 the discrepancy between model-predicted warming and (lower) real-world observations has inspired new respect for natural climate variability relative to greenhouse-gas forcing. 
 the discrepancy between model-predicted warming and (lower) real-world observations has inspired new respect for natural climate variability relative to greenhouse-gas forcing. 
attribution of recent climate change:199
models indicate that solar and volcanic forcings can explain periods of relative warmth and cold between ad 1000 and 1900, but human-induced forcings are needed to reproduce the late-20th century warming.