Satu Blog Satu Pohon

Sebenarnya sudah banyak gerakan yang bertujuan untuk menghijaukan dan Menjaga Bumi ini. Tujuannya jelas, agar Bumi tidak terancam pemanasan global (Global Warming). Pemanasan global memang harus menjadi perhatian kita bersama, karena Bumi ini adalah tempat tinggal kita, kita hidup di sini, ini adalah milik kita bersama, titipan Tuhan, agar kita menjaganya bersama-sama.



Sebagai blogger, tentu kita ingin memberikan kontribusi yang nyata untuk Bumi ini. Ya, salah satunya dengan gerakan ini yaitu: Satu Blog Satu Pohon. Gerakan kecil tapi bila dilakukan bersama-sama akan menjadi besar.

Dari banyaknya blogger di Indonesia, tentu harus diarahkan untuk memberikan sesuatu untuk Bumi ini. Nah, bila Anda memiliki sebuah blog, mari kita tanam satu pohon. Pasang banner di atas sebagai tanda bahwa blog kita berkontribusi untuk Bumi ini. Kodenya bisa Anda dapatkan di sidebar blog ini.

Selamatkan Bumi, Stop Global Warming, kita hanya punya satu Bumi.

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Global warming - extreme events and weird weather

After a few days to find complete information about global warming, finally I found the article by Andrew Freedman of the "will of global warming make the weather more extreme. " And this is quite interesting in my opinion, you can read the article below:

I've never been a fan of absolutes. People who espouse rigid beliefs - be they about climate change, religion, or politics (or a mix of all three) - instinctively make me question their evidence. As a reporter, I tend to see things in varying shades of gray, rather than black and white, and I gravitate towards stories that are full of nuance and complexity, where absolutes are rarely, if ever, to be found.

For this reason, the oft-made assertions that "global warming will make the weather more extreme" or that warming "caused" a particular severe weather event to occur, make me cringe.

There are core scientific findings in climate science that most climate researchers, and most science journalists, including myself, no longer consider to be hotly debated, such as the conclusion that most of global warming is very likely due to manmade emissions of greenhouse gases, such as carbon dioxide.

You can read more this articel here

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Public seminar today explores climate change

See how much you can learn about Public seminar today explores climate change when you take a little time to read a well-researched article? Don't miss out on the rest of this great information.

The public is invited to a seminar today about how climate change will change agriculture in this region.

"Climate change and Crop Production, Prospects for the Northern Great Plains" is the topic at the University of Manitoba Wednesday afternoon.

Soil scientist Paul Bullock from the university faculty is delivering the lecture from 3:30 p.m. to 4:30 p.m. at the Fort Garry campus, the Agriculture Building, #130 Carolyn Sifton Theatre.

The lecture marks the fifth Faculty Seminar Series this winter. Coffee and doughnuts will be served. Everyone is welcome. via

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Global warming is our common problems

Global warming is our common problems. This can not go unpunished. Increasing the temperature of the earth and climate change has become evidence of global warming. Clearly, global warming is a clear and present danger. The principle of common but differentiated responsibility, the cornerstone of the Kyoto Protocol, reflects historical reality. However, implementing the principle is near impossible in a world defined by states, which militate against a sense of global responsibility.

In 2010 actually confirms global warming because it was the 34th consecutive year with temperatures above the 20th century global average. One effect is the diminishing of the Arctic sea ice cover. It is at its third smallest since records began in 1979. Another effect is freak weather conditions across the globe. The earth's temperature was higher by 0.62 degrees Celsius on the 20th century average making 2010, along with 2005, the hottest years since US records began in 1880. Last year was also the warmest in India since our records began in 1901. via

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Recent facts about Global Warming in Spanish

Global warming still a hot issue for discussion. Recently, Spanish has a lot of facts about global warming. Southern Alliance for Clean Energy is now releasing Spanish versions of our newly created, state specific, global warming fact sheets. Through these translated materials, SACE is continuing its effort to educate the Latino community on the current and future impacts of global warming in the Southeast and the United States as a whole.

For far too long, Hispanics have been marginalized in the political process due to simple language barriers; an astounding fact given that over 15% of our country self-identifies as being of this ethnicity.

Global warming will affect everyone, yet studies show that it will affect some more than others. For example, there are nearly 4 million Hispanics in the state of Florida, comprising almost a quarter of the population.

Furthermore, Hispanics in the state earn on average $7,000 less a year than the average non-Hispanic white person. This disparity in income is important because a recent Oxfam America report highlighted that race and economic status play a key role in how much a person will be impacted by global warming.

