Sbsp affirmative- arl lab- ndi 2011



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AT: Iris Hypothesis

The Iris Hypothesis is wrong – flawed model and small sample size prove



Herring, ‘2 - climate scientist at NASA [David, “Does the Earth Have an Iris Analog?” NASA Earth Observatory, http://earthobservatory.nasa.gov/Study/Iris/printall.php]
“The Iris Hypothesis is very exciting,” states Bing Lin, an atmospheric research scientist at NASA LaRC. “Everybody would like to see tropical clouds changing in response to surface warming and acting to stabilize the climate system. The problem is when we used measurements from the Clouds and the Earth’s Radiant Energy System (CERES) sensor, we got significantly different results (from Lindzen).” Copies of the CERES sensor fly aboard both the NASA/NASDA Tropical Rainfall Measuring Mission (TRMM), launched in November 1997, and NASA’s Terra satellite, launched in December 1999. Additional CERES sensors will be launched aboard Terra’s sister ship, Aqua, in the spring of 2002. CERES is the most advanced space-based sensor ever launched for measuring Earth’s radiant energy fluxes on a global scale. Lin’s team took the measurements made every day by CERES over the tropical oceans and plugged them into the same model that Lindzen used. Instead of the strong negative feedback that Lindzen’s team found, Lin’s team found a weak positive feedback (Lin et al. 2001). That is, Lin found that clouds in the tropics do change in response to warmer sea surface temperatures, but that the cloud changes serve to slightly enhance warming at the surface. Specifically, whereas Lindzen’s experiment predicts that cirrus clouds change in extent to reduce warming at the surface by anywhere from 0.45 to 1.1 degrees, Lin’s experiment predicts that changes in the tropical clouds will help warm the surface by anywhere from 0.05 to 0.1 degree (Lin et al. 2001). The difference between the two experiments can be summed up as follows. According to the Iris Hypothesis, for each square meter of tropical cloudy, moist area that disappears with increasing surface temperature, 70 watts of heat is lost from the planet—like turning off a 70 watt light bulb for every square meter of area. But CERES’ measurements of cloud properties tell a very different story—clouds are much more reflective (51 percent instead of 35 percent) and somewhat weaker in their greenhouse effect than Lindzen’s model predicts. So instead of turning off a 70-watt bulb for each square meter affected, it is as if a small 2-watt night-light bulb was turned on in every square meter. Hence, the slight warming found by Lin’s team instead of the very large cooling found by Lindzen’s team. Lin says the reason his team’s findings differ so dramatically is because some of the initial assumptions made in Lindzen’s model are incorrect. He says that while he has many minor differences of opinion with Lindzen on this subject, he has three major disagreements. For starters, he says, the Indo-Pacific warm pool region does not serve as a model for the tropics all around the world. The waters there are, on average, much warmer than the rest of the tropics and so convection (warm, upward-moving air) is much stronger. Therefore, the area covered by deep convective cumulus clouds (thunderheads, basically) and cirrus clouds is not the same throughout the tropics. In the Indo-Pacific warm pool, these two cloud types cover about 13 percent of the region, whereas they only cover about 10 percent of the world’s tropics on a global scale (Lin et al. 2001). Lin’s team found that while tropical cloudiness does change as sea surface temperature changes, there is a large reduction in total cloud amount—roughly 10 percent cloud cover as compared to the 22 percent proposed by Lindzen’s team. Secondly, Lin disagrees with Lindzen’s proposed physical model of the clouds themselves. “Deep convective clouds very strongly reflect sunlight back to space,” he states, “but their relative area of coverage is small.” Cirrus clouds, on the other hand, are very extensive and cover large areas. They can be thin enough to allow sunlight to pass through, or they can also have a high reflectivity. Cirrus provides a much larger “canopy” over the tropics so, from a radiative perspective, those clouds are actually more important than deep cumulus clouds. The third major disagreement between Lin’s and Lindzen’s experiments pertains to the amount of heat escaping from cloudy regions. CERES measurements reveal that 155 Watts per square meter escaped the atmosphere over cloudy, moist regions, which is significantly more than the 138 Watts per square meter that Lindzen’s team assumed (Lin et al. 2001). In summary, Lindzen’s team suggests that higher sea surface temperatures lead to less cloudy, moist skies and a corresponding increase in clear, dry skies. Lin disagrees with Lindzen’s interpretation of the cloud physics. In their paper, Lin’s team wrote that the much smaller albedo and lower outgoing heat flux assumed by Lindzen exaggerated the cooling effects of the outgoing radiation over cloudy, moist regions while minimizing the warming effects of incoming sunlight through regions covered by cirrus (Lin et al. 2001). Based upon CERES data, Lin’s team concluded that the reduction in cloudy, moist skies allows extra sunlight to warm the surface by up to 1.8 Watts per square meter—a small but positive net energy flux (Lin et al. 2001). “Our results are based upon actual observations that are used to drive global climate models,” Lin concludes. “And when we use actual observations from CERES we find that the Iris Hypothesis won’t work.”


