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Post by javelina on Aug 22, 2005 0:05:35 GMT -5
JULY 1999 - DRAFT #2
ENVIRONMENTAL NGO SUMMARY FOR POLICYMAKERS: IPCC SPECIAL REPORT ON AVIATION AND THE GLOBAL ATMOSPHEREwww.t-e.nu/docs/Fact-sheets,%20responses,%20etc/NGO%20summary%20for%20 Excerpts:The environmental NGOs welcome the publication of the Intergovernmental Panel on Climate Change's (IPCC) Special Report on "Aviation and the Global Atmosphere". While the Special Report contains a Summary for Policymakers (SPM), the paper at hand has been produced to (i) make policy-makers aware of the concerns of the environmental NGOs about aspects of the Special Report; (ii) draw policy-makers’ attention to several policy areas which received only limited discussion in the SPM; and (iii) highlight its most significant conclusions as viewed by the environmental NGOs. I) Concerns by the environmental NGOs (non-governmental organizations) The environmental NGOs are concerned that the Summary for Policy Makers does not fully reflect the discussion in Chapter 10 of the Report on the potential use of regulatory and market-based mitigation measures. The decision-makers need to be aware that it is no longer a question of whether mitigation measures are required to limit emissions from aircraft, but how such a strategy should be developed and implemented.
Attention is also drawn to the assumptions used in the reference scenario that the average traffic growth per year between 1990 and 2050 is expected to be 3.1%, while the average annual growth rate for fuel burn over the same period is forecast to be only 1.7%. While there will always be a high degree of uncertainty associated with any forecasts over such a long time frame, growth rates since 1990 have generally been well in excess of these figures.
As a result of operational improvements, the industry expects fuel efficiency to be improved by 8 to 18%, largely through the introduction of measures such as CNS/ATM***. It is important to note that all scenarios represented in this report take into account full implementation of CNS/ATM. Thus any further improvements will only approach the predictions but will not have any additional benefit. In addition, the Report does not address the issue of "rebound", which is the extra growth in demand that these improvements may stimulate. Chapter 8 of the report acknowledges that fuel-efficiency improvements may attract more traffic due to the cost savings accruing to airlines which may be reflected in lower air fares.*** CNS/ATM www.boeing.com/commercial/caft/tor/tor2.htmIt is clearly stated in the Report that technological improvements will not be sufficient to offset the demand. It is therefore important to consider innovative and creative ways in which the demand can be tackled. Thus, policies will need to be developed that put the emphasis on the avoidance of unnecessary travel, such as the use of telecommunications instead of physical traveling.Although some uncertainties still exist, the scientific facts provided in the report should prompt decision-makers to act based on the "precautionary principle", which is the starting point for any environmental action. The trade-offs between different environmental impacts are highlighted in the report, which conveys the idea that actions initiated to reduce some environmental impacts would create other, more acute problems somewhere else. The erroneous impression is created that aircraft emissions could have positive effects or could compensate for other environmental problems. Three important factors call the need for precautionary action: -- the rapid growth of the aviation sector and its environmental impact, -- the current understanding that technical measures alone will not be sufficient to ensure the sustainability of the sector and -- the tremendous long time taken for alleviating techniques to find their way into the fleet. Although the basic scenario considered in this report is making business as usual assumptions, its predictions are very weak in terms of the growth rate of aviation and the implementation of the Kyoto Protocol is not taken into account when considering the comparison with other global warming effects (Annex shows that if one takes into account the Kyoto Protocol, given its rapid growth, the share of aviation emissions will be much higher than the one considered in the report). Policy-makers need to apply the precautionary principle based on a higher growth scenario than the basic scenario. ( … ) The IPCC Report considers various operational and policy measures aimed at reducing emissions from aviation. Based on information supplied by the industry, the Report takes account of the likely effects of improvements in fuel-efficiency, the development of low-emission technology, and improved operational procedures (largely relating to the introduction of air traffic management improvements). The following types of measures are envisaged to improve the fuel efficiency: 1. Technological improvements The industry forecasts that changes to engine and airframe designs will result in a further 40 to 50% improvement in fuel efficiency by 2050. Further reductions in NOx emissions are also predicted. The IPCC Report considered that alternative fuels to kerosene were unlikely to be in commercial use within the time-scale covered by the study; 2.Operational improvements The report estimates that further reductions in fuel burn could be made in the region of 8 to 18%, largely through the direct routing opportunities available through the introduction of CNS/ATM. Higher load factors, and optimising aircraft speed were also considered; However, the most significant finding of the report is that: Technological and operational efficiency improvements alone will not be sufficient to fully offset the effects of increasing emissions.
