I believe the ability to measure, with precision, the degree of human activity's impact on the climate is subject to more debate on whether the climate is changing or whether human activity contributes to it.

I believe the ability to measure, with precision, the degree of human activity's impact on the climate is subject to more debate on whether the climate is changing or whether human activity contributes to it.

The climate is changing, and human activity contributes to that in some manner.

I believe the ability to measure with precision the degree of human activities' impact on the climate, is subject to more debate on whether the climate is changing or whether human activity contributes to it.