Slate hosts the largest online collection of climate humor:  344 cartoons, count 'em.

"What was the best climate or energy humor of 2010?"

In January 2011, Climate Progress posted a collection that blog visitors could vote on.   Some posts include links to other humor sites.

Marc Roberts may very well be (in NY Times Andy Revkin's words) "the world's best -- and only -- cartoonist to focus almost exclusively on climate humor

Robert's dense, ironic and dark comic strips are definitely an "acquired taste," more likely to trigger rueful chuckles more than full belly-laughs.   But he has the field largely to himself and definitely "tells it like it is."

Here are the 19 winners and finalists from an international climate cartoon competition published in The Guardian    Some 150 cartoonists from 50 countries entered the competition sponsored by the Ken Sprague Fund.   

Manpollo Project (Greg Craven) has seven pages of climate humor, including scores of cartoons.   What distinguishes this cartoon collection from most others is that it is 1) highly eclectic, including many different cartoonists, and 2) highly selective -- many of these 'toons are actually funny.   

Several associations/websites devoted to political cartoons are searchable by topic.

In the Cartoonist Group website, keyword search for "climate" pops up nearly 450 entries, in very small thumbnails, including the caption in larger (readable) font alongside.   Copyright protection blocks copy/pasting.

Searching for "climate" in The American Association of Editorial Cartoons (AAEC) site, yields 30-80 small thumbnails for each recent year.   Captions are unreadable, unfortunately.

Each site has its own rules regarding use and copyright