GLOBAL WARMING
For past climate change, see paleoclimatology and geologic temperature record.
Global mean surface temperature difference from the average for 1961–1990
Comparison of ground based (blue) and satellite based (red: UAH; green: RSS) records of temperature variations since 1979. Trends plotted since January 1982.
Mean surface temperature change for the period 1999 to 2008 relative to the average temperatures from 1940 to 1980
Global warming is the increase in the average temperature of the Earth's near-surface air and oceans since the mid-20th century and its projected continuation. Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) between the start and the end of the 20th century.[1][A] The Intergovernmental Panel on Climate Change (IPCC) concludes that most of the observed temperature increase since the middle of the 20th century was caused by increasing concentrations of greenhouse gases resulting from human activity such as fossil fuel burning and deforestation.[1] The IPCC also concludes that variations in natural phenomena such as solar radiation and volcanoes produced most of the warming from pre-industrial times to 1950 and had a small cooling effect afterward.[2][3] These basic conclusions have been endorsed by more than 40 scientific societies and academies of science,[B] including all of the national academies of science of the major industrialized countries.
EFFECTS OF GLOBAL WARMING
The effects of global warming and climate change[2] are of concern both for the environment and human life. Evidence of observed climate change includes the instrumental temperature record, rising sea levels, and decreased snow cover in the Northern Hemisphere.[3] According to the IPCC Fourth Assessment Report, "[most] of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in [human greenhouse gas] concentrations". It is predicted that future climate changes will include further global warming (i.e., an upward trend in global mean temperature), sea level rise, and a probable increase in the frequency of some extreme weather events. Ecosystems are seen as being particularly vulnerable to climate change. Human systems are seen as being variable in their capacity to adapt to future climate change.[4] To reduce the risk of large changes in future climate, many countries have implemented policies designed to reduce their emissions of greenhouse gases.
MEASURES TO REDUCE THE EFFECTS OF GLOBAL WARMING
Scientific consensus on global warming, together with the precautionary principle and the fear of abrupt climate change[3] is leading to increased effort to develop new technologies and sciences and carefully manage others in an attempt to mitigate global warming. Unfortunately most means of mitigation appear effective only for preventing further warming, not at reversing existing warming.[4]
The Stern Review identifies several ways of mitigating climate change. These include reducing demand for emissions-intensive goods and services, increasing efficiency gains, increasing use and development of low-carbon technologies, and reducing non-fossil fuel emissions[5].
The energy policy of the European Union has set a target of limiting the global temperature rise to 2 °C [3.6 °F] compared to preindustrial levels, of which 0.8 °C has already taken place and another 0.5 °C is already committed. The 2 °C rise is typically associated in climate models with a carbon dioxide concentration of 400-500 ppm by volume; the current level as of January 2007 is 383 ppm by volume, and rising at 2 ppm annually. Hence, to avoid a very likely breach of the 2 °C target, CO2 levels would have to be stabilised very soon; this is generally regarded as unlikely, based on current programs in place to date.[6][7] The importance of change is illustrated by the fact that world economic energy efficiency is presently improving at only half the rate of world economic growth.[8]
At the core of most proposals is the reduction of greenhouse gas emissions through reducing energy use and switching to cleaner energy sources. Frequently discussed energy conservation methods include increasing the fuel efficiency of vehicles (often through hybrid, plug-in hybrid, and electric cars and improving conventional automobiles), individual-lifestyle changes and changing business practices. Newly developed technologies and currently available technologies including renewable energy (such as solar power, tidal and ocean energy, geothermal power, and wind power) and more controversially nuclear power and the use of carbon sinks, carbon credits, and taxation are aimed more precisely at countering continued greenhouse gas emissions. More radical proposals which may be grouped with mitigation include biosequestration of atmospheric carbon dioxide and geoengineering techniques ranging from carbon sequestration projects such as carbon dioxide air capture, to solar radiation management schemes such as the creation of stratospheric sulfur aerosols. The ever-increasing global population and the planned growth of national GDPs based on current technologies are counter-productive to most of these proposals.[9]