The only way we can protect Latinos living in vulnerable areas is through education and encouraging increased participation to demand strong state and federal climate and energy policies from their legislators. via

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The dinosaur age may become extinct due to global warming

Extinction of dinosaurs in New Zealand caused by global warming. Several types of extinct reptiles. It has survived ice ages, volcanic eruptions and the intrusion of humans on its South Pacific island home, but New Zealand's last survivor of the dinosaur age may become extinct due to global warming.

Mounted with spiny scales from head to tail and covered by rough, grey skin that disguises them among the trees, the tuatara is one of the world's oldest living creatures.

But the lizard-like reptile is facing increasing risk of extinction from global warming because of its dependency on the surrounding temperature which determines the sexes of unborn young while still in their eggs.

"They've certainly survived the climate changes in the past but most of them (past climate changes) have been at a more slower rate," said Jennifer Moore, a Victoria University researcher investigating the tuatara's sexual behaviour.

"So you wouldn't expect these guys to be able to adapt to a climate that's changing so rapidly."

The sex of a tuatara depends on the temperature of the soil where the eggs are laid. A cooler temperature produces females, while a warmer soil temperature results in male offsprings. [source]

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Human activities are warming the planet at a dangerous rate

By Juliet Eilperin

An international panel of climate scientists said yesterday that there is an overwhelming probability that human activities are warming the planet at a dangerous rate, with consequences that could soon take decades or centuries to reverse.

The Intergovernmental Panel on Climate Change, made up of hundreds of scientists from 113 countries, said that based on new research over the last six years, it is 90 percent certain that human-generated greenhouse gases account for most of the global rise in temperatures over the past half-century.

Declaring that "warming of the climate system is unequivocal," the authors said in their "Summary for Policymakers" that even in the best-case scenario, temperatures are on track to cross a threshold to an unsustainable level. A rise of more than 3.6 degrees Fahrenheit above pre-industrial levels would cause global effects -- such as massive species extinctions and melting of ice sheets -- that could be irreversible within a human lifetime. Under the most conservative IPCC scenario, the increase will be 4.5 degrees by 2100.
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Richard Somerville, a distinguished professor at the Scripps Institution of Oceanography and one of the lead authors, said the world would have to undertake "a really massive reduction in emissions," on the scale of 70 to 80 percent, to avert severe global warming.

The scientists wrote that it is "very likely" that hot days, heat waves and heavy precipitation will become more frequent in the years to come, and "likely" that future tropical hurricanes and typhoons will become more intense. Arctic sea ice will disappear "almost entirely" by the end of the century, they said, and snow cover will contract worldwide.

read more www.washingtonpost.com

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Global warming and evolution

You can see that there's practical value in learning more about Global warming and evolution. Can you think of ways to apply what's been covered so far?

The battle over the science of global warming has long been a street fight between mainstream researchers and skeptics. But never have the scientists received such a deep wound as when, in late November, a large trove of e-mails and documents stolen from the Climatic Research Unit at Britain's University of East Anglia were released onto the Web.

In the ensuing "Climategate" scandal, scientists were accused of withholding information, suppressing dissent, manipulating data and more. But while the controversy has receded, it may have done lasting damage to science's reputation: Last month, a Washington Post-ABC News poll found that 40 percent of Americans distrust what scientists say about the environment, a considerable increase from April 2007. Meanwhile, public belief in the science of global warming is in decline.

The central lesson of Climategate is not that climate science is corrupt. The leaked e-mails do nothing to disprove the scientific consensus on global warming. Instead, the controversy highlights that in a world of blogs, cable news and talk radio, scientists are poorly equipped to communicate their knowledge and, especially, to respond when science comes under attack.
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A few scientists answered the Climategate charges almost instantly. Michael Mann of Pennsylvania State University, whose e-mails were among those made public, made a number of television and radio appearances. A blog to which Mann contributes, RealClimate.org, also launched a quick response showing that the e-mails had been taken out of context. But they were largely alone. "I haven't had all that many other scientists helping in that effort," Mann told me recently.

This isn't a new problem. As far back as the late 1990s, before the news cycle hit such a frenetic pace, some science officials were lamenting that scientists had never been trained in how to talk to the public and were therefore hesitant to face the media.

"For 45 years or so, we didn't suggest that it was very important," Neal Lane, a former Clinton administration science adviser and Rice University physicist, told the authors of a landmark 1997 report on the gap between scientists and journalists. ". . . In fact, we said quite the other thing."

