Impacts & Responses

Climate Change Scenarios and Models

Climate scientists use models and scenario’s to predict how the climate is going to change and how the change will affect us. Models are ways of using mathematics and physics to describe how the climate operates. Scenarios are inputs to these models; they describe how humans may behave to affect the climate.

Scenarios [1][2]
In their 2001 report the International Panel on Climate Change (IPCC) developed a set of forty greenhouse gas emission scenarios. They included economic, environmental, global and regional considerations in estimating the quantities of CO2 that humans may produce over the next 100 years. They have used data from these scenarios in a set of six models for the predictions published in their reports "Climate Change 2001: The Scientific Basis". An updated "Summary for policy makers issued in February 2007 is based on a greater number of scenarios and models and these confirm the predictions of the 2001 report.

IPCC Scenario Labelling [2][3]

This diagram describes the IPCC numbering code used to label scenarios in graphs of predictions. "A" refers to models that focus more on economic considerations. "B" focuses on the environment. "1" looks at regional and "2" looks at global factors. For example A1 scenario's describe global scenario's in which economic considerations play the major role while B2 would describe regional scenario's focusing on environmental considerations.

The IPCC describes these scenarios as "storylines" : -

Example B2 . “ The B2 storyline and scenario family describe a world in which the emphasis is on local solutions to economic, social and environmental sustainability. It is a world with continuously increasing global population, at a rate lower than A2, intermediate levels of economic development, and less rapid and more diverse technological change than in the B1 and A1 storylines. While the scenario is also oriented towards environmental protection and social equity, it focuses on local and regional levels.” [2]

Models [4]
A model that took into account everything we understand about climate would be far too complex to run on a computer. The approach taken by IPCC is to use a set of models simplified in different ways and then to compare them [4]. The models have been developed through a world wide collaboration of scientists. The figure below gives some idea of how they were drawn together.

Some Predictions [5]

IPCC have applied the data from 40 scenarios to six models to predict climate behavious over the next 100 years. The figure below [1] is an example showing how seven scenarios might mitigate impacts on global temperature and sea rise. The 2007 report increases the likelihood of these predictions. [2] A key message from this figure and the scenario modelling of the IPCC is that multiple measures would be required to withstand or modify the possible impacts of global warming. There are no single solutions, no magic bullets.

» Read more here . . .

References & Links

1. “Summary for Policymakers” Climate Change 2001: Synthesis Report.
   Available: » http://www.grida.no/climate/ipcc_tar/vol4/english/pdf/spm.pdf [accessed 2007, Feb. 24]
   
   
2. "Summary for Policymakers" IPCC Climate Change 2007: The Physical Science Basis
   Available: » http://www.ipcc.ch/SPM2feb07.pdf [accessed 2007, March 14]
   
   
3. “9.1.2 New Types of Model Experiments since 1995” IPCC - Climate Change 2001: The Scientific Basis
   Available: » http://www.grida.no/climate/ipcc_tar/wg1/343.htm [accessed 2007, Feb. 24]
   
   
4. "Simulation of the Climate System and its Changes" IPCC - Climate Change 2001: The Scientific Basis
   Available: » http://www.grida.no/climate/ipcc_tar/wg1/021.htm [accessed 2007, March. 15]
   
   
5. “Human influences will continue to change atmospheric composition throughout the 21st century”
   IPCC Climate Change 2001: The Scientific Basis.
   Available: » http://www.grida.no/climate/ipcc_tar/wg1/008.htm [accessed 2007, Feb. 24]

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Some Robust findings on Climate Change and Impact

2001 IPCC Report [1] [2]

“A robust finding for climate change is defined as one that holds under a variety of approaches, methods, models, and assumptions and one that is expected to be relatively unaffected by uncertainties”

“Projected climate change will have beneficial and adverse effects on both environmental and socio-economic systems, but the larger the changes and the rate of change in climate, the more the adverse effects predominate.”