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Post by javelina on Aug 22, 2005 0:07:03 GMT -5
January 18, 2005
National Geographic News
Airbus Unveils A380 "Superjumbo" Jetnews.nationalgeographic.com/news/2005/01/0118_050118_airbus.htmlAirbus calls it the "green giant." The new Airbus 380 "superjumbo" jet, unveiled today in Toulouse, France, will carry 555 passengers (when configured for three classes of seating). Its wingspan stretches nearly the length of a football field—50 feet (15 meters) wider than any commercial plane in the air today. (See pictures of the A380.) Airbus claims greater size equals greater environmental benefits. The new plane, the company boasts, will help ease the increasingly congested airspace. By transporting more people, the plane's fuel-burn per passenger will make it more environmentally friendly than most cars, Airbus says. Many critics are not so sure. They say Airbus officials may be stretching their math by calculating for more passengers than most A380 flights will actually carry. Furthermore, critics argue, the plane's technological improvements are simply what is to be expected in any new airplane. "Megajets are not the way to greener, or cleaner, skies," said Alan Durning, executive director of Northwest Environment Watch in Seattle, Washington. "On almost no count is the A380 particularly green." Fuzzy Numbers? The Airbus 380, which makes its maiden voyage this spring before entering passenger service in 2006, is the world's first twin-deck, four-aisle airliner. A wide staircase leads to the upper level, where first-class and business-class passengers will likely be seated. In an Airbus conception, each first-class seat folds open into a bed. On the main deck, the coach section will look similar to coach sections on airplanes today but with an extra inch (2.5 centimeters) of width in each seat. In spite of its more powerful engines, the A380 will make less noise than its closest competitor, the Boeing 747. The noise dampening is thanks to new engine and wing technology, Airbus says. The company says the plane's fuel consumption will be 2.9 liters (0.76 gallon) per passenger per 100 kilometers (60 miles). "The Airbus A380 will generate about half of the noise of a 747-400 [the biggest of the 747s], for example, and is also more fuel efficient than a small car," said David Velupillai, a spokesperson for Airbus in Toulouse. "It is able to do this through a host of new technology—newer, more efficient engines from either Rolls-Royce or Engine Alliance , better aerodynamic design, and the use of newer and lighter materials."
But analysts have questioned the Airbus numbers. Boeing, not surprisingly, says the seat-mile cost differential between its 747 airliner and the A380 is very slim.
"The problem in analyzing the claims is that the companies make different underlying assumptions, particularly on the number of passengers the respective aircraft carry and the average flight length," said Kieran Daly, group editor with the publisher of Flight International magazine, in London.
Airbus envisions that airlines will use the ample space aboard the A380 for cocktail lounges and business conference rooms. That would reduce passenger capacity and cause the fuel consumption ratio to go up. Two of the A380 customers, Emirates Airlines and Singapore Airlines, both announced that they will configure their A380s with fewer than 500 seats.
And what if the Airbus flies at less than full capacity?
"Imagine if you're flying a vast aircraft with half of the seats empty, the economics—and the emissions per passenger mile might look very different," said Simon Thomas, who heads Trucost, a London-based environmental research firm..... (continued in next post)
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Post by javelina on Aug 22, 2005 0:09:47 GMT -5
Airbus Unveils A380 "Superjumbo" Jetnews.nationalgeographic.com/news/2005/01/0118_050118_airbus.html(continued from previous post) Rebuilding Airports Airbus officials say increased demand and greater air congestion are driving the need for bigger planes. "Traffic is doubling every 15 years, and airlines, airports and air traffic controllers have to find a way of facing up to this challenge," Velupillai said. "This challenge exists, whether the A380 exists or not." Airbus envisions a network of international hubs that will ease congestion problems at major gateways. Most of the large airports that will be served by the A380—from Munich, Germany, to Bangkok, Thailand—are already ready to handle the giant planes. However, Los Angeles International Airport, which is expected to be one of the biggest hosts of A380 planes, is planning to build a new terminal for A380s. The bigger quarters would allow two A380s to park next to each other. If two A380 planes parked side-by-side in the biggest LA terminal today, their wings would hit each other. So far, Airbus has sold 139 of the 280-million-U.S.-dollar A380s. Its largest customer is Emirates, a rapidly expanding state-owned carrier based in Dubai. No U.S. airlines have commissioned an A380, though Federal Express has ordered ten cargo versions of the plane. A Fork in the Sky While Airbus is banking on its giant plane, its main competitor, Boeing, is scheduling to debut—in 2008—its 7E7, a double-aisle aircraft aimed at the growing market for mid-size aircraft flown by low-fare carriers. The two ventures illustrate the companies' opposing views of the future of commercial aviation, experts say. So which future is more environmentally efficient? The A380 will serve routes between large cities, using so-called megahubs. Many of those airports have a lot of congestion for takeoffs and landings, and the A380 is designed to solve that problem. But Boeing believes passengers will prefer to fly smaller planes on services that connect more directly to destinations. Its 7E7 will be the lightest commercial airliner in the sky, Boeing claims, and the plane will be powered by the most efficient engines by far. These innovations, some experts say, more than compensate for the economies of scale that the A380 achieves. "It would take less energy, and emit fewer pollutants, to fly several 7E7s from point A to point B than to put the same number of passengers on a single A380 for the trip," Durning said. Smoggy Future Whichever way the wind takes the airline industry, experts warn that the environmental challenges will only increase. Airliners rate as one of the most polluting forms of transportation, with the world's 16,000 commercial jets producing over 600 million metric tons of carbon dioxide every year, according to one estimate. The United Nations Intergovernmental Panel on Climate Change estimates that aviation causes 3.5 percent of man-made global warming, and that figure could rise to 15 percent by 2050. Thomas, of Trucost, says technological improvements will help trim airline emissions by one percent a year. However, the aviation industry is forecasting 5 percent annual traffic growth worldwide for the next decades. "Better technology alone is not going to solve this problem," he said._______________
