Climatologists will argue for many years whether the greenhouse warming has started.

The greenhouse warming had not yet melted them bare.

Even another sweltering summer won't mean the greenhouse warming has begun.

The danger in asserting they prove greenhouse warming has arrived is obvious.

Nor do they see reliable evidence that the greenhouse warming has yet begun.

They are focusing their detective efforts on various subtle changes that a greenhouse warming would be expected to induce.

An especially significant indicator of greenhouse warming would be any increase in atmospheric water vapor.

Those who say the greenhouse warming has already begun are also valuable voices, even though the point is far from proved.

In the next couple of years, you're going to see overwhelming public and political acknowledgment that greenhouse warming is real.

Most climatologists are unwilling to state that any degree of greenhouse warming has begun.