As a percentage of scientists actually in the field (who said "beware of experts outside their field of expertise"?), the number of dissenters is vanishingly small. Used to be much larger, but the concensus is pretty broad that (in descending order of unanimity):

1) it is happening,

2) it could have cataclysmic consequences,

3) whatever the cause, we would be wise to do whatever we can to, if not prevent it, at least slow it,

4) human activities are at least partially implicated.

The people who continue to crow that it is an liberal environmnetalist whacko myth are the crackpots.