Hansen is supposed to be taken seriously because he converted to global warming alarmist after looking at the data as a skeptical scientist. It's easily seen to be BS when looking at his statements about climate zones moving and stress. He obviously knows nothing about the science, just wants to sound an alarm.
His tone of voice is exactly what grandfathers develop from explaining to grandkids why grass is green and the sky is blue and where the world came from even though the kids world extends to the street in front of their house and the bus ride to school. It is the 'I am being sincere' tone. All the senior Art Bell guests have that tone.