Climate 3 - Difficulties in modeling climate change...

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Difficulties in modeling climate change: scientific Establishing anthropogenic origins. Feedbacks, positive (de-stabilizing) and negative (stabilizing). Oceans – competing effects Warming releases CO 2 (Coke) Warming may or may not increase plankton growth. Particulates – smoke, haze, aerosols. Net reflectors or absorbers? Albedo – reflectivity of Earth’s surface. Temperature of converted rain forests is 3° higher (soil is darker than trees).
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Difficulties in modeling climate change; population growth and development Population predicted to reach between 6 and 11 billion by 2100 Economic growth rates predicted to range from 1 – 3 % annually. 3 scenarios have been used (in textbook) Low-end 6 million people at 1.2% Midrange 11 million people at 1.2% High-end 11 million people at 3% Will introduce IPPC scenarios later
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Compelling evidence that recent increases in atmospheric CO 2 come from burning fossil fuels 1. 14 C is radioactive and decays over a few thousand years. 2. Living things have 14 C/ 12 C ratios that reflect current atmospheric composition due to respiration. 3. Fossil fuels have no 14 C since they derive from plants that died millions of years ago. 4. The 14 C/ 12 C ratio in the atmosphere has decreased concurrently with the increase in atmospheric CO 2 , strongly suggesting a fossil fuel origin. 5. 13 C/ 12 C ratios are actually used but the argument is a bit more complicated.
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Glacial-interglacial ice core data Grey bands are interglacial periods
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IPCC 2007 terminology Confidence terminology – degree of confidence in scientific understanding. 10% levels of separation Value uncertainty – incomplete determination of values or results Structural uncertainty – incomplete understanding of processes Likelihood terminology – likelihood of a particular occurrence/outcome expressed using Gaussian distributions. There is much overlap between these in the report.
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Confidence terminology
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2 standard deviations 1 standard deviation 3 standard deviations Likelihood terminology Added for forcing Added for forcing
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Radiative forcing Global warming potentials have been converted to
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Climate 3 - Difficulties in modeling climate change...

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