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Debate: Upper oceanic heat transport

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Should upper oceanic heat transport be utilized?

Background and context

Upper oceanic heat transport is the natural mixing of oceanic layers of differing temperatures and the mixing of different substances. Recently it has been suggested that heat transport could be synthetically created and used to combat global warming. This would be a type of geo-engineering. The modern concept of geo-engineering is usually taken to mean proposals to deliberately manipulate the Earth's climate to counteract the effects of global warming from greenhouse gas emissions. The National Academy of Sciences defined geo-engineering as "options that would involve large-scale engineering of our environment in order to combat or counteract the effects of changes in atmospheric chemistry."

Ocean temperature and motion fields can be separated into 3 distinct layers: 1) mixed (surface) layer, 2) upper ocean, and 3) deep ocean. The mixed layer is nearest to the surface and can vary in thickness from 10 to 500 meters. The upper ocean, characterized by warm temperatures and active motion, varies in depth from 100m or less in the tropics and eastern oceans to in excess of 800meters in the western subtropical oceans. This layer exchanges properties such as heat and freshwater with the atmosphere on timescales of a few years. Below the mixed layer the upper ocean is generally governed by the hydrostatic and geo-strophic relationships. The deep ocean is both cold and dark with generally weak velocities. The deep ocean is supplied with water from the upper ocean in only a few limited geographical regions: the sub-polar North Atlantic and several sinking regions around the Antarctic Because of the weak supply of water to the deep ocean the average residence time of water in the deep ocean is measured in hundreds of years. In this layer as well the hydrostatic and geo-strophic relationships are generally valid and mixing is generally quite weak.

This approach to alleviating the affects of global warming could also help with lessening the power of hurricanes. Scientists hypothesize that by using this strategy hurricanes could be lessened by a full category.

Contents

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Is climate change a problem?

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Pro

  • Many scientists who state that climate change is a myth are being paid by private interests. A free-market think tank which in November 2004, said global warming was a "myth", and described David King as "an embarrassment", received money from ExxonMobil.
  • The effect climate change has on the planet is measurable. In 2000, researchers based at Imperial College London examined satellite data covering almost three decades to plot changes in the amount of infrared radiation escaping from the atmosphere into space--an indirect measure of how much heat is being trapped. In the part of the infrared spectrum trapped by CO2--wavelengths between 13 and 19 micrometres--they found that between 1970 and 1997 less and less radiation was escaping. They concluded that the increasing quantity of atmospheric CO2 was trapping energy that used to escape, and storing it in the atmosphere as heat. The results for the other greenhouse gases were similar.
  • Rising levels of carbon dioxide (CO2) and other greenhouse gases (GHGs) correlate with global warming. Carbon dioxide accounts for about 383 parts per million by volume (ppm) of the Earth's atmosphere, increasing from 278 ppm in the 1880s to over 380 ppm in 2005. Carbon dioxide causes between 9 and 26% of the natural greenhouse effect.
  • Global warming is causing the arctic ice caps to melt at an alarming rate. Because of the rapid response of the Arctic to global warming, it is often seen as a high-sensitivity indicator of climate change. Scientists also point to the potential for release of methane from the Arctic region, especially through the thawing of permafrost and methane calthrates.


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Con

  • The Earth goes though climate cycles over time this is just another era. A team of MIT scientists recorded a nearly simultaneous world-wide increase in methane levels -the first increase in ten years. What baffles the team is that this data contradicts theories stating humans are the primary source of increase in greenhouse gas. It takes about one full year for gases generated in the highly industrial northern hemisphere to cycle through and reach the southern hemisphere. Since all worldwide levels rose simultaneously throughout the same year, however, it is probable that this may be part of a natural cycle - and not the direct result of man's contributions.
  • There is no proof that the Earth is warming at an accelerated rate. Satellite measurements show no appreciable trend in the temperature of much of the troposphere--the lowest layer of the atmosphere--since 1979. This has been interpreted variously as showing that warming is not extending into the atmosphere as far as models suggest it should, and that global warming itself is a myth.
  • Solar cycles can explain most of the changes. This case was first made by Danish scientists Knud Lassen and Eigil Friis-Christensen in 1991. They found a correlation between sunspot activity and temperature changes on Earth from 1850 onwards.
  • Climate Change may dry out the upper levels of the innermost atmospheric layer, the troposphere, and less water means a weaker greenhouse effect. Richard Lindzen of the Massachusetts Institute of Technology, has made an interesting case that warming may dry out the upper levels of the innermost atmospheric layer, the troposphere, and less water means a weaker greenhouse effect. Lindzen, who is one of the few sceptics with a research track record that most climate scientists respect, says this drying effect could negate all the positive feedbacks and bring the warming effect of doubling CO2 levels back to 1[degrees]C.


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Should we risk the health of our oceans in order to try and end global warming?