The scientist's job description had long been to conduct research and to teach, Lane noted; conveying findings to the public was largely left to science journalists. Unfortunately, despite a few innovations, that broad reality hasn't changed much in the past decade.

read more www.washingtonpost.com

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Center For American Progress: Snowstorm Doesn't Disprove Global Warming!

by Chris Good -- staff editor at TheAtlantic.com

Irked by the suggestion of climate change doubters that the East Coast snowstorm is proof that global warming doesn't exist, the liberal Center for American Progress pulled together a conference call today to tell reporters not only that that's not the case, but, basically, to stop being a mouthpiece for people who doubt the science.

Jeff Masters, director of meteorology at Weather Underground, got on the call to remind everyone that snowfall does not equal a drop in temperature--that as long as it's cold enough for snow, precipitation means a snowstorm.

More precipitation--including heavy snowstorms--is a sign of global warming, he said, as atmospheric moisture levels have increased with warmer temperatures, meaning more storms with heavy snow or rain.


"We still will have snowstorms, and the signs of record snowstorms being evidence against global warming is just not true," Masters said. "In the future we shouldn't be surprised to find heavier precipitation events."

Center for American Progress climate change fellow Joseph Romm criticized John M. Broder's New York Times story, in which Romm was quoted, which noted the uptick of global warming debate during the snowstorm. A chorus of Republicans have mocked Al Gore since the snowstorm hit. The family of Sen. James Inhofe (R-OK), the leading climate change skeptic in the nation (and, by extension, perhaps the world) built an igloo on Capitol Hill bearing a sign that read "Al Gore's New Home." This is not new; cold weather often sparks criticisms of climate change, and of Gore.

"We're not in a deep freeze," Romm said of the NY Times headline, "Climate-Change Debate Is Heating Up in Deep Freeze."

"This actualy is, according to the satellite record, it's the warmest winter on record," Romm said. "The scientific literature predicts that you will see more intense winter storms because of global warming."

Romm pointed to warm temperatures (in the upper 40s) and likely rain during the Winter Olympics in Vancouver.

"I realize that this can be a complicated matter to report," Romm said. "The challenge for the media is gonna be how do you report about this statistical increase in extreme weather and not let those who don't understand the science obfuscate it."

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Western Fuels Association

The Western Fuels Association is a not-for profit cooperative that supplies coal and transportation services to consumer-owned electric utility in the Great Plains, Rocky Mountain and Southwest regions. It is based in Westminster, Colorado.

Controversy

The Western Fuels Association has played a controversial role in the debate over global warming. Their 2005 Annual report refers only to 'environmental and regulatory uncertainty', but they have been more outspoken in past annual reports. They have established groups such as the Greening Earth Society which promote various forms of climate change skepticism and have funded individual skeptics, such as Patrick Michaels, Craig D. Idso and Sherwood Idso. Groups established by industry bodies like the Western Fuels Association have been criticized as Astroturf organizations, since they appear superficially to be grassroots initiatives.

From http://en.wikipedia.org/

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The Weather Makers

The Weather Makers: The History and Future Impact of Climate Change (2005) is a book by Tim Flannery.

The book received critical acclaim, and won the major prize at the 2006 New South Wales Premier's Literary Awards.

Description

The book includes 36 short essays predicting the consequences of global warming. The book reviews evidence of historical climate change and attempts to compare this with the current era. The book argues that if atmospheric carbon dioxide levels continue to increase at current rates, the resulting climate change will cause mass species extinctions. The book also asserts that global temperatures have already risen enough to cause the annual monsoon rains in the Sahel region of Africa to diminish, causing droughts and desertification. This in turn, according to Flannery, has caused the conflict in the Darfur region through competition for disappearing resources. Further consequences, argued in the book, include increasing hurricane intensity, and decline in the health of coral reefs.

The final third of the book discusses proposed solutions. Flannery advocates individual action as well as international and governmental actions. He argues that a few industries such as the coal industry, currently responsible for 40% of the energy consumed in the U.S., remain opponents of needed action. The book retraces the evidence that the administration, motivated by coal-industry donations to the Republican party, undermines political action by omitting mention of climate change from government documents. The book cites evidence against the argument that conservation is bad for economies.

From http://en.wikipedia.org/

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WAIS Divide

The West Antarctic Ice Sheet (WAIS) Divide is a deep ice core drilling project run by the United States Antarctic Program (USAP) and funded by the National Science Foundation (NSF). The general purpose of the WAIS Divide project is to collect a deep ice core from the flow divide in central West Antarctica that can be used for scientific analysis and research. Specifically, scientists are looking to create the largest and most detailed record of greenhouse gases possible for the last 100,000 years, and also plan to look at the role climate change could have had on these amounts.