[edit] Quota on fossil fuel production
Most mitigation proposals imply - rather than directly state - an eventual reduction in global fossil fuel production. Also proposed are direct quotas on global fossil fuel production.[10][11]
[edit] Pacala and Socolow
Pacala and Socolow of Princeton [12] have proposed a program to reduce CO2 emissions by 1 billion metric tons per year − or 25 billion tons over the 50-year period. The proposed 15 different programs, any seven of which could achieve the goal, are:
1. more efficient vehicles − increase fuel economy from 30 to 60 mpg (7.8 to 3.9 L/100 km) for 2 billion vehicles,
2. reduce use of vehicles − improve urban design to reduce miles driven from 10,000 to 5,000 miles (16,000 to 8,000 km) per year for 2 billion vehicles,
3. efficient buildings − reduce energy consumption by 25%,
4. improve efficiency of coal plants from today's 40% to 60%,
5. replace 1,400 GW (gigawatt) of coal power plants with natural gas,
6. capture and store carbon emitted from 800 GW of new coal plants,
7. capture and reuse hydrogen created by #6 above,
8. capture and store carbon from coal to syn fuels conversion at 30 million barrels per day (4,800,000 m3/d),
9. displace 700 GW of coal power with nuclear,
10. add 2 million 1 MW wind turbines (50 times current capacity),
11. displace 700 GW of coal with 2,000 GW (peak) solar power (700 times current capacity),
12. produce hydrogen fuel from 4 million 1 MW wind turbines,
13. use biomass to make fuel to displace oil (100 times current capacity),
14. stop de-forestation and re-establish 300 million hectares of new tree plantations,
15. conservation tillage − apply to all crop land (10 times current usage).
Nature.com argued in June 2008 that "If we are to have confidence in our ability to stabilize carbon dioxide levels below 450 p.p.m. emissions must average less than 5 billion metric tons of carbon per year over the century. This means accelerating the deployment of the wedges so they begin to take effect in 2015 and are completely operational in much less time than originally modelled by Socolow and Pacala."[13]
Further information: Stabilization Wedge Game and Global warming game
[edit] Energy efficiency and conservation
Main articles: Energy efficiency and Energy conservation
Developing countries use their energy less efficiently than developed countries, getting less GDP for the same amount of energy.
The Energy Information Administration predicts world energy usage will rise in the next few decades.
Reducing fuel use by improvements in efficiency provides environmental benefits and as well as net cost savings to the energy user. Building insulation, fluorescent lighting, and public transportation are some of the most effective means of conserving energy, and by extension, the environment. However, Jevons paradox poses a challenge to the goal of reducing overall energy use (and thus environmental impact) by energy conservation methods. Improved efficiency lowers cost, which in turn increases demand. To ensure that increases in efficiency actually reduces energy use, a tax must be imposed to remove any cost savings from improved efficiency.
Energy conservation is the practice of increasing the efficiency of use of energy in order to achieve higher useful output for the same energy consumption. This may result in increase of national security, personal security, financial capital, human comfort and environmental value. Individuals and organizations that are direct consumers of energy may want to conserve energy in order to reduce energy costs and promote environmental values. Industrial and commercial users may want to increase efficiency and maximize profit.
On a larger scale, energy conservation is an element of energy policy. The need to increase the available supply of energy (for example, through the creation of new power plants, or by the importation of more energy) is lessened if societal demand for energy can be reduced, or if growth in demand can be slowed. This makes energy conservation an important part of the debate over climate change and the replacement of non-renewable resources with renewable energy. Encouraging energy conservation among consumers is often advocated as a cheaper or more environmentally sensitive alternative to increased energy production.
