Climate sensitivity analysis: ‘Using a single value for sensitivity is unlikely to capture how climate responds to CO2’
'Since scientists have little idea what mechanisms are at work regulating global climate, they have no idea what value of sensitivity should be applied at the present. And because Earth's climate system is always changing, science cannot simply look to the recent past for an answer. Yet modelers are constantly setting a value for sensitivity and then 'validating' their models against climate data from the recent past—a process called backcasting'