TO BE CONTINUED
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Post by javelina on Aug 22, 2005 2:01:09 GMT -5
February 2, 2005
Aircraft emissions to be debated under UK presidencywww.euractiv.com/Article?tcmuri=tcm:29-134896-16&type=News(Euractiv) -- Several options are being considered to reduce the growing global warming impact of aeroplanes. Proposals will be unveiled under the UK Presidency, after impact assessments are made on the economy, jobs and the environment. Background: A seminar on "Tackling the global warming impact of aviation" was organised in the European Parliament on 31 January. The seminar was organised by the European Federation for Transport and the Environment, Milieudefensie (Friends of the Earth Netherlands) the Aviation Environment Federation and hosted by Chris Davies MEP (UK, ALDE). The seminar took place after Prime Minister Tony Blair pledged to seek a breakthrough on climate change when he takes the EU Presidency in the second half of this year (see EurActiv, 27 Jan. 2005). Issues: The highly politically charged debate on how to tackle the global warming impact of aviation will be launched under the UK Presidency, according to Roberto Salvarani, head of Environment and Safety Unit at the Commission's Transport directorate. Several options are being assessed to reduce the global warming impact of the aviation sector..... (continued)
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Post by javelina on Aug 22, 2005 2:03:38 GMT -5
February 5, 2005
Science Daily coverage of the below-referenced study with links to related informationwww.sciencedaily.com/releases/2005/02/050204213009.htm*** Source: Imperial College of Londonwww.ic.ac.uk/Press Release Issued by EPSRC
For Immediate Use 25th January 2005www.ic.ac.uk/p5997.htmResearchers are investigating how air travel can be adapted to ease its impact on the environment. The investigation focuses on how aircraft can avoid creating vapour trails, also known as contrails. These spindly threads of condensation may not seem important but some persist for hours and behave in the same way as high altitude cirrus clouds, trapping warmth in the atmosphere and exacerbating global warming. IMAGE www.sciencedaily.com/images/2004/04/040428061056.jpgAir travel is currently growing at between 3 and 5% per year and cargo transportation by air is increasing by 7% per year. Uniquely, the researchers at Imperial College London are combining predictions from climate change models with air traffic simulations to predict contrail formation and identify ways of reducing it. The Engineering and Physical Sciences Research Council (EPSRC) is funding the work, which is a joint effort between the Department of Civil & Environmental Engineering and the Department of Physics at Imperial College London. As the climate changes, so will the general condition of the atmosphere and the new work aims to understand how this will affect contrail formation. They have already found that aircraft could generally minimise contrail formation by flying lower in the atmosphere. Their work suggests that in the summer, when the air is warmer, restricting jets to an altitude of 31,000 feet could be beneficial. In winter, when the air cools, and contrail formation becomes more likely, the ceiling should be no more then 24,000 feet. Day to day variability in atmospheric conditions was also found to have a substantial effect on the ability of simple altitude restrictions to be an effective policy. Current work is aiming to examine more complex aircraft routing strategies aimed at avoiding air masses that lead to persistent contrail formation. At present the production of contrails and their effect on the environment is not taken into account in government assessments of the environmental impact of air travel. Team leader, Dr Robert Noland, thinks it should be. He says, We'd like this research to inform government policies, not just in the UK but throughout the EU and the rest of the world so that decision makers can take all the environmental issues into account and do the right thing. Dr Noland also believes that the work has direct relevance to aircraft manufacturers. He says, There is little more that aircraft designers can do to increase engine fuel efficiency at high altitude, but designing new aircraft that can be as fuel efficient flying at 20,000 feet as todays aircraft are at 35,000 feet, would help eliminate contrails. Notes for Editors:Contrails form when hot, humid air created in a jet engine mixes with the low pressure, cold surrounding air of the atmosphere. Generally, the higher the altitude, the colder the air and the more likely contrail formation becomes. It is similar to the way your breath condenses into a vaporous cloud on a cold day. A key consideration in this study is the proliferation of short-haul flights. These are currently thought to be more environmentally disruptive than long-haul flights because of the high quantity of fuel needed for take-off and landing. In a short haul, this is not balanced by a long, fuel-efficient cruise. However, contrail effects are not taken into account in current environmental risk assessments of air travel. The team are investigating whether the picture would change if they were. The reason is that short-haul flights seldom reach the altitude where contrails form and this might make them overall more environmentally friendly than high-flying long-haul flights. As well as the seasonal variation in atmospheric conditions, which the team estimated would require a general ceiling on flight altitudes (summer: 31,000 feet, winter: 24,000 feet), they also found significant day-to-day variations, so any contrail reduction strategy would work better if it were reactive on a daily basis. They also found days when the atmospheric conditions made it almost impossible to avoid contrail formation. Aircraft already measure the exterior air conditions, so a simple piece of software, programmed with the details of the jet exhaust temperature and humidity could immediately alert a pilot to when his aircraft is creating a contrail. Although lower flying aircraft expend more fuel to push themselves through the thicker atmosphere (also, lower altitude flying increases CO2 emissions) the team found this less damaging than the (positive) radiative forcing* effect of the contrails. Lower altitude flying does, however, slightly increase travel time. *Radiative forcing is any change in the balance between radiation coming into the atmosphere and radiation going out. Positive radiative forcing tends to warm the surface of the Earth, and negative radiative forcing tends to cool it. This effort is being led by Dr. Robert Noland in Civil & Environmental Engineering. Dr Ralf Toumi in the Physics Dept is the co-investigator and Dr Victoria Williams in Civil & Environmental Engineering is an EPSRC-funded Research Fellow.