[edit] The energy landscape
Residential buildings, commercial buildings, and the transportation of people and freight use the majority of the energy consumed by the United States each year. Specifically, the industrial sector uses 38 percent of total energy, closely followed by the transportation sector at 28 percent, the residential sector at 19 percent, and the commercial sector at 16 percent. On a community level, transportation can account for 40 to 50 percent of total energy use, and residential buildings use another 20 to 30 percent.[14]
In developed nations, the way of life today is completely dependent on abundant supplies of energy. Energy is needed to heat, cool, and light homes, fuel cars, and power offices. Energy is also critical for manufacturing the products used every day, including the cement, concrete and bricks that shape our communities.[15]
While the U.S represents only five percent of the world's population, it consumes 25 percent of its energy and generates about 25 percent of its total greenhouse gas emissions. U.S. citizens, for example, use more energy per capita for transportation than do citizens of any other industrialized nation—which in part, reflects the greater distances traveled by Americans compared with citizens of other nations.[16]
[edit] Urban planning
Main article: Urban planning
Urban planning also has an effect on energy use. Between 1982 and 1997, the amount of land consumed for urban development in the United States increased by 47 percent while the nation's population grew by only 17 percent.[17] Inefficient land use development practices have increased infrastructure costs as well as the amount of energy needed for transportation, community services, and buildings.
At the same time, a growing number of citizens and government officials have begun advocating a smarter approach to land use planning. These smart growth practices include compact community development, multiple transportation choices, mixed land uses, and practices to conserve green space. These programs offer environmental, economic, and quality-of-life benefits; and they also serve to reduce energy usage and greenhouse gas emissions.
Approaches such as New Urbanism and Transit-oriented development seek to reduce distances travelled, especially by private vehicles, encourage public transit and make walking and cycling more attractive options. This is achieved through medium-density, mixed-use planning and the concentration of housing within walking distance of town centers and transport nodes.
Smarter growth land use policies have both a direct and indirect effect on energy consuming behavior. For example, transportation energy usage, the number one user of petroleum fuels, could be significantly reduced through more compact and mixed use land development patterns, which in turn could be served by a greater variety of non-automotive based transportation choices.
See also: Smart Growth
[edit] Building design
Main articles: Sustainable architecture and Green building
BedZED zero-energy housing in the UK
Emissions from housing are substantial,[18] and government-supported energy efficiency programmes can make a difference.[19]
New buildings can be constructed using passive solar building design, low-energy building, or zero-energy building techniques, using renewable heat sources. Existing buildings can be made more efficient through the use of insulation, high-efficiency appliances (particularly hot water heaters and furnaces), double- or triple-glazed gas-filled windows, external window shades, and building orientation and siting. Renewable heat sources such as shallow geothermal and passive solar energy reduce the amount of greenhouse gasses emitted. In addition to designing buildings which are more energy efficient to heat, it is possible to design buildings that are more energy efficient to cool by using lighter-coloured, more reflective materials in the development of urban areas (e.g. by painting roofs white) and planting trees.[20][21] This saves energy because it cools buildings and reduces the urban heat island effect thus reducing the use of air conditioning.
[edit] Transport
Bicycles have almost no carbon footprint compared to cars.
Main article: Sustainable transport
Modern energy efficient technologies, such as plug-in hybrid electric vehicles, and development of new technologies, such as hydrogen cars, may reduce the consumption of petroleum and emissions of carbon dioxide.
A shift from air transport and truck transport to electric rail transport would reduce emissions significantly.[22][23]
Increased use of biofuels (such as biodiesel and biobutanol, that can be used in 100% concentration in today's diesel and gasoline engines) could also reduce emissions if produced environmentally efficiently, especially in conjunction with regular hybrids and plug-in hybrids.
For electric vehicles, the reduction of carbon emissions will improve further if the way the required electricity is generated is low-carbon (from renewable energy sources).
Effective urban planning to reduce sprawl would decrease Vehicle Miles Travelled (VMT), lowering emissions from transportation. Increased use of public transport can also reduce greenhouse gas emissions per passenger kilometer.
[edit] Alternative energy sources
Main article: Energy development
[edit] Nuclear power
Cattenom Nuclear Power Plant.