History

The WAIS Divide project began during the 2005/2006 field season when the first team of scientists established the seasonal field camp and began construction on the ice core handling and processing facility. During this first season, they also dug a few shallow ice cores to test out the site. Over the 2006/2007 season, work continued on the arch handing and processing facility, as well as set up for the eventual Deep Ice Sheet Coring (DISC) drill. Currently, the WAIS Divide project is in its 2007/2008 field season and work is being done to finish both the arch facility and the DISC Drill. Upon completion, scientists plan on beginning the deep drilling that is central to this project. Projected plans for future field seasons can be found at the following website: http://www.waisdivide.unh.edu/about/schedule.html

Why the WAIS Divide?

In order to the get the necessary types of ice core samples for successful research, scientists sought out an area of the Antarctic Continent that would be the most beneficial. The WAIS Divide was chosen specifically due to some of the characteristics that make the site ideal for the project. Scientists chose the site because of the relative smoothness of the bed topography, the fact that the internal layers of ice are flat and undisturbed, and that the annual layers, each about 1 cm thick, will be detectable to at least 40,000 years within the ice sheet. Also significant is the fact that at the WAIS Divide, there is minimal horizontal ice flow, which guarantees more accurate data due to the ability to pin-point the specific atmospheric conditions in the same location as the ice sheet. One last important fact about the WAIS Divide location is the significance that the gas-age to ice-age difference is about 200 years for the Holocene epoch, and about 300 to 500 years for the last glacial period.

Research

The research being done at the WAIS Divide involves climate, ice sheet history, and cryobiology. With the undisturbed and ideal nature of ice at the WAIS Divide, scientists are planning to come up with some of the best and most detailed research in greenhouse gases, hemispherical climate changes and how these interrelate. These results will in turn be used to take a broader look at global warming, one of the main issues that faces mankind. While significant ice core sampling and detailed related research has been done in Greenland, the WAIS Divide project marks the first Southern Hemisphere and Antarctic venture of this kind.

Focus: Climate

The main purpose and project of the WAIS Divide is to develop the most accurate and detailed record of greenhouse gases for the last 100,000 years. Another area where the WAIS Divide project is expected to excel (more so than the Greenland projects) is in the development of an excellent CO2 record, since the Antarctic ice has less dust than the Greenland ice. The ability to compare research and environmental conditions between the Northern and Southern Hemispheres and the study of greenhouse gases relative to each will allow for a more detailed analysis of global warming.

In addition to studying climate and related changes, the WAIS Divide project will be able to measure many other gases (greenhouse and non-greenhouse) and their isotopes with unprecedented precision and resolution.



Focus: Ice Sheet and Biology

In addition to climate research, scientists plan on looking at the ice sheet and seeing how it influences the environment around it: i.e. seeing how the ice sheet affects changes in sea level. Scientists also want to develop an ice sheet history/timeline that can give an idea of when it was formed and changes that the ice sheet has undergone. Along with this, cryobiologists plan on looking for and observing both signs of past life and current (if any) biological life that exists within the ice sheet.

From http://en.wikipedia.org/

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UK Youth Climate Coalition

The UK Youth Climate Coalition (UKYCC) is a youth organisation in the United Kingdom. The coalition consists of several other youth organisations, which includes the National Union of Students, the National Trust's You, Me & The Climate (YOMAC) and the UK Youth Parliament. The charity aims to encourage young people to take action on climate change. Internationally, the coalition is part of the Global Youth Climate Movement.

History

In June 2008, the United Kingdom ambassadors to the WWF's Voyage for the Future programme, Emma Biermann and Casper ter Kuile, returned from the Arctic to found the UK Youth Climate Coalition (UKYCC).

Campaigns

In December 2008, the coalition participated in the National Climate March organised by the Campaign against Climate Change, with a campaign called "Our time is now" to raise awareness amongst young people.

In 2008, the Coalition organised a youth delegation to the 2008 United Nations Climate Change Conference to advocate on behalf of young people. At the event, the delegation coordinated the 'Call Gordon' project, a viral telephone campaign asking Prime Minister Gordon Brown to pursue a tougher agreement on climate change at the talks. Similarly in December 2009, the organisation will send a second youth delegation to the 2009 United Nations Climate Change Conference along with other members of the Youth Climate Movement.

On the 9th-12th October 2009, the UK version of Power Shift will be held at the Institute of Education in London. The event is a summit that intends to develop the youth climate movement. The event is modelled on a similar event to one organised by the Australian Youth Climate Coalition and carries the same name as the Energy Action Coalition event in the USA.