AT: Stopped in 1998

Warming didn’t stop in 1998 – ocean models prove



LePage, ‘8 - Director, Rowan Williams Davies & Irwin Inc., [Michael, “Special Report Climate Change: Climate myths: Global warming stopped in 1998,” http://environment.newscientist.com/channel/earth/climate-change/dn14527-climate-myths-global-warming-stopped-in-1998.html, DS]
In fact, the planet as a whole has warmed since 1998, sometimes even in the years when surface temperatures have fallen Imagine two people standing at the South Pole, one dressed in full Antarctic gear and the other wearing not much at all. Now imagine that you're looking through one of those infrared thermal imagers that show how hot things are. Which person will look warmest - and which will be frozen solid after a few hours? The answer, of course, is that the near-naked person will appear hotter: but because they are losing heat fast, they will freeze long before the person dressed more appropriately for the weather. The point is that you have to look beyond the surface to understand how a body's temperature will change over time - and that's as true of planets as it is of warm-blooded bipeds. Now take a look at the two main compilations (see figures, right) of global surface temperatures, based on monthly records from weather stations around the world. According to the dataset of the UK Met Office Hadley Centre (see figure), 1998 was the warmest year by far since records began, but since 2003 there has been slight cooling. But according to the dataset of NASA's Goddard Institute for Space Studies (see figure), 2005 was the warmest since records began, with 1998 and 2007 tied in second place. Tracking the heat Why the difference? The main reason is that there are no permanent weather stations in the Arctic Ocean, the place on Earth that has been warming fastest. The Hadley record simply excludes this area, whereas the NASA version assumes its surface temperature is the same as that of the nearest land-based stations. It is possible that the NASA approach underestimates the rate of warming in the Arctic Ocean, but for the sake of argument let's assume that the Hadley record is the most accurate reflection of changes in global surface temperatures. Doesn't it show that the world has cooled since the record warmth of 1998, as many claim? Not necessarily. The Hadley record is based only on surface temperatures, so it reflects only what's happening to the very thin layer where air meets the land and sea. In the long term, what matters is how much heat is gained or lost by the entire planet - what climate scientists call the "top of the atmosphere" radiation budget - and falling surface temperatures do not prove that the entire planet is losing heat. Swaddling gases Think again about that scantily clad person at the South Pole. If they put on some clothing, they'll appear cooler to a thermal imager, but what's really happening is that they are losing less heat. Similarly, if you could look at Earth through a thermal imager, it would appear slightly cooler than it did a few decades ago. The reason is that the outer atmosphere, the stratosphere, is cooler because we've added more "clothing" to the lower atmosphere in the form of greenhouse gases like carbon dioxide. As a result, the planet is gaining as much heat from the sun as usual but losing less heat every year as greenhouse gas levels rise (apart from the exceptional periods after major volcanic eruptions, such as El Chichon in 1982 and Pinatubo in 1991). How do we know? Because the oceans are getting warmer. Tricky oceans Water stores an immense amount of heat compared with air. It takes more than 1000 times as much energy to heat a cubic metre of water by 1 degree Celsius as it does the same volume of air. Since the 1960s, over 90% of the excess heat due to higher greenhouse gas levels has gone into the oceans, and just 3% into warming the atmosphere (see figure 5.4 in the IPCC report (PDF)). Globally, this means that if the oceans soak up a bit more heat energy than normal, surface air temperatures can fall even though the total heat content of the planet is rising. Conversely, if the oceans soak up less heat than usual, surface temperatures will rise rapidly. In fact, most of the year-to-year variability in surface temperatures is due to heat sloshing back and forth between the oceans and atmosphere, rather than to the planet as a whole gaining or losing heat. The record warmth of 1998 was not due to a sudden spurt in global warming but to a very strong El Niño (see figure, right). In normal years, trade winds keep hot water piled up on the western side of the tropical Pacific. During an El Niño, the winds weaken and the hot water spreads out across the Pacific in a shallow layer, which increases heat transfer to the atmosphere. (During a La Niña, by contrast, as occurred during the early part of 2008, the process is reversed and upwelling cold water in the eastern Pacific soaks up heat from the atmosphere.) A temporary fall in the heat content of the oceans at this time may have been due to the extra strong El Niño. What next? Since 1999, however, the heat content of the oceans has increased (despite claims to the contrary). Global warming has certainly not stopped, even if average surface temperatures really have fallen slightly as the Hadley figures suggest. In the long term, some of the heat being soaked up by the oceans will inevitably spill back into the atmosphere, raising surface temperatures. Warmer oceans also mean rising sea levels, due to both thermal expansion and the melting of the floating ice shelves that slow down glaciers sliding off land into the sea. The West Antarctic Ice Sheet, which rests on the seabed rather than on land, is also highly vulnerable to rising sea temperatures. Some climate scientists are predicting that surface temperatures will remain static or even fall slightly over the next few years, before warming resumes. Their predictions are based largely on the idea that changes in long-term fluctuation in ocean surface temperatures known as the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation will bring cooler sea surface temperatures. If these predictions are right - and not all climate scientists think they are - you can expect to hear more claims from climate-change deniers about how global warming has stopped. But unless we see a simultaneous fall in both surface temperatures and ocean-heat content, claims that the "entire planet" is cooling are nonsense. And while some events such as a big volcanic eruption could indeed trigger genuine cooling for a few years, global warming will resume again once the dust has settled.



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