Nuclear power currently produces over 15% of the world's electricity. Due to its low emittance of greenhouse gases (comparable to wind power[24]) and reliability it is seen as a possible alternative to fossil fuels, but is controversial for reasons of capital cost and possible environmental impacts. Also, there are political impacts in some countries.
[edit] Life-cycle greenhouse gas emissions comparisons
Most comparisons of life cycle analysis (LCA) of carbon dioxide emissions show nuclear power as comparable to renewable energy sources.[25][26]
A life cycle analysis centered around the Swedish Forsmark Nuclear Power Plant estimated carbon dioxide emissions at 3.10 g/kWh[27] and 5.05 g/kWh in 2002 for the Torness Nuclear Power Station.[28] This compares to 11 g/kWh for hydroelectric power, 950 g/kWh for installed coal, 900 g/kWh for oil and 600 g/kWh for natural gas generation in the United States in 1999.[29]
The Vattenfall study found Nuclear, Hydro, and Wind to have far less greenhouse emissions than other sources represented.
The Swedish utility Vattenfall did a study of full life cycle emissions of nuclear, hydro, coal, gas, solar cell, peat and wind which the utility uses to produce electricity. The net result of the study was that nuclear power produced 3.3 grams of carbon dioxide per KW-Hr of produced power. This compares to 400 for natural gas and 700 for coal (according to this study). The study also concluded that nuclear power produced the smallest amount of CO2 of any of their electricity sources.[30]
[edit] Enrichment
The bulk of CO2 emission from nuclear power plants can be eliminated if nuclear power plants themselves generate the electricity required during the uranium enrichment process (already being done in France and to some extent by the Tennessee Valley Authority's many nuclear units in the U.S.). In addition, gas centrifuge technology has/will greatly reduced the energy required for enrichment, thus reducing the LCA carbon emissions per kilowatt-hour (see Piketon plant).
[edit] Nuclear fuel reserves
Current uranium production is expected to be adequate at current consumption rates for about a century (from uranium mining, see also peak uranium).
There are a number of alternative nuclear fission technologies, such as breeder reactors, (see generation IV reactors) which could vastly extend fuel supplies if successfully developed and utilized.
Lower-risk thorium cycles have been demonstrated in the past.
Nuclear fusion is another variant of providing nuclear energy, but it will not provide any immediate mitigation to global warming as the time horizon for its commercial deployment is expected to be after 2050.[citation needed]
[edit] Renewable energy
This three-bladed wind turbine is the most common modern design because it minimizes forces related to fatigue.
Main articles: Renewable energy and Renewable energy development
One means of reducing carbon emissions is the development of new technologies such as renewable energy such as wind power. Most forms of renewable energy generate no appreciable amounts of greenhouse gases except for biofuels derived from biomass.[citation needed]
Helioculture is a newly developed process which is claimed to be able to produce 20,000 gallons of fuel per acre per year, and which removes carbon dioxide from the air as a feedstock for the fuel.[31]
Generally, emissions are a fraction of fossil fuel-based electricity generation. In some cases, notably with hydroelectric dams--once thought to be one of the cleanest forms of energy—there are unexpected results. One study shows that a hydroelectric dam in the Amazon has 3.6 times larger greenhouse effect per kW·h than electricity production from oil, due to large scale emission of methane from decaying organic material.[32] This effect applies in particular to dams created by simply flooding a large area, without first clearing it of vegetation. There are however investigations into underwater turbines that do not require a dam.