From http://en.wikipedia.org/

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Twisted, The Distorted Mathematics of Greenhouse Denial

Twisted, The Distorted Mathematics of Greenhouse Denial is a 2007 book by Ian G. Enting, who is the Professorial Research Fellow in the ARC Centre of Excellence for Mathematics and Statistics of Complex Systems (MASCOS) based at the University of Melbourne.

The book analyses the arguments of greenhouse sceptics and the use and presentation of statistics. Enting contends there are contradictions in the various arguments of the climate change sceptics.

The author also presents calculations of the actual emission levels that would be required to stabilise CO2 concentrations. This is an update of calculations that he contributed to the pre-Kyoto IPCC report on Radiative Forcing of Climate.

From http://en.wikipedia.org/

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Tonne of oil equivalent

The tonne of oil equivalent (toe) is a unit of energy: the amount of energy released by burning one tonne of crude oil, approximately 42 GJ (as different crude oils have different calorific values, the exact value of the toe is defined by convention; unfortunately there are several slightly different definitions as discussed below).

The toe is sometimes used for large amounts of energy, as it can be more intuitive to visualise, say, the energy released by burning 1000 tonnes of oil than 42,000 billion joules (the SI unit of energy).

Multiples of the toe are used, in particular the megatoe (Mtoe, one million toe) and the gigatoe (Gtoe, one billion toe).

Definitions

The IEA/OECD define one toe to be equal to 41.868 GJ or 11.63 MWh. Some organisations use other definitions of toe, for example:

* 1 toe = 42 GJ
* 1 toe = 41.85 GJ
* 1 toe = 7.11, 7.33, or 7.4 barrel of oil equivalent (boe)
* 1 tonne petroleum equivalent (TPE), as used in renewable energy, 45.217 GJ.

Conversion factors

* 1 barrel of oil equivalent (boe) contains approximately 0.146 toe (i.e. there are approximately 6.841 boe in a toe).
* 1 t diesel = 1.01 toe
* 1 m3 diesel = 0.98 toe
* 1 t petrol = 1.05 toe
* 1 m3 petrol = 0.86 toe
* 1 t biodiesel = 0.86 toe
* 1 m3 biodiesel = 0.78 toe
* 1 t bioethanol = 0.64 toe
* 1m3 bioethanol = 0.51 toe
* 1 MWh = 0.22 toe (assumes 39% thermal to electrical conversion efficiency)
* 1 MWh = 0.086 toe
It is important to note that toe should be used carefully when converting electrical units - for instance, BP's 2007 report used a factor of 38% efficiency (the average efficiency of OECD thermal generating units in 2006), or roughly 16 GJ per toe, when converting kilowatt-hours to toe.

From http://en.wikipedia.org/

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Stratospheric sulfur aerosols (geoengineering)

The ability of stratospheric sulfur aerosols to create a global dimming effect has made them a possible candidate for use in geoengineering projects to limit the effect and impact of climate change due to rising levels of greenhouse gases. Delivery of precursor gases such as hydrogen sulfide (H2S) by artillery, aircraft and balloons has been proposed.

Tom Wigley calculated the impact of injecting sulfate particles, or aerosols, every one to four years into the stratosphere in amounts equal to those lofted by the volcanic eruption of Mount Pinatubo in 1991, but did not address the many technical and political challenges involved in potential geoengineering efforts. If found to be economically, environmentally and technologically viable, such injections could provide a "grace period" of up to 20 years before major cutbacks in greenhouse gas emissions would be required, he concludes.

Direct delivery of precursors is proposed by Paul Crutzen. This would typically be achieved using H2S or sulfur, delivered using artillery, aircraft (such as the high-flying F15-C) or balloons, which would be oxidized to produce SO2.

According to estimates by the Council on Foreign Relations, "one kilogram of well placed sulfur in the stratosphere would roughly offset the warming effect of several hundred thousand kilograms of carbon dioxide."

Aerosol formation

Primary aerosol formation, also known as homogeneous aerosol formation results when gaseous SO2 combines with water to form aqueous sulfuric acid (H2SO4). This acidic liquid solution is in the form of a vapor and condenses onto particles of solid matter, either meteoritic in origin or from dust carried from the surface to the stratosphere. Secondary or heterogeneous aerosol formation occurs when H2SO4 vapor condenses onto existing aerosol particles. Existing aerosol particles or droplets also run into each other, creating larger particles or droplets in a process known as coagulation. The larger the particles or droplets, the shorter their residence time in the stratosphere and the less effective they are at scattering visible sunlight.

