claim: The discrepancy between model-predicted warming and ( lower ) real-world observations has inspired new respect for natural climate variability relative to greenhouse-gas forcing.
evidence: Barnett and colleagues ( 2005 ) say that the observed warming of the oceans cannot be explained by natural internal climate variability or solar and volcanic forcing, but is well simulated by two anthropogenically forced climate models, concluding that it is of human origin, a conclusion robust to observational sampling and model differences.