• “Global average surface temperature during 21st century rising at rates very likely without precedent during last 10,000 years”
• “Nearly all land areas very likely to warm more than the global average, with more hot days and heat waves and fewer cold days and cold waves”
• “Rise in sea level during 21st century that will continue for further centuries.”
• “Increase in globally averaged precipitation and more intense precipitation events very likely over many areas.”
• “Increased summer drying and associated risk of drought likely over most mid-latitude continental interiors.”
• “Some [ecosystems and species] will be irreversibly damaged or lost.”
• “In some mid- to high latitudes, plant productivity (trees and some agricultural crops) would increase with small increases in temperature.”
• “Plant productivity would decrease in most regions of the world for warming beyond a few °C.”
• “Many physical systems are vulnerable to climate change (e.g., the impact of coastal storm surges will be exacerbated by sea-level rise, and glaciers and permafrost will continue to retreat).”

Extreme Events
“While the incidence of extreme temperature events, floods, droughts, soil moisture deficits, fires and pest outbreaks is expected to increase in some regions, it is unclear whether there will be changes in the frequency and intensity of extreme weather events such as tropical storms, cyclones, and tornadoes. However, even if there is no increase in the frequency and intensity of extreme weather events there may be shifts in their geographic location to places less prepared and more vulnerable to such events.”

2007 IPCC report [3]

References & Links

1. “Table SPM-3: Robust findings and key uncertainties - Summary for Policymakers” IPCC Climate Change 2001: Synthesis Report.
   Available: » http://www.grida.no/climate/ipcc_tar/vol4/english/015.htm [accessed 2007, Feb. 24]
   
   
2. “Presentation of Robert T. Watson, Chair IPCC” Sixth Conference of Parties UNFCC November 13, 2000.
   Available: » http://www.grida.no/climate/ipcc_tar/vol4/english/015.htm [accessed 2007, Feb. 24]
   
   
3. "Summary for Policymakers" Climate Change 2007 IPCC Impacts, Adaptation and Vulnerability
   Available: » http://www.ipcc.ch : [accessed 2007, March. 24]
   

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Climate Impact Timing

The importance of this slide is that it indicates a time frame for the climate’s response to anthropogenic CO2 emissions. It shows how slowly the world recovers.

References & Links

1. “Antarctic IPCC Climate Change 2001: Synthesis Report - Summary for Policymakers”: Figure SPM-5:; pg 17
   Available: » http://www.ipcc.ch/pub/un/syreng/spm.pdf [accessed 2007, Feb. 24]

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Social and Environmental Impacts

Below is a cut down extract from "Impacts, Adaptation and Vulnerability-Summary for Policymakers" Climate Change 2007 [1].

The selected items have been referred to by IPCC as having "high" or "very high" confidence levels (with the exception of ocean acidity where confidence is unassigned)

• enlargement and increased numbers of glacial lakes
• increasing ground instability in permafrost regions, and rock avalanches in mountain regions
• changes in some Arctic and Antarctic ecosystems, including those in sea-ice biomes, and also predators high in the food chain
• increased run-off and earlier spring peak discharge in many glacier- and snow-fed rivers
• warming of lakes and rivers in many regions, with effects on thermal structure and water quality
• earlier timing of spring events, such as leaf-unfolding, bird migration and egg-laying [1.3];
• poleward and upward shifts in ranges in plant and animal species [1.3, 8.2, 14.2].
• a trend in many regions towards earlier ‘greening’ of vegetation in the spring linked to longer thermal growing seasons
• shifts in ranges and changes in algal, plankton and fish abundance in high-latitude ocean
• increases in algal and zooplankton abundance in high-latitude and high-altitude lakes
• range changes and earlier migrations of fish in rivers [1.3].
• oceans are becoming more acidic with an average decrease in pH of 0.1 units

Of the more than 29,000 observational data series, from 75 studies, that show significant change in many physical and biological systems, more than 89% are consistent with the direction of change expected as a response to warming (Figure SPM-1) [1.4].

Future Impacts
Where any of the statements below include the term "likely" this has been capitalised and set in bold. The term "likely" corresponds to a range of from 66% to 90% and "very likely" corresponds to a range of 90% to 99% probability in IPCC terminology.