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Post by javelina on Aug 22, 2005 2:08:43 GMT -5
Measuring and modelling the effects of aviation on the atmosphere
By: Michiel van Weele, Dominik Brunner, Hennie Kelder, Ernst Meijer, Veerle Pultau, Peter van Velthoven, Wiel Wauben KNMI 1999
Last update: Monday, 09-Feb-2004 16:41:28 UTCwww.knmi.nl/onderzk/atmosam/English/Service/aviation.htmlExcerpts:The use of aircraft in transporting people and goods is an important part of today's economy. But what is the environmental impact of all those airplanes, flying ceaselessly through the atmosphere? This contribution to the ‘Recent highlights’ aims to give a short overview of our present knowledge of the effects of aviation on the atmosphere and also of the work that has recently been done in this field in the Atmospheric Composition Division at KNMI. Even though most aircraft fly in so-called 'flight corridors', the effects of their emissions on atmospheric composition and chemistry propagate far beyond these regions and may even affect climate. The CO2 emitted by aircraft contributes 2-3% to the total anthropogenic CO2 emissions. Studies with global chemistry transport models show that aircraft emissions of nitrogen oxides NOx (= NO + NO2) in the North Atlantic Flight Corridor (NAFC) change the concentrations of long-lived greenhouse gases such as ozone and methane throughout the Northern Hemisphere. When the aircraft emissions are injected in the stratosphere, they may affect the ozone concentrations in the ozone layer. Paul Crutzen [1] explained in the early seventies that ‘an artificial increase of nitrogen oxides in the stratosphere ... may lead to observable changes in the atmospheric ozone level’. Some years later these results became significant in the discussion on the effects of a fleet of supersonic aircraft flying in the stratosphere.[1]Crutzen, P., 1970. The influence of nitrogen oxides on the atmospheric ozone content. Quart. J. Roy. Meteor. Soc., 96, 320-325. Aircraft NOx emissions account for only about 2-3% of the total anthropogenic NOx emissions. However, aircraft emissions have a larger impact than surface emissions due to the longer residence time of the emitted species at high altitudes. Furthermore, it is known that climate is especially sensitive to changes in atmospheric composition near the tropopause, which unfortunately coincides with the main cruise altitudes at mid-latitudes (8-13 km). A potentially large climate effect of air traffic is the formation of contrails. Contrails are ice clouds (cirrus) that form in the wake of an aircraft. It is suspected that persistent contrails may initiate the formation of longer-lived cirrus cloud fields. Even a small increase in the frequency of occurrence of cirrus clouds would exert a large climate forcing.( ... ) Calculation of the possible climate effects of aircraft emissions is still a relatively new research field and present results are still rather uncertain. Most important climate forcings are probably CO2 emissions, ozone formation, contrail formation, and water vapour exhaust in the stratosphere. Further, it has recently been hypothesised that the aircraft NOx emissions may significantly reduce the lifetime of methane, which is also an important greenhouse gas. The estimated ozone increase (here they're talking about the troposphere, not the stratosphere) due to current air traffic causes a global mean radiative forcing of 0.02 Wm-2, which is about 1% of the total forcing due to the increase in greenhouse gases since pre-industrial times and is comparable with the forcing by the aircraft CO2 emissions. A side effect of changes in the (total) ozone amount is a change in the damaging ultraviolet (UV) radiation that is incident at the Earth's surface. An increase in total ozone of 1 DU (Dobson Unit) due to aircraft NOx emissions would decrease the incident damaging UV radiation by about one percent. (NOx emissions increase ozone in the troposphere and deplete it in the stratosphere.)Water vapour that is emitted in the dry stratosphere has a very long residence time and may enhance the prevalence of polar stratospheric clouds, which play an important role in the stratospheric ozone depletion at high latitudes. END excerpts.
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Post by javelina on Aug 22, 2005 2:11:07 GMT -5
January 25, 2005
Longer Airline Flights Proposed to Combat Global Warmingwww.livescience.com/environment/050126_contrail_climate.htmlTendrils of condensation that mark the paths of high-flying jets sometimes form a loose lacework of man-made clouds in the upper atmosphere. The extra blanket of atmospheric insulation from these spreading contrails, as they are called, could accelerate global warming, studies have shown. Now a group of researchers says something should be done. Their proposal would lengthen the typical airline flight. High-altitude cirrus clouds, both natural and jet-induced, are unlike thicker low-altitude clouds, which block sunlight from reaching the surface. The thinner cirrus, which float in the sky at 20,000 feet or higher, act like a see-through blanket – letting sunlight pass in, while trapping reflected heat. A rise in contrail formation -- and therefore blanketing -- is expected in the future, because air travel is growing at 3 percent to 5 percent a year, and cargo transportation by air is increasing by 7 percent a year.In a recent investigation of air traffic trends, researchers at the Imperial College London came up with guidelines for minimizing the climate impact from contrails. They propose setting ceilings on the altitude that jets can fly: 31,000 feet in the summer and 24,000 feet in the winter. On long flights, most jets cruise at about 35,000 feet. This conserves fuel, since there is less drag through the thinner, high-altitude air. But the environmental benefit of better fuel efficiency may be offset by the warming aspect of contrail formation. "We'd like this research to inform government policies, not just in the UK but throughout the [European Union] and the rest of the world so that decision makers can take all the environmental issues into account and do the right thing," said Robert Noland, leader on the investigation. Contrail effects are not now included in governmental assessments of the impact from air travel. Heat-trapping web Condensation trails -- contrails -- form when hot, humid air coming out of a jet engine mixes with the colder surrounding air of the atmosphere. Water in the air condenses around particles in the exhaust. Depending on how much moisture is in the air, contrails can be long-lived, spreading out to look more like the wispy cirrus clouds made by Nature. Because the atmosphere becomes generally colder at higher altitudes, it is easier for contrails to form behind higher-flying aircraft. Therefore, imposing a maximum altitude for commercial flights could reduce contrail formation. The impact from jet exhaust became evident in the days after the Sept. 11, 2001, terrorist attacks, when most air traffic in the United States was halted. During the stoppage, astronaut Frank Culbertson, on the International Space Station, told flight controllers, "Normally when we go over the U.S., the sky is like a spider web of contrails. And now the sky is just about completely empty." During this period, a study found that the difference between high and low temperatures rose one degree Celsius (1.8 degrees Fahrenheit) when the skies were clear of contrails. A more recent report from NASA documented a 1 percent per decade increase in cirrus cloud cover over the United States, presumably due to increased air travel. The researchers claimed that this extra cloudiness could account for a warming trend of half a degree Fahrenheit per decade in the years between 1975 and 1994. Policy changes Requiring planes to cruise at lower altitudes would cause longer flights and require more fuel. But in weighing the two possibilities, Noland and his collaborators conclude that a rise in the number of contrails would be worse for the environment."There is little more that aircraft designers can do to increase engine fuel efficiency at high altitude," Noland said, "but designing new aircraft that can be as fuel efficient flying at 20,000 feet, as today's aircraft are at 35,000 feet, would help eliminate contrails." Besides altitude, the researchers discovered that weather conditions affect the likelihood of contrails. In fact, there are days when the atmospheric conditions make it almost impossible to avoid forming the spindly clouds. The ultimate strategy might entail day-to-day decisions to avoid air masses that are susceptible to contrail formation. Moreover, simple software could be developed to warn a pilot when his or her plane is leaving a "jetprint" in the sky.