Currently governments subsidize fossil fuels by an estimated $235 billion a year.[33] However, in some countries, government action has boosted the development of renewable energy technologies—for example, a program to put solar panels on the roofs of a million homes has made Japan a world leader in that technology, and Denmark's support for wind power ensured its former leadership of that sector. In 2005, Governor Arnold Schwarzenegger promised an initiative to install a million solar roofs in California, which became the California Solar Initiative.[34]
In June 2005, the chief executive of BT allegedly became the first head of a British company to admit that climate change is already affecting his company, and affecting its business, and announced plans[35] to source much of its substantial energy use from renewable sources. He noted that, "Since the beginning of the year, the media has been showing us images of Greenland glaciers crashing into the sea, Mount Kilimanjaro devoid of its ice cap and Scotland reeling from floods and gales. All down to natural weather cycles? I think not."[36]
[edit] Eliminating waste methane
Methane is a significantly more powerful greenhouse gas than carbon dioxide. Burning one molecule of methane generates one molecule of carbon dioxide. Accordingly, burning methane which would otherwise be released into the atmosphere (such as at oil wells, landfills, coal mines, waste treatment plants, etc.) provides a net greenhouse gas emissions benefit.[37] However, reducing the amount of waste methane produced in the first place has an even greater beneficial impact, as might other approaches to productive use of otherwise-wasted methane.
In terms of prevention, vaccines are in the works in Australia to reduce significant global warming contributions from methane released by livestock via flatulence and eructation.[38]
[edit] Carbon intensity of fossil fuels
Natural gas (predominantly methane) produces less greenhouses gases per energy unit gained than oil which in turn produces less than coal, principally because coal has a larger ratio of carbon to hydrogen.[citation needed] The combustion of natural gas emits almost 30 percent less carbon dioxide than oil, and just under 45 percent less carbon dioxide than coal. In addition, there are also other environmental benefits.[39]
A study performed by the Environmental Protection Agency (EPA) and the Gas Research Institute (GRI) in 1997 sought to discover whether the reduction in carbon dioxide emissions from increased natural gas (predominantly methane) use would be offset by a possible increased level of methane emissions from sources such as leaks and emissions. The study concluded that the reduction in emissions from increased natural gas use strongly outweighs the detrimental effects of increased methane emissions. Thus the increased use of natural gas in the place of other, dirtier fossil fuels can serve to lessen the emission of greenhouse gases in the United States.[37]
[edit] Reforestation and avoided deforestation
Main articles: Deforestation, Reforestation, and Biosequestration
Almost 20% (8 GtCO2/year) of total greenhouse-gas emissions were from deforestation in 2007. The Stern Review found that, based on the opportunity costs of the landuse that would no longer be available for agriculture if deforestation were avoided, emission savings from avoided deforestation could potentially reduce CO2 emissions for under $5/tCO2, possiblly as little as $1/tCO2. Afforestation and reforestation could save at least another 1GtCO2/year, at an estimated cost of $5/tCO2 to $15/tCO2[5]. The Review determined these figures by assessing 8 countries responsible for 70% of global deforestation emissions.
Pristine temperate forest has been shown to store three times more carbon than IPCC estimates took into account, and 60% more carbon than plantation forest[40]. Preventing these forests from being logged would have significant effects.
Further significant savings from other non-energy-related-emissions could be gained through cuts to agricultural emissions, fugitive emissions, waste emissions, and emissions from various industrial processes[5].
[edit] Carbon capture and storage
Schematic showing both terrestrial and geological sequestration of carbon dioxide emissions from a coal-fired plant.
Main article: Carbon capture and storage
See also: Bio-energy with carbon storage and Biochar
Carbon capture and storage (CCS) is a plan to mitigate climate change by capturing carbon dioxide (CO2) from large point sources such as power plants and subsequently storing it away safely instead of releasing it into the atmosphere. Technology for capturing of CO2 is already commercially available for large CO2 emitters, such as power plants. Storage of CO2, on the other hand is a relatively untried concept and as yet (2007) no powerplant operates with a full carbon capture and storage system. When this technique is used with biomass, the technique is known as biomass energy with carbon capture and storage and may be carbon negative.