Fresh water resources and their management

• By mid-century, annual average river runoff and water availability are projected to increase by 10-40% at high latitudes and in some wet tropical areas, and decrease by 10-30% over some dry regions at mid-latitudes and in the dry tropics, some of which are presently water stressed areas. In some places and in particular seasons, changes differ from these annual figures.
• Drought-affected areas will LIKELY increase in extent.
• Heavy precipitation events, which are VERY LIKELY to increase in frequency, will augment flood risk.
• Water supplies stored in glaciers and snow cover are projected to decline, reducing water availability in regions supplied by meltwater from major mountain ranges, where more than one-sixth of the world population currently lives.

Ecosystems

• The resilience of many ecosystems is LIKELY to be exceeded this century by an unprecedented combination of climate change, associated disturbances (e.g., flooding, drought, wildfire, insects, ocean acidification), and other global change drivers (e.g., land use change, pollution, overexploitation of resources).
• net carbon uptake by terrestrial ecosystems is LIKELY to peak before mid-century and then weaken or even reverse, thus amplifying climate change.
• Approximately 20-30% of plant and animal species assessed so far are LIKELY to be at increased risk of extinction if increases in global average temperature exceed 1.5-2.5oC.
• For increases in global average temperature exceeding 1.5-2.5°C and in concomitant atmospheric carbon dioxide concentrations, there are projected to be major changes in ecosystem structure and function, species’ ecological interactions, and species’ geographic ranges, with predominantly negative consequences for biodiversity, and ecosystem goods and services e.g., water and food supply.
• The progressive acidification of oceans due to increasing atmospheric carbon dioxide is expected to have negative impacts on marine shell forming organisms (e.g., corals) and their dependent species.

Food, fibre and forest products

• Crop productivity is projected to increase slightly at mid- to high latitudes for local mean temperature increases of up to 1-3°C depending on the crop, and then decrease beyond that in some regions.
• At lower latitudes, especially seasonally dry and tropical regions, crop productivity is projected to decrease for even small local temperature increases (1-2°C), which would increase risk of hunger.
• Globally, the potential for food production is projected to increase with increases in local average temperature over a range of 1-3°C, but above this it is projected to decrease.
• Increases in the frequency of droughts and floods are projected to affect local crop production negatively, especially in subsistence sectors at low latitudes.
• Adaptations such as altered cultivars and planting times allow low- and mid- to high-latitude cereal yields to be maintained at or above baseline yields for modest warming.
• Globally, commercial timber productivity rises modestly with climate change in the short- to medium term, with large regional variability around the global trend.
• Regional changes in the distribution and production of particular fish species are expected due to continued warming, with adverse effects projected for aquaculture and fisheries.

Coastal systems and low-lying areas

• Coasts are projected to be exposed to increasing risks, including coastal erosion, due to climate change and sea-level rise. The effect will be exacerbated by increasing human-induced pressures on coastal areas.
• Corals are vulnerable to thermal stress and have low adaptive capacity. Increases in sea surface temperature of about 1-3°C are projected to result in more frequent coral bleaching events and widespread mortality, unless there is thermal adaptation or acclimatisation by corals.
• Coastal wetlands including salt marshes and mangroves are projected to be negatively affected by sea-level rise especially where they are constrained on their landward side, or starved of sediment.
• Many millions more people are projected to be flooded every year due to sea-level rise by the 2080s. Those densely-populated and low-lying areas where adaptive capacity is relatively low, and which already face other challenges such as tropical storms or local coastal subsidence, are especially at risk. The numbers affected will be largest in the mega-deltas of Asia and Africa while small islands are especially vulnerable.
• Adaptation for coasts will be more challenging in developing countries than in developed countries, due to constraints on adaptive capacity.

