But it is a challenge and a very logical and significant one at that. Is the human induced portion of climate change 50.0% of the total or 5.0% or 0.5%. The whole debate on public policy turns on the question of how much the climate is changing, how fast the changes are occurring, and how much is anthropogenic. Should we turn our lives inside out to stop a 0.2° C change in mean temperature in 2120? It is generally not illegitimate in a scientific argument to attack opponents for failing to quantify their assertions. If observations differ by more than the margin of error from predictions, then the theory is disproved. That’s science.