posted 09-02-2003 09:54 PM            

Reference
Keith, D. W. 1999. Geoengineering. In Encyclopedia of Global Change. New York: Oxford University Press, forthcoming.

Abstract
Geoengineering is the intentional large-scale manipulation of the global environment. The term has usually been applied to proposals to manipulate the climate with the primary intention of reducing undesired climatic change caused by human influences. These geoengineering schemes seek to mitigate the effect of fossil-fuel combustion on the climate without abating fossil fuel use; for example, by placing shields in space to reduce the sunlight incident on the Earth. Possible responses to the problem of anthropogenic climate change fall into three broad categories: abatement of human impacts by reducing the climate forcings, adaptation to reduce the impact of altered climate on human systems, and deliberate intervention in the climate system to counter the human impact on climate— geoengineering. It is central to the common meaning of geoengineering that the environmental manipulation be deliberate, and be a primary goal rather than a side-effect. This distinction is at the heart of the substantial moral and legal concerns about geoengineering. For example, while it may be argued that modern agriculture constitutes geoengineering, the global-scale transformations of the nitrogen cycle it causes is a side-effect of food production, and is usually viewed differently from the deliberate modification of the global environment.
http://hdgc.epp.cmu.edu/publications/abstracts/geoengineering.htm

JCM is based on scientific formulae from IPCC-TAR, and can replicate key TAR predictions. It is also evolving further to investigate new research questions.

Yet JCM is also very easy to use. Drag the arrows (policy options or scientific uncertainties), and see the effect instantly.

In JCM everything is connected, from emissions to impacts (or sometimes, the other way). Try the "flowchart" and click on plots or modules to find the interactions.

Emissions, Scenarios, Stabilisation, Distribution
Climate Processes, Timescales, Uncertainties
Climate Impacts and Adaptation

Developed by Dr Ben Matthews with UCL Louvain-la-neuve, KUP Bern , DEA Copenhagen , UNEP/GRID Arendal ,
http://www.chooseclimate.org/jcm/index.html

A critical review of global-scale technical fixes for climate change
2.2.2 Sulphate aerosols or Dust in the stratosphere.
Aerosols or dust in the stratosphere survive much longer than in the troposphere, and are already known to cool the planet, as observed following large volcanic eruptions. In the early 1990s, dust from mount Pinatubo checked global warming, and the observed cooling effect matched well with the most recent model predictions.

It has been suggested that we could deliberately inject either sulphate aerosols or dust into the stratosphere. For a recent review refer to Dickinson (1996).The idea is first credited to the Soviet scientist Budyko (1974) and developed by many others since, mainly in the US, even reaching a US government report (National Academy of Sciences 1992). Originally rockets or rifle shells would have carried the dust, but Penner (1984) suggested that it could be done more easily by a slight modification of commercial jet fuel, and this would be very cheap. In a policy statement to an International Energy Workshop in San Diego in 1992, he presented the dust idea as a "Low-cost no regrets" option for mitigating greenhouse warming, showing that it would cost just 0.1 cents (using coal dust) to cool the planet to compensate for one tonne of Carbon as CO2 in the atmosphere, or 1 cent if SiH4 was used to make inert SiO2 dust (Penner 1993). However, he first attempts to rubbish the whole global warming scenario, and clearly doesn't intend that we carry this out unless, by some strange chance, all those scientists in IPCC happen to be right and we really do find we have a problem. Then, "for intolerable warming, low-cost planetary albedo augmentation may become the method of choice some decades in the future".

Besides being cheap, the aerosol fix is also promoted as "reversible", i.e. you can easily stop if it doesn't work, and within a few years the dust would fall out. On the other hand, most greenhouse gases have a much longer lifetime so if they are to be offset with stratospheric aerosols, we would have to rely on the ability of future generations to keep flying those planes, to keep repairing the shield or be faced with sudden warming.

Even if we are content to pass on that burden, we would also be cutting the amount of sunlight reaching plants on the surface, and presumably also changing its spectral composition. Perhaps the plants would take up less CO2? And do we really want to live under a constant haze in the sky to keep us cool? Do a few scientists and policymakers have the right to impose this on all other life on the planet?

Another obvious objection is that the injected particles might provide a very efficient surface for ozone destruction, as polar stratospheric clouds already do every spring. It seems the engineers have not yet looked at this in any detail.

2.5 Soaking up ozone-destroying chemicals, by adding more.

This proposal is not directly concerned with global warming, more with damage from the increased UV flux passing through holes in the ozone layer. On the other hand, stratospheric ozone destruction is intimately linked to climate change, both because ozone is a greenhouse gas, and because surface warming results in stratospheric cooling and therefore more polar stratospheric clouds which provide the surface for ozone-destroying chemistry.