Arguments for the technique

The arguments in favour of this approach are:

* Natural process - Stratospheric sulfur aerosols are created by existing atmospheric processes (especially volcanoes), the behaviour of which has been studied observationally. Other, more speculative geoengineering schemes do not have natural analogs (e.g. space sunshade).
* Speed of action - Solar radiation management works quickly, in contrast to carbon sequestration projects such as carbon dioxide air capture which would take longer to have an effect, as the latter relies on removing large amounts of carbon dioxide before they become effective; however, gaps in understanding of these processes exist (e.g. the effect on stratospheric climate and on rainfall patterns, and further research is needed.
* Technological feasibility - In contrast to other geoengineering schemes, such as space sunshade, the technology required is pre-existing: chemical manufacturing, artillery shells, fighter aircraft, weather balloons, etc.
* Cost - The low-tech nature of this approach has led commentators to suggest it will cost less than many other interventions. Costs cannot be derived in a wholly objective fashion, as pricing can only be roughly estimated at an early stage. However, an assessment reported in Newscientist suggests a relatively low cost.
* Efficacy - Most geoengineering schemes can only provide a limited intervention in the climate - one cannot reduce the temperature by more than a certain amount with each technique. New research by Lenton and Vaughan suggests that this technique may have a high radiative 'forcing potential'.

Efficacy problems

All geoengineering schemes have potential efficacy problems, due to the difficulty of modelling their impact and the inherently complex nature of the global climate system. Nevertheless, certain efficacy issues are specific to the use of this particular technique.

* Lifespan of aerosols - Tropospheric sulfur aerosols are short lived. Delivery of particles into the lower stratosphere will typically ensure that they remain aloft only for a few weeks or months. To ensure endurance, high-level delivery is needed, ensuring a typical endurance of several years. Further, sizing of particles is crucial to their endurance.

* Aerosol delivery - Even discounting the challenges of lifting, there are still significant challenges in designing a delivery system that is capable of delivering the precursor gases in the right manner to encourage effective aerosol formation. For example, it is unclear whether aerial shells should be designed to leak slowly or burst suddenly. The size of aerosol particles is also crucial, and efforts must be made to ensure optimal delivery.

* Distribution - It is logistically difficult to deliver aerosols evenly around the globe. Challenges therefore exist in creating a network of delivery points sufficient to allow viable geoengineering from a limited number of launching sites.

Side effects

Geoengineering in general is a controversial technique, and carries problems and risks, such as weaponisation. However, certain problems are specific to, or more pronounced with this particular technique.

* Drought, particularly monsoon failure in Asia and Africa is a major risk.
* Ozone depletion is a potential side effect of sulfur aerosols; however, the effect has been well studied by the Nobel laureate Paul Crutzen.

* Whitening of the sky: Aerosols will noticeably affect the appearance of the sky, resulting a potential whitening effect, and altered sunsets.
* Tropopause warming and the humidification of the stratosphere.
* Effect on clouds: Cloud formation may be affected, notably cirrus clouds and polar stratospheric clouds.
* Effect on ecosystems: The diffusion of sunlight may affect plant growth.
* Effect on solar energy: Incident sunlight will be lower, which may affect solar power systems both directly and disproportionately, especially in the case that such systems rely on direct radiation.
* Deposition effects: Although predicted to be insignificant, there is nevertheless a risk of direct environmental damage from falling particles.
* Uneven effects: Aerosols are reflective, making them more effective during the day. Greenhouse gases block outbound radiation 24hrs a day.

Further, the delivery methods may cause significant problems, notably climate change and possible ozone depletion in the case of aircraft, and litter in the case of untethered balloons.

Delivery methods

Various techniques have been proposed for delivering the aerosol precursor gases (H2S and SO2). The required altitude to enter the stratosphere is the height of the tropopause, which varies from 11 km (6.8 miles/36,080 feet) at the poles to 17 km (11 miles/58,080 feet) at the equator.

* Aircraft such as the F15-C variant of the F-15 Eagle have the necessary ceiling, but limited payload. Existing transport aircraft and bombers are not able to reach the necessary altitude.
* Modified Artillery might have the necessary capability, but unfortunately requires a polluting and expensive cordite charge to loft the payload.
* High-altitude balloons can be used to lift precursor gases, in tanks, bladders or in the balloons' envelope. Balloons can also be used to lift pipes and hoses, but no moored balloon has ever been deployed to the necessary altitude.