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Post by javelina on Aug 22, 2005 2:13:14 GMT -5
Free Route Airspace Project (FRAP)
Environmental Benefit Analysis
Environmental Studies Business Area EUROCONTROL Experimental Centre
European Organization for the Safety of Air Navigation: EUROCONTROL January 2002www.eurocontrol.int/frap/doc...APReport-v4.pdfExcerpts:Following completion of the FRAP study by the EUROCONTROL Airspace Management & Navigation Unit in 1999/2000, which investigated the feasibility of the Free Route concept in the northern and west-central European airspace, the Business Area "Environmental Studies" of the EUROCONTROL Experimental Centre performed an additional analysis focusing on environmental aspects of such an ATM (Air Traffic Management) scenario. The objective of this study was to test the hypothesis that the Free Route Concept leads to reduced aviation emissions and fuel burn, since it offers the possibility to shorten flight trajectories and optimise flight profiles.( ... ) This study specifically investigates the potential benefit of the FRAP in terms of CO2, H2O and NOx, since those three emissions are seen to be the main actors in the chemical processes leading to radiative forcing (green house effect) and a reduced ozone layer. Aviation produces 2-3% of the overall man-made CO2 emissions [Ref 3]. CO2 is a stable component in the atmospheric chemistry. Its lifetime is estimated to be about 100 years. It is mixed in a homogenate way all over the atmosphere and cannot be associated with local emitters. For an analysis of its impact on the atmosphere, precise knowledge of the geographical position and altitude of the emission source is of low importance. CO2 emissions have to be reviewed in a global context. This study tests the hypothesis of reduced CO2 emissions as a result of the Free Route concept.The lifetime of water emissions in the atmosphere is estimated to be about 2 weeks. It is rapidly eliminated in form of precipitation. H2O emissions as a result of the combustion process can lead in form of water vapour, in certain atmospheric conditions, to condensation trails (Contrails).Condensation trails can evolve into cirrus clouds. Currently the contrail cover remains weak (0.1%of the global sky compared to the about 20% global mean coverage of natural cirrus clouds) but locally over regions with intense air traffic the contrails cover can reach up to 5% of the sky [Ref 4]. By this effect, H2O emissions participate indirectly to radiative forcing and man-made climate change. The hypothesis of reduced H2O emissions as a result of FRAP is tested in this study.The contribution of aviation to global NOx (nitrogen oxide) emissions is estimated to be only 1.8% [Ref 5]. Several studies indicate for the North Atlantic track system an increase of NOx following aircraft emissions of 10 -100% [Ref 6], [Ref 7], [Ref 8]. NOx has two contradictory effects on Ozone. In high altitudes of the stratosphere NOx emissions contributes to the reduction of Ozone, where in typical cruise altitudes (8-13 km) NOx emissions cause an Ozone increase. The study tests the hypothesis that the FRAP would lead to reduced global NOx emissions. END excerpts.
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Post by javelina on Aug 22, 2005 2:16:08 GMT -5
February 10, 2005
Jet pollution: drawing a line in the sky Although cars generate more greenhouse gases, airliner exhaust has an exaggerated effect, scientists say. Is it time to take action?www.csmonitor.com/2005/0210/p14s02-sten.htmlGazing into a clear blue Wisconsin sky, David Travis was amazed by what he did not see: not one fluffy airliner contrail. Not that day or in the two days that followed the 9/11 terror attacks, when commercial airliners in the United States were grounded. For Dr. Travis, a climatologist at the University of Wisconsin at Whitewater, that tragedy had a tiny silver lining. A sky without jet contrails became a once-in-a-lifetime opportunity to see if the skinny, man-made clouds really did affect climate, as he had long suspected. Little is known about the global climate effects of airliner exhaust. Although jets create far less greenhouse gas than power plants or automobiles, they have an outsize impact because of where they spew it - the delicate upper troposphere and lower stratosphere, five to seven miles up from Earth's surface. And an expected boom in airline travel in coming years is likely to swamp any efficiency gains from the next generation of airliners, such as the just unveiled Airbus A380. The result: growing scientific concern that jets may be turning the skies into a hazier, heat-trapping place. "Airliners are special because even though their total emissions are relatively small, compared to other sources, they're putting their emissions directly into the upper troposphere," says Joyce Penner, a University of Michigan professor of atmospheric science and lead author of a landmark report on aviation and the atmosphere. "It's a special location." When injected together into the icy atmosphere, the mix of exhaust gases - including water vapor, unburned hydrocarbons, particulates, sulfates, nitrogen oxides (NOX), and carbon dioxide - produces clouds and has two to three times the warming effect of carbon dioxide alone, Massachusetts Institute of Technology researchers reported last year. That finding meshes with what Travis found. Comparing ground temperature readings during the 9/11 flight ban with those after and before it, Travis found that those seemingly inconsequential wisps fanning out miles above the earth were like a blanket, reducing temperature fluctuations nationwide. Travis's findings heightened scientists earlier suspicions that the cirrus clouds formed from contrails did much more than just suppress temperatures - perhaps playing a