Mitigation of global warming

• ReducingGlobalWarming?

Mitigation of global warming involves taking actions aimed at reducing the extent of global warming. This is in contrast to adaptation to global warming? which involves taking action to minimize the effects of global warming.

Overview

The scientific consensus on global warming, together with the precautionary principle and the fear of non-linear climate transitions is leading to increasing action to mitigate global warming.

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.

There are five categories of actions that can be taken to mitigate global warming:

1. Reduction of energy use (per person)
2. Shifting from carbon-based fossil fuels to alternative energy sources
3. Carbon capture and storage
4. Geoengineering including carbon sequestration
5. Birth control, to lessen demand for resources such as energy and land clearing

A valid criticism of this strategy is that it offers only temporary symptomatic relief, allowing the continual expansion of the growth economy to a point where compensating for its impacts with efficiencies and new technologies will not be possible. World economic energy efficiency is presently improving at about half the rate of world economic growth (US DOE World Trends), and there's no reason to think the thermodynamic limits of efficiency do not apply to the efficiency of natural and human services just because their measures don't have comparable units. Both common sense and the consistent pattern that all technologies and efficiencies are quickly exhausted (technology lifecycle) indicate that relying on technical fixes to allow continually exploding economic expansion is faulty. One alternative would be to learn how to mature the economic systems following the example of maturing natural growth systems.

Strategies for mitigation of global warming include development of new technologies; carbon offsets; renewable energy such as biodiesel, solar power, tidal and ocean energy, geothermal power, and wind power; electric or hybrid automobiles; fuel cells; zero-energy buildings; energy conservation; carbon credits; carbon taxes; enhancing natural carbon dioxide sinks; population control; and carbon capture and storage. Many environmental groups encourage individual-lifestyle and political action against global warming, and there has been business action on climate change.

Pacala and Socolow of Princeton 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. efficient vehicles − increase fuel economy from 30 to 60 mpg for 2 billion vehicles,
2. reduce use of vehicles − improve urban design to reduce miles driven from 10,000 to 5,000 miles 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 gigawatts of coal power plants with natural gas,
6. capture and store carbon emitted from 800 gigawatts of new coal plants,
7. capture and reuse hydrogen created by #6 above,
8. capture and store carbon from coal to synfuelsconversion at 30 million barrels per day,
9. displace 700 gigawatts of coal power with nuclear,
10. add 2 million 1 megawatt windmills (50 times current capacity),
11. displace 2,000 gigawatts of coal with solar power (700 times current capacity),
12. produce hydrogen fuel from 4 million 1 megawatt windmills,
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).

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-- GeirThomasAndersen - 23 Jun 2007