From http://en.wikipedia.org/

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Stratospheric sulfur aerosols

Stratospheric sulfur aerosols are tiny sulfur-rich particles of solid or liquid, or a mixture of the two, which exist in the stratosphere region of the Earth's atmosphere. When present, after a strong volcanic eruption such as Mount Pinatubo, they produce a cooling effect for a few years before the particles fall out, by reflecting sunlight, and by modifying clouds as they fall out of the stratosphere.

An aerosol is a suspension of fine solid particles or liquid droplets in a gas. The sulfate particles in the atmosphere are about 0.1 to 1.0 micrometer (a millionth of a meter) in diameter.

Sulfur aerosols are common in the troposphere as a result of pollution with sulfur dioxide from burning coal, and from natural processes. Volcanos are the major source of particles in the stratosphere as the force of the volcanic eruption propels sulfur-containing gases into the stratosphere.

Creating stratospheric sulfur aerosols deliberately is a proposed geoengineering technique which offers a possible solution to some of the problems caused by global warming. However, this will not be without side effects and it has been suggested that the cure may be worse than the disease.

Origins



Natural sulfur aerosols are formed in vast quantities from the SO2 ejected by volcanoes, which may be injected directly into the stratosphere during very large (Volcanic Explosivity Index (VEI) of 4 or greater) eruptions. A comprehensive analysis, dealing largely with tropospheric sulfates in the atmosphere, is provided by Bates et al.

The IPCC AR4 says explosive volcanic events are episodic, but the stratospheric aerosols resulting from them yield substantial transitory perturbations to the radiative energy balance of the planet, with both shortwave and longwave effects sensitive to the microphysical characteristics of the aerosols. There have been no explosive and climatically significant volcanic events since Mt. Pinatubo. Consequently, stratospheric aerosol concentrations are now at the lowest concentrations since the satellite era and global coverage began in about 1980.

During periods lacking volcanic activity (and thus direct injection of SO2 into the stratosphere), oxidation of COS (carbonyl sulfide) dominates the production of stratospheric sulfate aerosol.

Chemistry

The chemistry of stratospheric sulfur aerosols varies significantly according to their source. Volcanic emissions vary significantly in composition, and have complex chemistry due to the presence of ash particulates and a wide variety of other elements in the plume.

The chemical reactions affecting both the formation and elimination of sulfur aerosols are not fully understood. It is difficult to estimate accurately, for example, whether the presence of ash and water vapour is important for aerosol formation from volcanic products, and whether high or low atmospheric concentrations of precursor chemicals (such as SO2 and H2S) are optimal for aerosol formation. This uncertainty makes it difficult to determine a viable approach for geoengineering uses of sulfur aerosol formation.

Scientific study



Understanding of these aerosols comes in large part from the study of volcanic eruptions,notably Mount Pinatubo in the Philippines, which erupted in 1991 when scientific techniques were sufficiently far advanced to study the effects carefully.

The formation of the aerosols and their effects on the atmosphere can also be studied in the lab. Samples of actual particles can be recovered from the stratosphere using balloons or aircraft.

Computer models can be used to understand the behaviour of aerosol particles, and are particularly useful in modelling their effect on global climate.

Biological experiments in the lab, and field/ocean measurements can establish the formation mechanisms of biologically-derived volatile sulfurous gases.

Effects

Effect on climate

It has been established that emission of precursor gases for sulfur aerosols is the principle mechanism by which volcanoes cause episodic global cooling.

The Intergovernmental Panel on Climate Change AR4 regards stratospheric sulfate aerosols as having a low level of scientific understanding.

The aerosol particles form a whitish haze in the sky. This creates a global dimming effect, where less of the sun's radiation is able to reach the surface of the Earth. This leads to a global cooling effect. In essence, they act as the reverse of a greenhouse gas, which tends to allow visible light from the sun through, whilst blocking infra-red emitted from the Earth's surface and its atmosphere. The particles also radiate infra red energy directly, as they lose heat into space.

Effects on light transmission through the atmosphere



All aerosols both absorb and scatter solar and terrestrial radiation. This is quantified in the Single Scattering Albedo (SSA), the ratio of scattering alone to scattering plus absorption (extinction) of radiation by a particle. The SSA tends to unity if scattering dominates, with relatively little absorption, and decreases as absorption increases, becoming zero for infinite absorption. For example, sea-salt aerosol has an SSA of 1, as a sea-salt particle only scatters, whereas soot has an SSA of 0.23, showing that it is a major atmospheric aerosol absorber.