bigger role in global climate change than many had suspected. A key 1999 international report had cited airliner exhaust as responsible for 3.5 percent of the climate warming shift. By 2050, carbon-dioxide emissions from airliners are expected to grow two to 10 times the 1992 level, thanks to increasing air traffic, according to the Intergovernmental Panel on Climate Change report co-authored byDr. Penner. By then, aircraft emissions will have risen to 5 percent of the cause of global warming, IPCC says. New research suggests the problem could be even bigger. "Contrails can be called a cause of warming and definitely need to be considered in climate-change models," says Patrick Minnis, an atmospheric scientist at Langley Research Center in Hampton, Va., part of the National Aeronautics and Space Administration. Hot under the contrail Contrails not only can reduce temperature variations, but also increase surface temperatures - enough to account for the entire warming trend in the US between 1975 and 1994, according to a study Dr. Minnis published last year. Still, he notes, additional research is needed. Just because contrails "could account for all the warming, it's not absolutely certain they did," he says. Other scientists say neither contrails nor airliner exhaust poses much of a warming threat. "If you're worried about the planet warming up, airplanes are not the first place to look to reduce the impact," says Andrew Gettleman, an atmospheric scientist at the National Center for Atmospheric Research in Boulder, Colo. "It's a fairly small piece of the puzzle.... More than 95 percent of global warming is caused by other things, like power plants." Much of the concern over contrails' potential impact on climate is coming from the European Community, which, ironically, unveiled the world's largest airliner last month. The four-engine Airbus A380 - far larger than a Boeing 747 - carries up to 840 passengers. Not to be outdone, Boeing is ramping up production of its twin-engine 7E7 Dreamliner, the first carbon-composite airliner that will be lighter and burn far less fuel per passenger mile than older airliners. Improving fuel efficiency is one of the big environmental success stories in aviation. Better engines, aerodynamics, and other factors have improved airliner fuel efficiency 60 percent in the past 35 years, says Ian Waitz, a professor of aeronautics at the Massachusetts Institute of Technology and an authority on airliner emissions impact on the atmosphere. Although the A380 and 7E7 will sport even more fuel-efficient engines, they will add to an already burgeoning global fleet of some 12,000 airliners. Airbus hopes to sell more than 700 of its megaliners; and Boeing, more than 2,500 of its Dreamliners. "Even with a 40 to 50 percent improvement in fuel efficiency, you're faced with a 3 to 20 factor increase in the amount of travel, so we are going to have to have big increases in emissions with that kind of growth," says David Greene, a coauthor of the IPCC report and scientist at the Center for Transportation Analysis at Oak Ridge National Laboratory in Tennessee. Because it will take decades to turn over the global fleet, pollution will moderate only very slowly, he says.Future contrail scenarios depend much on how much fuel is burned - and at what altitude. One possible solution, noted by researchers in England, would be to fly at lower, warmer altitudes. Contrails require moist yet very cold air to form - prevalent over some regions, such as the American Midwest, or Northern and Western Europe. By flying 6,000 feet lower, aircraft would produce fewer contrails, a team of scientists from Manchester Metropolitan University reported in 2003. But flying lower in denser air would cut fuel efficiency. Burning more fuel would increase carbon dioxide output, possibly neutralizing benefits, other point out..... (continued below)
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Post by javelina on Aug 22, 2005 2:19:49 GMT -5
(continued from above) www.csmonitor.com/2005/0210/p14s02-sten.htmlProblem with efficiency Even today's more efficient engines have a downside. The ever higher pressures and internal fuel-combustion temperatures that such engines require tend to increase NOX emissions - a major ingredient in smog. Special combustion-chamber designs and technology can reduce NOX formation. And such "low-NOX" exhaust options have been available for one of today's most popular engines - yet few are purchased because of the extra cost, experts say. Unless low-NOX engines become more popular, NOX could grow more than fourfold over 1992 levels by 2050, IPCC forecasts. Even so, the NOX issue is small potatoes, says Professor Waitz in an e-mail. "We should be concerned about all potentially important environmental impacts, but we must also recognize that aviation is a relatively small contributor." For others, however, contrails pose a threat of growing gradually into a murky blanket that reduces earth's temperature swings and dims the sun - a scenario that would hurt crops and even maple-sap harvests by helping harmful insects survive. "The jet-contrail problem is not really a pollution problem - it's a cloud problem," notes Dr. Travis back in chilly Wisconsin. "We're disrupting the natural radiation and energy balance of the planet ... trapping outgoing radiation and blocking incoming sunshine. And that makes the world a cloudier, warmer, less enjoyable place." _______________
TO BE CONTINUED
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Post by javelina on Aug 22, 2005 22:59:01 GMT -5
February 10, 2005 Clouds could clear way to saving planet