Industry, settlement and society

• Costs and benefits of climate change for industry, settlement, and society will vary widely by location and scale. In the aggregate, however, net effects will tend to be more negative the larger the change in climate.
• The most vulnerable industries, settlements and societies are generally those in coastal and river flood plains, those whose economies are closely linked with climate-sensitive resources, and those in areas prone to extreme weather events, especially where rapid urbanisation is occurring.
• Poor communities can be especially vulnerable, in particular those concentrated in high-risk areas. They tend to have more limited adaptive capacities, and are more dependent on climate-sensitive resources such as local water and food supplies.
• Where extreme weather events become more intense and/or more frequent, the economic and social costs of those events will increase, and these increases will be substantial in the areas most directly affected. Climate change impacts spread from directly impacted areas and sectors to other areas and sectors through extensive and complex linkages.

Health
Projected climate change-related exposures are LIKELY to affect the health status of millions of people, particularly those with low adaptive capacity, through:

• increases in malnutrition and consequent disorders, with implications for child growth and development;
• increased deaths, disease and injury due to heat waves, floods, storms, fires and droughts;
• the increased burden of diarrhoeal disease;
• the increased frequency of cardio-respiratory diseases due to higher concentrations of ground level ozone related to climate change; and the altered spatial distribution of some infectious disease vectors.

Climate change is expected to have some mixed effects, such as the decrease or increase of the range and transmission potential of malaria in Africa. Studies in temperate areas have shown that climate change is projected to bring some benefits, such as fewer deaths from cold exposure. Overall it is expected that these benefits will be outweighed by the negative health effects of rising temperatures world-wide, especially in developing countries. The balance of positive and negative health impacts will vary from one location to another, and will alter over time as temperatures continue to rise. Critically important will be factors that directly shape the health of populations such as education, health care, public health prevention and infrastructure and economic development. "

In the figure below the IPCC describe the cyclic impact of climate change on socio-economic development paths and how mitigation or adaptation can affect the cycle. [2]. Yellow arrows show cycle of cause and effect. The blue arrow indicates the societal response [2].

References & Links

1. "Impacts, Adaptation and Vulnerability - Summary for Policymakers" Climate Change 2007:
   Available: » http://www.ipcc.ch/SPM13apr07.pdf [accessed 2007, March. 15]
   
   
2. “Summary for Policymakers” Climate Change 2001: Synthesis Report.
   Available: » http://www.grida.no/climate/ipcc_tar/vol4/english/pdf/spm.pdf [accessed 2007, Feb. 24]

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Adaptation

Meaning

“Climate adaptations, which can be autonomous or policy-driven, are adjustments in practices, processes, or structures to take account of changing climate conditions” [1]

Some examples

• Melting glaciers
  • as glaciers recede dams may be needed because glaciers supply water to many communities
  • populations may relocate
  • new sources of water may be accessed (rainwater, groundwater)
    
    
• Increase in malaria mosquitoes
  • improved housing
  • deveopment better and more widely available medical treatments: vaccines, medicines
  • improved pest control methods
    
    
• Crop failure through drought
  • development of salt resistant crops
  • improved irrigation methods
  • water trading
    
    
• Cities and islands threatened by rising sea & ocean levels
  • relocating populations
  • building sea walls
  • land reclamation

References & Links:

1. "Impacts, Adaptation and Vulnerability - Summary for Policymakers" Climate Change 2007:
   Available: » http://www.ipcc.ch/SPM13apr07.pdf [accessed 2007, March. 15]
   
   
2. “Overview of Impacts, Adaptation, and Vulnerability to Climate Change” IPCC Impacts, Adaptation and Vulnerability.
   Available: » http://www.grida.no/climate/ipcc_tar/wg2/pdf/wg2TARchap1.pdf [accessed 2007, Feb. 24]

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Mitigation

Meaning [1]

In the context of climate change "mitigation" is used to mean taking local actions to reduce the effect of anthropogenic activities on climate. It mainly refers to reducing the 30bn tonnes of atmospheric CO2 produced per year by human activity. For example: -

• Fossil fuel demand reduction
  • voluntary reduction in energy use
  • improved efficiency through innovative technology or management
  • alternative energy substitutes for fossil fuel
  • carbon credits
    i.e a cost placed on CO2 emissions from fossil fuel leading to greater efficiency of use
    
    
• Removal of anthropogenic CO2 after it has been produced
  • geo-sequestration of concentrated streams of CO2 produced by power stations and other industry processes
    
  • bio-sequestration using agriculture, environmental management or bio-reactors
    

The distinction between mitigation and geo-engineering is blurred. Some of the techniques of biosequestration carried out on a large enough scale could be regarded as geoengineering, for example ocean fertilisation for enhanced phytoplankton growth.

