Reading some academic literature by warming alarmists on the appropriate way to respond to criticism suggests that we have a shift in the meaning of key concepts in the debate. Cutting to the chase, in this literature the role of human emissions has shifted from “likely one of the causes of warming” in 1988 through “discernible human influence” in 1995 to causing “most of the Earth’s warming” since then.
So the image or the connotation of human-generated CO2 has shifted from “traces of plant food added to the air by human activities that could have some influence on the climate” to “a global emergency that calls for trillions of expenditure to fix although it might be too late.”
The technical term for this kind of thing is semantic drift or shift.
Awful — Originally meant “inspiring wonder (or fear)”, now usually has negative meaning.
Demagogue — Originally meant “a popular leader” from the Greek dēmos “people” + agōgós “leading, guiding”. Now a politician who panders to emotions and prejudice.
Egregious — Originally meaning good from the Latin egregius “illustrious, select”, literally, “standing out from the flock”, now really bad or flagrant.
Gay — Originally meant (13th century) “lighthearted”, “joyous” or (14th century) “bright and showy”, it also came to mean “happy”.
Disinterested, once even handed or objective, now not interested.
In “Climate scepticism and the manufacture of doubt” [Ref below for nerds] we read “Since at least the mid-1990s there has been a consensus that most of the Earth’s warming over the last half a century is likely due to increases in greenhouse gas emissions. In 1988 James Hansen testified [that it is] very likely on one of the causes…In 1995 the IPCC Second Assessment concluded that ‘the balance of evidence suggests that there is a discernible human influence’…and since that time the debate within the field of climate science [re the dominant contribution of human emissions] has largely been settled”.
Observe the drift from ‘likely one of the causes’ (1988) through ‘discernible’ (IPCC 1995) to ‘most of the Earth’s warming …and debate largely settled’ since that time. Moreover the warming is alarming and it is mostly CO2 that is to blame.
Observe how the drift is propagated by the Reuters report on the 97.4% consensus paper by Cook and others. Incidentally the paper itself, read closely, indicates that most of the climate scientists think like most climate realists, that there has been some warming in recent times and there is a human influence (magnitude of both unspecified).
The Reuters item leads off with a summary paragraph which is the take-home message for busy people. There is a picture that is worth a thousand words as well.
Ninety-seven percent of scientists say global warming is mainly man-made…The report found an overwhelming view among scientists that human activity, led by the use of fossil fuels, was the main cause of rising temperatures in recent decades.
So the perception of warming, embedded in the minds of the alarmists and the MSM, is that it is alarming and overwhelmingly driven by CO2. Despite the fact that the so-often cited Cook paper indicates no such thing even if you take their data at face value and ignore issues about their methods.
Reading the academic commentary it is apparent that the alarming and CO2 driven nature of warming is so entrenched that any different opinion calls for a political or psychological explanation and hence it can be dismissed without serious consideration apart from references to papers out of the “alarm manufacturing industry” that purport to justify the thoroughly discredited hockey stick effect and Al Gore’s flights of fantasy, etc.
Ref. Justin Biddle and Anna Leuschner 2015 “Climate scepticism and the manufacture of doubt: can dissent in science be epistemically detrimental?”, European Journal of Philosophy of Science, 5:261-278.