, but legally binding, emissions-trading market.

  • PRO

    Nearly 33% higher than it has ever been in the last...

    Global Warming is Real and is Manmade!

    In ROUND 3 I will continue my ROUND 2 response, where I will show the link between carbon dioxide emitted by human activity and the increase in global surface temperatures. In the final ROUND I will go over the effects of climate change caused by global warming. Carbon Dioxide (and Other Green House Gases) are Causing Global Warming and Climate Change With the advent of the industrial revolution, human-induced global warming--through such actions as the burning of fossil fuels and deforestation--has led to an unprecendented increase in CO2 concentrations and other green house gases [1][2]. However, climate scientists overwhelmingly pin the blame of global warming on carbon dioxide because it is the most widely and most abundantly emitted green house gas of human activity [3]. According to the Intergovernmental Panel on Climate Change (IPCC), carbon dioxide and methane are responsible for more than 84% of the warming being inflicted on our planet because of green house gases [3]. The remaining percent of warming can be attributed to green house gases like nitrous oxide and flourinated gases [3]. By itself, the IPCC has affirmed that carbon dioxide is reponsible for 54.7% of the global warming caused by green house gases; that's because it is the most abundantly produced green house gas of human activity and because it has an enormous radiative impact compared to other green house gases when accounting for its abundance in the atmosphere, its indirect heating effects, and because of the CO2 molecule's long lifetime in the atmosphere [3][4]. In fact, only water vapor has a stronger green house gas effect than carbon dioxide in our atmosphere, but unlike CO2 water vapor isn't being emitted naturally by any known source at a large enough scale to be blamed for global warming [4]; water vapor does contribute to global warming, but this is because of a feedback loop caused as other green house gasses in our atmosphere increase in concentration and heat up the Earth's lower atmosphere [5]. As the Earth's atmosphere and surface become warmer because of green house gas emissions, this drive's more water vapor to be absorbed into the air, further heating our planet; this water vapor loop is well-understood and contributes to anthropogenic (human induced) global warming [5]. However, other green house gases emitted by human activity drive this loop and are primarily responsible for global warming. As the statistic above shows, carbon dioxide is responsible for 54.7% of the warming being inflicted on our planet because of human activity. As I demonstrated with the graph on carbon dioxide concentration in our atmosphere in ROUND 2 (and as I reported in ROUND 1), never in the last 400,000 years has the CO2 concentration been quite so high as it is today! Ice core analysis shows that in the last half-million years the peak concentration (the highest concentration) of CO2 was almost 300 parts per million--and that was 300,000 years ago [1]. Today the concentration of atmospheric CO2 is 398 parts per million! Nearly 33% higher than it has ever been in the last half-million years [1]! This unprecedented increase in atmospheric carbon dioxide can be attributed almost entirely to human activity, such as through large-scale deforestation, land use changes (such as methane emission from ammonia-based fertilizers), and the burning fossil fuels (which include coal and gasoline) [2]. The IPCC reports that in the last 150 years, human activity has increased atmospheric carbon dioxide levels from 280 parts per million to 398 parts per million today [2]! According to the United States Environment Protection Agency (EPA), humans largely emit carbon dioxide and other green house gases from the production of electricity and from transportation; in the U.S. these two behaviors contribute to 60.8% of all the nation's emitted green house gases in a single year [3]. Other behaviors, such as those of industry, businesses, of agricultural, and of energy use in homes, contribute to the remaining 39% of the nation's green house gas emissions [3]. Global warming is produced when green house gases in the atmosphere--water vapor, carbon dioxide, methane, nitrous oxide--accumulate in the atmosphere and act as a thermal blanket for the Earth, absorbing the sun's radiative heat and warming the Earth's surface [2]. Nature uses green house gases to facilitate heat trapping from the sun's rays to warm the Earth and make biological life on the planet possible. But if the concentrations of green house gases in the atmosphere become excessive, this can overheat the planet, alter the Earth's climate system, injure natural ecosystems, and make it harder for biological