Geoengineering

  • Geoengineering: "the deliberate large-scale intervention in the Earth's climate system, in order to moderate global warming" (Royal society paper, in Goodell, 16)
  • Two main approaches to geoengineering: carbon engineering & engineering of the earth's albedo Goodell, 17
  • Main promise of geoengineering: delay inevitable catastrophic warming of the earth. It's a desperate measure, but it seems likely that we'll have to use it at some point Goodell, 115
  • Three main arguments against geoengineering: (1) we don't understand the system we're messing with and we'd be likely to mess it up in a really catastrophic way. (2) geoengineering distracts from the main problem, which is that we're still emitting too many greenhouse gases and need to figure out how to stop doing that. (3) Western civilization in the modern era is unsustainable regardless of the planet's temperature, and we'd end up depleting even more resources on the industry of planetary cooling Goodell, 18-21

Albedo engineering

  • Albedo engineering to change reflectivity of the earth- painting roofs and roads white, injecting reflective particles into the atmosphere Goodell, 17
  • With albedo engineering, blocking 2% of Earth's sunlight returns climate to preindustrial levels - though this doesn't fix the other problems high CO2 causes Goodell, 17
  • Surest way to have a quick impact and stop Arctic ice from melting is albedo engineering, which is either brightening clouds or filling the stratosphere with particles. Either of these could in theory cool the Arctic quickly enough to immediately stop ice melt. Goodell, 114
  • Computer models suggest that albedo engineering will cause massive droughts, particularly in Africa and Asia. These were seen when Mt. Pinatubo erupted, and they would be worse over time. There is every likelihood that the albedo engineering approach would create problems beyond those immediately caused by global warming. Klein, 248
  • Planting trees in previously unforested areas in an attempt to offset carbon is controversial because of the change in albedo - it's unclear whether it is a net positive or negative. Lovins, 239

Particles injected into the stratosphere

  • We know for sure that particles in the atmosphere can cool the planet by a degree or two because that has happened with some big volcanoes in the past.
  • How do you inject the stratosphere with particles? Teller & Wood looked into this problem: for $1 billion/year, set off an artificial volcano every 5-6 years full of particles 1/10th of a micron in diameter made of some nonreactive metallic substance Goodell, 123
  • Testing the stratospheric albedo approach: over 70 deg latitude, shade 20% to stop melting; 50% to grow the ice. The particles would rain out in a year or so. (Caldeira) Goodell, 127
  • Particles in the stratosphere might trigger the creation of chlorine, which degrades the ozone Goodell, 131
  • Particles in the stratosphere might affect monsoons and destroy agriculture Goodell, 132
  • If we stopped putting particles in the air, the heat would come back right away Goodell, 133

Cloud brightening

  • Smaller particles are more reflective than bigger particles of the same substance. Making the water droplets smaller could make them brighter Goodell, 169
  • Spraying atomized salt water from the ocean into the air could make the moisture in clouds form around the salt, which would be smaller particules than their current form Goodell, 169
  • According to Latham, 50-70% of the world's ocean-covering clouds would have to be brightened in order to offset a doubling of CO2 Goodell, 182
  • This could impact global weather patterns, esp. rainfall Goodell, 184

Carbon engineering

  • Carbon engineering is less controversial than albedo engineering, more similar to Earth's natural carbon cycle. E.g. air scrubbers, iron in the ocean to create plankton blooms, huge plantations of trees Goodell, 17
  • Plankton blooms: if we dump several tons of iron into the ocean, we can cause a phytoplankton bloom. Phytoplankton are 1% of photosynthetic material but take in 50% of the carbon on Earth, then sink to the bottom of the ocean when they die (trapping carbon for centuries-millennia) Goodell, 137
  • Not sure what would eat the phytoplankton, and not sure what changing the nutritional balance of the ocean would do to other life forms Goodell, 137
  • Carbon-sucking machines: "There's no way you can do a useful amount of carbon dioxide removal in less than a third of a century or maybe half a century." -David Keith, geoengineer & creator of a carbon-sucking machine Klein, 229
  • Sucking carbon out of the atmosphere is highly experimental. One specific project posits the deployment of artificial trees that circulate a carbon-sucking liquid (likely an aqueous solution of calcium hydroxide). Each of these trees could theoretically suck up to 90k tons per year, so it would take only 160k of these to remove half of global carbon emissions from 2005 — assuming the trees have access to lots of wind (for high throughput) or high elevation (where carbon concentrations are higher). Circulation of the fluid and extraction of the carbon from it may be energy-intensive. Then, the problem of sequestering the carbon is yet unsolved. Key areas of work with the “trees” mentioned are the energy required to keep the sorbent fluid circulating (especially in high wind), and the heat-intensive CO2 gas extraction process from the aqueous solution of calcium hydroxide Smil, 89.

Other

  • Hydroxyl radicals reduce methane concentration but are depleted by air pollution. Meadows, 166 What would it look like to artificially increase their concentration, especially near natural gas burning sites?

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