Aerosols, natural and anthropogenic, can affect the climate by changing the way radiation is transmitted through the atmosphere. Direct observations of the effects of aerosols are quite limited so any attempt to estimate their global effect necessarily involves the use of computer models. The Intergovernmental Panel on Climate Change, IPCC, says: While the radiative forcing due to greenhouse gases may be determined to a reasonably high degree of accuracy... the uncertainties relating to aerosol radiative forcings remain large, and rely to a large extent on the estimates from global modelling studies that are difficult to verify at the present time.However, they are mostly talking about tropospheric aerosol.

Effect on ozone

The aerosols have a role in the destruction of ozone due to surface chemistry effects.Destruction of ozone has in recent years created large holes in the ozone layer, initially over the Antarctic and then the Arctic. These holes in the ozone layer have the potential expand to cover inhabited and vegetative regions of the planet, leading to catastrophic environmental damage.

Ozone destruction occurs principally in polar regions, but the formation of ozone occurs principally in the tropics. Ozone is distributed around the planet by the Brewer-Dobson circulation. Therefore, the source and dispersal pattern of aerosols is critical in understanding their effect on the ozone layer.

Effect on sky appearance



Aerosols scatter light, which affects the appearance of the sky and of sunsets. Changing the concentration of aerosols in the atmosphere can dramatically affect the appearance of sunsets. A change in sky appearance during the year without a summer (attributed to the eruption of Tambora) was the inspiration for the paintings of J. M. W. Turner. Further volcanic eruptions and geoengineering projects involving sulfur aerosols are likely to affect the appearance of sunsets significantly, and to create a haze in the sky.

Effect on the biosphere

Aerosol particles are eventually deposited from the stratosphere onto land and ocean. Depending on the volume of particles descending, the effects may be significant to ecosystems, or may not be. Modelling of the quantities of aerosols used in likely geoengineering scenarios suggest that effects on terrestrial ecosystems from deposition is not likely to be significantly harmful.

Geoengineering

The ability of stratospheric sulfur aerosols to create this global dimming effect has made them a possible candidate for use in geoengineering projects to limit the effect and impact of climate change due to rising levels of greenhouse gases. Delivery of precursor gases such as H2S and SO2 by artillery, aircraft and balloons has been proposed.

Understanding of this proposed technique is partly based on the fact that it is the adaptation of an existing atmospheric process. The technique is therefore potentially better understood than are comparable (but purely speculative) geoengineering schemes. It is also partly based on the speed of action of any such solution deployed, in contrast to carbon sequestration projects such as carbon dioxide air capture which would take longer to work. However, gaps in understanding of these processes exist, for example the effect on stratospheric climate and on rainfall patterns, and further research is needed.

This technique has been studied more extensively than most other geoengineering techniques, and is suggested by commentators including Tom Wigley.

From http://en.wikipedia.org/

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Space sunshade

A space sunshade or sunshield can be described as analogous to a parasol that diverts or otherwise reduces some of a star's rays, preventing them from hitting a planet and thereby reducing its insolation, which results in less heating of the planet. This can be of particular interest towards mitigating global warming through solar radiation management. Such shades could also be used to produce space solar power, acting as solar power satellites.

Cloud of small spacecraft near L1

One proposed such sunshade for use towards that effect would be composed of 16 trillion small disks at an altitude of 1.5 million kilometers, otherwise known as the L1 Orbit. A sunshade that blocks 2% of the sunlight, reflecting it off into space, would be enough to halt global warming, giving us ample time to cut our emissions back on earth.



Such a sunshade would have a diameter of 1800 km; it would cost tens of trillions of dollars to get the disks into space. It has been proposed that this would be accomplished most easily with a large railgun or coilgun which fires a capsule containing a million 1-gram shades into space.

Even so, it would still take years to launch enough of the disks into orbit before they have any effect. Thus, if using this technology should become essential, enough time would be needed to implement it.

Roger Angel of the University of Arizona presented the idea for the Sunshade at the U.S. National Academy of Sciences in April, 2006 and won a NASA Institute for Advanced Concepts grant for further research in July, 2006. His team members working on the grant are David Miller of the Massachusetts Institute of Technology, Nick Woolf of UA's Steward Observatory, and NASA Ames Research Center Director S. Pete Worden.

Creating this sunshade in space was estimated to cost in excess of US$5 trillion, thus leading Professor Angel to conclude that "the sunshade is no substitute for developing renewable energy, the only permanent solution. A similar massive level of technological innovation and financial investment could ensure that. But if the planet gets into an abrupt climate crisis that can only be fixed by cooling, it would be good to be ready with some shading solutions that have been worked out."

From http://en.wikipedia.org/

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