Could these changes arise from natural climate variability alone? The answer is no. Even today, one can hear statements sometimes from senior members of our government saying we know nothing about the causes and effects of climate change. That's really not true.

When people come up with extraordinary claims -- like the troposphere is cooling -- then you demand extraordinary proof. What's happening now is that people around the world are subjecting these data sets to the scrutiny they need.

Now we're learning that the disconnect is more apparent than real.

Could these changes arise from natural climate variability alone? The answer is no.

Could these changes arise from natural climate variability alone? The answer is no. Even today, one can hear statements — sometimes from senior members of our government — saying we know nothing about the causes and effects of climate change. That's really not true.

Could these changes arise from natural climate variability alone? The answer is no. Even today, one can hear statements — sometimes from senior members of our government — saying we know nothing about the causes and effects of climate change. That's really not true.