Sure, the climate is changing...it has been ever since the earth was formed, will always continue to do so.
Where I grew up in the great midwest in the 60's and 70's, every winter we would have a few snowstorms that would drop three feet of snow on the ground. It was so bad that the county maintenance department had to put snow fence in the farmers' fields about 100 yards north of the east-west highways...that stopped the drifts short of the roads and kept the county mobile. These days, the norm is about 3 inches of snow per storm, fewer storms per winter, and increasingly people are feeling lucky to get that much.
OK, so that was 40, 50 years ago. I can see that the contribution from greenhouse gas production by humans could have an impact, but I can also see that methane production by cattle and other livestock could have an impact. Both, however, seem to be rather "recent" events, in the grand scheme of things. Those human contributions, however, are only recent and could not have explained the most recent "ice-age" that gripped the earth, spreading glaciers over most of North America, Europe and Asia.
So, IMHO, we humans could be partially responsible....more of us and all of us needing to get around in an increasingly mobile world; all of us have to eat so there are more domesticated livestock animals to produce methane, yada-yada-yada.
The amazing thing about humans, though, is their adaptability. Look at us now, we have our own self-produced "climates" (fully enclosed structures in which we live, in which most of us work, and in which most of us even transport ourselves between work and home and elsewhere), so we have managed to in large part negate the overall impact of nature's wrath to the point that it can often be little more than a nuisance during the twice daily commute.
We'll be here, earth will be here, and we'll continue to "adapt" to make survival possible....it's just what we humans do.
We may all be eating algae and our only transportation may come in mazes of tubes, or through particle transportation of some kind, but adapt we will.
Anyone ever see the Bruce Dern movie "Silent Running"? Mankind had destroyed all vegetation on the earth and had established space-based "greenhouses" so that there would be genetic plant stock to (hopefully) help replant the earth once the leftover radiation and other effects of our cataclysmic event had disipated. Good movie, search it out.
Cheers!
Doug