The destruction of ozone is catalysed by free radicals of chlorine or nitrogen oxides, derived mainly from CFCs or aircraft exhaust respectively The suggestion was (see Baum 1994), to add ethane or propane to the stratosphere to soak up the chlorine radicals, forming hydrochloric acid. About 50,000 tonnes would be needed in the Antarctic stratosphere each spring. However, to predict exactly what will happen, you have to solve simultaneously about 150 equations describing chemical reactions. Some simplifications have to be made, yet it isn't intuitive, which reactions will matter. Ralph Cicerone, who came up with this idea, found later that introducing a couple of new reactions, previously thought unimportant, changed the balance substantially. Now he is not so enthusiastic about the proposal. Perhaps we should be relieved!

It is now increasingly difficult to get a job in physics without working for the military, in plant biology without working for agribusiness giants, in chemistry without working for the chemical industry, or in medical research, without working for drug companies. Myself, I joined global change research, not because it was lucrative, but because I was inspired by the mysteries of the oceans, atmosphere, and how life controls our climate, and concerned that the balance of these systems was in grave danger from our pollution.<
>>Most climate engineering schemes are less dramatic, and are often considered "reversible". But while it is true, that we could stop the initial action - e.g. putting iron into the southern ocean or dust into the stratosphere -, it is by no means certain that the response would cease too. The possibility of a runaway iron fertilisation has already been mentioned. Whether the proposed mechanism is correct or not, we do know that there must be positive feedbacks associated with cooling, since the ice ages began and ended very suddenly. >>
http://www.chooseclimate.org/

GEOPHYSICAL RESEARCH LETTERS, VOL. 27, NO. 14, doi:10.1029/1999GL006086, 2000

Geoengineering Earth’s radiation balance to mitigate CO2-induced climate change
Bala Govindasamy
Climate and Carbon Cycle Group, Lawrence Livermore National Laboratory, Livermore, California

Ken Caldeira
Climate and Carbon Cycle Group, Lawrence Livermore National Laboratory, Livermore, California

Abstract

To counteract anthropogenic climate change, several schemes have been proposed to diminish solar radiation incident on Earth’s surface. These geoengineering schemes could reverse global annual mean warming; however, it is unclear to what extent they would mitigate regional and seasonal climate change, because radiative forcing from greenhouse gases such as CO2 differs from that of sunlight. No previous study has directly addressed this issue. In the NCAR CCM3 atmospheric general circulation model, we reduced the solar luminosity to balance the increased radiative forcing from doubling atmospheric CO2. Our results indicate that geoengineering schemes could markedly diminish regional and seasonal climate change from increased atmospheric CO2, despite differences in radiative forcing patterns. Nevertheless, geoengineering schemes could prove environmentally risky.

Index Terms: 1600 Global Change; 1620 Global Change: Climate dynamics (3309); 3319 Meteorology and Atmospheric Dynamics: General circulation; 6620 Public Issues: Science policy.
http://www.agu.org/pubs/crossref/2000/1999GL006086.shtml

Climate Modification Schemes

Military agencies in the U.S. (and presumably in the Soviet Union) supported research not only on cloud seeding but on other ways that weather might be altered by injecting materials into the atmosphere. Although much of this was buried in secrecy, the public learned that some sort of climatological warfare might become possible. In a 1955 Fortune magazine article, von Neumann himself explained that "Microscopic layers of colored matter spread on an icy surface, or in the atmosphere above one, could inhibit the reflection-radiation process, melt the ice, and change the local climate." The effects could be far-reaching, even world-wide. "What power over our environment, over all nature, is implied!" he exclaimed. He foresaw "forms of climatic warfare as yet unimagined," perhaps more dangerous than nuclear war itself. He hoped it would force humanity to take a new, global approach to its political problems>>snip

>>snip

Already back in 1965, a Presidential advisory panel had suggested that if greenhouse effect warming by carbon dioxide gas ever became a problem, the government might take countervailing steps. The panel did not consider curbing the use of fossil fuels. They had in mind geoengineering schemes — spreading something across the ocean waters to reflect more sunlight, perhaps, or sowing particles high in the atmosphere to encourage the formation of reflective clouds. Some back-of-the-envelope arithmetic indicated such steps were feasible, and indeed could cost less than many government programs.(13) In 1974, Budyko calculated that if global warming ever became a serious threat, we could counter it with just a few airplane flights a day in the stratosphere, burning sulfur to make aerosols that would reflect sunlight away

http://www.aip.org/history/climate/RainMake.htm

posted 09-02-2003 11:49 PM            

NOW we're cooking with gas.

posted 09-03-2003 07:15 AM            

NASA/Goddard Space Flight Center
Date:
2003-05-14

NASA Finds Soot Has Impact On Global Climate
A team of researchers, led by NASA and Columbia University scientists, found airborne, microscopic, black-carbon (soot) particles are even more plentiful around the world, and contribute more to climate change, than was previously assumed by the Intergovernmental Panel of Climate Change (IPCC).

