GUS 0821 Lecture Notes - Lecture 30: Radiative Forcing, Special Report On Emissions Scenarios, Magic 2Ch
12 Jul 2018
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Document Summary
Greenhouse gas concentrations, compared to natural changes over the past 10,000 years, the spike in concentrations of co2 & ch4 in the past 250 years is extraordinary, humans are responsible for the recent dramatic increase emissions. Ch4 lack carbon-14, and the observed drop in atmospheric c-14 is measurable: figure spm. 1. Atmospheric concentrations of carbon dioxide, methane and nitrous oxide over the last 10,000 years (large panels) and since 1750 (inset panels). Measurements are shown from ice cores (symbols with different colours for different studies) and atmospheric samples (red lines). The corresponding radiative forcings are shown on the right hand axes of the large panels. 6. 4: best estimate of global radiative forcing, figure spm. 2. The net anthropogenic radiative forcing and its range are also shown. These require summing asymmetric uncertainty estimates from the component terms, and cannot be obtained by simple addition. Additional forcing factors not included here are considered to have a very low losu.