Bio-sequestration and geo-sequestration

"Source: Energy Information Administration."

geo-sequestration [2]
i.e the burial of CO2 waste extracted from power stations or other industries, burial locations include: -

• oil/gas wells
  • CO2 is currently pumped into oil wells to assist with oil recovery. Trials are now being conducted on sites where this process is used to determine the leakage rate of CO2 and assess their use for CO2 disposal.
• saline aquifers
  • Deep saline aquifers are believed to have enough capacity to store about 100 years CO2. As with oil wells trials are underway to establish leakage rates.
• unmined coal seams
  • Coal contains methane and experiments are being carried out to displace and recover the methane by injecting CO2 into uneconomic coal seams. This would allow the methane to be recovered for fuel while burying CO2. The trials are at an early stage. The potential for using coal seams as sites for disposal of significant quantities of CO2 is not yet known.
• deep ocean burial by direct injection [3]
  • This can be carried out by direct injection where the low temperature and high pressure of the deep ocean would cause the CO2 to physically combine with water and form an ice like clathrate structure. Such structures for CO2 are not known in nature although methane clathrates are found in ocean sediments. This approach is controversial with concerns expressed about the possible release of CO2 from the ocean floor due to geological activity or ocen warming.
    

bio-sequestration
i.e the absorption of atmospheric CO2 into soil, vegetation or ocean sediments including: -

• forests, land reclamation & improved agriculture
  • Tree plantations have significant potential in tropical countries for the recovery of degraded land while simultaneously burying carbon and producing fuel. An example is the process known as "Terra Preta" in which charcoal is used to improve soil quality. A widely expressed concern with the use of forestry for mitigation is that at an estimated US$5 per tonne of CO2 it is such a cheap option that it might discourage other measures that have their own importance. [4][5]
    
    
  • "The current tropical deforestation rate is 10 - 20 Mha per annum, resulting in a carbon release of 1.6 - 2.4 Gt C per annum to the atmosphere. Fossil fuel burning releases 5.5 Gt C per annum. About half of the anthropogenic carbon emissions stay in the atmosphere. A quarter is absorbed in the oceans and temperate forests, and another quarter is absorbed by an unknown terrestrial sink. Recent research results give good reasons to assume that tropical rain forests form the major part of this unknown sink. Theoretically, mature rain forests as well as mature temperate or boreal forests should not be carbon sinks, since about the same amount of carbon that is fixed in photosynthesis is released by microbial and plant and animal respiration in the balanced forest ecosystem. However, forests may form a temporal sink when they grow faster due to an increased atmospheric CO2 concentration. It is also possible that the global warming may cancel such a situation, for instance, because the CO2 release in respiration is also likely to increase in a warmer climate." [6]
    
    
• algae cultivation or bio-reactors
  • Algae can be grown for fuel, sequestration and/or fertiliser. Originally it was proposed to grow algae in cultivated ponds with tthe option to use fresh or brackish water, or as part of sewage treatment plants. However, there is a trade off between photosynthetic efficiency and stability of the algae species used. The more photosynthetically efficient species usually revert to the less efficient wild type over time. Algae can also be grown with much greater photosynthetic efficiency in reactors that provide controlled conditions and access to concentrated CO2 from the waste streams of power stations or other industrial sources. Pilot plants currently being assessed suggest annual yields per acre of 20,000 to 40,000 litres of biodiesel compared with about 1,500 litres for palm oil. [7][8]
    