By bouncing more incoming sunlight back into space we could buy time to sort out global warming, writes Kate Ravilioussociety.guardian.co.uk/environment/story/0,14124,1409233,00.html Earth looks as if it is about to overheat. Temperatures are rising, ice sheets are melting and all the evidence points towards a greenhouse future. But what if we could reduce the planet's temperature? Would that give us some time to wean ourselves off fossil fuels and find alternative sources of energy? This is what a group of eminent atmospheric physicists and an engineer are proposing, and they have come up with an idea to halt the Earth's warming. Using nothing more than salt water and wind power, they have designed a device that will increase the reflectivity of some of the Earth's clouds, bouncing more incoming sunlight back into space. They argue that this natural heat shield could be turned on and off at will, giving us a vital extra few decades to sort out the mess we are in. John Latham, an atmospheric physicist based at the National Center for Atmospheric Research in Colorado, first came up with the idea about 15 years ago. "I outlined my idea in Nature, but at that time there wasn't a strong awareness of the global warming problem and so there wasn't a big response," he says. But more recently, the idea of a greenhouse world has become a dinner-party conversation topic and suddenly everyone is interested in ways of preventing the Earth from turning into a sauna. Together with colleagues, Latham has resurrected the idea and this time people are starting to take it seriously. Clouds come in different colours, shapes and sizes and occur at various altitudes; not just any old cloud will do. An increase in the high-level, wispy, cirrus clouds would actually have the opposite of the desired effect: making the Earth warmer as they trap more heat in. It turns out that the low-level, lumpy grey clouds, known as stratocumulus, are the best for the job, bouncing sunlight back into space, off their bright, shiny tops. Which is all very well, but how do you go about making stratocumulus cloud more reflective? Stephen Salter, the innovative Edinburgh University engineer, (known best for his invention of Salter's duck - the 300-tonne floating canister designed to drive a generator from the motion of bobbing up and down on waves) thinks he has the key. "We need to atomise seawater and throw tiny droplets into the air," he says. The idea is that this fine mist of sea-spray evaporates, leaving tiny particles of sea salt that get sucked up into marine stratocumulus clouds on rising currents of air. These little particles act as centres for extra droplets to form. "Clouds become more reflective if you increase the number of droplets in them," explains Latham. A bonus of filling the clouds with smaller droplets is that they tend to last for longer, reflecting more sunlight back into space, before they disperse.To produce this fine mist of sea spray artificially, Salter envisages thousands of unmanned yachts zigzagging across the sea, carrying equipment to make very choppy waves, known as Faraday waves. A high-frequency ultrasonic generator would spin seawater around inside a grooved drum, producing tiny waves that are thinner than a human hair. "It looks a bit like a cup of coffee on a rattling train, but it would be nearly vertical," says Salter. Once the waves are steep enough, drops of water are thrown up from their crests. "All we need to do is try and get these fine droplets into the first few metres of air, and meteorology will do the rest," says Latham. To remain truly environmentally friendly, the yachts would be driven by wind acting on the spinning drum, like a sail. Movement of the boat through the water would drive propellers acting as turbines, to produce the electrical power for spinning the drums and driving the ultrasonics. Meanwhile, satellites would direct their movements, placing the yachts in the areas of ocean where the most effective stratocumulus clouds could be modified. But would it really work? If calculations and computer models are to be believed, then yes, the physics of this idea is sound. Working together with Tom Choularton, of Manchester University, and Mike Smith, of Leeds University, Latham has done extensive calculations to make sure he has got his sums right. In addition, they have tested the idea using the Meteorological Office's Global Climate Model and shown that increasing the droplet numbers in marine stratocumulus clouds could have a significant effect. "Modifying an area covering around 3% of the Earth's surface produced a cooling that more or less balances the warming from doubled carbon dioxide levels," says Latham. Now the scientists are looking for funding to take their idea to the next stage, testing it with a small-scale pilot project over the oceans, using natural stratocumulus clouds. If they find that the extra cloud brightness would do its job and that there would be no adverse effect to rainfall on land, then Latham's original idea may begin to make good sense. Nonetheless, all the scientists stress that increasing cloud brightness is not a long-term solution to global warming, but a stopgap. "Our endeavours are directed towards buying time," says Latham. If recent reports of the melting of the Antarctic ice cap are anything to go by, we may need to start buying time very soon. END
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Post by javelina on Aug 22, 2005 23:01:35 GMT -5
The Research Plan for the First ISCCP Regional Experiment: FIRE, a U.S. program in the context of the International Satellite Cloud Climatology Project: ISCCPSubmitted to the U.S. National Climate Program Office November 1983asd-www.larc.nasa.gov/fire/FIRE_I/2.7.htmlExcerpt:EXECUTIVE SUMMARY 1. The Concept of FIRE 1.1 The Cloud-Climate Feedback Problem Many aspects of life on earth are affected by climate, its year to year fluctuations and possible long term changes due to increasing atmospheric carbon dioxide and other manmade causes.
