Sbsp affirmative- arl lab- ndi 2011
*** Warming = Anthropogenic*** CO2 Key
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- Water vapor’s a positive feedback – residence time proves
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*** Warming = Anthropogenic***CO2 KeyCO2 is the root cause of warming – linear relationship provenScienceDaily, ‘9 – [6/11/2009, Science Daily, “Carbon Emissions Linked to Global Warming in Simple Linear Relationship,” http://www.sciencedaily.com/releases/2009/06/090610154453.htm, DS] Damon Matthews, a professor in Concordia University’s Department of Geography, Planning and the Environment has found a direct relationship between carbon dioxide emissions and global warming. Matthews, together with colleagues from Victoria and the U.K., used a combination of global climate models and historical climate data to show that there is a simple linear relationship between total cumulative emissions and global temperature change. These findings will be published in the next edition of Nature, to be released on June 11, 2009. Until now, it has been difficult to estimate how much climate will warm in response to a given carbon dioxide emissions scenario because of the complex interactions between human emissions, carbon sinks, atmospheric concentrations and temperature change. Matthews and colleagues show that despite these uncertainties, each emission of carbon dioxide results in the same global temperature increase, regardless of when or over what period of time the emission occurs. These findings mean that we can now say: if you emit that tonne of carbon dioxide, it will lead to 0.0000000000015 degrees of global temperature change. If we want to restrict global warming to no more than 2 degrees, we must restrict total carbon emissions – from now until forever – to little more than half a trillion tonnes of carbon, or about as much again as we have emitted since the beginning of the industrial revolution. “Most people understand that carbon dioxide emissions lead to global warming,” says Matthews, “but it is much harder to grasp the complexities of what goes on in between these two end points. Our findings allow people to make a robust estimate of their contribution to global warming based simply on total carbon dioxide emissions.” In light of this study and other recent research, Matthews and a group of international climate scientists have written an open letter calling on participants of December’s Conference of the Parties to the U.N. Framework Convention on Climate Change to acknowledge the need to limit cumulative emissions of carbon dioxide so as to avoid dangerous climate change. AT: Water Vapor MoreCO2’s the root cause – water vapor’s irrelevantBBC, ‘7 [British Broadcasting Corporation, 11/12/07, “Climate onizingm: The top 10,” http://news.bbc.co.uk/2/hi/in_depth/629/629/7074601.stm, DS] Sceptic The natural greenhouse effect keeps the Earth’s surface about 33C warmer than it would otherwise be. Water vapour is the most important greenhouse gas, accounting for about 98% of all warming. So changes in carbon dioxide or methane concentrations would have a relatively small impact. Water vapour concentrations are rising, but this does not necessarily increase warming – it depends how the water vapour is distributed. Counter Water vapour is essentially in balance with the planet’s temperature on annual timescales and longer, whereas trace greenhouse gases such as CO2 stay in the atmosphere on a timescale of decades to centuries. The statement that water vapour is “98% of the greenhouse effect” is simply false. In fact, it does about 50% of the work; clouds add another 25%, with CO2 and the other greenhouse gases contributing the remaining quarter. Water vapour concentrations are increasing in response to rising temperatures, and there is evidence that this is adding to warming, for example in Europe. The fact that water vapour is a feedback is included in all climate models. Water vapor’s a positive feedback – residence time provesRealClimate, ‘5 – online climate scientist discussion/information page [4/6/2005, http://www.realclimate.org/index.php/archives/2005/04/water-vapour-feedback-or-forcing/, DS] While water vapour is indeed the most important greenhouse gas, the issue that makes it a feedback (rather than a forcing) is the relatively short residence time for water in the atmosphere (around 10 days). To demonstrate how quickly water reacts, I did a GCM experiment where I removed all the water in the atmosphere and waited to see how quickly it would fill up again (through evaporation from the ocean) . The result is shown in the figure. It’s not a very exciting graph because the atmosphere fills up very quickly. At Day 0 there is zero water, but after only 14 days, the water is back to 90% of its normal value, and after 50 days it’s back to within 1%. That’s less than 3 months. Compared to the residence time for perturbations to CO2 (decades to centuries) or CH4 (a decade), this is a really short time. AT: Solar VariationsSolar variations don’t cause warming – actually causes slight coolingScienceDaily, ’10 – [10/7/2010, ScienceDaily, “Decline in Sun’s Activity Does Not Always Mean That Earth Becomes Cooler, Study Shows,” http://www.sciencedaily.com/releases/2010/10/101006141558.htm, DS] The Sun’s activity has recently affected Earth’s atmosphere and climate in unexpected ways, according to a new study published in the journal Nature. The study, by researchers from Imperial College London and the University of Colorado, shows that a decline in the Sun’s activity does not always mean that Earth becomes cooler. It is well established that the Sun’s activity waxes and wanes over an 11-year cycle and that as its activity wanes, the overall amount of radiation reaching Earth decreases. This latest study looked at the Sun’s activity over the period 2004-2007, when it was in a declining part of its 11-year activity cycle. Although the Sun’s activity declined over this period, the new research shows that it may have actually caused Earth to become warmer. Contrary to expectations, the amount of energy reaching Earth at visible wavelengths increased rather than decreased as the Sun’s activity declined, causing this warming effect. Following this surprising finding, the researchers behind the study believe it is possible that the inverse is also true and that in periods when the Sun’s activity increases, it tends to cool, rather than warm, Earth. This is based on what is already known about the relationship between the Sun’s activity and its total energy output. Overall solar activity has been increasing over the past century, so the researchers believe it is possible that during this period, the Sun has been contributing a small cooling effect, rather than a small warming effect as had previously been thought. 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