    
• ocean fertilisation for increased phytoplankton
  • Traditionally research in this area has been towards improving fisheries but one side effect could be the absorption of CO2. this was first proposed by John Martin. The approach is to encourage natural sequestration by encouraging the growth of phytoplankton which may become a food source for fish or decay and produce sediment on the deep ocean floor. This might also be regarded as geo-engineering. Again the approach is controversial. One potential risk is the uncontrolled growth of toxic algal blooms leading to reduction in fishery stocks. [9] [10]

References & Links

1. IPCC Climate Change 2001: Mitigation.
   Available: » http://www.grida.no/climate/ipcc_tar/wg3/index.htm [accessed 2007, Feb. 24]
   
   
2. "What Is Geosequestration?" The Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC)
   Available: » http://www.co2crc.com.au/understandccs.html [accessed 2007, May. 1]
   
   
3. "Ocean Sequestration Research" Information from the U.S. Department of Energy - Office of Fossil Energy
   Available: » http://www.fossil.energy.gov/programs/sequestration/ocean/ [accessed 2007, May. 1]
   
   
4. [Reply to George Monbiot] Policy Debate on Global Biofuels Development: Partners for Africa newsletter, June 2005
   Available: » http://www.partners4africa.org/goto.php/library.htm [accessed 2007, May. 1]
   
   
5. "Amazonian Dark Earths and the global climate" Terra Preta de Indio Soil Biogeochemistry Johannes Lehmann
   Available: » http://www.css.cornell.edu/faculty/lehmann/terra_preta/TerraPretahome.htm [accessed 2007, May. 1]
   
   
6. J.Koskela P.Nygren F.Berninger O.Luukkanen, "Implications of the Kyoto Protocol for tropical forest management and land use: prospects and pitfalls" University of Helsinki, Department of Forest Ecology, (2000),
   Available: » http://www.mm.helsinki.fi/mmeko/vitri/research/publications/kyoto.htm [accessed 2007, May. 1]
   
   
7. "A Look Back at the U.S. Department of Energy's Aquatic Species Program: Biodiesel from Algae Close-Out Report", J. Sheehan, Terri Dunahay, J. Benemann, and P. Roessler (July 1998)
   Available: » http://www.nrel.gov/docs/legosti/fy98/24190.pdf [accessed 2007, May. 1]
   
   
8. "Technology [algae bio-reactor]" Greenfuels technology Coporation
   Available: » http://www.greenfuelonline.com/technology.htm [accessed 2007, May. 1]
   
   
9. Martin, J. H. and Fitzwater, S. E. (1988) Iron-deficiency limits phytoplankton growth in the Northeast Pacific Subarctic. Nature 331, 341-343 » [home page]
   Available: » http://www.nature.com/nature/journal/v331/n6154/abs/331341a0.html [accessed 2007, May.1]
   
   
10. "More [ocean technology] Greenhouse Gas Mitigation References" Reports, Ocean Technology Group, University of Sydney
    Available: » http://www.otg.usyd.edu.au/ [accessed 2007, Feb. 24]

Geo-engineering

Geo-engineering involves actively manipulating climate to offset the effects of increased greenhouse gases in the atmosphere.

Some Examples

Obstructing incoming solar flux

Solar Mirrors
Professor Roger Angel, describes the use of earth based linear accelerators to throw reflective mirrors into an orbit 1.5 million km from the earth at a neutral gravity point "L1" between the earth and the sun to reduce sunlight by 2%. The mirrors would be 100 microns thick, with an onboard computer, camera and solar sails to assist their orientation. They would cover an area 100,000 km in diamtere. The cost is $4 trillion dollars, there are many technical issues to be resolved e.g construction of the mirrors, resilience of the mirror computer to radiation, the solar sail mechanism, calculation of an appropriate level of attenuation for the light flux. The process appears to be irreversible. [8]

Reflective Aerosols
Professor Paul Crutzen, renowned for his work on ozone layer depletion, has written a paper describing the use of reflective sulphur dioxide aerosols in the upper atmosphere. Professor Crutzen was inspired by the effects of volcanos and pollution both of which may cause the screening of sunlight by sulphur aerosols. Some of the associated hazards include acid rain, ozone depletion and the difficulty of reversing the effect. [2]