With the hope of avoiding a potentially adverse climate resulting from man's activities and also of improving the management of dwindling resources, a hierarchy of climate models has been developed.The hierarchy ranges in complexity from simple, even analytic, formulations based on the radiative energy balance of the earth, to highly sophisticated and computationally intensive general circulation models. These models have been shown to simulate convincingly many elements, such as wind and temperature fields, of the observed climate. Though imperfect they are nevertheless invaluable tools for investigating the causes of interannual variability and the effects of long-term changes such as increasing concentrations of atmospheric carbon dioxide. However, major areas of uncertainty are the interactions between atmosphere and ocean, and the feedbacks between cloudiness, radiation and dynamics. This research plan is directed toward the second of these problem areas. Owing to their strong influence on the earth's radiative energy budget, clouds undoubtedly play a major role in shaping the current climate and affecting the way it might change. Simple radiative energy balance calculations indicate for example that as small as a 4X increase in global cloud cover could be sufficient to offset the global warming predicted for the anticipated doubling of CO2.How clouds might be affected by changes due to a perturbation like increased CO2 and how in turn they would affect the response to the perturbation is still a mystery. 1.2 Why FIRE is needed As already indicated, a mayor limitation on confidence in forecasts of climate changes such as that due to increasing atmospheric carbon dioxide is the current lack of realistic models for large scale cloud systems and their influence on radiation. Together with ISCCP, FIRE should help remove this limitation..... (continued)
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Post by javelina on Aug 22, 2005 23:03:21 GMT -5
Interesting and instructive background material:THE LIVING SKIES Cloud Behavior and its Role in Climate Change Oliver Morton - The Hybrid Vigor Institute
Earth Systems April 2002www.hybridvigor.net/earth/pu...-2002.04.30.pdf[0.0] Overview The clouds above have always been a worldwide source of poetic inspiration, quotidian joy and curious speculation. They are also, at the moment, central to questions of great environmental, economic and thus political importance. The behaviour of clouds and the processes that produce them in the face of increased atmospheric greenhouse gas concentrations (1) will be a crucial element in future climate change, and as yet that behaviour is not well understood. It is possible that changes in cloud formation and structure could act to reduce the climatic effects of greenhouse gases quite markedly, and thus reduce the need to abate their production. Were this the case, it would have a profound influence on the current efforts in many countries to implement the Kyoto Protocol (the global accord outlining actions to be taken to minimize climate change) and develop global successor regimes to further reduce greenhouse gas emissions. However it is also possible that clouds will not reduce the effects of increased greenhouse gases, or will do so no more than is envisioned in current predictions, or will even exacerbate them..... (continued)
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Post by javelina on Aug 22, 2005 23:05:39 GMT -5
NCAR / ASP Annual Scientific Report - 2002 Research Summarieswww.asp.ucar.edu/asr2002/resold.htmExcerpt: John Latham has published two papers on and has been extending his research into a novel idea for the amelioration of global warming by the advertent and controlled enhancement of the albedo A and longevity L of low-level maritime clouds. His provisional calculations and some limited computer modelling support the quantitative validity of the proposed technique, which involves increasing the droplet concentration in such clouds, with a corresponding increase in both A and L: and thus cooling. The idea involves the dissemination at the ocean surface of small seawater droplets in sufficient quantities to act as the dominant CCN on which cloud droplets form. Satellite control of the dissemination is envisaged. Collaborators include Dr Keith Bower, Prof. Tom Choularton & Dr Alan Gadian (UMIST, Manchester, UK), Dr Alan Blyth & Prof. Mike Smith (University of Leeds, UK), Prof. Stephen Salter, (University of Edinburgh, UK) and Dr Tom Wigley (CGD, NCAR). If this technique were to prove workable on the scales required, it could be of great societal importance. *** NCAR / ASP Annual Scientific Report - 2004 Research Summarieswww.asr.ucar.edu/2004/ASP/narrative.htmlExcerpt: Possible mitigation of global warming by modification of cloud albedo : John Latham (ASP) continued exploration of a novel idea for the amelioration of global warming by the advertent and controlled enhancement of the albedo A and longevity L of low-Level maritime clouds. Detailed calculations coupled with computer modeling with the UK Meteorological Office GCM support the quantitative validity of the proposed technique, which involves increasing the droplet concentration in such clouds, with a corresponding increase in both A and L and thus cooling. The idea involves the dissemination at the ocean surface of small seawater droplets in sufficient quantities to act as the dominant CCN on which cloud droplets form. Satellite control of the overall dissemination rate is envisaged. Latham’s collaborators include Keith Bower and Tom Choularton (both of UMIST, Manchester, UK), Alan Blyth, Alan Gadian and Mike Smith (all of University of Leeds, UK), Stephen Salter, (University of Edinburgh, UK) and Andy Jones (Hadley Climate Centre, Meteorological Office, UK). If this technique were to prove workable on the scales required, it could be of great societal importance.
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Post by javelina on Aug 22, 2005 23:09:10 GMT -5
February 3, 2005
We need a plan for global coolingwww.guardian.co.uk/climatechange/story/0,12374,1404638,00.html It is crucial firm steps are urgently taken to limit and then reduce carbon dioxide emissions (Climate change, February 2). But it is deplorable that scant attention and no resources are being devoted to the examination of alternative techniques for producing atmospheric cooling sufficient to ameliorate the heating resulting from the burning of fossil fuels. One such idea, which I and my collaborators - Professors Tom Choularton (University of Manchester), Stephen Salter (Edinburgh) and Mike Smith (Leeds), and their colleagues - are investigating involves increasing the reflectivity (albedo) of the Earth to incoming sunlight. If a greater fraction of the sunlight arriving at the top of the atmosphere is reflected back into space, the overall result is a cooling of the Earth. This cooling could be achieved, in principle, by increasing the reflectivity of shallow maritime clouds - which cover a large fraction of the oceanic surface, by atomising sea water to produce tiny droplets which enter the clouds and, for well-established physical reasons, cause them to become more reflective. Tests using the Meteorological Office's global climate model show that the scheme could produce significant cooling. Further calculations and studies by members of our team provide additional encouragement, although more scientific and technological questions need to be resolved. The next logical stage is the execution of a limited area experiment to test the proposed technique using natural clouds. If this atmospheric reflectivity enhancement scheme (or any other) could successfully be deployed, it would not, of course, affect the atmospheric CO2, which will need to be addressed in addition to temperature enhancement. However, if it proved feasible, in a controlled way, to produce a cooling to compensate for global warming, we could buy time within which we could stave off catastrophic warming while carbon dioxide levels are being reduced to acceptable levels. In our view, the likely consequences of global warming are so devastating and so imminent that adequate resources should immediately be made available. Prof John Latham National Center for Atmospheric Research, Boulder, Colorado, USA
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