I don't think it's likely, but climate change could easily wipe out humanity by exacerbating pre-existing geopolitical tensions. For instance, Pakistan and India famously share a river, and the treaty that governs its water rights was written with the assumption that the river wouldn't reduce in output. A sufficiently severe drought could cause a war between India and Pakistan, and both countries have nukes.
You could dispute that WW3 would cause human extinction, and while I'm not remotely certain of it I think that WW3 could cause extinction, if there's a sufficient combination of 1) climate collapse and 2) worldwide economic collapse that makes high-tech systems impossible to sustain.