processes to take place and be maintained. This is exactly what's happening now and generating planet-altering climate change (these effects will be explicated in the final ROUND). Volcanes and Changes in the Sun's Solar Output are Not Contributing to Global Warming Some skeptics claim that erupting land and submarine volcanoes are causing global warming. But reports by the U.S. Geological Survey (USGS) shows that volcanoes primarily emit gases, like sulfur dioxide, at high enough concentrations so as to encourage global cooling [6]. In fact, the USGS takes the position that erupting volcanoes typically emit gases that are more likely to lead to global cooling[6]! The USGS asserts that CO2 emission by human activity dwarfs the output of CO2 by all volcanoes worldwide [6]. Some opponents of manmade global warming claim that the Sun's solar output is responsible for the current rise in atmospheric temperatures--that humans are not responsible for the modern warming trend. But this is a view that the scientists firmly dispute, based on a variety of evidence (2): --Scientists point out that, since 1750, the average amount of energy coming from the sun either remained constant or increased only slightly. --If the warming were caused by increased radiation coming from the sun, then scientists would expect to see warmer temperatures in all layers of the atmosphere. Instead what they observe is a cooling in the upper atmosphere, and a warming at the surface and in the lower parts of the atmosphere. Scientists say that this is a strong indication that green house gases are responsible for global warming, because they trap heat in the lower atmosphere. --Computer climate models that include solar irradiance changes can't reproduce the observed temperature trend over the past century or more without including a rise in green house gases. All of these bits evidence demonstrate that solar irradiance is not responsible for the rise in Earth's surface temperatures over the last century or more. Elevations in Atmospheric Carbon Dioxide Concentrations have been responsible for Prehistoric Rises in Global Surface Temperatures Scientists that study prehistoric ice ages and warming ages point out that carbon dioxide released into the atmosphere by geologic activity or other natural events has consistently led to warming trends in Earth's history. For example, the Ice Age that stretched during most of the Cryogenian Period (840 - 635 million years ago) had the potential to cover the entire globe and would have been a major setback for biological life and evolution in general had it been this severe. Scientists that study the period point out that this extreme condition never occured because, as the Earth froze, atmospheric oxygen was forced into the oceans, which oxidized organic matter and released CO2 into the atmosphere, preventing temperatures from falling any lower [7]. Presently scientists have no other plausible model to explain how the atmosphere was able to maintain warmth while the Earth froze [7]. Scientists also point out that a rise in atmospheric CO2 concentrations have led to prehistoric Warming Ages. 55 million years ago, the Earth entered a sudden and rapid global warming event, which scientists call the the Paleocene-Eocene Thermal Maximum (PETM). Analysis firmly demonstrates that the quantity of carbon and carbon dioxide in the atmosphere rose significantly at the beginning of this period [8] [9]. The increasing concentration of CO2 is considered the chief reason why the atmosphere warmed so rapidly during PETM [8] [9]. Ice core analysis also attributes the end of the last ice age to an increase in atmospheric CO2 levels[10]. That carbon dioxide is a heat-trapping greenhouse gas is sound; its heat-trapping effects have been studied in laboratories throughout the world. Its contribution to prehistoric global warming has long been understood, even before the concept of man-made global warming entered the imagination [11]. [1] (http://climate.nasa.gov...) [2] (http://climate.nasa.gov...) [3] (http://www.epa.gov...) [4] (http://en.wikipedia.org...) [5] (http://www.nasa.gov...) [6] (http://volcanoes.usgs.gov...) [7] (http://news.softpedia.com...) [8] (http://en.wikipedia.org...) [9] (http://smithsonianscience.org...) [10] (http://www.livescience.com...) [11] (http://en.wikipedia.org...)

    • https://www.debate.org/debates/Global-Warming-is-Real-and-is-Manmade/1/
    • score
      BM25 score: 18.57
      climate: 7.39
      premises: 6.16 (idf 4.80, tfNorm 1.28)
      sourceText: 1.23 (boost 0.20, idf 2.98, tfNorm 2.07)
      change: 2.89
      premises: 2.52 (idf 2.58, tfNorm 0.98)
      sourceText: 0.37 (boost 0.20, idf 0.93, tfNorm 1.98)
      real: 8.28
      conclusion: 7.94 (boost 1.50, idf 4.74, tfNorm 1.12)
      sourceText: 0.34 (boost 0.20, idf 0.92, tfNorm 1.84)

CON