CCS applied to a modern conventional power plant could reduce CO2 emissions to the atmosphere by approximately 80-90% compared to a plant without CCS.[citation needed]
Storage of the CO2 is envisaged either in deep geological formations, deep oceans, or in the form of mineral carbonates. Geological formations are currently considered the most promising, and these are estimated to have a storage capacity of at least 2000 Gt CO2.[citation needed] IPCC estimates that the economic potential of CCS could be between 10% and 55% of the total carbon mitigation effort until year 2100.[citation needed]
In October 2007, the Bureau of Economic Geology at The University of Texas at Austin received a 10-year, $38 million subcontract to conduct the first intensively monitored, long-term project in the United States studying the feasibility of injecting a large volume of CO2 for underground storage.[41] The project is a research program of the Southeast Regional Carbon Sequestration Partnership (SECARB), funded by the National Energy Technology Laboratory of the U.S. Department of Energy (DOE). The SECARB partnership will demonstrate CO2 injection rate and storage capacity in the Tuscaloosa-Woodbine geologic system that stretches from Texas to Florida. The region has the potential to store more than 200 billion tons of CO2 from major point sources in the region, equal to about 33 years of U.S. emissions overall at present rates. Beginning in fall 2007, the project will inject CO2 at the rate of one million tons per year, for up to 1.5 years, into brine up to 10,000 feet (3,000 m) below the land surface near the Cranfield oil field about 15 miles (24 km) east of Natchez, Mississippi. Experimental equipment will measure the ability of the subsurface to accept and retain CO2.[citation needed]
[edit] Non-CO2 climate actors
Action has been suggested on soot, HFCs and other climate drivers, in addition to that proposed for CO2 [2]. Emissions of some of these actors are considered by the Kyoto Protocol.
[edit] Geoengineering
Main article: geoengineering
Geoengineering is seen by some as an alternative to mitigation and adaptation, but by others as an entirely separate response to climate change. Carbon sequestration is a form of mitigation, but is not mitigation as defined by climate activists. To them, the term is clearly defined as exclusively associated with reduction of greenhouse gas emissions.[citation needed]
Chapter 28 of the National Academy of Sciences report Policy Implications of Greenhouse Warming: Mitigation, Adaptation, and the Science Base (1992) defined geoengineering as "options that would involve large-scale engineering of our environment in order to combat or counteract the effects of changes in atmospheric chemistry." [42] They evaluated a range of options to try to give preliminary answers to two questions: can these options work and could they be carried out with a reasonable cost. They also sought to encourage discussion of a third question - what adverse side effects might there be. The following types of option were examined: reforestation, increasing ocean absorption of carbon dioxide (carbon sequestration) and screening out some sunlight. NAS also argued "Engineered countermeasures need to be evaluated but should not be implemented without broad understanding of the direct effects and the potential side effects, the ethical issues, and the risks.".[42]
[edit] Solar radiation management
Jets have been suggested to deliver aerosol precursors to the stratosphere, although the feasability of using them has not been evaluated [43]
Main articles: Solar radiation management, Stratospheric sulfur aerosols (geoengineering), and Marine cloud brightening
Some scientists have suggested using aerosols and/or sulfate dust to alter the Earth's albedo, or reflectivity, as an emergency measure to increase global dimming and thus stave off the effects of global warming. A 0.5% albedo increase would roughly halve the effect of CO2 doubling.[44] In 1974, Russian expert Mikhail Budyko suggested that if global warming became a problem, we could cool down the planet by burning sulfur in the stratosphere, which would create a haze. Paul Crutzen suggests that this would cost 25 to 50 billion dollars/year. It would, however, increase the environmental problem of acid rain[45][46][47] (although optimized engineering is thought to reduce this to insignificant levels[citation needed])and drought.[48]
An alternative technique, which may be more benign, is marine cloud brightening. Others have proposed building a literal solar shade in space.
[edit] Greenhouse gas remediation
Main articles: Greenhouse gas remediation and Carbon sequestration
Carbon sequestration has been proposed as a method of reducing the amount of radiative forcing. Carbon sequestration is a term that describes processes that remove carbon from the atmosphere. A variety of means of artificially capturing and storing carbon, as well as of enhancing natural sequestration processes, are being explored. The main natural process is photosynthesis by plants and single-celled organisms (see biosequestration). Artificial processes vary, and concerns have been expressed about their long-term effects.[49]
Although they require land, natural sinks can be enhanced by reforestation and afforestation carbon offsets, which fix carbon dioxide for as little as $0.11 per metric ton[citation needed].