The researchers concluded if these soot particles are not reduced, at least as rapidly as light-colored pollutants, the world could warm more quickly.

The findings appear in the latest issue of the Proceedings of the National Academy of Sciences. It is authored by Makiko Sato, James Hansen and others from NASA's Goddard Institute for Space Studies (GISS) and Columbia University, New York; Oleg Dubovik, Brent Holben and Mian Chin of NASA's Goddard Space Flight Center, Greenbelt, Md.; and Tica Novakov, Lawrence Berkeley National Laboratory, Berkeley, CA.

Sato, Hansen and colleagues used global atmospheric measurements taken by the Aerosol Robotic Network (AERONET). AERONET is a global network of more than 100 sun photometers that measure the amount of sunlight absorbed by aerosols (fine particles in the air) at wavelengths from ultraviolet to infrared. The scientists compared the AERONET data with Chin's global-aerosol computer model and GISS climate model, both of which included sources of soot aerosols consistent with the estimates of the IPCC.

The researchers found the amount of sunlight absorbed by soot was two-to-four times larger than previously assumed. This larger absorption is due in part to the way the tiny carbon particles are incorporated inside other larger particles: absorption is increased by light rays bouncing around inside the larger particle.

According to the researchers, the larger absorption is attributable also to previous underestimates of the amount of soot in the atmosphere. The net result is soot contributes about twice as much to warming the world as had been estimated by the IPCC.

Black carbon or soot is generated from traffic, industrial pollution, outdoor fires and household burning of coal and biomass fuels. Soot is a product of incomplete combustion, especially of diesel fuels, biofuels, coal and outdoor biomass burning. Emissions are large in areas where cooking and heating are done with wood, field residue, cow dung and coal, at a low temperature that does not allow for complete combustion. The resulting soot particles absorb sunlight, just as dark pavement becomes hotter than light pavement.

Both soot and the light-colored tiny particles, most of which are sulfates, pose problems for air quality around the world. Efforts are beginning to reduce the sulfate aerosols to address air quality issues.

"There is a pitfall, however, in reducing sulfate emissions without simultaneously reducing black carbon emissions," Hansen said. Since soot is black, it absorbs heat and causes warming. Sulfate aerosols are white, reflect sunlight, and cause cooling. At present, the warming and cooling effects of the dark and light particles partially balance.

This research continues observations of global climate change. It was funded by NASA's Earth Science Enterprise. The Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather, and natural hazards using the unique vantage point of space.

For more information and images on the Internet, visit:
http://www.gsfc.nasa.gov/topstory/2003/0509pollution.html

For information the about the AERONET program on the Internet, visit:
http://aeronet.gsfc.nasa.gov/

For information about NASA and Earth Science initiatives on the Internet, visit:
http://www.nasa.gov
http://www.sciencedaily.com/releases/2003/05/030514081323.htm

Penn State
Date:
2002-08-08

Jet Contrails Alter Average Daily Temperature Range
For three days after September 11, the Federal Aviation Administration grounded commercial aircraft in the U.S., stranding travelers, hindering mail delivery and interrupting courier service, but for scientists at Penn State and the University of Wisconsin–Whitewater, the three-day shutdown provided a rare glimpse of the climate effects of jet contrails.

"In the past, some studies have compared the climate of areas with little overhead air traffic with those under heavily used flight paths," says Dr. Andrew M. Carleton, professor of geography. "Other studies looked at cloud cover before the advent of heavy jet traffic in the 1960s and afterwards, but these studies really provide circumstantial evidence."

Carleton, and Dr. David Travis, climatologist at University of Wisconsin-Whitewater and Ryan Lauritsen, then an undergraduate at UW-W, looked at high and low temperatures recorded throughout the country during the three days of commercial air shutdown and at satellite photos taken during that time. The satellite photos show where contrails were occurring, mostly absent over the U.S. between Sept 11-14, but still occurring in Canada and northern Mexico.

"We show that there was an anomalous increase in the average diurnal temperature range for the period Sept. 11-14, 2001," the researchers reported in today's (Aug. 8) issue of the journal Nature. "Because persisting contrails can reduce the transfer of both incoming solar and outgoing infrared radiation and so reduce the daily temperature range, we attribute at least a portion of this anomaly to the absence of contrails."

The diurnal temperature range is the difference between the nighttime low temperature and the daytime high temperature, usually for a given day.

"Because the shutdown occurred before noon on Sept. 11, the low temperature had already been reached, so we looked at 24-hour periods beginning with the high on Sept. 11 to the low on Sept. 14," said Carleton.