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Pro

  • If we can’t ‘heal the planet’ directly, we may be able to help the planet heal itself. Water pumped up pipes — say, 100 to 200 metres long, 10 metres in diameter and with a one-way flap valve at the lower end for pumping by wave movement — would fertilize algae in the surface waters and encourage them to bloom. This would pump down carbon dioxide and produce dimethyl sulphide, the precursor of nuclei that form sunlight-reflecting clouds.
  • This would help improve the health of our oceans. The intention was to cool the surface directly, to encourage algal blooms as well as help keep the arctic ice caps from melting any faster than they are already.
  • The risk is worth the reward. Renowned scientist James Lovelock has stated that, "The stakes are so high that we must try such schemes, even if they may fail. The Earth is fast becoming a hotter planet than anything yet experienced by humans."
  • This would lower greenhouse gas concentrations. This technology would fertilize algae in the surface waters and encourage them to bloom. This would pump down carbon dioxide and produce dimethyl sulphide, the precursor of nuclei that form sunlight-reflecting clouds.


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Con

  • Would causing an algal bloom truly remove CO2 from the atmosphere? All such schemes suffer from a major problem, because simply enhancing the growth of phytoplankton is not enough. It is the sinking flux of particulate organic carbon into the deep ocean — and ideally into the sediments (usually a small fraction of the total primary production) — that must be enhanced for sequestration to be effective.
  • The CO2 wouldn’t stay dissolved in the ocean. Also, this scheme would bring water with high natural pCO levels (associated with the nutrients) back to the surface, potentially causing exhalation of CO2.
  • The ecosystems are already at risk and fertilization may irreversible alter them. We do not consider ocean fertilization to be a promising approach, and on a large scale it would constitute major interference with an ecosystem which is still poorly understood. Fertilization is likely to alter the phytoplankton community composition and succession, and thus the structure of the oceans’ food webs. It might damage these remote and possibly fragile ecosystems, trigger unexpected feedbacks and even reduce their ability to sequester carbon.
  • Bringing cool water to the surface would mean introducing warm water to ecosystems adapted for cold water. Many species residing the deeper and colder parts of the ocean cannot survive in warmer waters and may die out if warm water was introduced to their environment.


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Should we be trying to control the weather?

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Pro

  • Lessening the strength of hurricanes would mean that 10 billion dollars a year could be used for other projects. Hurricanes are responsible for on average 10 billion dollars a year in damages, hurricane Katrina caused an estimated 81 billion dollars in damages.
  • Lessening the strength of hurricanes would mean that fewer human lives would be lost or ruined. Hurricanes kill an average of 23 people each year in the United States alone. In 2005 at least 1836 people lost their lives in Hurricane Katrina and in the subsequent floods, making it the deadliest U.S. hurricane since the 1928 Okeechobee Hurricane. In addition over 10 thousand people lost their homes.


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Con

  • Trying to Control the weather could have unanticipated side effects. “The best, surest, and clearest way to reduce environmental risk associated with greenhouse gas emissions is to reduce greenhouse gas emissions”
  • Developing and employing this technology would cost more than it would save. The pipes cost a large sum of money to make and place in the ocean. It is still very new at this point.
  • Hurricanes actually help the envrionment. Hurricanes displace living plants and animals into areas that may need more nutrients. “Think of it this way, if a possum dies on a highway and is left on the pavement animals can eat the meat, but the decomposition is lost on the asphalt, the same holds true for a tree growing on a sidewalk. The hurricanes actually move the nutrients to a more accessible place."


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Would using this technology truly end global warming?

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Pro

  • This technology would remove large amounts of CO2 from the atmosphere.
  • This technology would cool the ocean. The oceans, which cover more than 70% of the Earth’s surface, are a promising place to seek a regulating influence.
  • This technology would help the earth heal its self. The removal of 500 gigatonnes of carbon dioxide from the air by human endeavor is beyond our current technological capability. If we can’t ‘heal the planet’ directly, we may be able to help the planet heal itself.
  • This technology would encourage the development of clouds. Water pumped up pipes, say,100 to 200 meters long, 10 meters in diameter and with a one-way flap valve at the lower end for pumping by wave movement, would fertilize algae in the surface waters and encourage them to bloom. This would pump down carbon dioxide and produce dimethyl sulphide, the precursor of nuclei that form sunlight-reflecting clouds.


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Con

  • This technology does not reduce how much radiation (heat) is absorbed in the atmosphere. A problem with these approaches, however, is that the cooling is not generated by reducing the amount of absorbed solar radiation, but rather by mixing energy down into the ocean, which would tend to sustain and even enhance both global warming and sea level rise.
  • This technology does not remove CO2 from the atmosphere. The CO2 taken from the atmosphere is only temporarily removed as organisms that contain the carbon will die off and release it into the atmosphere.
  • This technology could damage fragile and essential ecosystems. Drastically changing any ecosystem poses all sorts of risks. Allowing algae, plankton, and other one celled organisms to reproduce this quickly will reek havoc upon the oceanic ecosystem. It will use up the dissolved oxygen and create an overpopulation that will kill off all other food sources for the larger animals and, in turn, our food, medicine, and general products from the ocean.

See also

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