[edit] Biochar
Main article: Biochar
Charcoal, or biochar, created by pyrolysis of biomass can be buried to create terra preta. The production of biochar may or may not involve energy recovery. The intention is that the carbon in the biomass is removed from the atmosphere for a longer period of time than would otherwise be the case.
[edit] Bio-energy with carbon capture and storage, BECCS
Main article: Bio-energy with carbon capture and storage
During its growth, biomass traps carbon dioxide from the atmosphere through photosynthesis. When the biomass decomposes or is combusted, the carbon is again released as carbon dioxide. This process is part of the global carbon cycle. Through the use of biomass for energy and materials, eg. in biomass fuelled power plants, parts of this cycle is controlled by man. Combining these biomass systems with carbon capture and storage technologies, so called bio-energy with carbon capture and storage, BECCS, is achieved. BECCS systems results in net-negative carbon dioxide emissions, ie. the removal of carbon dioxide from the atmosphere.[50] In comparison with other geoengineering options, BECCS has been suggested as a low-risk, near-term tool to effectively remove carbon from the atmosphere.[49][51][52]
[edit] Carbon air capture
Main article: Carbon air capture
See also: Carbon dioxide air capture and BECS
It is notable that the availability of cheap energy and appropriate sites for geological storage of carbon may make carbon dioxide air capture viable commercially. It is, however, generally expected that carbon dioxide air capture may be uneconomic when compared to carbon capture and storage from major sources - in particular, fossil fuel powered power stations, refineries, etc. In such cases, costs of energy produced will grow significantly.[citation needed] However, captured CO2 can be used to force more crude oil out of oil fields, as Statoil and Shell have made plans to do.[53] CO2 can also be used in commercial greenhouses, giving an opportunity to kick-start the technology. Some proposals have been made to use algae to capture smokestack emissions,[citation needed] but this has not reached commercial level yet.
[edit] Seeding oceans with iron
An oceanic phytoplankton bloom in the South Atlantic Ocean, off the coast of Argentina covering an area about 300 miles by 50 miles
See also: Iron fertilization
The so-called Geritol solution to global warming, first proposed by oceanographer John Martin, is a carbon sequestration strategy whimsically named for a tonic advertised to treat the effects of iron-poor blood. It is motivated by evidence that seeding the oceans with iron will increase phytoplankton populations, and thereby draw more carbon dioxide from the atmosphere. A report in Nature, 10 October 1996, by K. H. Coale et al., measured the effects of seeding equatorial Pacific waters with iron, finding that 700 grams of CO2 were fixed by the resulting phytoplankton bloom per 1 gram of iron seeded.[54]. Lenton and Vaughan found this technique to be potentially useful, but limited in its total capacity.[55]
Opponents of this approach argue that fertilizing the ocean is dangerous and lacks any guarantee of efficacy. The original researchers themselves assert that, far from being a panacea for global warming, iron seeding may be entirely ineffective. Among their concerns are that nobody knows where the carbon goes after it is absorbed by phytoplankton. Instead of being drawn down to the ocean floor and acting as a carbon sink, the carbon could be reabsorbed by the water, effectively negating any initial gain. They also express concern that any attempt at geoengineering could result in massive, unpredictable changes to the environment. They point out that, considering the immense damage caused by adding nutrients to lakes and ponds, it would be a logical conclusion that adding nutrients to the ocean would also cause environmental damage. Large-scale growth in phytoplankton could reduce oxygen levels, creating dead zones where the ocean cannot support marine-life. They suggest that there is even the possibility that blooms would release more carbon dioxide equivalent greenhouse gas in the form of methane than it would sequester.[56] [57]