The change in the temperature difference was plus 1.1 degree Celsius, equal to plus 2 degrees Fahrenheit, above the 30-year long-term mean diurnal temperature range. The researchers compared the temperature ranges on these three days to those of the three days directly before Sept. 11 and the three days after Sept. 14, finding that the days before and after were similar, but that the three days in question differed by 1.8 degrees Celsius or 3.2 degrees Fahrenheit.

"Sept. 11-14, 2001, had the biggest diurnal temperature range of any three-day period in the past 30 years," said Carleton. Contrails form when water vapor and particles from jet engine exhaust enter the atmosphere. If the atmospheric temperature is cool enough, and the humidity high enough, the exhaust forms ice crystals that create the contrail. Contrails generally last one to two hours, but can last as long as six.

All jet exhausts do not create contrails. In warmer areas, contrails are rare, while in temperate areas, especially in the Midwest and Great Plains, contrails are common, especially in the winter and spring. Sometimes, the added moisture of a series of jets will increase the atmospheric humidity enough so that subsequent aircraft will form contrails even though earlier ones did not.

"The fact that the three jetless days were in the late summer should suggest that there was less of an effect than would have occurred during a cooler time of the year when more contrails occur," said Carleton.

Contrails alter temperature the same way that natural high clouds do. During the day, the layer of ice crystals shields the ground from some of the sun's energy. At night, the layer of ice crystals prevents some of Earth's heat from dissipating into the vacuum. Without the contrails, the daytime temperature would be slightly higher and the nighttime temperature would be slightly lower, creating the increased range between lowest and highest temperatures.

The researchers note that the greater range reported was an average and that some areas had an even larger range increase. They also investigated whether those three days were unusually dry, which would account for an absence of natural cloud cover and a greater temperature range.

"Satellite images showed that cloud cover on Sept. 11 was light, but that cloud cover and humidity increased on the 12th, 13th and 14th," says Carleton. "These clouds and greater humidity should have suppressed the range, but the temperature range was still the largest in 30 years."

Carleton and Travis are collaborating on a general study of contrails and climate change funded by the National Science Foundation that also funded this work.
http://www.sciencedaily.com/releases/2002/08/020808075457.htm

American Geophysical Union
Date:
1999-06-24

Jet Contrails To Be Significant Climate Factor By 2050
WASHINGTON -- By the year 2050, increased flights by jet airplanes will impact global climate through the greater number of contrails they will produce, according to a new study in the July 1 issue of the journal, Geophysical Research Letters. Contrails are ice clouds created by jet engines and are short lived in dry air, but can persist for hours in moist air and become indistinguishable from natural cirrus clouds.

A research team of American and German scientists, headed by Patrick Minnis of the NASA Langley Research Center in Hampton, Virginia, reports that contrails cause a warming of the Earth's atmosphere, although their impact is currently small as compared to other greenhouse effects. They predict, however, that it may grow by a factor of six over the next 50 years. In 1992, for example, contrails added an estimated 0.02 watts of warming per square meter globally, about one percent of all manmade greenhouse effects.

Air traffic and, therefore, contrails, are not evenly distributed around the globe.They are concentrated over parts of the United States and Europe, where local warming reaches up to 0.7 watts per square meter, or 35 times the global average. The resulting temperature increase is not computed in this study, but is estimated to reach between 0.01 and 0.1 degrees Celsius (0.02 and 0.2 degrees Fahrenheit) over the northern temperate zones for current air traffic. In the future, increased air traffic will raise these values.

Large, linear contrails can be observed in satellite imagery. Although their total global coverage has not yet been determined, it is computed from traffic and weather data to amount to 0.1 percent. In the parts of Europe and eastern North America with the heaviest air traffic, however, contrails currently cover up to 3.8 percent and 5.5 percent of the sky, respectively.

Minnis and his colleagues report that global air traffic rose by over seven percent per year from 1994 to 1997, in terms of passenger miles flown. Growth is likely to continue, meaning contrails will play a larger role in future climates than they do today. Taking into account such factors as number of flights per day, fuel consumption, and altitudes flown, they conclude that by 2050, average contrail coverage over Europe will be four times higher than at present, or about 4.6 percent. In the United States, the increase will be 2.6 times current levels, or 3.7 percent coverage; and in Asia, the increase will be ten times current levels, or 1.2 percent.

posted 09-06-2003 12:55 AM            

.....Maybe they should have read the "earlier" research. It seems from the documents above someone already knew what "carbon black" could do.....

Indeed yes. And they also know what water vapor [warming], nitrogen oxide [destroys methane], methane [warming], sulfur dioxide [cooling], and sulfur hexafluoride [warming] can do. And, of course, atmospheric aerosols. They didn't study the net cooling effect of the Mt. Pinatubo eruption so intensively for nothing.

Gee whiz, just the right balance of emissions pollutants could cancel each other out in the cooling and warming departments, no?

But that would be unthinkable, wouldn't it?