Qualitive v. Quantitive
It's true a degree is a degree is a degree. A change of 1 degree is a change of one degree.
What TB's ideology blinds him to is the delta. A change of 1 degree per century is exactly the same as 1 degree a decade, except that a change of 10 degrees a century is different than a change of 1 degree a century.
When people start to ignore reality it gets harder and harder to face reality, and the slimmest of straws become a highway for denial.
This is only one in a long, long string of denials of reality, and will be maintained long, long after it's even more clear it's wrong. It's a case of mind over matter.