Manipulating the global carbon cycle

John Martin in America originally proposed increasing CO2 uptake by fertilising marine plankton. This approach is being investigated by: Professor Ian Jones in Australia using urea, and several groups in America using iron, as a "fertiliser" for plankton. (see "Bio-sequestration" above and references [3][4] below)

Direct absorption of CO2 from the atmosphere [5][6]

Professor Klaus Lackner has suggested setting up structures that support plates over which sodium hydroxide flows absorbing CO2 in the process.

1. the plates would have a collection area of 50x60m absorb CO2 in sodium hydroxide solution to produce sodium carbonate
2. 90,000 tonnes CO2 would be absorbed by one unit per year i.e 250,000 needed to absorb annual anthropogenic CO2
3. To recycle the sodium hydroxide the sodium carbonate could be treated with solid calcium hydroxide to produce calcium carbonate
4. calcium carbonate could then be heated to 900C to produce a concentrated stream of CO2
   [or perhaps the calcium carbonate could be used industrially or buried
5. 40 per cent of the energy in a fuel such as gasoline would be required to clean the fuel

Geo-engineering is controversial

Many of the ideas seem impossibly expensive or hazardous. Other seem intriguing possibilities. The IPCC was negative in its 2001 report saying “Such approaches generally are likely to be ineffective, expensive to sustain and/or to have serious environmental and other effects that are in many cases poorly understood.”[1].

Nevertheless there are many respected proponents of geo-engineering approaches, although in general along with the inventors of the ideas above, they see such methods as a last resort.

Sir Richard Branson (Virgin Group of Companies) and Al Gore have announced a competition for ways of reducing atmospheric CO2. "The Virgin Earth Challenge is a prize of $25m for whoever can demonstrate to the judges' satisfaction a commercially viable design which results in the removal of anthropogenic, atmospheric greenhouse gases so as to contribute materially to the stability of Earth’s climate." The scale of impact being sought is 1bn tonnes per year. Although not specifically advocating a geo-engineering approach, the competition will encourage such options to be considered. [7]

References & Links

1. “Options to Reduce Emissions and Enhance Sinks of Greenhouse Gases” IPCC Summary for Policymakers:Scientific-Technical Analyses of Impacts, Adaptations and Mitigation
   Available PDF: » http://www.ipcc.ch/pub/sarsum2.htm#four [accessed 2007, March. 15]
   
   
2. P.Crutzen1 "Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma?" Journal Climatic Change, Vol 77, 3-4 (Aug, 2006)
   
   
3. "The Global Impact of Ocean Nourishment" Ian S F Jones Lamont Doherty Earth Observatory Columbia University, NY
   Available PDF: » http://www.netl.doe.gov/publications/proceedings/01/carbon/_seq/6b2.pdf [accessed 2007, Feb. 24]
   
   
4. Martin, J. H. and Fitzwater, S. E. (1988) Iron-deficiency limits phytoplankton growth in the Northeast Pacific Subarctic. Nature 331, 341-343 [home page]
   Available PDF: » http://www.nature.com/nature/journal/v331/n6154/abs/331341a0.html [accessed 2007, May.1]
   
   
5. "Saving the forest by the trees" Columbia University Science News
   Available PDF: » http://www.columbia.edu/cu/alumni/Magazine/Spring2006/trees.html [accessed 2007, May.1]
   
   
6. "Climate - Soaking up CO2" Discover Magazine (2005 Oct' 24)
   Available PDF: » http://discovermagazine.com/2005/oct/climate/ [accessed 2007, March. 15]
   
   
7. "The Virgin Earth Challenge"
   Available PDF: » http://www.virginearth.com/ [accessed 2007, March. 15]
   
   
8. "Five Ways to Save the World" BBC
   Available PDF: » http://news.bbc.co.uk/2/hi/programmes/6298507.stm [accessed 2007, March. 15]
   
   

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